ALBERT

Description: The past decade has shown a marked increase in the use of high-throughput assays in clinical research into human cancer, including acute myeloid leukemia (AML). In particular, genome-wide gene expression profiling (GEP) using DNA microarrays has been extensively used for improved understanding of the diagnosis, prognosis, and pathobiology of this heterogeneous disease. This review discusses the progress that has been made, places the technologic limitations in perspective, and highlights promising future avenues

Description: Abstract 1689 Poster Board I-715 Introduction The use of the proteasome inhibitor bortezomib has demonstrated activity in multiple myeloma and lymphomas. The HDAC inhibitor romidepsin is being evaluated in CTCL and PTCL, though its activity in B-cell lymphomas is less clear. We hypothesized that the combination of bortezomib and romidepsin would result in synergistic apoptosis in different B-cell NHL cell lines based upon the observed activity of this combination in more mature B-cell malignancies such as myeloma. Experimental Design Daudi, HT, Ramos and SUDHL-4 cell lines were exposed to different concentrations of bortezomib and romidepsin, separately, concurrently, and sequentially. Cell viability was assessed using MTT-assay, induced apoptosis was evaluated using Annexin V and PI staining from 24-48 hours. Apoptosis was also evaluated using western blot analysis of caspases and PARP cleavage. LC3 and HDAC6 level expressions were performed to determine if the effect of the combination was a result of the aggresome or autophagy pathway. Cell cycle studies were also performed to study if there were any changes after treating cells with the combination. Results The combination of bortezomib and romidepsin resulted in synergistic B-cell apoptosis as measured by MTT-assay with combination indices of 〈 0.5. This was associated with increased caspases and PARP cleavage as early as 24 hours after exposure. Order of addition experiments demonstrated definite sequence specificity. When romidepsin was added first, and 6 hours later followed by bortezomib, apoptosis was enhanced, compared to both agents being given concurrently or when bortezomib was administered first. Cell cycle analysis studies demonstrated that pretreatment of cells with romidepsin for 6 hours followed by the addition of bortezomib arrested the cells in G2M phase. HDAC6 expression was significantly reduced following combination therapy, and LC3-I was cleaved to LC3-II in treated cells suggesting that the combination affected aggresome formation and autophagy. Conclusion The combination of romidepsin and bortezomib at low nanomolar concentrations suggests that this may be an important clinical combination to test in patients with relapsed or refractory B-cell malignancies. Sequence of administration data is currently being tested to determine if the effect is a result of autophagy inhibition as is seen in myeloma cell lines. Additional mechanistic studies will be presented with the goals of identifying predictors of response that can then be validated in prospective clinical trials. Disclosures Lechowicz: Gloucester: Consultancy. Kaufman:Millennium: Consultancy; Genzyme: Consultancy; Celgene: Consultancy; Merck: Research Funding; Celgene: Research Funding. Lonial:Gloucester: Research Funding; Novartis: Consultancy; BMS: Consultancy; Millennium: Consultancy, Research Funding; Celgene: Consultancy. Flowers:Millennium: Research Funding.

Description: Abstract 3701 Poster Board III-637 Background Romidepsin is an anti-neoplastic agent that has been identified as a novel pan-HDAC inhibitor with single-agent activity in T-cell lymphoma. In a combined analysis of 167 patients (pts) with cutaneous T-cell lymphoma (CTCL) from 2 clinical studies (GPI and NCI studies), the overall response rate was 35%, including 10 pts with a complete clinical response (CCR). Median duration of response was 13.8 months and 42% of pts with advanced disease (stage ≥IIB) responded [Demierre et al. J Clin Oncol 27:15s, 2009 (suppl; abstr 8546)]. The most common hematologic abnormalities in these pts included anemia (41%), thrombocytopenia (34%), neutropenia (27%), and lymphopenia (26%). Most hematologic toxicities were Grade 1 or 2, although 'Grade 3 events were observed. These events were reversible and a small portion of the patients discontinued the study drug because of these events (2%). This report details an analysis of platelet counts in pts receiving romidepsin and an investigation into the mechanism of thrombocytopenia in nonclinical studies. Methods Pts with CTCL who received ≥1 prior systemic therapy failure and had an ECOG PS of 0-2 were enrolled in 2 single-arm, open-label, multicenter and international clinical studies. Treatment with QTc prolonging therapies or CYP34A inhibitors was prohibited and pts with significant cardiovascular abnormalities were excluded. Romidepsin at 14 mg/m2 was administered as a 4-hr IV infusion on days 1, 8, and 15 of a 28 day cycle. Nonclinical studies were conducted in mice to investigate the mechanism of romidepsin effects on platelets. Romidepsin was administered to female BALB/c mice at doses of 1 or 4 mg/kg by tail-vein injection on days 1, 5 and 9. Blood samples were collected every 2 days from alternating groups of mice to minimize effects of bleeding on platelet counts. Results In clinical studies, there is a mean decrease in platelet counts during the treatment period of each cycle, and a return to baseline levels or above between cycles observed in both clinical studies as described in the table below. No clinically meaningful change has been observed in the central tendency over 4 cycles of treatment in both studies. In the mouse studies, dose-dependent effects were seen on both WBC and platelet counts. Day 2 WBC counts dropped to 45% and 10% of normal at the 1 and 4 mg/kg doses, respectively. WBC counts remained low until after the dosing period in the 1 mg/kg romidepsin group, but recovered more quickly in the 4 mg/kg group. Day 2 platelet counts were 70% of normal at the 1 mg/kg dose and remained near this level until day 10, followed by recovery to normal at day 15. At the 4 mg/kg dose, profound thrombycytopenia was induced, with platelet counts only 20% of normal on days 4-6. Platelet counts slowly recovered to 70% of normal by day 15. Plasma thrombopoietin levels were normal throughout the experiment for the 1 mg/kg group, and showed a large increase to 275% of normal on day 6 in the 4 mg/kg group, which is the expected response to thrombocytopenia as a signal to increase platelet production and indicates that platelet reduction is not attributable to defective TPO production. Bone marrow megakaryocyte populations are being examined to determine the effects of romidepsin on these platelet-producing cells. Conclusions Following romidepsin administration, a saw tooth pattern is observed in the reduction and recovery of platelets. Recovery of platelets appears to occur more rapidly in humans than in mice; however, the effects are reversible after dosing in clinical studies and in murine models. In the clinical data the recovery pattern suggests that the transient effects are direct and are not effects on bone marrow. Disclosures: Whittaker: Gloucester Pharmaceuticals: Research Funding. Prince:Gloucester Pharmaceuticals: Consultancy. Demierre:Gloucester Pharmaceuticals: Consultancy, Honoraria. Lonial:Gloucester Pharmaceuticals: Honoraria. Kim:Gloucester Pharmaceuticals: Consultancy, Honoraria. Nichols:Gloucester Pharmaceuticals: Employment, Equity Ownership. Nix:Gloucester Pharmaceuticals: Employment.

Description: Precursor T-cell acute lymphoblastic leukemia (T-ALL) in children represents a clinical challenge, because relapses are usually fatal. It is thus necessary to identify high-risk patients as early as possible to effectively individualize treatment. We aimed to define novel molecular risk markers in T-ALL and performed array-based comparative genomic hybridization (array-CGH) and expression analyses in 73 patients. We show that DNA copy-number changes are common in T-ALL and affect 70 of 73 (96%) patients. Notably, genomic imbalances predicted to down-regulate the TGF-β or up-regulate the PI3K-AKT pathways are identified in 25 of 73 (34%) and 21 of 73 (29%) patients, suggesting that these pathways play key roles in T-ALL leukemogenesis. Furthermore, we identified a deletion at 6q15-16.1 in 9 of 73 (12%) of the patients, which predicts poor early treatment response. This deletion includes the CASP8AP2 gene, whose expression is shown to be down-regulated. The interaction of CASP8AP2 with CASP8 plays a crucial role in apoptotic regulation, suggesting a functional link between the clinical effect of the deletion and the molecular mode of action. The data presented here implicate the TGF-β and PI3K-AKT pathways in T-ALL leukemogenesis and identify a subgroup of patients with CASP8AP2 deletions and poor early treatment response.

Description: Abstract 1955 Poster Board I-978 The detection of chromosome abnormalities in mature B-cell neoplasms by conventional cytogenetics remains difficult, mainly due to the low proliferative rate of mature lymphoid cells. The current FISH panel for chronic lymphocytic leukemia (CLL) is designed to detect some of the more common abnormalities of prognostic significance in CLL [i.e., del(6q), del(11q), +12, del(13q), del(17p)]. This CLL FISH panel has improved the detection rate of these markers by making it possible to obtain cytogenetic information from interphase cells; however, as it is limited to only these 5 markers, it cannot detect all abnormalities associated with CLL. More importantly, the impact of other chromosome abnormalities on prognosis and disease progression, with and without the presence of these 5 prognostic markers, is not known. CpG-oligodeoxynucleotides (ODNs) such as DSP30 activate cells of the immune system in a sequence-dependent manner and promote proliferation of CLL cells in vitro [Decker et al. Blood 2000;95:999-1006]. They also upregulate costimulatory molecules and potential target antigens during immunotherapy. The use of DSP30 in combination with interleukin 2 (IL2) has proven effective in increasing the detection of chromosome abnormalities in CLL [Dicker et al. Blood 2006;108:3152-60] and other mature B-cell lymphoid malignancies by conventional cytogenetics [Struski et al. Leukemia 2009;23:617-9], when compared to the well-established B-cell mitogens. In our extensive clinical experience of incorporating DSP30/IL2 into our culture media, this cocktail has significantly increased the detection of chromosome abnormalities in CLL by conventional cytogenetics, from 55% to greater than 80%. We thus decided to investigate if various other lymphoid malignancies would respond to the mitogen activity of DSP30/IL2 as well as or better than CLL. Specifically, we evaluated 812 cases of mature B-cell lymphoid malignancies that were abnormal by flow cytometry, morphology, or cytogenetic analysis. All samples (bone marrow or blood) were cultured for approximately 72 hours using the DSP30/IL2 mitogen cocktail. Of these 812 cases, 746 (91%) provided sufficient mitotic index and quality for a complete cytogenetic analysis and interpretation. Of the CLL cases (n=509), 79 were initially interpreted as normal by conventional cytogenetic analysis, but were later interpreted as abnormal by FISH for deletion 13q only. In view of the known cryptic nature of this deletion in CLL, these cases were not included in the study, leaving a total of 430 CLL cases, and thus bringing the total number of cytogenetically successful study cases to 667. In addition to the 430 CLL cases, there were 14 variant CLLs; 36 diffuse large B-cell lymphomas (DLBCLs); 35 follicular lymphomas; 34 non-Hodgkin lymphomas (not further specified); 29 marginal zone B-cell lymphomas of splenic type (sMZBCL); 27 mantle cell lymphomas (MCLs), of which 8 were blastoid; 16 MZBCL of MALT type; 13 hairy cell leukemias (HCLs); 12 lymphoproliferative disorders (not further specified); 10 lymphoplasmacytic lymphomas (LPLs); 6 Burkitt lymphomas; 3 Hodgkin lymphomas; and 2 B-cell prolymphocytic leukemias (PLLs). Of particular interest is the fact that we detected clonal abnormalities in 100% of HCLs, blastoid MCLs, variant CLLs, and B-cell PLL, as well as in 97% of sMZBCLs, 89% of DLBCLs, and 80% of LPLs This is of great importance since HCLs and LPLs are rarely abnormal by conventional cytogenetics using the more traditional combinations of mitogens making it difficult to identify markers of prognostic significance. In conclusion, our findings demonstrate that the DSP30/IL2 cocktail induces proliferation of various B-cell mature lymphoid disorders and that its mitogenic action is not limited to CLL. We are continuing to develop our understanding of the considerable response of specific lymphoid malignancies to the DSP30/IL2 cocktail by correlating additional clinical data, and hope that the end result will open new avenues in regards to prognostic outcome and therapeutic approaches. Disclosures: No relevant conflicts of interest to declare.

Description: Higher levels of procoagulant factors and factor XII deficiency may be risk factors for first venous thromboembolism (VTE). We studied associations of coagulation factors IX through XIII with risk of future VTE in 2 general population samples. Using a nested case-control study combining the 21 860 participants of the Atherosclerosis Risk in Communities study and the Cardiovascular Health Study, we determined antigenic levels of these coagulation factors in primarily pre-event blood samples from 462 participants who subsequently developed VTE and 1047 participants who remained free of VTE. Only elevated levels of factors IX and XI were associated with increased risk of VTE after adjustment for age, sex, race, and study. For factor IX, the odds ratio (OR) was 1.4 (95% confidence interval [CI], 1.0-2.0) comparing the top to bottom quintile. The OR for factor XI was higher: 2.0 (95% CI, 1.4-2.9). With further adjustment for body mass index and diabetes, only elevated factor XI remained associated with VTE risk: OR 1.8 (95% CI, 1.3-2.7). Associations were similar by study and whether the thrombosis was idiopathic or secondary. Factor XII deficiency was not related to VTE risk. Among these procoagulant factors, only elevated factor XI was a risk factor for VTE.

Description: The concept of endothelial progenitor cells (EPCs) has attracted considerable interest in cardiovascular research, but despite a decade of research there are still no specific markers for EPCs and results from clinical trials remain controversial. Using liquid chromatography–tandem mass spectrometry, we analyzed the protein composition of microparticles (MPs) originating from the cell surface of EPC cultures. Our data revealed that the conventional methods for isolating mononuclear cells lead to a contamination with platelet proteins. Notably, platelets readily disintegrate into platelet MPs. These platelet MPs are taken up by the mononuclear cell population, which acquires “endothelial” characteristics (CD31, von Willebrand factor [VWF], lectin-binding), and angiogenic properties. In a large population-based study (n = 526), platelets emerged as a positive predictor for the number of colony-forming units and early outgrowth EPCs. Our study provides the first evidence that the cell type consistent with current definitions of an EPC phenotype may arise from an uptake of platelet MPs by mononuclear cells resulting in a gross misinterpretation of their cellular progeny. These findings demonstrate the advantage of using an unbiased proteomic approach to assess cellular phenotypes and advise caution in attributing the benefits in clinical trials using unselected bone marrow mononuclear cells (BMCs) to stem cell-mediated repair.

Description: Abstract 18 Introduction: Long-term survival in pediatric relapsed AML is only 20-30%. Optimal reinduction therapy is unknown, and there is a concern about cardiotoxicity with repeated anthracycline use at relapse. Preclinical in vitro and animal studies, and limited clinical data suggest that liposomal daunorubicin (DaunoXome®, DNX) is less cardiotoxic. These considerations lead to a phase III study, in the setting of the International BFM Study Group. Materials and methods: FLAG was randomised against FLAG/DNX in the 1st reinduction course. The conventional 5-days FLAG only was recommended as the 2nd course. DNX was dosed at 60 mg/m2/day on days 1, 3 and 5. After induction, allogeneic stem cell transplantation was generally recommended, but time-to-transplant could be bridged by high- or low-intensive consolidation therapy. Primary endpoint of the study was early treatment response, based on bone marrow examination shortly before reinduction course 2, and defined as either good (≤20% leukemic blasts) or poor (〉20% leukemic blasts). This endpoint was chosen because of its prognostic value in earlier relapsed AML BFM-trials, and because compliance with an extended protocol guideline was likely to be suboptimal within the context of a highly multinational and multicenter AML Relapse protocol. However, secondary endpoints were defined, including the CR2 rate determined after 2 courses, long-term survival, and toxicity. Patients with AML M3 and those 〉18 years of age at initial diagnosis were ineligible. The study opened in most countries in 2002/2003. The study closed for accrual on April 1, 2009 when the required 360 fully eligible and evaluable patients had been randomized. Early and late relapsed AML was defined as a relapse within or after 1 year from initial diagnosis, but this only influenced treatment in that early relapsed AML patients were eligible for haploidentical SCT, while late relapsed AML patients were eligible for autologous SCT, if a matched or partly mismatched transplant was not possible. Thirteen groups from 20 countries and 〉100 centers have enrolled patients, with informed consent and after approval of the study by regulatory authorities. Data are presented according to intention-to-treat, with a median follow-up of 2.7 years for patients at risk. Results: Overall 4-year probability of survival (pOS) was 35% SE 2%, the overall CR2 rate 62%. The good early responders had a 4-year pOS of 45% SE 3% versus 10% SE 3% for poor responders (p

Description: Abstract 634 FLT3, a transmembrane receptor tyrosine kinase constitutively activated via mutation in blasts of patients (pts) with AML, is an important therapeutic target. Blasts from approximately 25% of pts have a length or internal tandem duplication (ITD) mutation in the juxtamembrane region or tyrosine kinase domain (TKD1) of FLT3, which is associated with reduced disease-free survival and overall survival (OS), particularly in pts with normal cytogenetics. Blasts from 5–10% of pts have a point mutation (typically D835Y) in the tyrosine kinase domain (TKD); the effect of this mutation on prognosis is uncertain. Midostaurin (PKC412) is a multi-targeted kinase inhibitor with demonstrated clinical activity in FLT3-mutant (FLT3–mut) and FLT3-wild-type (FLT3–wt) AML (peripheral blood blast reduction in 70% and 30% of pts, respectively) but rarely produces complete remissions). Preclinical studies demonstrated synergy between FLT3 inhibitors and chemotherapy. We conducted a Phase 1b trial to investigate the feasibility of administering daunorubicin (60 mg/m2 IV, days 1–3) and cytarabine (100 mg/m2 IVCI, days 1–7) induction and high-dose cytarabine post-remission therapy (3 gm/m2 over 3h every 12h, days 1, 3, and 5 for 3 cycles) plus oral midostaurin at 100 mg or 50 mg each twice daily on days 8–21 (sequentially) or days 1–7, 15–21 (concomitantly) with all chemo cycles in newly diagnosed pts under age 61 with de novo AML. Whereas 100 mg of midostaurin plus induction chemotherapy was poorly tolerated due to nausea and vomiting, the 40 pts who received 50 mg of midostaurin orally twice daily ( 20 each on the sequential and concomitant schedules; 27 FLT3–wt; 13 FLT3–mut [9 with an ITD]), tolerated the combination well. Median midostaurin exposure was 133 days (range 21–975) for the FLT3–mut pts and 90 days (range 7–1016) for FLT3–wt pts. Maintenance therapy with midostaurin was allowed with investigator discretion and was received by 5 pts (3 FLT3–mut, 2 FLT–wt). The median ages for the FLT3–wt and FLT3–mut pts were 50 years (range 25–60) and 46 years (range 20–65), respectively. 77% of the FLT3–mut pts displayed normal, 15% adverse and 8% other intermediate cytogenetics compared with 18.5%, 26%, and 26%, respectively, for FLT3-wt (also 18.5% favorable; 11% unknown). Complete response occurred in 32/40 (80%) of all pts (20/27 [74%] of FLT3–wt patients, 12/13 [92%] of FLT3–mut pts). Patients were censored at the last date they were known to be alive with a median post treatment follow-up for FLT3-mut pts of 1059 days and 1086 days for FLT3-wt. Even accounting for their differing cytogenetics and ages, the OS of the FLT3–mut subgroup was expected to be inferior to that of the FLT3–wt subgroup. However, we report that the 1 and 2 year OS for the pts with FLT3–mut AML was 85% and 62%, respectively, and was comparable to that of the FLT3–wt subgroup (81% and 59%, respectively). Although based on small numbers and not stratified for type of FLT3 mutation (TKD, ITD, ITD length, location, or allelic ratio), these long-term results suggest that combination therapy with a FLT3 inhibitor and chemotherapy might be effective enough to obviate the perceived need for allogeneic stem cell transplantation for FLT3–mut AML pts in first complete remission. Moreover, these data support the rationale for the ongoing international phase 3 study of induction, post-remission intensification, and maintenance with midostaurin (50 mg po bid) or placebo. Disclosures: Stone: Novartis: Research Funding, ad hoc consultancy; Cephalon: ad hoc consultancy. Off Label Use: midostaurin with chemothereapy for AML. Paquette:Novartis: Honoraria, Research Funding, Speakers Bureau. Schiller:Novartis: Research Funding, Speakers Bureau; Millenium: Research Funding, Speakers Bureau; Genzyme: Research Funding; Vion: Research Funding; Centocor: Research Funding; Eli Lilly: Research Funding; Celgene: Research Funding. Schiffer:Novartis: Consultancy, Research Funding; Genzyme: Consultancy. Ehninger:Novartis: Honoraria, Research Funding. Cortes:Novartis: Research Funding; Bristol-Myers Squibb: Research Funding; Wyeth: Research Funding. Kantarjian:Novartis: Research Funding. DeAngelo:Bristol-Myers Squibb: Speakers Bureau; Celgene: Speakers Bureau; Enzon: Speakers Bureau; Novartis: Speakers Bureau. Huntsman-Labed:Novartis: Employment, Equity Ownership. Dutreix:Novartis: Employment, Equity Ownership. Rai:Novartis: Employment, Equity Ownership. Giles:Novartis: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Research Funding; Vion: Research Funding.

Description: Abstract 2168 Poster Board II-145 The deregulated tyrosine kinase associated with t(9;22) fusion protein BCR-ABL is efficiently targeted by tyrosine kinase inhibitors (Imatinib, Nilotinib and Dasatinib). It is generally believed that most patients have residual disease. The inability to eliminate the refractory leukemia stem cell in chronic myeloid leukemia (CML) is not well understood. The refractory stem cell is present despite effective inhibition of the BCR-ABL kinase in these cells, and dissociation between kinase inhibition and cell death implies lack of dependency on BCR-ABL aberrant kinase activity, unlike the one seen in more mature CML cells. Thus the oncogene addictive dependency of these leukemia stem cells may be overcome by intrinsic and/or extrinsic factors/pathways. One such pathway involved in hematopoeitic stem cell maintenance is the Wnt/β-catenin signaling pathway. BCR-ABL signaling is known to directly activate the Wnt/β-catenin pathway. The loss of function of a negative regulator of the Wnt/β-catenin pathway, known as GSK3β is associated with CML progression from chronic phase to the blast phase. Lastly, the loss of β-catenin in murine models impairs the self renewal capacity of both the normal and the BCR-ABL+ leukemia stem cell. Thus this pathway is important during various stages of the disease. We explored the effect of Wnt inhibition using a novel Wnt pathway inhibitor (AG-214, University of Michigan). AG-214 is structurally related to a previously reported Wnt-inhibitor. AG-214 is able to antagonize β-catenin/TCF in luciferase reporter assays, and expression of Wnt targets in colon cancer cell lines. We utilized a serum free culture system with 5 added cytokines and treated both CML blast crisis CD34+ as well as chronic phase CD34+ cells with AG-214. Our in vitro experiments show that primary blast crisis CD34+ cells are induced to undergo apoptosis at an IC-50 of approximately 2 μM. Furthermore, combination of 1.25 μM of AG-214 with 2 μM Imatinib achieved greater than 50% apoptosis. Analysis of chronic phase CML CD34+ cells showed that targeting of Wnt/β-catenin pathway requires higher concentration of the Wnt-inhibitor (〉2.5 μM), and that the addition of Imatinib can cooperate to enhance the apoptotic response. Furthermore, chronic phase progenitors (Lin-CD38+/CD34+) are more sensitive to lower concentrations of AG-214 whereas 5 μM is required to induce significant apoptosis of ∼70% in the primitive leukemia stem cell (Lin-/CD38-/CD34+) population, and addition of 2 μM Imatinib increased their apoptotic response to ∼84%. Normal CD34+ cells do not undergo significant apoptosis with 5 μM of AG-214 (∼10%) even when combined with 2 μM Imatinib (∼20%). Targeting of the Wnt/β-catenin pathway enhances apoptosis in both blast crisis and chronic phase CML progenitors and leukemia stem cells. Disclosures: No relevant conflicts of interest to declare.

Description: Although well characterized in the mouse, the role of Notch signaling in the human T-cell receptor αβ (TCR-αβ) versus TCR-γδ lineage decision is still unclear. Although it is clear in the mouse that TCR-γδ development is less Notch dependent compared with TCR-αβ differentiation, retroviral overexpression studies in human have suggested an opposing role for Notch during human T-cell development. Using the OP9-coculture system, we demonstrate that changes in Notch activation are differentially required during human T-cell development. High Notch activation promotes the generation of T-lineage precursors and γδ T cells but inhibits differentiation toward the αβ lineage. Reducing the amount of Notch activation rescues αβ-lineage differentiation, also at the single-cell level. Gene expression analysis suggests that this is mediated by differential sensitivities of Notch target genes in response to changes in Notch activation. High Notch activity increases DTX1, NRARP, and RUNX3 expression, genes that are down-regulated during αβ-lineage differentiation. Furthermore, increased interleukin-7 levels cannot compensate for the Notch dependent TCR-γδ development. Our results reveal stage-dependent molecular changes in Notch signaling that are critical for normal human T-cell development and reveal fundamental molecular differences between mouse and human.

Description: During surface-initiated blood coagulation in vitro, activated factor XII (fXIIa) converts factor XI (fXI) to fXIa. Whereas fXI deficiency is associated with a hemorrhagic disorder, factor XII deficiency is not, suggesting that fXI can be activated by other mechanisms in vivo. Thrombin activates fXI, and several studies suggest that fXI promotes coagulation independent of fXII. However, a recent study failed to find evidence for fXII-independent activation of fXI in plasma. Using plasma in which fXII is either inhibited or absent, we show that fXI contributes to plasma thrombin generation when coagulation is initiated with low concentrations of tissue factor, factor Xa, or α-thrombin. The results could not be accounted for by fXIa contamination of the plasma systems. Replacing fXI with recombinant fXI that activates factor IX poorly, or fXI that is activated poorly by thrombin, reduced thrombin generation. An antibody that blocks fXIa activation of factor IX reduced thrombin generation; however, an antibody that specifically interferes with fXI activation by fXIIa did not. The results support a model in which fXI is activated by thrombin or another protease generated early in coagulation, with the resulting fXIa contributing to sustained thrombin generation through activation of factor IX.

Description: The ability of CD8+ T cells to engage a diverse range of peptide–major histocompatibility complex (MHC) complexes can also lead to cross-recognition of self and nonself peptide-MHC complexes and thus directly contribute toward allograft rejection or autoimmunity. Here we present a novel form of cross-recognition by herpes virus–specific CD8+ cytotoxic T cells that challenges the current paradigm of self/non-self recognition. Functional characterization of a human leukocyte antigen (HLA) Cw*0602-restricted cytomegalovirus-specific CD8+ T-cell response revealed an unusual dual specificity toward a pp65 epitope and the alloantigen HLA DR4. This cross-recognition of HLA DR4 alloantigen was critically dependent on the coexpression of HLA DM and was preferentially directed toward the B-cell lineage. Furthermore, allostimulation of peripheral blood lymphocytes with HLA DRB*0401-expressing cells rapidly expanded CD8+ T cells, which recognized the pp65 epitope in the context of HLA Cw*0602. T-cell repertoire analysis revealed 2 dominant populations expressing T-cell receptor beta variable (TRBV)4-3 or TRBV13, with cross-reactivity exclusively mediated by the TRBV13+ clonotypes. More importantly, cross-reactive TRBV13+ clonotypes displayed markedly lower T-cell receptor binding affinity and a distinct pattern of peptide recognition, presumably mimicking a structure presented on the HLA DR4 allotype. These results illustrate a novel mechanism whereby virus-specific CD8+ T cells can cross-recognize HLA class II molecules and may contribute toward allograft rejection and/or autoimmunity.

Description: Recent studies suggested that JAK2V617F mutation is frequent in patients with splanchnic vein thrombosis (SVT) but not in patients with other venous thromboembolic events (VTE). However, whether screening for the JAK2V617F mutation in VTE patients is justified remains unclear. Therefore, we performed a systematic review to assess the frequency of JAK2 mutation in VTE patients and the role of JAK2V617F mutation in the diagnosis of myeloproliferative neoplasms. MEDLINE and EMBASE databases were searched. Two reviewers independently performed study selection and extracted study characteristics. Pooled odds ratios of case-control studies and weighted mean proportion of the prevalence of JAK2V617F mutation of uncontrolled series were calculated. Twenty-four studies involving 3123 patients were included. Mean prevalence of JAK2 mutation was 32.7% (95% confidence interval, 25.5%-35.9%) in SVT patients. JAK2 mutation was associated with increased risk of SVT (odds ratio, 53.98; 95% confidence interval, 13.10-222.45). Mean prevalence of JAK2 mutation in other VTE patients was low (range, 0.88%-2.57%). Presence of JAK2V617F mutation in SVT patients was associated with a subsequent diagnosis of myeloproliferative neoplasm in many patients. JAK2 mutation is strongly associated with SVT, and routine screening of JAK2 mutation appears to be indicated in these patients.

Description: Abstract 3441 Poster Board III-329 Background CLL is characterized by the progressive accumulation of monoclonal B lymphocytes. One theory to explain how CLL cells avoid elimination through immune surveillance mechanisms is through a defect in the ability of T-cells to form immunological synapses with antigen-presenting tumor B-cells (Ramsay et al JCI 2008). Lenalidomide is an immunomodulatory agent with clinical activity in the treatment of B-cell malignancies. Recent laboratory studies showed that lenalidomide not only stimulates T- and natural killer (NK)-cell-mediated ADCC, it also restores the T-cell-mediated ability to form immunological synapses with CLL tumor cells. Since NK cells also exert cytotoxicity through immune synapse formation, here we explore how lenalidomide affects NK-cell-mediated cytotoxicity mechanisms and whether this activity is altered in the presence of rituximab since published studies showed that lenalidomide-pretreated B-cells have a down-regulated surface CD20 expression. Further, we investigated the molecular events associated with immune synapse formation and the effect of lenalidomide. Methods Immune synapse formation was assessed in NK cells (from healthy donors PBMCs) co-cultured with either B-CLL cells derived from pts or with K562 cells (positive control). Cells were fixed and the ability to form synapses was assessed via immunohistochemisty co-staining for either F-actin and CD2, or F-actin and perforin (a cytolytic protein found in NK cells). Synapse formation was visualized by microscopy and measured via relative mean fluorescent intensity. Activity of RhoA, Rac1, Cdc42 were measured using Rho GTPases assay kits. Inhibition of lenalidomide-mediated immune synapse activity was assayed using the cell permeable Rho inhibitor C3 (0.5 mM). Flow cytometry was used to measure changes in surface CD20 and CD54 (ICAM-1) expression in B-CLL samples from 3 pts after treatment with lenalidomide. Results Lenalidomide induced the formation of immunological synapses between NK cells and primary B-CLL cells (p

Description: The antiphospholipid syndrome (APS) is an acquired thrombophilia, characterized by the occurrence of venous and arterial events. This article examines the laboratory and key clinical aspects of APS. Particular focus is given to anti–beta 2-glycoprotein I (β2GPI) antibodies in view of their recent inclusion in the APS classification criteria. The clinical utility of using the β2GPI enzyme-linked immunosorbent assay, in conjunction with the established lupus anticoagulant assays and cardiolipin enzyme-linked immunosorbent assay, for diagnosing and risk stratifying patients suspected of having APS is discussed. The relative importance of the various assays in diagnosing obstetric APS (early and late gestation miscarriages) is explored. The implications of recent epidemiologic findings for possibly understanding the underlying pathophysiologic mechanisms of obstetric APS are highlighted. Insights into which patients with obstetric APS may be at most risk of thrombotic complications are presented.

Description: To study B-cell development from bone marrow (BM), we generated recombination-activating gene 1 (Rag1)–targeted mice lacking mature lymphocytes. B-cell development can be induced in such mice by B cell–specific restoration of a functional Rag1 transcription unit. Follicular and marginal zone B cells populated the spleen when Rag1 expression was permitted. Notably, the peritoneal cavity was dominated by bona fide B-1a cells, as judged by surface markers and functional properties. These BM-derived B-1a cells exhibited a polyclonal VDJ repertoire with substantial N nucleotide insertions. Nevertheless, physiologic frequencies of phosphatidylcholine-specific B cells were detected. Importantly, the BM of young and 5-month-old mice was indistinguishable with regard to the potential to generate B-1a cells.

Description: Historically, graft-versus-host disease (GVHD) beyond 100 days after hematopoietic cell transplantation (HCT) was called chronic GVHD, even if the clinical manifestations were indistinguishable from acute GVHD. In 2005, the National Institutes of Health (NIH) sponsored a consensus conference that proposed new criteria for diagnosis and classification of chronic GVHD for clinical trials. According to the consensus criteria, clinical manifestations rather than time after transplantation should be used in clinical trials to distinguish chronic GVHD from late acute GVHD, which includes persistent, recurrent, or late-onset acute GVHD. We evaluated major outcomes according to the presence or absence of NIH criteria for chronic GVHD in a retrospective study of 740 patients diagnosed with historically defined chronic GVHD after allogeneic HCT between 1994 and 2000. The presence or absence of NIH criteria for chronic GVHD showed no statistically significant association with survival, risks of nonrelapse mortality or recurrent malignancy, or duration of systemic treatment. Antecedent late acute GVHD was associated with an increased risk of nonrelapse mortality and prolonged treatment among patients with NIH chronic GVHD. Our results support the consensus recommendation that, with appropriate stratification, clinical trials can include patients with late acute GVHD as well as those with NIH chronic GVHD.

Description: Chronic immune activation is a major cause for progressive immunodeficiency in human immunodeficiency virus type-1 (HIV) infection. The underlying trigger, however, remains largely unknown. HIV single-stranded RNA is a potent immune activator by triggering Toll-like receptor (TLR) 7/8. Thus, we hypothesized that sustained TLR7 triggering induces chronic immune activation and thereby contributes to progressive immunodeficiency. We used the synthetic compound R848 or a mixture of uridine-rich HIV single-stranded (ss) RNA oligonucleotides—both are potent TLR7/8 agonists—to explore the effects of sustained TLR7 triggering on the murine lymphoid system. Sustained TLR7 triggering induced an immunopathology reminiscent of progressive lymphoid destruction in HIV disease; we observed lymphopenia, elevated proinflammatory cytokines, splenomegaly, contracted lymphoid subsets, and lymphoid microarchitecture alteration with reduced marginal zone B-lymphocytes. Upon exposure to inactivated vesiculo-stomatitis virus, antibody production was abolished, although splenic lymphocytes were activated and total IgG was elevated. Our data imply that HIV itself may directly contribute to immune activation and dysfunction by stimulating TLR7. Thus, manipulation of TLR7 signaling may be a potential strategy to reduce chronic hyper-immune activation and, thereby, disease progression in HIV infection.

Description: Polymorphisms in folate pathway genes may influence the susceptibility to acute lymphoblastic leukemia (ALL). DNA was isolated from 245 pediatric ALL patients (cases) and from 500 blood bank donors (controls). Polymorphisms in methylene-tetrahydrofolate reductase (MTHFR 677C〉T, 1298A〉C), methionine synthase (MTR 2756A〉G), methionine synthase reductase (MTRR 66A〉G), methylenetetrahydrofolate dehydrogenase (MTHFD1 1958G〉A), nicotinamide N-methyltransferase (NNMT IVS −151C〉T), serine hydroxymethyl transferase (SHMT1 1420C〉T), thymidylate synthase (TS 2R3R), and the reduced folate carrier (RFC1 80G〉A) were detected. In ALL patients, an increased occurrence was observed of the RFC1 80AA variant (odds ratio [OR] = 2.1; 95% confidence interval [CI] = 1.3-3.2; P = .002) and the RFC1 80A allele (OR = 1.5; 95% CI, 1.1-2.1; P = .02). Likewise, the NNMT IVS −151TT genotype showed a 2.2-fold increased ALL risk (OR = 2.2; 95% CI, 1.1-4.6; P = .04). A 1.4-fold reduction in ALL risk was observed for (heterozygous or homozygous) carriers of the TS 2R allele and the MTHFR 677T allele (OR = 0.7; 95% CI, 0.5-1.0; P 〈 .05). Furthermore, interactions between NNMT and MTHFR 677C〉T and RFC1 were observed. NNMT IVS −151CC/MTHFR 677CT + TT patients exhibited a 2-fold reduction in ALL risk whereas RFC1 80AA/NNMT IVS −151CT + TT subjects had a 4.2-fold increase in ALL risk (P = .001). For the first time, we associate the RFC1 80G〉A and NNMT IVS −151C〉T variants to an increased ALL susceptibility.

Description: Abstract 4311 Objectives Oral mucositis is a common complication of high-dose chemotherapy and radiotherapy followed by hematopoietic stem-cell support (HSCT). We evaluated the efficacy and safety of calcium phosphate mouth rinse (Caphosol) for prevention and reduction of severity and duration of oral mucositis in patients treated with HSCT. Methods In 2009 23 patients were treated. Three received allogeneic stem cells (ALLO): 2- Hodgkin disease (HD), 1-myeloma multiplex (MM) and twenty autologous transplantation (AUTO): 8-non-Hodgkin lymphomas (NHL); 7- HD; 3-MM. For ALLO conditioning regimens were composed of: fludarabine 150mg/m 2 and melphalan 140mg/m 2. AUTO were treated with: BEAM: carmustine, etoposide, cytarabine and melphalan (HD and NHL) and melphalan 200mg/m 2 (MM). The source of hematopoietic stem cells was peripheral blood. Caphosol was prepared according to the manufacturer‘s instructions and administered 4 times daily, starting from the day before the beginning of chemotherapy till the end of hospitalization. Control group was composed of patients, who had been treated with HSCT previously, before “palifermin and caphosol era”. The groups were comparable according to number of patients, their age, type of disease, transplant and conditioning regimen. Oral mucositis was assessed with the use of the five-grade World Health Organization (WHO) oral-toxicity scale. Oral mucositis was evaluated daily after the beginning of transplantation procedure until discharge from the BMT Unit. The number of days with painkillers or antibiotics were estimated. Total parenteral nutrition was given according to the standards [Martin-Salces M, De Paz R, Canales MA et al (2008) Nutritional recommendations in hematopoietic stem cell transplantation. Nutrition 24: 769-775]. Treatment with antibiotics was started when neutropenic fever occurred. Safety was assessed on the basis of the incidence of adverse events. Statistical analysis was performed using Wilcoxon‘ test for analysis of differences between groups. Results Oral mucositis grade 2-4 was not observed. In patients treated with calcium phosphate mouth rinse oral mucositis grade 2-4 was not observed. Nobody had to receive opioid analgesics or total parenteral nutrition. 30% patients developed the first degree of oral mucositis 4-5 days' duration. In the control group OM was observed in all cases, 50% patients had III- IV degree. Median duration of OM was 10 and 12 days (range 5- 20) for auto- and allogeneic patients, respectively. As compared with control group, treatment with calcium phosphate mouth rinse was associated with significant reduction of the incidence of oral mucositis in II- IV degrees (0 percent versus 50 percent, p 〈 0.001), duration of oral mucositis (4/ 5 days vs. 10/12 days, p 〈 0.001), duration of pain-killers‘ treatment (0- 22 days vs. 0- 3 days, p 〈 0.001) and number of days with antibiotics‘ treatment (0- 7 days vs. 7- 20 days, p= 0.002). These differences were observed in both types of transplantation. No side effects of calcium/phosphate oral rinse were observed. Conclusion In comparison with control group, treatment with Caphosol was associated with the significant reduction of the incidence of oral mucositis in II- IV degrees, duration of oral mucositis, pain-killers‘ treatment and number of days with antibiotics‘ treatment. Calcium phosphate mouth rinse is a very promising medicine for prevention of oral mucositis for patients treated with high dose chemotherapy supported with hematopoietic stem cell transplantation. Disclosures: No relevant conflicts of interest to declare.

Description: Acute lymphoblastic leukemia (ALL) diagnosed in the first month of life (congenital ALL) is very rare. Although congenital ALL is often assumed to be fatal, no studies have been published on outcome except for case reports. The present study reports the outcome of 30 patients with congenital ALL treated with the uniform Interfant-99 protocol, a hybrid regimen combining ALL treatment with elements designed for treatment of acute myeloid leukemia. Congenital ALL was characterized by a higher white blood cell count and a strong trend for higher incidence of MLL rearrangements and CD10-negative B-lineage ALL compared with older infants. Induction failure rate was 13% and not significantly different from that in older infants (7%, P = .14), but relapse rate was significantly higher in congenital ALL patients (2-year cumulative incidence [SE] was 60.0 [9.3] vs 34.2 [2.3], P 〈 .001). Two-year event-free survival and survival of congenital ALL patients treated with this protocol was 20% (SE 9.1%). Early death in complete remission and treatment delays resulting from toxicity were not different. The survival of 17% after last follow-up, combined with a toxicity profile comparable with that in older infants, justifies treating congenital ALL with curative intent. This trial was registered at www.clinicaltrials.gov as no. NCT 00015873, and at www.controlled-trials.com as no. ISRCTN24251487.

Description: The role of hematopoietic cytokines in lineage commitment remains uncertain. To gain insight into the contribution of cytokine signaling to myeloid lineage specification, we compared granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF) signaling in Ba/F3 cells expressing both the G-CSF and M-CSF receptors and in lineage-negative murine marrow cells. G-CSF and M-CSF serve as prototypes for additional cytokines that also influence immature myeloid cells. G-CSF specifically activated signal transducer and activator of transcription 3 and induced Src homology region 2 domain-containing phosphatase 2 (SHP2) phosphorylation, whereas M-CSF preferentially activated phospholipase Cγ2, and thereby extracellular signal-regulated kinase (ERK), to stabilize c-Fos and stimulate CCAAT/enhancer-binding protein (C/EBP)α(S21) phosphorylation. In contrast, activation of Jun kinase or c-Jun was similar in response to either cytokine. Inhibition of ERK prevented induction of c-Fos by M-CSF and reduced C/EBPα phosphorylation and formation of colony-forming unit–monocytes. SHP2 inhibition reduced ERK activation in G-CSF, but not M-CSF, and reduced colony-forming unit–granulocytes, underscoring divergent pathways to ERK activation. Phorbol ester mimicked the effect of M-CSF, activating ERK independent of SHP2. In summary, M-CSF activates ERK more potently than G-CSF, and thereby induces higher levels of c-Fos and phospho-C/EBPα(S21), which may directly interact to favor monopoiesis, whereas G-CSF activates signal transducer and activator of transcription 3 and SHP2, potentially shifting the balance to granulopoiesis via gene induction by C/EBPα homodimers and via effects of SHP2 on regulators besides ERK.

Description: To investigate the cell of origin linking follicular (FL) and transformed (t-FL) lymphomas, we analyzed the somatic hypermutation (SHM) pattern of the variable region of the immunoglobulin heavy gene (IgH-VH) in 18 sequential FL/t-FL samples and a father (donor) and son (recipient), who developed FL and t-FL, after transplantation. Genealogic trees showed a pattern compatible with a common progenitor cell (CPC) origin in 13 cases. The identification of the t-FL clonotype in the previous FL sample and of the putative CPC sequence in both the FL/t-FL biopsies showed that the intraclonal diversity of FL and t-FL germinal centers (GCs) is more intricate than previously described, and all 3 clonotypes (CPC, FL, t-FL) may occur simultaneously within the same lymph node. On the basis of the father/son model, this CPC must be long-lived, providing a possible explanation for the incurable nature of this disease.

Description: Hematogenous metastasis is promoted by interactions of tumor cells with leukocytes, platelets, and the endothelium in the local intravascular microenvironment. Here we show that the activation of the microvascular endothelium results in recruitment of monocytes to metastatic tumor cells and promotes the establishment of the metastatic microenvironment. This inflammatory-like endothelial response was observed in microvascular endothelial cells only. Microarray analysis of microvascular endothelial cells cocultured with tumor cells in the presence of leukocytes and platelets revealed a specific gene expression profile. Selectin-mediated interactions of tumor cells with platelets and leukocytes activated endothelial cells and induced production of C-C chemokine ligand 5 (CCL5). Inhibition of CCL5-dependent monocyte recruitment during the early phase of metastasis by a CCL5 receptor antagonist strongly reduced tumor cell survival and attenuated metastasis. Collectively, these findings demonstrate that the endothelial expression of CCL5 contributes to the formation of a permissive metastatic microenvironment.

Description: Platelet response to activation varies widely between individuals but shows interindividual consistency and strong heritability. The genetic basis of this variation has not been properly explored. We therefore systematically measured the effect on function of sequence variation in 97 candidate genes in the collagen and adenosine-diphosphate (ADP) signaling pathways. Resequencing of the genes in 48 European DNA samples nearly doubled the number of known single nucleotide polymorphisms (SNPs) and informed the selection of 1327 SNPs for genotyping in 500 healthy Northern European subjects with known platelet responses to collagen-related peptide (CRP-XL) and ADP. This identified 17 novel associations with platelet function (P 〈 .005) accounting for approximately 46% of the variation in response. Further investigations with platelets of known genotype explored the mechanisms behind some of the associations. SNPs in PEAR1 associated with increased platelet response to CRP-XL and increased PEAR1 protein expression after platelet degranulation. The minor allele of a 3′ untranslated region (UTR) SNP (rs2769668) in VAV3 was associated with higher protein expression (P = .03) and increased P-selectin exposure after ADP activation (P = .004). Furthermore the minor allele of the intronic SNP rs17786144 in ITPR1 modified Ca2+ levels after activation with ADP (P 〈 .004). These data provide novel insights into key hubs within platelet signaling networks.

Description: Abstract 3453 Poster Board III-341 Introduction Increasing insight into the biology of CLL suggests a relevant interplay between tumor cells and the microenvironment. Preclinical data point to the potency of Lenalidomide to favourably modulate such interactions and remarkable clinical activity has been demonstrated in monotherapy trials in pretreated and also in previously untreated CLL patients. However, tumor flare and tumor lysis have been observed as problems and the optimal dose and schedule is still under investigation. In addition, the potential for interaction with effective standard treatment for CLL is unknown. We used a combination of Fludarabine and Rituximab as a backbone to establish a tolerable Lenalidomide dose in a dose escalation design. Study design The study treatment follows two phases: In the induction phase the maximal tolerated dose (MTD) of Lenalidomide in combination with FR should be determined. The protocol combines 6 cycles of Fludarabine (40mg/m2 po d1-3) and Rituximab (375mg/m2 iv day 4 on cycle 1 and 500mg/m2 iv day 1 on cycles 2-6), both in a 28 day cycle. Lenalidomide is given at a starting dose of 2,5 mg daily (day 7-21 of cycle 1) and with dose escalation steps to 5, 10, 15, 20 and 25mg of Lenalidomide from day 1-21 of the following cycles, if toxicity of the combination permits. In a second phase, Rituximab (375mg/m2 iv) at 2, 4 and 6 months after the last cycle is combined with Lenalidomide (day 1-28 of 28 day cycles) at the last tolerated dose for 6 months of maintenance. 40 patients are planned for this study. We herewith present the planned interim analysis for dose finding and safety endpoints for the induction phase of the first 10 patients recruited into the study. Results Mean age of patients was 70 years (range 59-76). Six of 10 patients had stage Rai III/IV and mean WBC count was 159 G/L. Seven of 10 patients had at least one high risk feature from CD38 and FISH analysis or by mutation status. Of the 60 planned cycles 46 (77%) are currently evaluable for this analysis. No systematic toxicity determining MTD was found. 50% of patients proceeded through dose escalation steps as planned. Two patients have already tolerated 25mg of Lenalidomide with their FR cycles. Regarding toxicities, grade 3 and 4 neutropenia was expected in this combination and observed in 7/10 patients. However it was not used as a dose limiting toxicity per se. Still, one 75 year old patient was dose reduced because of febrile neutropenia in the previous cycle. Overall three infectious episodes were observed on treatment. Two patients experienced thrombotic events one of which was then taken off study because of Richter transformation, which might in hindsight have been present from study onset. Surprisingly, 5/10 patients experienced significant skin toxicity, mostly in the form of skin rashes, which was deemed dose limiting in two patients. It was, however, clearly associated with Pneumocystis prophylaxis in one patient, who then went on to receive the full Lenalidomide dose without further rashes. No tumor lysis or flare reaction was observed in the 10 patients reported. Preliminary efficacy data show that all patients achieved at least a PR after 3 cycles of therapy (except for the patient with the Richter transformation). Of the 3 patients currently evaluable after 6 cycles of treatment one CR and two very good PRs were observed before starting the maintenance phase of the study. Conclusions The combination of Lenalidomide with Fludarabine and Rituximab seems clinically feasible and no tumor lysis or flare reaction have been observed, possibly due to the Lenalidomide step up design, as well as the initial tumor load reduction by the chemo-immunotherapy backbone. No clear dose dependent toxicity has emerged as dose limiting for Lenalidomide escalation in this combination. However, 50% of patients had to be dose-limited due to not clearly dose-dependent skin and vascular toxicities. A regime of thromboprophylaxis as well as a delayed start of prophylaxis against pneumocystis have since been amended to improve the management of the patients. In addition, and remarkably, the regimen shows clinical efficacy despite controversial in vitro reports, suggesting a potential negative interaction between Lenalidomide and Rituximab. This might be due to the Lenalidomide pause before each Rituximab cycle or may reflect a difference between in vitro and in vivo. Disclosures Egle: Roche: Research Funding, Speakers Bureau. Off Label Use: Lenalidomide treatment in CLL, Rituximab maintenance in CLL. Greil:Roche: Honoraria, Research Funding; Celgene: Research Funding.

Description: Abstract LBA-2 Background: In a large proportion of patients that have completed 6 to 12 months of treatment with a vitamin K antagonist (VKA) for their acute episode of venous thromboembolism (VTE) the question arises whether to stop or continue this treatment. Continuation implies the need for regular laboratory control and subsequent dose adjustments. Furthermore, the risk of bleeding persists. New oral anticoagulants hold the promise of simple fixed-dose regimens without the need for monitoring and could make continuation of therapy more attractive. The Einstein-Extension study was therefore designed to assess the relative efficacy and safety of rivaroxaban, a direct oral factor Xa inhibitor, versus placebo in patients who had completed 6 to 12 months of anticoagulant treatment for their acute episode of VTE. Patients in whom there was a clear indication for continued anticoagulant treatment were not eligible. Study Design: This randomized, double-blind, placebo-controlled, superiority study evaluated therapy with rivaroxaban 20 mg once-daily for an additional 6 or 12 months. The primary efficacy outcome was symptomatic recurrent VTE (i.e., the composite of recurrent DVT, non-fatal PE, and fatal PE). The principal safety outcome was major bleeding. Also the occurrence of clinically relevant non-major bleeding (e.g. nose bleeds, large skin hematomas, and macroscopic hematuria) was recorded. The study was event-driven requiring a minimum of 30 confirmed recurrent events. All outcomes were adjudicated by an independent blinded committee. Results: A total of 1197 patients were randomized between February 2007 and May 2009 by 280 study sites in 28 countries. The intention-to-treat population consisted of 602 rivaroxaban and 594 placebo patients. Baseline characteristics and risk factors for VTE were comparable between the two groups. The mean duration of study treatment was 190 days in both groups. During the treatment period, symptomatic recurrent VTE events occurred in 42 (7.1%) of the placebo treated patients and in 8 (1.3%) of the rivaroxaban recipients (hazard ratio, 0.18; 95 % CI, 0.09 – 0.39; p〈 0.0001). After the stop of study medication, 6 symptomatic recurrent VTE events occurred in each group during the one month observational period. Major bleeding did not occur in placebo patients and was observed in 4 (0.7%) rivaroxaban recipients (p=0.106). None of these bleeding events were fatal or in a critical site. Clinically relevant non-major bleeding was noted in 7 (1.2%) and 32 (5.4%) of the placebo and rivaroxaban recipients, respectively. Two (0.3%) patients in the placebo group died versus 1 (0.2%) in the rivaroxaban group. No patients were observed to have an alanine aminotransferase (ALT) rise above 3 times the upper limit of normal (xULN) combined with a total bilirubin above 2 xULN. Conclusion: A fixed dose of 20 mg of rivaroxaban once-daily is associated with an 82% relative risk reduction in the recurrence of VTE in patients who had completed a 6 to 12 month course of anticoagulant therapy for their index event. Based on the estimated cumulative incidence rates, approximately, 15 patients need to be treated to prevent one recurrent VTE event. This clinically relevant reduction in recurrence was associated with a low incidence of major bleeding (0.7%). This oral once-daily regimen provides the clinician with a simple option for patients in whom continued anticoagulant treatment is indicated. Disclosures: Buller: Bayer Healthcare: Research Funding.

Description: BLyS and its major receptor BAFF-R have been shown to be critical for development and homeostasis of normal B lymphocytes, and for cell growth and survival of neoplastic B lymphocytes, but the biologic mechanisms of this ligand/receptor-derived intracellular signaling pathway(s) have not been completely defined. We have discovered that the BAFF-R protein was present in the cell nucleus, in addition to its integral presence in the plasma membrane and cytoplasm, in both normal and neoplastic B cells. BAFF-R interacted with histone H3 and IKKβ in the cell nucleus, enhancing histone H3 phosphorylation through IKKβ. Nuclear BAFF-R was also associated with NF-κB/c-Rel and bound to NF-κB targeted promoters including BLyS, CD154, Bcl-xL, IL-8, and Bfl-1/A1, promoting the transcription of these genes. These observations suggested that in addition to activating NF-κB pathways in the plasma membrane, BAFF-R also promotes normal B-cell and B-cell non-Hodgkin lymphoma (NHL-B) survival and proliferation by functioning as a transcriptional regulator through a chromatin remodeling mechanism(s) and NF-κB association. Our studies provide an expanded conceptual view of the BAFF-R signaling, which should contribute a better understanding of the physiologic mechanisms involved in normal B-cell survival and growth, as well as in the pathophysiology of aggressive B-cell malignancies and autoimmune diseases.

Description: Abstract 432 Elotuzumab is a humanized monoclonal IgG1 antibody directed against CS1, a cell surface glycoprotein, which is highly and uniformly expressed in multiple myeloma (MM). Elotuzumab induces significant antibody-dependant cytotoxicity (ADCC) against primary myeloma cells in the presence of either autologous or allogeneic peripheral lymphocytes (PBMC), which is significantly enhanced when PBMC effector cells were pretreated with lenalidomide (Tai et al., Blood 112:1329, 2008). The primary objective of the phase 1 portion of the study is to evaluate the maximum tolerated dose (MTD) of elotuzumab in combination with lenalidomide and low dose dexamethasone in patients with relapsed MM. The study is also evaluating safety, pharmacokinetics (PK) and clinical response. Lenalidomide (25 mg PO) is given on Days 1-21 of a 28-day cycle. Elotuzumab in three escalating dose cohorts (5, 10 and 20 mg/kg) is administered by IV infusion on Days 1, 8, 15 and 22 of the 28-day cycle in the first two cycles and then on Days 1 and 15 of each subsequent cycle. Dexamethasone is given weekly at 40 mg PO. Initially, patients received 6 cycles of treatment unless withdrawn earlier due to disease progression or unacceptable. toxicity. The protocol was amended to allow for patients in the 10 and 20 mg/kg cohorts to receive treatment for up to 12 months following enrollment of the last patient. Key entry criteria: age ≥ 18 years; MM with at least one relapse; measurable disease M-protein component in serum and/or in urine; and prior lenalidomide treatment, if any, more than 6 weeks of first dose. To date, 24 patients with a median age of 60 years have been enrolled in the study and 23 patients have received study drug. The median time from initial diagnosis of MM was 5 years and patients had received a median of 3 prior MM treatments. Patients had been previously treated with thalidomide (58%), bortezomib (67%) or lenalidomide (21%) and 42% were refractory to their most recent MM therapy. Patients have been treated in the 3 cohorts; 3 patients each in the first two cohorts (5 and 10 mg/kg elotuzumab) and 17 patients (7 in dose-escalation phase and 10 in the expansion phase) in the third cohort (20 mg/kg). No dose limiting toxicities were identified during the dose-escalation phase of the study and no MTD was established. One patient discontinued in the first cycle due to grade 4 allergic reaction resulting from elotuzumab infusion in the expansion phase of the study. Additional SAEs (1 of each) included grade 2 atrial fibrillation (related to lenalidomide/dexamethasone) and unrelated grade 4 ruptured diverticulum, grade 3 neutropenic fever and grade 3 diarrhea.. Other common grade 3 or 4 AEs included neutropenia (25%) and thrombocytopenia (25%), which were managed by dose withholding or dose reduction of lenalidomide. Approximately 25% of patients experienced grade 1 or 2 chills and/or pyrexia associated with elotuzumab infusion. The best clinical response (IMWG criteria) in the 13 patients who have received at least two cycles of treatment is shown in the table below. Preliminary PK analysis of elotuzumab suggests a serum half-life of 10-11 days at 10 and 20 mg/kg. Elotuzumab at all three doses resulted in near complete saturation of CS1 sites on plasma cells and NK cells in bone marrow and NK cells in the peripheral compartment. In conclusion, the combination of elotuzumab with lenalidomide and low-dose dexamethasone has a manageable adverse event profile and compared to historical data for lenalidomide and high-dose dexamethasone, the preliminary efficacy data (≥ PR of 92%) are very encouraging. Additional safety, efficacy and PK/PD data will be presented at the meeting. Disclosures: Lonial: Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Off Label Use: Lenalidomide/dexamethasone in combination with elotuzumab in patients with relapsed/refractory multiple myeloma. Vij:Celgene: Research Funding, Speakers Bureau. Harousseau:Celgene France: Advisory Board; Janssen Cilag France: Advisory Board; Celgene: Honoraria; Janssen Cilag: Honoraria; Novartis: Honoraria; Amgen: Honoraria. Facon:Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen Cilag: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Kaufman:Celgene: Consultancy, Research Funding; Millennium: Consultancy; Genzyme: Consultancy; Merck: Research Funding. Mazumder:Celgene: Speakers Bureau; Millennium: Speakers Bureau. Leleu:Celgene: Research Funding, Speakers Bureau. Fry:Facet Biotech: Employment. Singhal:Facet Biotech: Employment. Jagannath:Millennium: Advisory Board; Merck: Advisory Board.

Description: This phase 3 prospective randomized trial evaluated the efficacy and long-term safety of erythropoietin (EPO) with or without granulocyte colony-stimulating factor plus supportive care (SC; n = 53) versus SC alone (n = 57) for the treatment of anemic patients with lower-risk myelodysplastic syndromes. The response rates in the EPO versus SC alone arms were 36% versus 9.6%, respectively, at the initial treatment step, 47% in the EPO arm, including subsequent steps. Responding patients had significantly lower serum EPO levels (45% vs 5% responses for levels 〈 200 mU/mL vs ≥ 200 mU/mL) and improvement in multiple quality-of-life domains. With prolonged follow-up (median, 5.8 years), no differences were found in overall survival of patients in the EPO versus SC arms (median, 3.1 vs 2.6 years) or in the incidence of transformation to acute myeloid leukemia (7.5% and 10.5% patients, respectively). Increased survival was demonstrated for erythroid responders versus nonresponders (median, 5.5 vs 2.3 years). Flow cytometric analysis showed that the percentage of P-glycoprotein+ CD34+ marrow blasts was positively correlated with longer overall survival. In comparison with SC alone, patients receiving EPO with or without granulocyte colony-stimulating factor plus SC had improved erythroid responses, similar survival, and incidence of acute myeloid leukemia transformation.

Description: AML1-ETO is the chimeric protein product of the t(8;21) in acute myeloid leukemia. The ETO portion of the fusion protein includes the eTAFH domain, which is homologous to several TATA binding protein–associated factors (TAFs) and interacts with E proteins (E2A and HEB). It has been proposed that AML1-ETO–mediated silencing of E protein function might be important for t(8;21) leukemogenesis. Here, we determined the solution structure of a complex between the AML1-ETO eTAFH domain and an interacting peptide from HEB. On the basis of the structure, key residues in AML1-ETO for HEB association were mutated. These mutations do not impair the ability of AML1-ETO to enhance the clonogenic capacity of primary mouse bone marrow cells and do not eliminate its ability to repress proliferation or granulocyte differentiation. Therefore, the eTAFH-E protein interaction appears to contribute relatively little to the activity of AML1-ETO.

Description: Endothelial sialomucin CD34 functions as an L-selectin ligand mediating lymphocyte extravasation only when properly glycosylated to express a sulfated carbohydrate epitope, 6-sulfo sialyl Lewis x (6-sulfo SLex). It is thought that multivalent 6-sulfo SLex expression promotes high-affinity binding to L-selectin by enhancing avidity. However, the reported low amount of 6-sulfo SLex in total human CD34 is inconsistent with this model and prompted us to re-evaluate CD34 glycosylation. We separated CD34 into 2 glycoforms, the L-selectin–binding and nonbinding glycoforms, L-B-CD34 and L-NB-CD34, respectively, and analyzed released O- and N-glycans from both forms. L-B-CD34 is relatively minor compared with L-NB-CD34 and represented less than 10% of total tonsillar CD34. MECA-79, a mAb to sulfated core-1 O-glycans, bound exclusively to L-B-CD34 and this form contained all sulfated and fucosylated O-glycans. 6-Sulfo SLex epitopes occur on core-2 and extended core-1 O-glycans with approximately 20% of total L-B-CD34 O-glycans expressing 6-sulfo SLex. N-glycans containing potential 6-sulfo SLex epitopes were also present in L-B-CD34, but their removal did not abolish binding to L-selectin. Thus, a minor glycoform of CD34 carries relatively abundant 6-sulfo SLex epitopes on O-glycans that are important for its recognition by L-selectin.

Description: Abstract 3619 Poster Board III-555 Granulocyte colony-stimulating factor (G-CSF) controls neutrophil production in the bone marrow under steady state conditions and during demand-driven hematopoiesis occurring in response to infection. STAT3 is a principal signaling molecule activated by the G-CSF receptor (G-CSFR). We previously reported that STAT3 has an important role in demand-driven granulopoiesis, although its cellular and molecular mechanisms have been unclear. To address this, we investigated STAT3 function in emergency granulopoiesis stimulated by G-CSF administration or infection with Listeria monocytogenes, which is restrained by the G-CSF response pathway in vivo. Our results show that STAT3-deficiency renders hematopoietic stem cells and myeloid progenitors refractory to the proliferation-inducing effects of G-CSF or Listeria monocytogenes infection. STAT3-deficient myeloid progenitors have a cell autonomous defect in G-CSF-responsive cell cycle progression and undergo delayed granulocyte maturation relative to wild type cells. To define STAT3 target pathways in granulocytic progenitors, we investigated the expression of CCAAT enhancer binding protein (C/EBP) beta, a transcription factor that is necessary for G-CSF-driven emergency granulopoiesis. We found that STAT3 directly regulates G-CSF-responsive C/EBPbeta expression by binding to Cebpb promoter. Moreover, we show that STAT3 and C/EBPbeta co-regulate c-Myc during emergency granulopoiesis. These results place STAT3 as a crucial G-CSF-responsive signal transducer during demand-driven granulopoiesis, through its regulation of critical transcription factors in developing granulocytes. Disclosures: Zhang: Amgen: Research Funding. Nguyen-Jackson:Amgen: Research Funding. Watowich:Amgen, Inc: Research Funding.

Description: Extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) is thought to promote tumor angiogenesis mostly through its protease-inducing function and more recently by its ability to increase tumor cell expression of vascular endothelial growth factor (VEGF). In this study, we present evidence that EMMPRIN can promote angiogenesis by a direct effect on endothelial cells through a paracrine regulation of the VEGF/VEGF-receptor (VEGFR) system. Using human microvascular endothelial cell line–1 endothelial cells, we show that EMMPRIN selectively increased the soluble VEGF isoforms (121 and 165), but not the matrix-bound VEGF 189 form. In addition, EMMPRIN up-regulated the expression of VEGFR-2 without an effect on VEGFR-1. This increase in VEGFR-2 was responsible for the observed EMMPRIN stimulation of the migratory and tube formation capacity of endothelial cells. EMMPRIN′s effects, which were matrix metalloproteinase and urokinase-type plasminogen activator independent, were mediated primarily through hypoxia-inducible factor-2α expression, also up-regulated by EMMPRIN. VEGFR-2 increase was also observed in vivo in a mouse model of xenograph tumors overexpressing EMMPRIN. These results suggest that in addition to increasing protease production, EMMPRIN may contribute to the formation of a reactive stroma also through the up-regulation of hypoxia-inducible factor-2α, VEGFR-2, and the soluble forms of VEGF in endothelial cells, thus directly regulating the angiogenic process.

Description: Abstract 286 It is well established that deregulation of the PI3K signaling pathway plays an important role in the etiology of human malignancies including those of hematologic origin. In 30–50% of solid tumors, oncogenic activation of the PI3K pathway is the result of gain-of-function mutations in the PI3K p110α isoform or due to the loss-of-function of the PTEN phosphatase that is responsible for PI3K downregulation. In B cell malignancies these mutations are rarely observed in spite of the fact that PI3K pathway activation is commonly observed and often essential for tumor cell growth and survival. In this case, PI3K pathway activation has been shown to result from constitutive B cell receptor (BCR) activation and/or from exposure to survival factors present in the microenvironment. The activation of the PI3K pathway by cell surface receptors is directly mediated by the Class I isoforms (α, β, δ, and γ), however, their relative contribution in B cell tumors is unknown. Interestingly, genetic and pharmacological approaches that specifically inactivate the p110δ isoform have demonstrated its important role in normal B cell signaling in response to multiple factors including antigen, CD40L, BAFF, SDF-1 and CXCR13 making it an attractive target for therapeutic intervention in B cell malignancies. CAL-101 is an oral p110δ specific inhibitor which is currently being evaluated in a phase I clinical trial for the treatment of patients with select hematologic malignancies. This compound is a novel potent p110δ inhibitor with an IC50 of 2.5 nM against purified p110δ and EC50 of 65 nM in p110δ-mediated basophil activation in whole blood. CAL-101 demonstrates 300-, 200-, and 40-fold selectivity over the other class I family members (α, β, and, γ respectively) and no activity against class II and III PI3K family members or other PI3K-related proteins including mTOR and DNA-PK. Furthermore, a kinome-wide screen failed to detect activity against any additional kinases. To investigate the potential role of p110δ in B cell hematologic tumors we screened a wide range of leukemia and lymphoma cell lines for constitutive PI3K pathway activation. The expression of p110δ was observed in 〉90% of these cell lines and in many cases was accompanied by constitutive Akt phosphorylation. In this context, CAL-101 was able to reduce p-Akt levels and block additional downstream effectors such as p-S6, and GSK-3β in cells that represent a range of tumor types including follicular lymphoma, acute lymphoblastic leukemia (ALL), diffuse large B-cell lymphoma, and mantle cell lymphoma (MCL). Furthermore, treatment with CAL-101 resulted in growth suppression and induction of apoptosis which was accompanied by PARP and caspase-3 cleavage. Growing evidence suggests that signals from the microenviroment are essential for the expansion, homing, and survival of malignant B cells, in addition to promoting resistance to conventional drug therapy. To investigate the potential role p110δ plays during B cell signaling via interactions with the microenvironment, we examined invoked stimulation of leukemia and lymphoma cell lines with CXCL12, CXCL13, BAFF, or BCR crosslinking in the presence or absence of CAL-101. Stimulation with either chemokines or growth factors resulted in the phosphorylation of Akt which was inhibited by CAL-101 in a dose dependent manner. Moreover, p110δ inhibition with CAL-101 inhibits the chemotaxis of ALL and MCL cell lines to CXCL12. These studies have now been extended to the analysis of primary patient B-ALL and MCL cells to further establish preclinical proof of concept for therapeutic application of CAL-101. In summary, CAL-101 is a potent and selective p110δ kinase inhibitor with broad anti-tumor activity against cancer cells of hematologic origin. Our results demonstrate that selective inhibition of p110δ with CAL-101 inhibits malignant B cell growth, survival, and migration. Furthermore, p110δ inhibition may enhance the effect of cytotoxic drugs or overcome cell mediated drug resistance by inhibiting the protective signals of the microenviroment, providing a rational for combination therapy. These data suggest that p110δ may play an important role in regulating signals between malignant B cells and their microenvironment thereby providing the preclinical rationale for clinical evaluation of CAL-101 alone or in combination with cytotoxics or biologics in patients with hematologic malignancies. Disclosures: Lannutti: Calistoga Pharmaceuticals: Employment. Meadows:Calistoga Pharmaceuticals: Employment. Kashishian:Calistoga Pharmaceuticals: Employment. Steiner:Calistoga Pharmaceuticals: Employment. Johnson:Calistoga Pharmaceuticals: Research Funding. Giese:Calistoga Pharmaceuticals: Employment.

Description: Radioimmunotherapy (RIT) options for T-cell non-Hodgkin lymphomas (T-NHLs) are limited. We evaluated anti-CD45-RIT in human (h) and murine (m) T-NHL. CD45 was highly expressed on hT-NHL patient samples (median, 2.3 × 105 antigen-binding capacity units/cell) and hT-NHL cell lines (3.4 × 105 CD45 antigen-binding capacity units/cell). Biodistribution studies in hTNHL xenografts showed that 131I-labeled BC8 (anti-hCD45) delivered 154% (P = .01) and 237% (P = .002) more radioiodine to tumor sites over control antibodies at 24 hours and 48 hours, respectively. Importantly, tumor sites targeted with 131I-BC8 exhibited 2.5-fold (P = .05), 3.0-fold (P = .007), and 3.6-fold (P = .07) higher 131I retention over the nontarget organs of lungs, liver, and kidneys, respectively (24 hours). Because the clinical use of anti-hCD45 would target both T-NHL and other hematolymphoid tissues, we evaluated the ability of anti-mCD45 to target mT-NHL. mT-NHL grafts targeted with anti-mCD45 correspondingly retained 5.3 (P 〈 .001), 5.4 (P 〈 .001), and 8.7 (P 〈 .001) times the radioactivity in tumor sites compared with nontarget organs of lung, liver, and kidney. 131I-labeled BC8 therapy yielded improved complete remission rates (75% vs 0%, P 〈 .001) and progression-free survivals (median, 23 days vs 4.5 days, P 〈 .001) compared with controls. These data indicate that the high CD45 expression of T-NHL allows reliable tumor targeting and disease control supporting anti-CD45 RIT for T-NHL patients.

Description: The importance of donor-recipient human leukocyte antigen (HLA)-DPB1 matching for the clinical outcome of unrelated hematopoietic stem cell transplantation (HSCT) is controversial. We have previously described an algorithm for nonpermissive HLA-DPB1 disparities involving HLA-DPB1*0901,*1001,*1701,*0301,*1401,*4501, based on T-cell alloreactivity patterns. By revisiting the immunogenicity of HLA-DPB1*02, a modified algorithm was developed and retrospectively tested in 621 unrelated HSCTs facilitated through the Italian Registry for oncohematologic adult patients. The modified algorithm proved to be markedly more predictive of outcome than the original one, with significantly higher Kaplan-Meier probabilities of 2-year survival in permissive compared with nonpermissive transplantations (55% vs 39%, P = .005). This was the result of increased adjusted hazards of nonrelapse mortality (hazard ratio [HR] = 1.74; confidence interval [CI], 1.19-2.53; P = .004) but not of relapse (HR = 1.02; CI, 0.73-1.42; P = .92). The increase in the hazards of overall mortality by nonpermissive HLA-DPB1 disparity was similar in 10 of 10 (HR = 2.12; CI, 1.23-3.64; P = .006) and 9 of 10 allele-matched transplantations (HR = 2.21; CI, 1.28-3.80; P = .004), both in early-stage and in advanced-stage disease. These data call for revisiting current HLA matching strategies for unrelated HSCT, suggesting that searches should be directed up-front toward identification of HLA-DPB1 permissive, 10 of 10 or 9 of 10 matched donors.

Description: Abstract 3727 Poster Board III-663 Deacetylases (DACs) are enzymes that remove the acetyl groups from target proteins, leading to regulation of gene transcription and other cellular processes. Entinostat (SNDX-275) is a novel and potent DAC inhibitor that is selective for class I DACs and is currently undergoing pre-clinical and clinical testing in Hodgkin lymphoma (HL). Potent synergistic anti-tumor activity has been observed by combining less potent DAC inhibitors with bortezomib in pre-clinical models. In our efforts to develop more therapeutic options for refractory/resistant B-cell lymphoma, we evaluated the effects of Eentinostat as a single agent and in combination with bortezomib against B-cell non-Hodgkin's lymphoma (NHL) cell lines and primary NHL cells. Studies were conducted in a panel of 12 NHL cell lines representing various subtypes of B-cell lymphoma (i.e. DLBCL/ABC, DLBCL/GCB, Burkitt's, transformed and MCL), which included: rituximab-[chemotherapy]-sensitive cell lines (RSCL, Raji, RL and DHL-4), rituximab-[chemotherapy]-resistant cell lines (RRCL, Raji-4RH, Raji-2R, RL-4RH, and DHL-4 4RH), and primary lymphoma cells isolated from patients with various subtypes of NHL and HL. Patient-derived tumor cells were isolated from fresh specimens by negative selection using magnetic beads. NHL cells and patient-derived primary cells were exposed to entinostat at different doses (0.01 to 100uM) either alone or in combination with CDDP (1 to 100μM), doxorubicin (4 to 16μM), vincristine (1 to 5μM), or bortezomib (1 to 10nM). Anti-tumor activity was measured after a 24 or 48 hr incubation. In cell lines, changes in mitochondrial potential and cell proliferation were determined by alamar blue reduction using a kinetic assay measuring activity at 4 hr intervals for 24 and 48 hrs. For patient-derived primary NHL cells, changes in ATP content (apoptosis) was determined using the cell titer glow assay. Entinostat was highly active in all the cell lines tested including rituximab-[chemotherapy]-resistant cell lines. The IC50 of Entinostat in the majority of the cells tested was 0.5 to 5uM at 48 hrs. Similar findings were observed in primary tumor cells derived from lymphoma patients. In addition, synergistic activity was observed by combining entinostat and bortezomib in both NHL cell lines, as well as in primary NHL/HL tumor specimens. A lesser degree of augmented anti-tumor activity was also observed when entinostat was combined with cisplatin or doxorubicin (but not vincristine). In summary, our data suggests that entinostat is a novel and potent DAC inhibitor with a wide therapeutic spectrum. Entinostat is capable of inducing cell death against various subtypes of B-cell lymphoma cell lines including RSCL, RRCL, as well as patient-derived primary tumor cells and augments the anti-tumor effects of bortezomib and other chemotherapeutic agents. Given the isoform selectivity of entinostat, the results indicate that HDAC1 and 2 may be the key targets of DAC inhibitors in HL and NHL cells. Ongoing studies are evaluating the mechanisms responsible for the synergistic effects of entinostat plus chemotherapy and will be updated at the annual meeting. Current findings strongly suggest that entinostat added to bortezomib and/or other chemo agents may become a novel and potent strategy in the treatment of aggressive and indolent NHL and HL in the future. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4919 Waldenstrom's macroglobulinemia (WM) is characterized by the presence of lymphoplasmacytic cells in the bone marrow and the secretion of IgM monoclonal antibody in the serum. Several conventional therapies are available but the disease remains incurable. Recently, bortezomib (a proteasomal inhibitor) has shown promising anti-WM activity with enhanced responses when combined with traditional therapies. Resistance to bortezomib therapy is an important event that is associated with continued treatment. In order to understand the mechanism of bortezomib resistance in WM we exposed BCWM.1 (a known WM cell line) in vitro to increasing concentrations of bortezomib over prolonged periods of time and isolated the bortezomib resistant clone (BCWM.1/BR). This clone was compared with its parent wild type cell line (BCWM.1/WT). Investigation to understand the susceptibility of BCWM.1/Br cells to various therapeutic agents showed that these cells are resistant to many of the agents such as melaphalan, fludarabine or doxorubicin. Interestingly, verapamil, a broad spectrum inhibitor of multidrug resistance, failed to reverse the resistance induced by bortezomib indicating that bortezomib resistance is not because of an activation of multidrug resistance in these cells. While BCWM.1/WT cells showed an IC50 of 7.8nM when treated for 72h with bortezomib, the BCWM.1/BR cells were not inhibited at any concentration of the compound up to 100nM. Furthermore, the cells with the acquired resistance showed a 4 fold increase in the proteasomal activity as measured by the release of a fluorescent product (7-Amino-4-methylcoumarin (AMC)) from its peptide substrate, suc-LLVY-AMC. Biochemical analysis further revealed that many of the proteasomal components are altered in BCWM.1/BR cells as compared to their parental control cells. Interestingly, protein levels of two of the proteasomal catalytic subunits, PSMB5 and PSMB9 are upregulated in resistant cells suggesting a reason for the enhanced proteasomal activity of these cells. The resistant cells showed an altered gene expression profile that indicates a transformation of the parental wild type cell line to acquire resistance. A comparative analysis of the signal transduction pathways operated in these cells showed that many of the activation and cell survival pathways that are present in BCWM.1 cells are inhibited in the resistant cells. For example, BCWM.1 cells show a constitutive activation of AKT and ERK1/2 which are inhibited in the resistant cells thus making them insensitive to the inhibitors of these pathways. Similarly, HSP27 which was earlier shown to contribute to bortezomib induced resistance was completely inhibited in BCWM.1 resistant cells. Interestingly, there is an increase in Bcl-2 protein in BCWM.1/BR cells as compared to WT cells indicating that the resistant cells might be dependent on Bcl-2 family for their survival. Inhibition of Bcl-2 induced potent apoptosis in BCWM.1/BR cells. Thus the results presented here indicate that acquired bortezomib resistance in BCWM.1 cells alters their proteasomal activity, cellular signaling pathways to make them resistant to many of the known therapies but these cells retain the Bcl-2 mediated pathway for targeting thus inhibitors of Bcl-2 may be used in therapy against bortezomib-resistant WM. Disclosures Chanan-Khan: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immunogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Description: Abstract 4848 Background Myelodysplastic syndrome(MDS) belong to the most common hematological diseases however epidemiological data on MDS are sparse. Until 2008 there were no data about epidemiology of MDS in Poland. Methods From 03.2008-05.2009 we have registered 966 patients in Polish MDS Registry. We have included only alive patients of various time of diagnosis. Patients from 22 centers were diagnosed according to WHO 2001 criteria. Results There were 508(53%)males and 458(47%) females. Median age at diagnosis was 70(range 19-99). Under 50 were 83(9%) cases with preponderance of females- 51 cases( males 32cases), between 50-70 there were 353(41%) cases, half of the patients-432(50%) were above 70( 247 males and 185 females).Prior chemotherapy and/or radiotherapy had 37((3,8%) patients. Distribution of MDS subtypes was as follows: RA-170(20%) cases, RARS-58(7%), RCMD-244(28%), RCMD-RS-18(2%), RAEB-1-120(14%), RAEB-2-169(19,5%), 5q- -40(4,6%), MDS-U-44(5%).In 103(10%) subtype was not done. Karyotype was available in 276(28%) cases. Cytogenetic risk groups were: low risk-182(68%), intermediate-52(20%) and high risk-33(12%). The most frequent cytogenetic results were: normal karyotype 44%, isolated 5q deletion 19%, complex karyotype 6%, 5q deletion + another one change 3% and 5q deletion with at least 2 changes 3%. According to IPSS risk groups low risk was found in 61( 22%) of cases, intermediate-1 -130(48%), intermediate-2-47(17%) and high risk in 31(11,5%). Median values of Hb was 9,1 g/dL, plts 129 G/L, ANC 1,7 G/L. RBC transfusion dependent were 429(44%) patients and platelet transfusion dependent were 100( 11%) pts. At least 2 U/month RBC transfusion requirement was 140(14%) patients. Serum ferritin level was assessed in 530 cases-171 of them( 32%) had higher than 1000μg/L level. Conclusions We have observed predominance of females among MDS patients under 50. Half of the patients had RA or RCMD subtype. Isolated 5 q deletion was the most frequent cytogenetic abnormality. Forty four percentage of patients was RBC transfusion dependant. Serum ferritin level was significantly elevated in 32% of assessed patients at the moment of MDS diagnosis. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 4915 Multiple studies have highlighted the critical role of mutation and loss of p53 function in multiple myeloma (MM) when acquiring a more aggressive phenotype and refractoriness to treatment. Therefore, agents capable of overcoming p53 mutational status are important in the context of MM therapeutics. We have previously reported the in vitro and in vivo anti-MM activity of the multi-targeted small molecule inhibitor RGB-286638. Using a human MM cell xenograft model in SCID mice we demonstrated that RGB-286638 inhibited tumor growth and prolonged survival. Our data confirmed suppression of CDK1/cyclin B, CDK4, 6/Cyclin D1, D3, and CDK2/Cyclin E complexes in MM.1S MM cells containing wt-p53, which was correlated with rapid downregulation of Rb phosphorylation, resulting in effective G2/M cell cycle blockage and increased sub-G1phase. RGB-286638 induced dose and time-dependent inhibition of RNA pol II phosphorylation as an early event promptly followed by p53 induction. Moreover, RGB-286638 treatment was associated with p53 phosphorylation at ser 15, indicative of DNA damage followed by apoptosis, evidenced by caspases 8, 9 and 3 cleavage and confirmed by Annexin V/PI staining. All together these data suggested that RGB-286638-induced RNA pol II inhibition triggers cytotoxicity in MM cells via p53-dependent apoptosis. Interestingly, RGB-286638 demonstrated cytotoxic activity even in p53-deficient conventional drug-resistant RPMI 8226/Dox 40 MM cells. RGB-286638 treatment of RPMI 8226/Dox40 MM cells showed increased PARP response associated with enhanced NAD depletion followed by increased ATP consumption. Furthermore, concomitant assessment of RGB-286638-induced ATP depletion versus cytotoxicity demonstrated more than 60% ATP loss preceded cell death in RPMI 8226/Dox40 but not in MM.1S. This data suggests the role of either p53-mediated apoptosis (when active) or PARP-induced NAD/ATP depletion and bioenergetic crisis (when absent). Interestingly, the knockdown of p53 did not rescue MM.1S cells from RGB 286638-induced death, suggesting the existence of alternative p53-independent pathways through which RGB-286638 exerts its cytotoxic activity. Ongoing studies are addressing the molecular effects of p53 silencing in MM cells. In addition, dissecting the mechanism of RGB-286638 p53-independent cytotoxicity in MM cells will provide insights for future therapeutic strategies in patients with aggressive MM and associated mutated/deleted-p53. Disclosures Loferer: GPC Biotech AG: Employment. Munshi:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis : Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Anderson:Millenium: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Raje:Celgene: Research Funding; Novartis: Research Funding; AstraZeneca: Research Funding.

Description: Abstract 4886 Detection of high molecular weight light chain oligomers in urinary exosomes of patients with AL amyloidosis. Background Exosomes are microvesicles that are part of the multivesicular body (MVB) pathway. They are created by the inward budding of the cell surface membrane and contain both surface bound membrane proteins and cytosolic proteins which can be used to identify the cell of origin. Immunoglobulin light chain amyloidosis (AL) occurs as the result of amyloid formation by the misfolding of monoclonal light chains (LC) and deposition of these amyloid fibrils in various soft tissues. This reaction requires the organization of the monoclonal LC's into protofibrils which are then weave into amyloid fibrils. This study was undertaken to determine whether urinary exosomes of glomerular origin contain intermediate species of amyloid formation. Method Urine samples from patients with AL, light chain deposition disease (LCDD), multiple myeloma (MM) and monoclonal clonal gammopathy of undetermined significance (MGUS) were collected. Urinary exosomes were isolated and separated into fractions by gradient centrifugation. Western blots were performed on the urinary exosome fractions using anti-kappa or anti-lambda antibodies. Glomerular fractions were identified using antibodies directed toward podocin. Results Urine samples were collected from 5 patients with AL, 2 from LCDD, 1 from MM and 1 MGUS. On the Western blot, immunoglobulin LC were seen in all exosomal fractions in patients with AL amyloidosis, LCDD, MM but not MGUS which is similar to normal controls (not shown). In patients with AL, oligomeric species were found in the highest concentrations in fraction 4 and 5 (Figure 1). Fraction 4 and 5 were also stained for podocin, a glomerular protein (not shown). The highest molecular weight species was ∼250 kd which corresponds to a LC decamer. High molecular weight species were also identified in 1 of 2 LCDD patients corresponding to a tetramer. The band was identified in fraction 10 which had polycystin-1 expression suggesting a tubular origin. No high molecular weight LC species was found in patients with MM or MGUS. Conclusion Our study found high molecular weight LC species corresponding to the intermediates involved in protofibril formation in urinary exosomes of patients with AL. Smaller (tetramer) high molecular weight LC species were also found in a patient with LCDD but not in patients with MM and MGUS. Not only were the high molecular weight LC species found exclusively in the diseases characterized by deposition of LC aggregates, they were also found in the segments of the nephron where the deposits were expected: glomerulus for AL and tubular epithelium for LCDD. This is consistent with our current understanding of the pathogenic mechanisms of these diseases. We believe urinary exosomes are a powerful tool in the study of diseases involving self-aggregation of monoclonal proteins. It has tremendous potential in both diagnostic and scientific research in this area. Disclosures Gertz: celgene: Honoraria; millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Description: Abstract 4902 Introduction Cytogenetics and fluorescent-in situ hybridization (FISH) are important outcome predictors in multiple myeloma (MM). There were only few small studies that investigated prognostic implication of FISH and/or conventional karyotyping in Korean MM patients. We investigated the incidences and prognostic significances of chromosomal abnormalities detected by FISH and/or conventional karyotyping among Korean MM patients. Patients and Methods We collected data of patients from Korean Myeloma Registry and performed retrospective analysis. We compared the survival of patients with chromosomal abnormalities and other clinical findings. Results From 2000 to 2009, total of 801 newly diagnosed myeloma patients were enrolled in this study. Median age of patients was 62 years. Median overall survival was 82 months, and median follow up of time was 92 months. Among the patients who had conventional karyotype analysis, 17.1% were complex karyotype, followed by del13q (7.4%), hyperdiploidy (7.6%), hypodiploidy (3.0%), and t(11;14) (3.9%). Among the patients who had FISH analysis, 22.8% were del 13q, followed by t(11;14) (18.2%), t(4;14) (13.7%), del17p (11.8%) and t(14;16) (5.9%). Univariate analyses revealed that complex karyotype (p

Description: Abstract 4873 Angiogenesis plays a significant role in the biology of multiple myeloma (MM). Erythropoiesis stimulating agents (ESAs) have been recently associated with reduced survival in a subset of cancer patients who receive ESAs, including MM but the etiology for this correlation has not been sufficiently explored. It is known that the endothelial cells produce angiogenic factors, promote the growth and survival of MM cells and carry erythropoietin receptors which in hypoxic conditions they transport the signal for their own proliferation and expansion under the influence of the endogenous erythropoietin. The aim of this study was to investigate the possible impact of ESAs administration on post-therapy angiogenesis. We studied 84 newly diagnosed MM patients (47M/37F; median age: 65 years, range: 39-82 years) who underwent conventional anti-myeloma therapy: 62 patients received VAD (53 of whom within the context of the randomized study VAD vs. TVAD, conducted by the Greek Myeloma Study Group) and 22 patients received MP. Fifty-two patients received ESAs for at least 8 weeks (ESA group), while 32 did not receive ESA (non-ESA group). MVD was assessed in bone marrow biopsies at baseline and at the time of best response by using monoclonal antibodies targeting CD34. The number of microvessels expressing the CD34 antibody was counted by two experienced pathologists through a grid at a magnification of 400x and was finally divided to the number of the high power fields used for screening the whole marrow surface. The counts were finally expressed as number of vessels per mm2 area of the involved marrow. Fifteen individuals with normal findings in the bone marrow were used as controls. Furthermore, the following cytokines that are involved in the angiogenesis process in MM were measured in the serum of both patients and controls on the day of the trephine biopsy performance: VEGF, bFGF, TGF-b, IL-6, soluble IL-6R (sIL-6R), IL-1b and TNF-α, using an ELISA methodology (R&D, Minneapolis, MN, USA). Patients characteristics between the ESA and non-ESA groups at baseline were well balanced except of Hb which was, as expected, significantly lower in the ESA-group (p

Description: Abstract 4815 Algae preparations are commonly used in complementary and alternative medicine for presumed anti-oxidant, anti-inflammatory, and anti-cancer properties. In this study, we have examined the effects of extracts from algae and algae components on the proliferation of normal hematopoietic and leukemia cells. To prepare extracts, 1 gram of Dunaliella salina (Dun), Astaxanthin (Ast), Spirulina (C-phycocyanin) (Spir), or Aphanizomenon flos-aquae (AFA) were added to 10 ml of 70% ethanol and incubated at 4°C on a shaker for 24 hours. The slurry was centrifuged at 400 g for 10 minutes at 4°C, and the supernatant was filtered through 413-grade filter paper. Leukemia cell lines were purchased from ATCC and blood or marrow aspirates from normal subjects or patients with leukemia were subjected to Ficoll-Hypaque density gradient centrifugation. CD34+ cells were isolated using Miltenyi Biotec MiniMACS magnetic bead cell separation columns. To determine effects on cell proliferation, increasing concentrations of algae extracts were added in fresh medium to plated cells, and MTT reagent was added followed by detergent and absorbance readings were recorded at 570 nm. Leukemic cell lines such as HL60 and MV4-11 were significantly inhibited by Ast and AFA at concentration of 0.8 mg/mL of extract (p

Description: Abstract 4877 Introduction The CD138negCD20+ cell population has been suggested as the putative multiple myeloma (MM) cancer stem cells, both in MM cell lines and in patient specimens. CD200 is an immunosuppressive membrane glycoprotein reported to be co-expressed with other stem-cell markers in prostate, breast, brain, and colon cancers. Also, CD200 is a negative prognostic factor for MM. It remains unknown whether CD200 is expressed in the CD138negCD20+ MM cell population, the putative MM cancer stem cells. Here we addressed this question by assessing CD200 expression in different subpopulations of MM cells according to their CD138 expression levels. Methods Two MM cell lines (RPMI8226 and NCI-H929) were co-stained with FITC-labeled anti-CD200, PE-labeled anti-CD20, and APC-labeled anti-CD138 antibodies for multicolor flow cytometry analysis. The cells were gated into 4 subpopulations (h1〉h2〉h3〉h4 corresponding to CD138 expression levels: high〉dim〉low〉negative). In each gated cell population, CD200 expression was assessed, and the CD200+ and CD200neg cell subpopulations were further gated for analysis of their CD20 expression levels. Results In the RPMI 8226 cell line, the distribution of gated h1, h2, h3, and h4 populations was 87.51%, 5.86%, 5.26%, and 1.29%, respectively. In the h2 (CD138dim) population, 22.88% of the cells were CD200+. In contrast, CD200 was expressed at much lower levels in the other three populations, ranging from 7.28% (h1), 6.65% (h3), to 0.48% (h4). In CD200+ cells from the gated h1, h2, h3, and h4 population, CD20+ cells were 19.50%, 23.03%, 27.67%, and 18.75%, respectively, while in the CD200neg cells, CD20+ cells were 20.79%, 22.50%, 25.08%, and 28.02%, respectively. In the NCI-H929 cell line, 18.59% of the cells in the h2 population were CD200+, whereas only 1.61%, 1.69%, and 0.47% of the cells in the h1, h3, and h4 populations were CD200+. In each population, there were more CD20+ cells in CD200+ cells than in CD200neg cells, which were 24.52% vs 0.04% (h1), 41.94% vs 11.34% (h2), 11.11% vs 3.06% (h3), and 50.00% vs 2.25% (h4), respectively. Conclusions These results demonstrate that the immunosuppressive molecule CD200 is preferentially expressed in a CD138dim subpopulation of multiple myeloma cells. Depending on cell line, the putative myeloma stem cell marker CD20 is either preferentially, or not preferentially, expressed in the CD200+ cells, suggesting that an immune-resistant subpopulation of MM stem cells might exist, which may have important implications for designing immunotherapeutic approaches to treat this disease. Disclosures Goldenberg: Immunomedics, Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Description: Abstract 4841 Myelodysplastic syndromes (MDS) are a group of acquired clonal stem cell disorders that mainly affect the elderly population, characterized by ineffective hematopoiesis and high risk of leukemic transformation. MDS are heterogeneous in terms of morphology, clinical features and survival. An increasing body of work reveals that there might be differences in clinical features between Asian and Western cases. Japanese patients seem to be younger, have a lower frequency of refractory anemia (RA) with ringed sideroblast (RARS) and a higher frequency of RA, according to FAB classification, as well as different prognostic factors such as the frequency of cytogenetic abnormalities. Incidence rates for MDS in Brazil are unavailable. The purpose of the study was to obtain epidemiological data of MDS adult patients who presented from January 2003 to December 2007 in 10 Brazilian tertiary-care hematology centers from different regions of the country. Patient data collected by participating physicians were entered and stored with the use of an internet-based, data collection tool. Blood counts, bone marrow aspiration, trephine biopsy and chromosomal study were recorded. Survival was estimated through Kaplan-Meier method and the difference between survival curves was assessed by means of Log-Rank Test. Death incidence rates were estimated and compared. Statistical analyses of relevant variables were performed. Three hundred and forty three patients with diagnosis of MDS according to FAB/WHO classification were included in this retrospective analysis. The mean age at presentation was 68 years (range 17 to 98). Fifty percent of cases were male. Cigarette smoking, alcohol abuse and pesticide/herbicide exposure were reported in 33.5%, 13.4% and 14.3% respectively. Median hemoglobin was 8.7 g/dL, median neutrophils count was 1,575/mm3 and median platelets count was 97,000/mm3. There was no excess of blasts in 68.4% of cases. Bone marrow biopsy was performed in 78.5% of patients. Lymphoid nodules were seen in 11.3% and any degree of fibrosis in 28.6%. Cytogenetic analysis was performed in 67.8% of cases and showed chromosomal abnormalities in 50.5%. The del(5q) isolated or combined with other alterations were observed in 6.0%. Flow cytometry analysis for CD55 and CD59 was performed in 11,3% and was normal in 97,4%. Near 8% of cases were classified as secondary MDS. The distribution of disease subtypes according to FAB classification was: RA 42,3%, RARS 9,0%, RA with excess of blasts (RAEB) 20,7%, RAEB-t 4,2% and chronic myelomonocytic leukemia (CMML) 3,9%. According to IPSS patients were stratified as low-risk (low risk plus intermediate I) 55,9% and high risk (intermediate II and high risk) 13,1%. In 30,1% no stratification was possible. In 26,5% of cases iron overload was diagnosed although only 28,3% of cases had performed serum ferritin. The follow-up time ranged from 1 to 78 months (mean: 28 months). Thirty-six percent of patients died and the death was MDS-related in 68.3% of cases. The high and low risk survival curves were significantly different (p

Description: Abstract 2496 Poster Board II-473 Background: HMG-CoA reductase inhibitors (statins) have been used to treat hypercholesterolemia and hyperlipidemia for over 20 years. Statins competitively inhibit HMG-CoA reductase thereby blocking the synthesis of mevalonate. They directly inhibit synthesis of steroid hormones and cholesterol but also indirectly inhibit prenylation and ubiqitination. As all currently marketed statins are lipophillic, with the exception of Pravachol (pravastatin), several therapeutic trials have attempted to exploit these indirect actions to treat both neoplastic (glioblastoma, anaplastic astrocytoma) and degenerative (Alzheimer's, Parkinson's) neurologic disease. We studied the impact of incidentally prescribed statins on high-risk patients with primary central nervous system diffuse large B cell lymphoma (PCNSL). Methods: We used an IRB-approved clinicopathologic database, derived from comprehensive tumor registry data at the Massachusetts General Hospital, to identify all patients diagnosed with primary central nervous system lymphoma (PCNSL) between 1991 and 2007 (n=118). We excluded pediatric patients, patients who did not receive curative treatment and patients who failed to achieve a CR with initial therapy. Automated analysis of billing and medication administration records was used to identify the administration of statins to these patients. We compared the outcome of patients who were receiving statins to controls with PCNSL who did not receive statins. We excluded patients who did not receive statins within the time interval from 6 months prior to 2 years after their PCNSL diagnosis. As only a single statin pt was less than 50 we excluded all pts below this age from the cases and controls. All patients received high dose MTX based therapy. Overall survival (OS) was calculated from the date of first methotrexate. Results: Median age of statin patients was 66 yrs (range 52 – 76); median age of controls was 66 years (range 50 - 86). Nine patients were on atorvastatin, 9 were on simvastatin, 1 each were on pravastatin, rosuvastatin and fluvastatin. At a median follow-up of 47.5 months, concurrent statin therapy was associated with improved OS (62% vs. 37%)(p=0.04 Log-rank test). The median OS for all statin patients 〉 50 years old (n=21) was 60 months versus 37 months for all other patients 〉 50 years old (n=67) (p=

Description: Abstract 2475 Poster Board II-452 Introduction: Non-Hodgkin Lymphoma (NHL) is the fifth most common type of malignancy in Canada. The most common subtype of NHL is diffuse large B-cell lymphoma (DLBCL). Initial standard treatment for DLBCL includes combination immuno-chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). This regimen is typically administered every 21 days for a total of 6 cycles. Febrile neutropenia (FN) is a serious toxicity of lymphoma chemotherapy and patients with this condition must be treated aggressively as it could lead to complications such as prolonged hospitalization and death. Granulocyte-colony stimulating factors such as filgrastim and pegfilgrastim are efficacious in preventing FN, yet their cost-effectiveness has not been evaluated in the publicly funded Canadian healthcare system. Methods: A Markov model was constructed to evaluate the cost-effectiveness (cost-utility) of filgrastim and pegfilgrastim as primary prophylaxis versus no primary prophylaxis against FN in DLBCL patients receiving induction chemotherapy. Health states included in the model were hospitalization for FN, and receiving chemotherapy with no FN. It was assumed that patients in the no primary prophylaxis arm of the model who experienced a FN episode would receive secondary prophylaxis with filgrastim for all subsequent chemotherapy cycles. The time horizon of the model was 18 weeks, the time period over which the six cycles of chemotherapy are administered. The analysis was conducted from the hospital perspective. Costs are reported in 2009 Canadian dollars and outcomes in quality-adjusted life years (QALY). One-way sensitivity analyses were done on model parameters. A probabilistic sensitivity analysis was done to evaluate overall uncertainty in the model. Results: In the base case analysis costs associated with the no primary prophylaxis, filgrastim and pegfilgrastim interventions were $6044, $9450 and $15899, respectively. Quality-adjusted life years associated with the three interventions were 0.198, 0.200, and 0.202 respectively (over the 18-week model time horizon). The incremental cost-effectiveness ratio (ICER) of filgrastim compared to no primary prophylaxis was estimated to be $1.7 million (M)/QALY [95% confidence interval: -14M/QALY (dominated) to $15M/QALY]; for pegfilgrastim compared to filgrastim the ICER was estimated to be $4.4M/QALY [95% confidence interval: -25M/QALY (dominated) to $22.7M/QALY]. All one-way sensitivity analyses yielded ICERs of greater than $1M/QALY. Conclusions: The ICERs for filgrastim and pegfilgrastim when used as primary prophylaxis against FN in DLBCL patients receiving induction chemotherapy are well above the usually accepted cost-effectiveness threshold of $50,000/QALY. Disclosures: Mittmann: Amgen Canada: Unrestriced educational grant.

Description: Abstract 2484 Poster Board II-461 Background: Hematologic (HM) and solid tumor malignancy (STM) patients may be immunocompromised (IC) due to their underlying diseases and the immunosuppressive therapies they received. Availability of a practical and robust algorithm to classify HM and STM patients into IC levels using data from healthcare databases could be valuable for a variety of epidemiologic, health service or outcome research in the field of oncology. Classification of the IC status of patients also permits accurate prediction of the types of supportive care that such patients may need to prevent infectious complications that often accompany treatments for the underlying malignancy. Methods: An expert panel mainly comprised of hematologists and oncologists developed an algorithm to classify HM and STM patients' level of IC into either none/low, medium, or high, using data available in electronic databases. The algorithm was based on the following factors: (1) the type of chemotherapy agents and/or corticosteroids, (2) time since last chemotherapy/corticosteroid treatment, and (3) specific type of HM (for HM patients). Chemotherapy agents were classified into levels of IC, irrespective of dose used. Corticosteroid therapy was classified into levels of IC based on dose and duration of treatment. IC levels were allowed to change monthly to reflect what chemotherapy agents were used, dose and duration of corticosteroid if any, and time since the last IC treatment. In the base case scenario, the patient's IC level (based on treatment) stayed at an assigned level for 6 months after the last treatment and then moved to the next lower level for an additional 6 months. In alternative scenarios, sensitivity analyses were also performed using the 1, 3, 9, and 12 month cutoffs. If the patient received multiple chemotherapy agents/corticosteroid regimens, the most immunocompromising agent determined the IC level during that time period. We applied and tested this algorithm in a study of HM and STM patients diagnosed in 2001-2005 at Kaiser Permanente Northern California (KPNC). Herpes zoster (HZ), a viral disease caused by the reactivation of varicella zoster virus, is associated with impairment of cell-mediated immunity. Therefore, we used incidence of HZ as a proxy for true IC status. The KPNC cancer registry was used to identify cancer diagnoses and the type, stage and grade of the underlying HM. Data on specific chemotherapy agents and/or dose and duration of corticosteroids as well as time since last IC treatment were obtained from KPNC pharmacy databases. Potential episodes of HZ in 2001-2006 were identified from HZ diagnosis codes and antiviral use in various KPNC databases. HZ diagnosis was confirmed by clinical review of patient's medical records. We measured HZ incidence rates in HM and STM patients and examined whether they were correlated with IC level based on our algorithm. Results: In the base case scenario, among the 4,465 patient-years (py) of follow-up in HM patients, 25.3%, 34.4%, and 40.3% of follow-up time was categorized as none/low, medium, or high IC, respectively. The corresponding rates of HZ were 13, 25, and 48/1000 py. Among the 23,072 py of follow-up in STM patients, 74.9%, 8.0%, and 17.1% of follow-up time was categorized as none/low, medium, or high IC, respectively. The corresponding rates of HZ were 10, 20, and 19/1000 py, respectively. The algorithm was not sensitive to changes from 3 to 12 months, but was sensitive to the 1 month cutoff, in the assumption of duration of IC since the last IC treatment. Conclusions: It is feasible and practical to categorize cancer patients into IC levels using electronic pharmacy and cancer registry databases. The correlation between incidence of HZ and levels of IC in both HM and STM patients suggested that the proposed algorithm may appropriately assign IC levels in these patients. Additional testing in other cancer populations may be needed to further validate this algorithm. Disclosures: Tran: Merck & Co., Inc.: Employment. Ray:Merck & Co., Inc.: Investigative. Saddier:Merck & Co., Inc.: Employment. Trigg:Merck & Co., Inc.: Employment. Hayes:Merck & Co., Inc.: Consultancy. Li:Merck & Co., Inc.: Investigative. Rizzieri:Merck & Co., Inc.: Consultancy. Stein:Merck & Co., Inc.: Consultancy. Weber:Merck & Co., Inc.: Consultancy. Serody:Merck & Co., Inc.: Consultancy. Raasch:Merck & Co., Inc.: Consultancy. Habel:Merck & Co., Inc.: Investigative.

Description: Abstract 2456 Poster Board II-433 Murine T cells exposed to rapamycin maintain flexibility towards Th1/Tc1 differentiation; the degree to which rapamycin might inhibit human Th1/Tc1 differentiation has not been fully evaluated. In the presence of rapamycin, T cell co-stimulation and polarization with IL-12 or IFN-α permitted human CD4+ and CD8+ T cell differentiation towards a Th1/Tc1 phenotype: by intracellular flow, median percentage expression of Foxp3, IFN-γ, and T-bet was 4%, 20%, and 72%, respectively. Phospho-flow cytometry revealed that such Th1/Tc1 cells expressed activated STAT1 and STAT4 in spite of mTOR blockade; STAT activation was abrogated by PI3 kinase inhibition. Rapamycin-resistant human Th1/Tc1 cells (Th1/Tc1.R cells): (1) had increased expression of the autophagy-related gene LC3BII by gene array and protein analysis; (2) preferentially expressed anti-apoptotic bcl-2 family members (reduced Bax, Bak; increased phospho-Bad); (3) maintained mitochondrial membrane potentials; and (4) had reduced apoptosis relative to control Th1/Tc1 cells not generated in rapamycin (p=0.04). The anti-apoptotic phenotype of Th1/Tc1.R cells was abrogated by co-incubation with the autophagy inhibitor, 3-methyl adenine. The in vivo effect of the Th1/Tc1.R cells was evaluated using two xenogeneic GVHD (x-GVHD) models. First, in an LPS-induced x-GVHD model, Th1/Tc1.R cells resulted in lethality in 75% recipients; soluble TNF-α receptor therapy with etanercept reduced the frequency of lethality to 15%. Second, using a non-LPS natural history model of x-GVHD, recipients of Th1/Tc1.R cells (relative to recipients of control Th1/Tc1 cells) had increased human T cell engraftment (day 30 post-BMT, p=0.001), increased human T cell cytokine levels, increased human T cell expression of the cytotoxic degranulation molecule CD107 (p=0.05), and increased human T cell infiltration of skin, gut, and liver. In this model, lethality due to x-GVHD was also increased in Th1/Tc1.R cell recipients (lethality increased from 20% to 70%, p=0.04). We conclude that rapamycin therefore does not impair human T cell capacity for type I differentiation. Rather, by promoting autophagy rapamycin permits stable expression of T-bet and generates an anti-apoptotic Th1/Tc1 effector phenotype, thereby yielding increased x-GVHD. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2437 Poster Board II-414 Introduction: BK virus (BKV) is a polyomavirus that is ubiquitous in humans, infecting over 85% of normal individuals. After initial infection it persists in a latent state in the urothelium from whence it can reactivate causing disease in immunocompromised patients. BKV is a cause of haemorrhagic cystitis after allogeneic SCT and is emerging as one of the major causes of graft loss after renal transplant. Current treatment is limited to reduction of immunosuppression as possible. Aim: To develop a method for production of a T cell product with BKV specificity from normal donors for use in adoptive immunotherapy post hemopoietic stem cell transplantation. Methods: Peripheral blood mononuclear cells (PBMC) or monocyte derived dendritic cells (mo-DC) were pulsed with mixes of overlapping peptides covering the 5 BKV proteins (VP1, VP2, VP2 isoform 3, large T antigen (LTA) and small T antigen (sTA)). Mo-DC were produced by isolating monocytes by adherence to plastic and culturing for 7 days in GM-CSF and IL-4 containing media. On day 6 mo-DC were matured by the addition of TNF. T cells were stimulated on day 1 and 7 with peptide pulsed PBMC or mo-DC and cultured for 21 days with increasing doses of IL-2 from day 7. The cellular product was then analysed for phenotype, BKV specificity and functionality by examining cytokine production and cytotoxicity. Results: Cellular proliferation was seen in all of 10 normal donors with a mean increase of 6.4 fold in total cell number. All cellular products were 〉84% CD3 positive (Mean 96%, SEM 1.3) with CD4 and CD8 ratio varying significantly between individual donors (CD4 range 9.7 to 97.5%, mean 70.79; CD8 range 0.8 to 77.0%, mean 23.3). Cells were of memory phenotype, being CD28+ (mean 86.1%, SEM 6.5), CD45RO+ (mean 84.1%, SEM 5.9) and a variable proportion were of central memory phenotype (CD62L+ mean 21.6%, range 6.9 to 55.0). Cytokine responses to stimulation with BKV peptides could be elicited in 5 of 6 evaluable donors. Multiple cytokines were produced by the responding cells: IFN-γ (mean 29.9% of CD3 cells, range 4.5 to 78.8), TNF (mean 19.9%, range 2.7 to 63) and IL-2 (mean 12.8%, range 1.2 to 37.8). Cytokine responses were seen in both CD4 and CD8 cells and showed significant individual variation. VP1 and LTA specific cells dominated most cultures while a smaller percentage of the cells were specific for VP2, VP2 isoform 3 and sTA. CD8 specificity was mainly confined to a single protein whereas CD4 responses tended to be of lower magnitude but broader specificity. Cultures exhibited cytotoxic activity with the lysis of BKV antigen coated target cells in a pattern that correlated with the presence of CD8 positive cytokine producing cells (up to 78.9% specific lysis at effector to target ratio of 20:1). Discussion: The clinical utility of this product remains to be determined. Potential uses include prophylaxis and therapy of reactivation of BK virus after hemopoietic stem cell or renal transplantation. This method for large-scale expansion of BKV specific CTL could be utilised for analysis of BKV targeted immune responses and epitope identification. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2444 Poster Board II-421 Alloreactive effector T cells are the central to graft-versus-host disease (GVHD), a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HSCT). In GVHD host antigens are never cleared and alloreactive effector T cells are continuously generated over a period of several months or longer, but their suppression and control have proven to be difficult in practice. Using mouse models of GVHD directed against minor histocompatibility antigens (miHAs), we demonstrate that alloreactive effector T cells proliferate and persist upon chronic exposure to alloantigens via reactivation of stem cell transcriptional programs normally expressed in embryonic stem cells and neural stem cells. Many activated stem cell genes in effector T cells were distinct from those in memory T cells and were maintained at high levels upon T cell receptor activation, suggesting a specific role in chronically activated effector T cells. One of these genes, Ezh2, encodes a chromatin modifying enzyme essential to the proliferation, survival and differentiation of stem cells, was upregulated in CD8+ effector T cells upon antigenic stimulation and downregulated when the antigen was withdrawn. Pharmacologically inactivation of EZH2 with 3-Deazaneplanocin A inhibited effector T cell proliferation and survival. Silencing Ezh2 independently validated that Ezh2 was important for regulating effector T cell proliferation and expression of many stem cell genes. To further evaluate whether alloreactive CD8+ effector T cells obtained stem cell-like properties, e.g. the ability to self-renew to continually generate effector cells, we adoptively transferred highly purified miHA H60-specific (H60+) CD8+ effector T cells into secondary allogeneic and congenic recipients, respectively. As compared to congenic recipients, allogeneic recipients had 80-fold more proliferating H60+CD8+ effector T cells. These donor H60+CD8+ effector T cells expressed high levels of CD122, CD69, CXCR3, PD1, IFNγ and Granzyme B, required miHA H60 stimulation to sustain their replication with effector function and expression of stem cell genes, and caused severe GVHD in secondary allogeneic recipients. These results indicate that stem cell transcriptional programs expressed in embryonic and neural stem cells may play important roles in effector T cells. Among these stem cell genes, Ezh2 emerges as an important therapeutic target in modulating alloreactive T cell-mediated GVHD. Disclosures: Zhang: University of Michigan Comprehensive Cancer Center: Research Funding; Damon Runyon Cancer Research Foundation: Research Funding.

Description: Abstract 2436 Poster Board II-413 Sensitive in vivo imaging methods have advanced the fields of stem cell transplantation, graft-versus–host disease (GVHD) and graft-versus-tumor responses (GVT). Near-infrared (NIF) fluorescent proteins (FP) appear advantageous for deeper tissue penetration due to minimized absorbance by hemoglobin, water and lipids. Therefore we tested whether a recently published NIF FP (FP635, “Katushka”) could serve as a single reporter for whole body and single cell imaging. To compare signal intensities of eGFP and FP635 we generated fluorescent MOSEC cell lines (mouse ovarian cancer), titrated them in vitro and subcutaneously (s.c.) in vivo in Balb/c nu/nu mice. MOSEC FP635 showed twice the signal intensities compared to MOSEC eGFP in vitro by spectral fluorescence imaging (FLI). In vivo the eGFP signal was attenuated 〉60% in contrast to only 20% for FP635 from subcutaneous sites. However, FP635 signals from deep tissue layers were quenched. To address whether reduced signal attenuation of FP635 may allow sensitive visualization of immune processes by FLI and multiphoton-laser-scanning-microscopy (MPM) we generated transgenic mice in the genetic C57Bl/6 (B6) background, expressing FP635 under the ubiquitin promoter. Transgenic founders were selected upon signal intensities of leukocyte populations measured by flow cytometry in the PerCP channel. Combination of FP635 with colors other than red were possible for multiparameter flow cytometry. Next, eGFP, DsRed and FP635 splenocytes from transgenic donors were titrated as described above. In vitro signal intensities of FP635 splenocytes were 〉5 times lower compared to the other two FPs. FP635 signal absorption in vivo was low (30%) which is consistent with MOSEC titration results. In vivo DsRed detection was most sensitive and signals were similarly attenuated as FP635 in contrast to eGFP (60%). Subsequently, we aimed to visualize FP635 in a model of GVHD, where alloreactive T cells undergo massive expansion. Balb/c nu/nu mice were lethally irradiated and transplanted with 5×106 B6.WT bone marrow cells plus either 2×107 B6.DsRed+Luciferase+ or 2×107 B6.FP635 splenocytes. Sensitivity for DsRed cell detection was superior over FP635 cells. FP635 signal was only weakly detectable in lymph nodes (LN) by ex vivo FLI, where DsRed signals were detectable at earlier timepoints and LNs were even visualized by in vivo FLI. DsRed+ Luciferase+ double transgenic splenocytes allowed direct comparison of bioluminescence imaging (BLI) to FLI. Timely in vivo visualization of immune cells in deep tissues was feasible only by BLI. After whole body imaging the suitability of FP635 for MPM was checked by co-injecting eGFP B cells and either DsRed or FP635 T cells intravenously into RAG-/- mice. As FP635 is a NIF FP we expected to achieve deeper tissue penetration in hemoglobin rich organs, such as the spleen, in single cell microscopy. After 6 weeks of adoptive cell transfer we imaged spleens by MPM. Tissue penetration depths of DsRed or FP635 T cells were compared to eGFP B cells. No advantage in penetration depth of FP635 over DsRed was measured. Photobleaching is an important factor for microscopy, especially if cells are to be tracked over long time. FP635 transfected 293T cells bleached faster (t1/2=108 sec) than 293T cells transfected with eGFP (t1/2〉900 sec) or DsRed (t1/2=411 sec). These experiments indicate that very high expression levels of FP635 need to be achieved for imaging. The signal attenuation of FP635 is low which may increase the sensitivity but in our hands DsRed showed comparable characteristics. Yet, the fast photobleaching of FP635 compared to the broadly established FPs DsRed and eGFP may be disadvantageous for long term microscopic tracking of cells. Our data indicate that BLI is by far superior over FLI in sensitivity and tissue penetration for whole body imaging of immune cells. However, FLI of red or near-infrared clonally selectable tumor cell lines may provide a welcome color addition to study immune cell-tumor interactions in combined models of BLI and FLI. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2430 Poster Board II-407 After transplantation, hematopoietic stem/progenitor cells (HSPCs) home to the marrow, where they engraft and self-renew. To explore the mechanism of this multi-step and dynamic repopulation process, we performed the first in vivo adult vertebrate chemical screen aimed at identifying novel chemical modulators of HSPC repopulation using a novel competitive marrow transplantation assay in zebrafish. To distinguish between the donors, we used ubiquitous GFP or DsRed2 transgenic fish, Tg(β-actin:GFP) and Red GloFish®, for marrow cell isolation. 20,000 GFP+ cells were treated with a chemical and mixed with 80,000 untreated DsRed2+ marrows. This pool of cells was injected retro-orbitally into a transparent adult zebrafish. After a recovery period, the fish was then anesthetized and the region of the kidney (the adult site of hematopoiesis) was examined by fluorescence microscopy. The competition between the two donors was determined by analyzing the ratios of GFP and DsRed2 fluorescence intensity with ImageJ software. Using this assay, we demonstrated that dmPGE2 and/or GSK-3β inhibitor treatment of GFP+ marrows for 3 hrs could dramatically increase repopulation in fish. A chemical library of 480 chemicals with known bioactivities was screened using this in vivo assay. GFP+ marrows were incubated with different chemicals for 3 hrs and ten recipient fish were transplanted for each chemical. By examining engraftment at 4 weeks, we found 10 chemicals that improved HSPC repopulation. Based on the known bioactivity, these chemicals were categorized into several signaling pathways, including prostaglandin metabolism and retinoic acid pathways. Several of the compounds also increased HSC formation in zebrafish embryos, indicating that some pathways might be shared by different developmental stages. To examine whether the bioactivities of these hits are conserved in mammals, CD45.1 mouse whole bone marrow cells were treated with hit compounds for 3 hrs and competitively transplanted into CD45.2 recipients. Peripheral blood was sampled at 3, 6, 12, and 20 week post transplant. Several hits were confirmed to increase long-term chimerism in mice. The retinoic acid pathway has been shown to play an important role in hematopoiesis. Among the six retinoic acid receptor (RAR) agonists in the chemical library, which includes all-trans retinoic acid (ATRA), only two structurally highly related compounds, AM-580 and TTNPB scored positive in the screen. These two compounds have distinctive chemical moieties from ATRA. This structural difference likely leads to stronger agonistic effects on RAR than ATRA and resists degradation. In conclusion, the in vivo chemical screening using zebrafish competitive marrow transplantation provides a successful example of phenotypic screening in whole adult vertebrates. The discovery of novel repopulation modulators should provide a better understanding of signaling events that regulate homing and self-renewal, and may have clinical application in marrow or cord blood transplantation. Disclosures: Zon: FATE Inc: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Stemgent: Consultancy.

Description: Abstract 2398 Poster Board II-375 B-catenin is the central effector molecule of the canonical wnt signaling pathway which governs cell fate and differentiation during embryogenesis as well as self-renewal of hematopoietic stem cells. Deregulation of the pathway has been observed in various malignancies including myeloid leukemias where over-expression of β-catenin is an independent adverse prognostic factor. In the present study we examined the functional outcome of stable β-catenin down-regulation through lentivirus-mediated expression of short hairpin RNA (shRNA). Reduction of the β-catenin levels in AML cell lines and patient samples diminished their in vitro proliferation ability without significantly affecting cell viability. In order to study the role of β-catenin in vivo, we transplanted leukemic cell lines with control or reduced levels of β-catenin in NOD/SCID animals and analyzed the engraftment levels in the bone marrow. We observed that while the immediate homing of the cells was not affected by the β-catenin levels, the bone marrow engraftment was directly dependent on its levels. Subsequent examination of bone marrow sections revealed that the reduced engraftment was partly due to the inability of the cells with lower β-catenin levels to dock to the endosteal niches, a finding that was confirmed in competitive repopulation assays with untransduced cells. When we examined the expression levels of adhesion molecules and integrins in engrafted cells in vivo, we observed a significant down-regulation of CD44 expression, a molecule that participates in the interaction of HSCs with the niche. Gene expression analysis of the components of the wnt signaling pathway showed that the pathway is subject to tight transcriptional regulation with minor expression deviations. We did, however, observe an up-regulation in components that participate in the non-canonical wnt signaling pathways such as the WNT5B ligand. Ongoing experiments in normal cord blood CD34+ cells will determine the in vivo role of β-catenin signaling in normal hematopoietic progenitors. In conclusion, our study showed that β-catenin comprises an integral part in the development and progression of AML in vivo, indicating that manipulation of the wnt pathway may hold a therapeutic potential in the management of AML. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 245 Background: The incidence of MDS in Canada is not known. Diagnosis of MDS is often challenging as dysplastic features on bone marrow may be non-specific, requiring exclusion of other disorders. The province of Manitoba, with a population of 1.2 million, has a cancer registry which has included patients with MDS since 2001. In this province, hematology diagnostic services are centralized at two teaching hospitals and the few bone marrows performed outside are reviewed centrally. This provided us with the opportunity to use registry data and bone marrow records to determine the incidence of MDS. We hypothesized that for an accurate estimate, a proportion of MDS cases would require follow-up data. Methods: Retrospective study to examine all cases of MDS, which included chronic myelomonocytic leukemia (CMML) diagnosed in Manitoba. All adult Manitobans diagnosed with MDS and CMML (excluding RAEB-T), from 01/2006 to 12/2007 were identified from the cancer registry using ICD-O-3 topography code C42.1 and morphology codes 9980/3, 9982/3, 9983/3, 9985/3, 9986/3, 9987/3, 9989/3 and 9945/3. Bone marrow records for the same period were reviewed to identify all cases that had features of MDS. The clinical charts of all these patients were reviewed centrally to exclude those whose clinical course or repeat investigations suggested an alternative diagnosis. Results: A total of 80 patients with newly diagnosed MDS were identified. The age adjusted incidence of MDS was 3.26/100,000. Incidence was higher in men (4.05/100,000) as against women (2.57/100,000). Incidence varied significantly with age at diagnosis: 80yr: 21.93. Eleven cases (13.75%) were not known to the cancer registry but were detected on reviewing the bone marrow data. From the registry, nine cases (11.25%) were excluded as the chart review and follow-up revealed alternative diagnoses. Conclusions: The incidence of MDS for Manitoba is similar to published rates in Europe and the USA. This may be an underestimation of the actual incidence, as elderly patients may not undergo bone marrow examination if the therapeutic intervention is only supportive. Cancer registries that include MDS based on one-time bone marrow reports should include a review process of confirming or excluding the diagnosis of MDS based on follow up investigations and course of illness. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2447 Poster Board II-424 Allogeneic bone marrow transplantation (BMT) represents the most effective treatment for patients with high risk and relapsed hematologic malignancies. One of the major complications of allogeneic BMT is graft-versus-host disease (GvHD), which is caused by donor T cells reacting against host antigens. These same alloreactive donor T cells can provide a beneficial ¡°graft-versus-leukemia¡± (GvL) effect as well resulting in reduction in leukemia relapse. Because regulatory T cells (Tregs) have been shown to suppress GvHD while preserving GvL, their use in the allogeneic transplant setting provides a promising strategy to treat GvHD. However, three major obstacles prevent their routine use in human clinical trials: 1) the low circulating numbers of Tregs in peripheral blood, 2) loss of suppressor activity following ex vivo expansion and 3) the lack of Treg-specific markers to purify ex vivo expanded Tregs. Foxp3 is a forkhead transcription factor which is both exclusively expressed in Tregs and, when overexpressed in conventional effector T cells (Teff), can convert these Teff into functionally suppressive Treg-like T cells. The Foxp3 locus is unmethylated in Tregs while highly methylated and silenced in all other T cells. Several groups have shown that the hypomethylating agent azacitidine (AzaC) induces FOXP3 expression in non-Tregs. Furthermore, we have shown that treatment of anti-CD3/CD28 antibody-coated bead-activated CD4+CD25- T cells with AzaC results in robust and prolonged (〉7 days) expression of FOXP3. AzaC-induced FOXP3 expression is also associated with a potent Treg-like suppressive phenotype in vitro. Thus, we hypothesize that AzaC treatment of mice after allogeneic BMT will dramatically mitigate GvHD while preserving GvL via transcriptional regulation of Foxp3 in alloreactive Tconv. In murine T-cell depleted BMT model (B6¡æBalb/c; 900 cGy TBI) with delayed infusion of conventional T cells (Tconv) (2 ×106) at day 11 post BMT, followed by subcutaneous treatment of AzaC (2 mg/kg at days 15, 17, 19, and 21 post BMT), we found that AzaC dramatically suppressed GvHD caused by allogeneic donor T cells while maintaining donor (H2Kb) engraftment of all lineages. We found that the AzaC group had significantly higher FOXP3+ Tregs than in PBS control group and that these Tregs were derived from donor T cells, suggesting that the suppression of GvHD was mediated by AzaC-induced Tregs. We further tested whether AzaC treatment of mice transplanted with allogeneic T cells preserve GvL while mitigating GvHD. Using the same murine allogeneic BMT model, Click Beetle Red luciferase-expressing A20 leukemia cells (BALB/C derived) were injected with T-cell depleted BM and 10 × 106 Tconv and in vivo bioluminescence imaging was performed to assess tumor burden in vivo post transplant. We found that AzaC treatment mitigated GvHD without abrogating GvL (Fig. 1) or donor engraftment. Thus, the adminstration of hypomethlating agents like AzaC in vivo after allogeneic stem cell transplant dramatically reduces GvHD while maintaining both donor engraftment and a potent GvL effect providing the foundations for future clinical trials. Disclosures: DiPersio: Genzyme Corporation: Honoraria.

Description: Abstract 2383 Poster Board II-360 Elevated expression of CXCR4, a receptor for SDF1, with Internal Tandem Duplication of Flt3 (ITD-Flt3) is an indicator of poor prognosis in patients with acute myeloid leukemia. We previously showed that ITD-Flt3 enhances migration of hematopoietic cells to SDF1, suggesting that ITD-Flt3 may facilitate dissemination of leukemia cells by modulating SDF1/CXCR4 signaling and that blocking this functional cross-talk between ITD-Flt3 and CXCR4 pathways may have therapeutic benefit. While identification of selective pathways in cells transformed by ITD-Flt3, which are distinct from normal cells is crucial to develop therapeutic agents without hematopoietic toxicity, the mechanisms responsible for aberrant migration induced by ITD-Flt3 are not known. We now demonstrate the existence of CXCR4 signaling pathways regulated by ITD-Flt3 that are distinct from normal CXCR4 signaling using genome wide transcription analysis. Ectopic expression of ITD-Flt3 in Ba/F3 cells enhances random cell migration and modulates expression of 1,675 genes out of 41,174 genes (4.1%) examined compared to control cells lacking ITD-Flt3. ITD-Flt3 down-regulated CXCR4 mRNA by 55% compared to control and modulated 36 additional transcripts implicated in cell migration and localization (0.09%, P

Description: Abstract 2381 Poster Board II-358 The natural history of patients (pts) who fail or relapse after chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab (FCR) has not been established. Three hundred pts received FCR as initial therapy for progressive or advanced chronic lymphocytic leukemia (CLL) (Tam CS; Blood 112(4):975-980, 2008). Fifteen (5%) pts failed to respond, 72% achieved a CR and 22% a PR. Treatment failure occurred in 18 pts because of the development of AML, MDS or Richter's transformation and there were 15 deaths in remission (infection (7), cancer (6), or cardiac events (2)). Fourteen relapsed pts have not received therapy and are considered to be “watch and wait.” One hundred and twelve pts have received therapy. A large variety of treatment programs were administered at time of relapse during the ten years of the study. The most commonly used were FCR-like regimens (33) with or without lumiliximab or bevacizumab, FCR + alemtuzumab (CFAR) 9 pts, rituximab-based regimens (28) +/- GMCSF or steroids, Campath-based regimens (16) +/- rituximab, and a variety of other phase I and miscellaneous salvage treatments. 79 pts received salvage therapy at M. D. Anderson Cancer Center (MDACC) and the 33 others in their local community. 17 patients (16%) achieved a CR and 46 a PR (4%). CR rates were 15% for FCR, 56% for CFAR, 4% for rituximab regimens, 31% for alemtuzumab regimens and 4% for other regimens. While higher CR rates were noted in alemtuzumab regimens, no difference in time-to-treatment failure or survival was noted. The median overall survival was 33 months with a 40% five-year survival rate. A number of characteristics shown in Table 1 associated with complete remission and overall response rate. Outcome of 1st Salvage – FCR Relapsed/Refractory (112 pts) Characteristic Value Patients %CR %OR Med Surv (Mths) Age / years

Description: Abstract 2377 Poster Board II-354 Fludarabine containing regimens has become the gold standard for first-line treatment of CLL. The prognosis for the response is usually done by mutation analysis and cytogenetics. These types of analyses are time consuming and could not be available in general practice. Staging is very easy tool for predicting the response, although it is not a matter of individual prognosis. The aim of the study was to find clinical data predicting the response. As a model, we have evaluated the response after 3 fludarabine containing regimens. Patients and methods 75 patients treated by fludarabin containing regimens (FC and FCR) were included (2002-2008). Staging was performed according to Binet (1977). Stage B and C patients were included. Lymph nodes were evaluated by CT and ultrasound. CD38 was done by CytoFlow (cut off 30%). Mutation analysis was studied by PCR and sequencing with cut off 98%. Early response(ER) was defined as PR and CR after 3 cycles of therapy, others were considered as nER. CR was defined according to NCI criteria. The patients were treated and followed-up by the single team of physicians, there were no losses of follow-us.SPSS - 17 statistical program was used for analysis. Results. In the whole group, median PFS was 25 mons . There were 40 ER pts(33 - PR and 7 - CR).Median PFS in ER patients was 38mons, in other patients (nER) – 17mons (p= 0.0001). After 6 cycles of therapy, the overall response was 100%; CR was 83% and 7% PR I ER pts, in nER- resp- 67%, 23% and 41% ( p 〈 0,001). Differences of median PFS according to standard prognostic factors is presented in table 1: Thus, ER patients with standard adverse prognostic factors did better than nER with similar prognostic factors. ER patients in comparison to nER had higher median PFS on both FC (28 mons vs 14 mons, p=0.001) and FCR (58 mons vs 18 mons, p=0.018) regimens. Conclusion. The early response (PR and CR) after three fluadarabine containing regimens is a good predictor for PFS. More intensive treatment should be considered for patients without early response. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2284 Poster Board II-261 Background: To evaluate the role of autologous and allogeneic SCT in the treatment of PTCLs, Japan Study Group for Cell Therapy and Transplantation conducted a multicenter retrospective survey in Japan and Korea. Methods: After excluding patients with adult T-cell leukemia/lymphoma and NK-cell tumors, patient data were newly collected from 330 patients (222 male and 108 female) with a median age of 49 years (range, 13–71) who underwent SCT between 9/1991 and 12/2008 (196 autologous and 134 allogeneic including 31 patients with previous autograft). Allogeneic SCT (53 BM, 54 PB, 1 BM+PB, 26 CB) was performed using a reduced-intensity conditioning (RIC) in 84 patients (63%). While a pathologic central review will be performed, currently there were 159 (48%) patients with PTCL, not otherwise specified, 63 (19%) with angioimmunoblastic T-cell lymphoma, 47(14%) with anaplastic large cell lymphoma (23 ALK-negative, 14 ALK-positive and 10 unknown), 12 (4%) with enteropathy-associated T-cell lymphoma, and others. The disease status at transplant in the allo-group was significantly worse than that in the auto-group (Table 1). The median number of chemotherapy regimens was 2 (range, 1–7), and the median duration between diagnosis and transplant was 267 days (range, 120-4889 days). Results: The median follow-up for surviving patients was 45 mo (range, 2.3–141 mo). There was no significant difference in overall survival among different groups, including histological subtypes, RIC and myeloablative conditioning in the allo-group and high-dose chemotherapy regimens in the auto-group. Early survival rate after transplant was significantly better for auto-group than allo-group (Wilcoxon P=0.001), but the difference was marginal in the total course (Logrank P=0.06) (Figure). The non-relapse mortality (NRM) in the auto-group was significantly lower than that in the allo-group (P1), cell source (CB/BM+PB), and performance status (PS; 〉1), stage, chemorefractory disease, international prognostic index (IPI; H-I/H risk) and prognostic index for PTCL, unspecified (PIT; group 3/4) at transplant. The risk factors in the allo-group were bulky mass at diagnosis, age (〉50 years), cell source, and PS, stage, IPI and PIT at transplant, while those in the auto-group were age (〉40 years), recurrence after frontline therapy, number of chemotherapy regimens, and stage, chemorefractory disease, IPI and PIT at transplant. Conclusions: Despite a worse disease status at transplant in the allo-group, the overall survival was comparable to that in the auto-group. This supports the notion that early allogeneic SCT is a valuable treatment option for PTCLs, although a large-scale randomized trial to identify a suitable upfront-transplant type for chemosensitive patients with PTCLs is warranted. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 230 Allogeneic hematopoietic stem cell transplantation (HSCT) provides powerful therapeutic activity through elimination of cancer cells by donor T cells. However, its success is limited by life-threatening graft-versus-host disease (GVHD). Novel immunomodulatory approaches are needed to effectively control GVHD. Notch signaling is a highly conserved cell-cell communication that plays an essential role in T cell development and can influence differentiation and function of mature T cells in a context-dependent fashion. Using several mouse models of allogeneic HSCT, we report that inactivation of Notch signaling in donor T cells inhibits the induction of severe GVHD while preserving significant graft-versus-leukemia (GVL) activity. To block canonical Notch signaling in mature T cells without interfering with T cell development, we used conditional expression of the pan-Notch inhibitor DNMAML (ROSADNMAMLf × Cd4-Cre mice). DNMAML CD4+ T cells derived from donor C57BL/6 (B6) mice had normal initial activation, proliferation and expansion, but failed to differentiate into effector T cells mediating severe GVHD in lethally irradiated major histocompatibility complex-mismatched BALB/c recipient mice. Notably, Notch-deprived alloreactive T cells retained potent GVL activity, leading to improved overall survival of the recipients. Alloreactive DNMAML T cells showed impaired production of IL-2 and multiple inflammatory cytokines (e.g. TNFα, IFNγ and IL-17), as well as defective induction of selected effector molecules (e.g. granzyme B and perforin). The specificity of these findings was independently validated using donor CD4+ T cells with conditional inactivation of Rbpj, encoding CSL/RBP-Jk, a transcription factor that is absolutely required for Notch-mediated transcriptional activation. To further evaluate the effects of Notch signaling in both CD4+ and CD8+ alloreactive T cells, we infused control B6 or DNMAML B6 T cells into unirradiated haploidentical B6xDBA/2 F1 and irradiated minor histocompatibility antigen (miHA)-mismatched BALB/b recipients. Donor DNMAML CD4+ and CD8+ T cells both showed significantly reduced ability to induce severe GVHD in these CD4+ help-dependent CD8+ T cell-mediated GVHD mouse models. These results indicate that Notch is a novel critical signaling pathway regulating CD4+ and CD8+ T cell responses in multiple mouse models of allogeneic HSCT. Given the beneficial immunomodulatory effects of Notch inhibition in alloreactive donor T cells, Notch signaling appears as a promising therapeutic target to limit the harmful effects of GVHD while preserving beneficial GVL activity after allogeneic HSCT. Disclosures: Zhang: University of Michigan Comprehensive Cancer Center: Research Funding; Damon Runyon Cancer Research Foundation: Research Funding. Maillard:University of Michigan Comprehensive Cancer Center: Research Funding; Damon Runyon Cancer Foundation: Research Funding; ASH Scholar Awards : Research Funding.

Description: Abstract 2291 Poster Board II-268 Haploidentical bone marrow transplantation (BMT) is an alternative treatment to patients with high-risk hematologic malignancy lacking a HLA-matched donor and those urgently need transplantation. We used a haploidentical-BMT protocol without ex vivo T cell depleted based on the knowledge that marrow grafts have 10 times fewer lymphocytes compared to peripheral blood stem cell grafts and granulocyte colony-stimulating factor (G-CSF) donor priming reduce the incidence of acute GvHD. Materials and Methods: 40 patients (median age of 32, 12-63) with advanced disease or leukemia with poor prognostic features underwent unmanipulated haplo-BMT: 22 with AML, 9 with ALL, 3 with CML, 3 with Hodgkin lymphoma and 3 with plasmacell leukemia. Status at disease: 22 early (first or second comple! te remission), 18 advanced (progressive or refractory disease). All pairs of donors and recipients were identical for one HLA haplotype and incompatible at 2 or 3 loci.The myeloablative conditioning regimens used were different; antithymocyte globuline, cyclosporine, metotrexate, mycophenolate mofetil and basiliximab were used for GvHD prophylaxis. Donors were primed with filgrastim at 4 micrograms/Kg/d for 7 consecutive days. Bone marrow cells were harvest on the 8 day and were infused unmanipulated. Results: the median dose of total nucleated, CD34+ and CD3+cells was 7×10e8/Kg (1.01-28.7), 2.3×10e6/Kg (1.17-6.0) and 23.3×10e6/Kg (9.7-66.6) respectively. 1 patients had a primary graft failure and 5 patients died early prior to engraftment. In the remaining 34 patients, engraftment was seen with median time to granulocyte and platelet recovery of 22 and 27 days respectively; acute GvHD was grade 0 in 17 patients (50%), grade I in 9 (26%), grade II in 7 (20%) and grade IV in 1 (3%). In 29 evaluable patients, chronic GvHD was limited in 3 (10%) and extensive in 1 (3%). Transplant-related mortality at 6 months for early and advantage stage was 22% and 35% respectively. After a median follow up of 18 (3-42) months, 8 patients relapsed; 11 patients (50%) in the early stage and 4 (22%) in advanced phase are now living in haematological remission. The 1-year Kaplan-Meyer probability of disease-free survival is 45% for all patients. Conclusion: the high engraftment rate, low incidence of grade II-IV acute GvHD and an acceptable TRM suggest that G-CSF-primed marrow grafting along with sequential immunosuppression could provide an excellent alternative for patients who lack matched donors. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2341 Poster Board II-318 Background. The clinical heterogeneity of chronic lymphocytic leukemia (CLL) requires parameters to stratify patients into prognostic subgroups to adapt treatment ranging from ‘watch and wait’ to allogeneic stem cell transplantation. To this end, several parameters such as lymphocyte doubling time, β-2 microglobulin, CD38 and ZAP-70 expression, immunoglobulin variable heavy chain (IgVH) mutation status and genetic abnormalities, as assessed by fluorescence in situ hybridization (FISH), have been integrated in clinical practice. Aims. In the present study, we investigated by FISH the incidence of the known major cytogenetic alterations (+12 and 13q14, 17p13, 11q23 deletions) in a series of Binet A B-CLL patients included in the prospective O-CLL1 GISL study started in April 2007. Methods. Molecular markers characterization and FISH analyses were performed as previously reported (Cutrona et al. Haematologica, 2008; Fabris et al. GCC, 2008). A cut-off value of 2% was used to distinguish mutated and unmutated patients. CD38 and ZAP-70 were determined by flow-cytometry and a 30% cut-off was used to distinguish between positive or negative cases. Results. Up to date, 326 patients have been enrolled in the trial and FISH data concerning trisomy 12 and 13q14, 17p13, 11q23 deletions were available in 305 patients. At least one abnormality was found in 197 (64%) cases. The most frequent was del(13)(q14) (150/305, 49%), followed by +12 (40/303, 13%) (in one and three cases accompanied by 17p13 and 13q14 deletions, respectively), del(17)(p13) (7/305, 2%) and del(11)(q23) (17/305, 5%). 13q14 deletion was found as a sole abnormality in 134 patients; in the remaining cases, it was combined with +12 (3 pts) and 17p13 (3 pts) or 11q23 (10 pts) deletions. Among patients with 13q14 deletions, 99 were monoallelic, 12 biallelic and 39 showed a combination of the two patterns. Biomarkers data were available in all of the patients: 95/305 (31%) cases had unmutated IgVH genes; ZAP-70 and CD38 were positive in 117/305 (38%) and 72/305 (23%) cases, respectively. Concerning the distribution of cytogenetic aberrations, the unmutated IgVH group included 29/150 (19%) 13q14 deleted cases, 23/40 (57%) cases with trisomy 12 and 4/7 (57%) and 16/17 (94%) with 17p13 and 11q23 deletions, respectively. ZAP-70-positive groups included 43/150 (28%) 13q14 deleted cases, 26/40 (65%) cases showing trisomy 12 and 5/7 (71%) and 12/17 (70%) with 17p13 and 11q23 deletions, respectively. Finally, CD38-positive cases included 18/150 (12%) 13q14 deleted cases, 26/40 (65%) cases carrying trisomy 12 and 5/7 (71%) and 7/17 (41%) with 17p13 and 11q23 deletions, respectively. The percentages of IgVH mutations significantly correlated with cytogenetic alterations; namely, 5.8±0.3 for cases with del(13)(q14), 4.6±0.4 for normal karyotype, 2.6±0.5 in +12, 0.3±0.2 in del(11)(q23), and 1.7±0.9 in del(17)(p13) cases (p for trend

Description: Abstract 2281 Poster Board II-258 Background: A decision analysis using the Markov process is a flexible and convenient analytical method that tracks the clinical events that occur after a certain decision with different probabilities and utilities over time. To address the role of allogeneic hematopoietic cell transplantation (allo-HCT) for acute myeloid leukemia (AML) in CR1, we performed a Markov decision analysis using newly collected clinical data from 2029 patients. Methods: Probabilities and other outcome data were derived from a database of adult AML patients that was constructed from case report files collected for this study. We included patients who were diagnosed with AML other than M3 between 1999 and 2006, aged 16 to 70 years, and who had achieved CR1 after 1 or 2 courses of induction chemotherapy. Using the software package TreeAge Pro 2009, we constructed a Markov decision model that compared 2 strategies: allo-HCT in CR1 (HCT group) and no allo-HCT in CR1 (CTx group). Possible health states considered in each decision included, for the HCT group, 1) no relapse without chronic GVHD, 2) no relapse with chronic GVHD, 3) relapse, and 4) dead, and, for the CTx group, 1) no relapse, 2) relapse, 3) second remission, 4) after salvage allo-HCT, and 5) dead. Quality-of-life (QOL) adjustments were made by incorporating time trade-off utilities that were derived from a questionnaire to 12 physicians who were familiar with the treatment of AML. The cycle length between state transitions was set at 3 months. Results: A total of 2029 patients were eligible for this analysis. The median age was 50 years, and the median follow-up of the surviving patients was 4.10 years. The proportions of patients with favorable, intermediate, unfavorable and unknown cytogenetic risk by SWOG criteria were 20%, 54%, 17% and 9%, respectively. Therapies performed at CR1 were allo-HCT in 494 patients (24%) and chemotherapy in 1535 patients (76%). Among 1076 patients whose HLA typing was performed for allo-HCT in CR1, 431 had HLA-matched or 1-antigen-mismatched related donors. Life expectancy and quality-adjusted life expectancy for the HCT and CTx groups in each risk category are summarized in Table 1. Life expectancy of the HCT group was longer than that of the CTx group (4.96 years vs. 4.44 years). However, quality-adjusted life expectancy of the HCT group was comparable to that of the CTx group (4.06 years vs. 3.98 years) due to a larger reduction of expected life length in the HCT group after QOL adjustment. In a subset analysis of the CTx group, patients with more favorable cytogenetic risk had a longer life expectancy. Whereas allo-HCT in CR1 was associated with a shorter life expectancy in patients with favorable-risk AML, allo-HCT in CR1 was associated with a longer life expectancy in those with intermediate-risk or unfavorable-risk AML. Adjustment for QOL did not change the preferred decision in the intermediate- and unfavorable-risk groups, although the survival advantages for allo-HCT in CR1 were less than those without QOL adjustment. In a subset of patients who had related donors, both life expectancy and quality-adjusted life expectancy were longer in the HCT group. Conclusion: The results of our decision analysis using the Markov process indicated that patients with intermediate- or unfavorable-risk AML have a longer life expectancy and quality-adjusted life expectancy with a decision of allo-HCT in CR1. Our results also showed that a Markov decision analysis that incorporates QOL may be useful as a decision-making tool for patients who might be candidates for allo-HCT. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2276 Poster Board II-253 Introduction: Mycophenolate Mofetil (MMF) controls the rate of synthesis of guanine monophosphate in the de novo pathway of purine synthesis thus suppressing the proliferation of B and T lymphocytes and preventing allograft rejection. Methods: 27 patients (pts) with age ( 21-66 yrs), diagnosed with acute myeloid leukemia (AML,n = 16), acute lymphoblastic leukemia (ALL,n=3), chronic myeloid leukemia (CML,n=2), aplastic anemia (AA,n=1), Hodgkins lymphoma (n=2), Non- Hodgkins Lymphoma (n=2), Myeloproliferative disorder (MPD, n=1) received GvHD prophylaxis with tacrolimus, methotrexate and MMF. Post BMT and before engrafment patients received MMF doses as shown in figure 1 to determine which MMF dosing strategy best targets the therapeutic Area Under the Curve (AUC) which is between 30 and 60 h*mcg/ml. Patients had normal bilirubin levels at the time of drug testing. Other factors including age, gender, disease, conditioning regimen intensity (Myeloablative (MAC) vs Reduced Intensity Conditioning (RIC), disease, organ function and concomitant medications were analyzed. We found the intravenous (iv) dose of 1.5 gm Q 6 to be optimal based on observed pharmacokinetics.We used a cohort of six patients (AML=4, CML=1, MPD=1). MPA and MPAG levels for a dose of 1.5 gm iv q 6 hrly and oral MMF at 1 gm q 8 hrly, were collected at pre-defined time points before engraftment, analyzed using liquid chromatography mass spectrometry. AUC0-8 (for q 8 hr oral dosing) and AUC0-6 (for q 6 hr intravenous dosing frequency) were calculated using a non-compartmental pharmacokinetic (PK) model with PK software (WinNonlin Professional 5.2). Oral dosing beyond 1 gm q 8 hours was not attempted due to GI intolerance. Results: The Cmax of MPA at an iv dose of 1.5 gm q 6hr ranged from 2-16.70 mcg/ml with a median Cmax of 9.40 mcg/ml and a median AUC 0-6* hr of 26.14 mcg/ml. The Cmax MPA for oral dosing of 1 gm q 8 hr ranged from 3.70- 9.40 mcg/ml with a median Cmax of 4.45 ug/ml at 3 hrs and a median AUC 0-8* hr of 18.40 ug/ml. The box and whisker plot of MPA concentration (mcg/ml) vs Dose/regimen reveals the median concentration achieved by dosing intravenously q 6 hr and through oral at q 8 hr are similar, the box representing 25th -75th quartile and the error bars representing 10th -90th quartile. In data not shown, MPAG levels increased linearly while MPA levels increased less than proportionally with dose, suggesting that the nonlinear PK relationship of MPA levels is not due to the influence of glucuronidation but may be an indicator of a saturable distribution process to tissues or erythrocytes”. Conclusion: The conditioning intensity, GVHD prophylaxis did not affect MPA levels in this cohort of six pts with normal hepatic function. The maximum IV dose at 1.5 gm q 6 hrs generated similar levels to those with 1 gm orally q 8 hrs. Further dose escalation does not result in higher MPA levels. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 1843 Poster Board I-869 Introduction: The mammalian target of rapamycin (mToR) plays a crucial role in cell growth due to its role as nutrient dependent regulator of important cytokine signaling pathways. In multiple myeloma, mToR is involved in the phosphoinositide-3-kinase (PI3K)-AKT pathway which can be activated by the loss of the tumor suppressor phosphatase and tensin homolog (PTEN) or by stimulation with growth and survival factors such as interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1). Inhibitors of the mToR pathway (sirolimus/rapamycin, everolimus and temsirolimus) are approved for immunosuppression and/or cancer treatment. However, the clinical activity of mToR inhibitors may be limited by the fact that, after inhibition of the rapamycin-sensitive mToR-Raptor complex, AKT is activated by the rapamycin-insensitive mToR-Rictor complex. In this regard, the inhibitory effect of mToR inhibitors was evaluated in combination with PI3K inhibitors in vitro and in vivo. Results: Rapamycin and everolimus induced a dose-dependent growth inhibition in six human malignant plasma cell lines. Growth inhibition was mediated by G1 cell cycle arrest and in a subset of cell lines by induction of apoptosis. Overexpression of Bcl-XL or Mcl-1 proteins did not prevent from apoptosis induction by mToR inhibitors, nor did sensitivity to rapamycin-induced apoptosis correlate with the p53 mutation status. In the INA-6 SCID mouse xenograft model, treatment with rapamycin resulted in a significant survival benefit compared to untreated mice. Six out of 14 rapamycin treated mice did not develop plasmacytomas during the observation period of 149 days. Remarkably, short term treatment of plasmacytoma bearing mice led to a significant shrinkage of the plasma cell tumor. Explanted tissue showed apoptotic plasma cells, a finding confirmed by immunohistological staining using an antibody specific for the human cleaved form of poly (ADP-ribose) polymerase (PARP). The combination of rapamycin and the PI3K inhibitor Ly294002 led to an increase of growth inhibition in all tested plasma cell lines. The additional growth inhibition by Ly294002 appeared to be due to AKT activation upon mToR inhibition by the rapamycin-insensitive Rictor complex, indicated by increased AKT phosphorylation at Ser473 as determined by Western blot analysis. Conclusion: Clinical trials currently evaluate mToR inhibitors for their potential to expand treatment options for myeloma patients. The data presented here suggest that a combination of mToR inhibitors with PI3K inhibitors may lead to additive therapeutic chances. Disclosures: Guenther: Novartis: Consultancy, Research Funding. Gramatzki:Novartis: Consultancy, Research Funding, Speakers Bureau.

Description: Abstract 1826 Poster Board I-852 Patients with multiple myeloma (MM) typically present with the disease spread diffusely throughout the bone marrow (BM). This fact points to the role MM cell trafficking plays in disease progression. Like normal plasma cells, MM cell trafficking is directed by the cytokine, SDF-1 and its receptor, CXCR4. Using the small bicyclam molecule, AMD3100, to block the SDF-1/CXCR4 interaction, and in vivo flow cytometry to measure circulation time of MM cells in a xenograft model, we have previously shown that homing of injected AMD3100-treated MM cells to the bone marrow is perturbed. Soon after injection fewer AMD3100-treated than untreated MM cells are detected in mouse skull BM using in vivo fluorescence confocal microscopy. Furthermore, the combined treatment of established tumors with AMD3100 and bortezomib enhanced survival. Here we present data that the 2nd generation SDF-1/CXCR4 small monomacrocyclic inhibitor, AMD3465 behaves like its predecessor in blocking antibody binding to CXCR4 on MM cells, migration of MM cells toward SDF-1, and in vivo homing, but at concentrations 10-50 fold lower than AMD3100. Incubation with either 1uM AMD3465 or 50uM AMD3100 reduced antibody binding to CXCR4 on MM cells to isotype control levels. Likewise, treatment with AMD3465 reduced MM1S migration to 15% of that of untreated cells in a transwell migration assay. These in vitro effects translated in vivo into longer circulation times for AMD3465-treated MM cells than control cells. In vivo flow cytometry revealed that 40-50% of AMD3465-pre-treated cells remained in the circulation one hr after injection whereas untreated cells depleted to 20% of their original circulating cell count by that time. Future experiments will further describe the effect of AMD 3465 on MM cells in the BM microenvironment to answer whether AMD3465 can be used to mobilize MM cells from the BM environment or enhance survival when used in conjunction with therapeutic drugs. Disclosures Ghobrial: Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau.

Description: Abstract 182 Chromosomal alterations are a hallmark of acute lymphoblastic leukemia (ALL), but many cases lack a recurring cytogenetic abnormality. To identify novel alterations contributing to leukemogenesis, we previously performed genome-wide profiling of genetic alterations in pediatric ALL using single nucleotide polymorphism (SNP) microarrays. This identified a novel focal deletion involving the pseudoautosomal region (PAR1) of Xp/Yp in 15 B-progenitor ALL cases lacking sentinel chromosomal abnormalities, including six of eight cases of ALL associated with Down syndrome (DS-ALL). The deletion involved hematopoietic cytokine receptor genes, including IL3RA and CSF2RA, but due to poor array coverage, it was not possible to define the limits of deletion using SNP array data alone. To characterize this abnormality, we examined an expanded cohort of 329 B-ALL cases, including 22 B-progenitor DS-ALL cases. Strikingly, 12 (55%) DS-ALL cases harbored the PAR1 deletion. Mapping using high density CGH arrays showed the deletion to be identical in each case, and involved a 320kb region extending from intron 1 of the purinergic receptor gene P2RY8 to the promoter of CRLF2 (encoding cytokine receptor like factor 2, or thymic stromal lymphopoietin receptor). The deletion resulted in a novel fusion of the first, non-coding exon of P2RY8 to the entire coding region of CRLF2 in each case. The P2RY8-CRLF2 fusion resulted in elevated expression of CRLF2 detectable by quantitative RT-PCR, and flow cytometric analysis of leukemic cells. One DS-ALL case with elevated CRLF2 expression lacked the PAR1 deletion, but had an IGH@-CRLF2 translocation detected by fluorescence in situ hybridization (FISH). CRLF2 alteration was associated with gain of chromosome X (which was shown by FISH to result in duplication of the PAR1 deletion), deletion of 9p, and the presence of Janus kinase (JAK1 and JAK2) mutations. Ten (53%) of patients with CRLF2 alteration had JAK mutations, compared with two patients lacking CRLF2 abnormalities (P

Description: Abstract 1823 Poster Board I-849 The proteasome inhibitor bortezomib, a novel anti-myeloma (MM) agent, has recently drawn considerable attention to its anabolic actions on bone formation in patients with MM. Bortezomib was reported to enhance the activity of Runx2/cbfa1, an essential transcription factor for osteoblast (OB) induction, in mesenchymal stem cells to induce OB differentiation. However, because over-expression of Runx2 unexpectedly suppresses terminal OB differentiation or mineralization, there may be critical factors involved in OB differentiation in concert with Runx2 to achieve terminal OB differentiation in the treatment with bortezomib. Proteasome inhibition accumulates a variety of proteins and induces ER stress or unfolded protein response. Among proteins induced by ER stress, activating transcription factor-4 (ATF-4) plays a critical role in OB differentiation. ATF-4 is expressed in osteoprogenitors and preOBs following Runx2, and acts in concert with Runx2 to facilitate terminal maturation of OBs. However, it is unknown whether a change in ATF-4 protein levels plays any role in OB differentiation induced by proteasome inhibition. In the present study, we therefore explored the role of ATF-4 in OB differentiation by proteasome inhibition in Runx2-expressing immature OB lineage cells. Bortezomib dose-dependently increased ATF-4 protein levels in primary bone marrow stromal cells and ST-2 stromal and MC3T3-E1 preosteoblastic cell lines at concentrations higher than 10 nM as early as 3 hours. Because serum bortezomib levels reach around 100 nM (Cmax) with T1/2 of 3 hours after iv injection at therapeutic doses, bortezomib treatment in MM patients is expected to enhance ATF-4 protein levels in OB lineage cells. Interestingly, bortezomib treatment did not change mRNA levels of ATF-4 as well as βTrCP1, E3 ligase for ATF-4. Because translation of ATF-4 mRNA is triggered by ER stress response, it is plausible that the ATF-4 accumulation by bortezomib is mediated by the suppression of proteasomal degradation with subsequent induction of ER stress response. MM cell-derived factors and TGF-β released from bone by enhanced bone resorption suppress OB differentiation in MM bone lesions. Treatment with bortezomib was able to accumulate ATF-4 in the presence of MM conditioned media (CM) or TGF-β to the levels similar to those without MM CM nor TGF-β. Furthermore, bortezomib enhanced promotor activity of osteocalcin, a marker of mature OBs, as well as BMP-2-induced mineralized nodule formation in MC3T3-E1 cells, and these effects of bortezomib were suppressed by ATF-4 siRNA. These results demonstrate that bortezomib treatment accumulate ATF-4, and suggest that the effect of bortezomib on OB differentiation is mediated via an accumulation of ATF-4 protein in OB lineage cells. We have previously demonstrated that OB differentiation is suppressed in MM bone lesions, and that differentiated OBs suppress MM cell growth and survival. Thus, resumption of bone formation by bortezomib may further suppress MM cell growth in concert with its direct anti-MM actions. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 1820 Poster Board I-846 T cells contribute to the immunomodulatory control of the tumor in patients with monoclonal gammopathies. We previously found that CD3+CD8+CD57+TCRVβ+restricted cytotoxic T cell expansions were present in 48% of patients with multiple myeloma (n=221) and conferred a significant favorable prognosis. We now report the presence of these expansions in 70% of patients with Waldenstrom's Macroglobulinaemia (WM) (n=20) with a wide spectrum of the TCRVβ repertoire represented. Previous nucleoside analogue (NA) therapy, known to be associated with an increased incidence of transformation to aggressive lymphoma, significantly influenced the presence of TCRVβ expansions (χ2=11.6; p

Description: Abstract 2358 Poster Board II-335 Background: Chronic Lymphocytic Leukemia (CLL) is a common incurable hematologic malignancy. When therapy is required, maximizing durable responses is often at the risk of increasing toxicity. Thus, developing novel therapeutic agents that have minimal overlapping toxicity with currently used chemotherapy would be advantageous. To this end, we investigated LMP-420, a boronic acid containing purine nucleoside analogue, that potently inhibits tumor necrosis factor alpha (TNF) transcription in stimulated peripheral blood mononuclear cells (PBMCs) without affecting cell viability. Since TNF has been implicated in promoting CLL cell viability and can be produced by CLL cells themselves, we hypothesized that LMP-420 would be cytotoxic for CLL lymphocytes, either alone or in combination with fludarabine. Methods: To test the activity of LMP-420, we negatively selected circulating CLL cells from blood collected from patients using the RosetteSep B-cell enrichment cocktail (StemCell Technologies) and a Ficoll-Hypaque gradient. This method yields greater than 95% purity of malignant lymphocytes, determined by immunophenotyping CD5+CD19+ cells. Prognostic markers such as IgVH mutation status, CD38 and ZAP70 expression, and interphase cytogenetics were determined as previously described. We assessed the fractional toxicity and 50% effective dose (ED50) of LMP-420, fludarabine, or the combination, with the MTS colorimetric cytotoxicity assay, in which CLL cells were incubated for three days in Hybridoma media + 10% fetal bovine serum with serial dilutions of drug alone or in combination. Apoptosis was measured via annexin V flow cytometry methods and caspase 3/7 activity assays. We determined the effect of LMP-420 compared to fludarabine on the normal hematopoietic system by testing serial dilutions of both agents in killing normal PBMCs and in suppressing erythroid and myeloid colony formation. Results: The median ED50 of LMP-420 for CLL cells was 423 nM (range 0.01 to 2224 nM, n = 21). Two patients had high-risk cytogenetics (17p or 11q deletions), and their ED50 values for LMP-420 were 691 and 90 nM, respectively. The cytotoxic effect of fludarabine was potentiated on average 80 or 261 fold with the addition of LMP-420 at concentrations of 62 or 250 nM, respectively (ranges 1.14 – 947 and 1.19 – 2754). This agent killed malignant lymphocytes by apoptotic mechanisms in a dose-responsive fashion, as demonstrated by both Annexin V staining and caspase 3/7 activity assays. While LMP-420 has potent anti-CLL activity, it has minimal effects on normal hematologic cells. For example, fludarabine suppresses erythroid and myeloid colony formation by greater than 50% at a concentration of 1 uM, while this level of inhibition is seen for LMP-420 at a concentration of 90 uM. The average cytotoxic ED50 of LMP-420 on normal PBMCs using the MTS assay was greater than 90 uM, whereas for fludarabine, it was 5.3 uM. This finding was confirmed with apoptosis assays. Conclusions: The results of these experiments demonstrate that LMP-420, a novel inhibitor of TNF expression, has cytotoxic activity against CLL cells, including those with high-risk features. LMP-420 appears to increase the cytotoxic effect of the chemotherapy agent fludarabine, while imparting minimal increase in hematologic toxicity. Thus, LMP-420 is promising new therapeutic agent in CLL. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2347 Poster Board II-324 The human T cell leukemia/lymphoma 1 (TCL1) oncogene was initially identified as a target of chromosomal translocations and inversions at the 14q32.1 chromosome breakpoint region in T-cell prolymphocytic leukemia (T-PLL). Increased TCL1 expression is seen in follicular lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma, and chronic lymphocytic leukemia (CLL). Transgenic mice over-expressing TCL1 under control of the mu immunoglobulin gene enhancer develop a CD5+ B cell lymphoproliferative disorder that mimics human CLL, indicating that TCL1 plays a central and/or causal role in the pathogenesis of CLL. However, chromosome aberrations that constitutively activate TCL1 have not (yet) been identified in the vast majority of CLL patients, and therefore the oncogenic mechanism(s) of TCL1 activation in CLL remain unclear. There is growing evidence that external signals from the microenvironment control and regulate the survival and proliferation of CLL cells. Marrow stromal cells (MSC) are highly effective in protecting CLL cells from spontaneous and drug-induced apoptosis, and are used as a model system to study the marrow microenvironment. In order to explore the molecular cross talk between CLL cells and MSC, we co-cultured CLL cells with different MSC and analyzed gene expression changes induced by co-cultures with MSC, an approach similar to our recent study with nurselike cells (Blood 113:3050-8, 2009). For this, RNA was extracted from 19-purified CLL cells from 10 different patients (baseline expression, day 0). Also, the same patients' samples were co-cultured on stroma cells (KUSA-H1, NK-Tert) for 2 and 7 days. At these time points, RNA again was isolated after CD19-purification. Then, gene expression was determined using HG U133 plus 2.0 oligonucleotide arrays from Affymetrix. Gene expression changes were analyzed in individual patients' samples, comparing baseline samples' gene expression to samples after 2 and 7 of co-culture on MSC. We observed relatively homogeneous gene expression changes in CLL cells after co-culture with MSC. We found that TCL1 was among the top 5 genes that were most highly up-regulated by MSC, based on at least 3-fold up-regulation in at least 6 of the paired samples. We also found an up-regulation of TCL1 at the protein level when assessed by immunoblotting and flow cytometry in CLL samples after co-culture with MSC. These findings indicate that MSC can induce and regulate TCL1 expression in CLL, suggesting that the microenvironment plays an even greater role in the pathogenesis of this disease than previously recognized. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 1817 Poster Board I-843 Deletion of the short arm of chromosome 17 [del(17p)] is known to confer a poor prognosis in multiple myeloma (MM). However, no large study has been specifically dedicated to this purpose, especially in the novel drug era. We analyzed a series of 1324 patients with MM at diagnosis, treated within or according to IFM trials, and analyzed for del(17p). Most of the patients were under 65 years of age (1122 of the 1324 patients), and were treates either with a VAD-based induction or a Velcade®/Dexamethasone-based induction, followed by one or two courses of high-dose melphalan. Del(17p) was correlated to the major other prognostic parameters, both for event free survival and overall survival. Del(13) was observed in 71% of the patients with del(17p). A significant association was observed with anemia 〈 10g/dl (p=.05), with thrombocytopenia 〈 130 G/l (p3.5 mg/l (p=.006). No specific association was observed with t(4;14) (17% of the del(17p)-positive patients displayed t(4;14)). Del(17p) was observed in 10% of the patients. Del(17p) was associated with a very poor outcome, both in young and elderly patients. Actually, the prognostic value was observed only in patients displaying del(17p) in at least 70% of their plasma cells. The median EFS and OS were 18 and 28 months respectively, versus 30 and 69 months for patients lacking the del(17p). A particularly poor outcome was observed in patients presenting both del17p and t(4;14), with a median EFS of 4.5 months and a median OS of 12 months. Of particular importance, none of the treatment modality (high-dose melphalan, thalidomide, bortezomib) overcame the poor prognosis associated with del(17p), although patients lacking del(17p) displayed a better outcome when treated with Vel/Dex or MP-Thalidomide. In conclusion, del(17p) is associated with an especially poor outcome, independently of the type of treatment, including novel drugs. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 1811 Poster Board I-837 The prognostic significance of achieving complete remission (CR) in Multiple Myeloma (MM) has finally been accepted. However, available studies have been based on series with a median follow-up around 5 years. This time period is insufficient according to the current life expectation of MM. Aim To establish the real effect of prognosis of the different response categories in a cohort of MM patients treated with autologous stem cell transplantation (ASCT) after long term follow up. Patients and methods Follow-up from diagnosis of 344 MM patients transplanted between 1989 and 1998 has been updated. These patients were previously included in a study aimed at establishing the post-ASCT response significance in MM and to validate the EBMT classification (Br J Haemat 2000;109:438-46). It was possible to update the follow up of 322 patients as at April 2009. At this date 99 patients were alive with a median follow-up form diagnosis of 12.5 years. Response categories and evaluated cases were: i) Complete Response (IF-) (CR), n= 84 ii) near Complete Response (EF-/IF+) (nCR), n= 66 iii) Very good partial response (VGPR) (

Description: Abstract 1827 Poster Board I-853 Background It is now well established that cytogenetic abnormalities can affect the responses to therapies in multiple myeloma (MM) patients. Bortezomib, used alone or in combination with other agents, has been shown to overcome the adverse impact of several common unfavorable cytogenetic features. More recently, responses with lenalidomide and dexamethasone have been reported in patients with some types of unfavorable cytogenetics. Carfilzomib (CFZ) is a novel proteasome inhibitor that has demonstrated single agent activity in relapsed and/or refractory MM patients. The objective of this analysis was to provide the first preliminary information on the influence of cytogenetics in patients (pts) with relapsed and/or refractory MM treated with CFZ. Methods We evaluated 79 pts treated on two single agent CFZ studies (PX-171-003 and PX-171-004) in relapsed and/or refractory myeloma in which metaphase cytogenetics and/or FISH analysis for del 13q, t(4:14), and t(14;16) chromosomal abnormalities were available. Metaphase cytogenetics was conducted for all pts in the analysis; fluorescence in situ hybridization (FISH) results were available for 28 of the 79 pts. Twenty-one pts with relapsed and refratory MM (PX-171-003) and 58 pts with relapsed or refractory MM (PX-171-004) received CFZ at 20 mg/m2 IV on days 1, 2, 8, 9, 15, and 16 in a 28-day cycle for up to 12 cycles. For this analysis, responders were defined as pts who achieved at least a Minor Response (MR) [MR + Partial Response (PR) + Very Good Partial Response (VGPR) + Complete Response (CR)] by IMWG and EBMT criteria. Results The median age of analysed pts was 63 yrs and 100% of pts were relapsed, with 70% refractory to their last therapy. Analysis of their histories demonstrated prior thalidomide treatment in 75% of pts, prior lenalidomide treatment in 57%, prior bortezomib treatment in 55%, and prior stem cell transplantation in 84%. The response rate (≥MR) for the entire group of patients was 40.5%. Twenty three of 79 pts had at least one of the abnormalities. The presence of del 13q, t(4;14), or t(14;16) did not significantly change the response rates, with 43.5% of pts with one or more abnormalities responding compared to 39.3% with none. The median time to progression (TTP) for all patients in this analysis was 203 days. The TTP for pts with one or more of the abnormalities was 195 days and was not significantly different from the TTP of 208 days for pts with none of the abnormalities (Figure; P 〉 0.05). Conclusion In this preliminary analysis, CFZ showed comparable activity in relapsed and relapsed/refractory MM with del 13q and/or t(4:14), and/or t(14;16) versus none of these abnormalities, with ≥MR in 43.5% vs. 39.3% of patients, and a TTP of 195 vs. 208 days, respectively. Updated efficacy data and TTP data will be presented at the meeting. Disclosures Jakubowiak: Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Wang:Proteolix, Inc.: Research Funding. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Stewart:Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy; Takeda, Millenium: Research Funding; Genzyme, Celgene, Millenium, Proteolix: Honoraria. Kukreti:Celgene: Honoraria. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. McDonagh:Proteolix: Research Funding. Vallone:Proteolix, Inc.: Employment. Kauffman:Proteolix, Inc.: Employment. Vij:Proteolix: Research Funding.

Description: Abstract 1815 Poster Board I-841 Bortezomib is the first-in-class proteasome inhibitor with established activity in multiple myeloma (MM), which also increases osteoblast function both in vitro and in vivo. The addition of bortezomib to the combination of lenalidomide and dexamethasone (RD) regimen seems to increase the RD efficacy. There are very limited data in the literature for the effect of RD on bone metabolism while there are no reports for the effect of BRD on myeloma bone disease. The aim of this study was to evaluate the effect of BRD and RD on bone remodeling of patients with relapsed/refractory MM. We studied 91 patients who participated in a prospective study in which patients with pre-existing peripheral neuropathy (PN) grade

Description: Abstract 2283 Poster Board II-260 Background: Reduced intensity allogeneic transplantation was developed to harness graft versus leukemia immune effect to treat older patients and patients with comorbidities who are not eligible for conventional myeloablative transplant. Aim: To prospectively study the safety and efficacy of reduced intensity HCT in patients with myelofibrosis. Methods: Patients with intermediate or high risk MF were eligible if they had adequate organ function and at least 9/10 matched related or unrelated donor. Fifteen patients were conditioned with Fludarabine 40mg/m2 × 4 (days -5, -4, -3 -2) and Busulfan 130mg/m2 × 2 (day -3,-2). Thymoglobulin 2.5 mg/kg x 3 (day -3,-2 and 1) was additionally given to patients receiving unrelated donor graft. Because of high incidence of relapse, Busulfan dose was increased to a target AUC of 4000 μmol/L or a fixed dose of 100mg/m2 × 4 (days -5, -4, -3 -2) in 11 patients. Tacrolimus and mini Methotrexate were used as graft versus host disease prophylaxis. All patients received standard supportive care. Results: Between 6/2005 and 07/2009, 26 consecutive patients with myelofibrosis were treated. There were 13 males and 13 females with a median age of 58 (range 27-74). Seventeen patients had primary MF, 3 post PV MF and 6 Post ET MF. Based on Lille criteria, 14 patients had intermediate risk disease and 12 had high risk disease. Ten patients had splenectomy prior to transplant; remaining 16 patients had enlarged spleen at the time of transplant. Fourteen patients had mutated Jak 2. Median peripheral blood CD 34 count was 57/μl(range 1-3770/μl). Karyotype was abnormal in 11 patients and diploid in 15. Donors were matched siblings for 10 patients, matched unrelated for 12, and one antigen or allele mismatched unrelated for 4 patients. Stem cell source was marrow in 3 and peripheral blood in 23. All patients engrafted with a median time to neutrophil engraftment of 13 days (0-27) days) and a median time to platelet engraftment of 24 (0-105) days. Jak 2 positive patients achieved molecular remission post transplant with negative JaK 2. With a median follow up of 21 (1-43) months, 2 year overall and event free survival are 71% (SE 10%) and 46% (SE 11%), respectively. Cumulative incidence of non relapse mortality was 14% (SE 7%). Cumulative incidence of relapse was 39% (SE10%). Eight patients relapsed; 3 in blast phase and 5 in chronic phase. Four of these 8 are currently disease free after a second transplant. Including these 4 patients, 18 out of 26 patients are currently disease free. These include 10 of 11 patients treated with higher dose of busulfan compared with 8 of 15 patients treated with lower busulfan dose. Conclusion: RISCT induces molecular remission with very low non relapse mortality in older patients with myelofibrosis, but the relapse rate is high. Increasing the intensity of conditioning regimen may reduce the relapse risk and needs to be studied further. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 1809 Poster Board I-835 Bone marrow infiltration by myeloma cells and osteolytic bone lesions are the major features of Multiple Myeloma. Magnetic Resonance Imaging (MRI) has been used in MM not only to image bone marrow (BM) and to identify lytic bone disease but to also evaluate therapeutic response and prognosis. Gadolinium (Gd)-based contrast agents are frequently used to enhance MRI resolution. We evaluated effect of the most common Gd-containing agent, Omniscan, on myeloma cells. We observed that Omniscan induced both time and dose dependent MM cell growth in vitro (8-20 fold increase relative to control). Importantly, the presence of BMSC enhanced the effect of Omniscan on growth of both MM cell lines and primary MM cells. However, Omniscan was not able to overcome cytotoxic effects of conventional and novel agents in MM. This growth promoting effects were not observed on normal BM stromal cells. Evaluating the molecular mechanism of action of Omniscan on MM cells, we observed time dependent ERK1/2 phosphorylation as well as reversal of growth promoting effects of Omniscan by specific inhibition of ERK signaling; however, Omniscan had no effect on STAT3 and AKT signaling pathways. Next, we investigated in vivo effect of Omniscan in a murine xenograft model of MM. Following detection of tumor, mice were treated with either iv Omniscan or PBS. Treatment with Omniscan significantly induced MM tumor growth compared to control mice (1042 ±243 mm3 vs 502 ±137 mm3 respectively; p=0.0001). Finally in autopsies in 8 MM patients with repeated exposure to Omniscan, we quantified gadolinium in various tissues using Inductively-coupled mass spectrometry. We observed massive quantities of gadolinium accumulation in tissues of these MM patients regardless of their renal function. These results, confirming both in vitro and in vivo growth promoting effects of Gd-containing contrast agent on MM, suggest the need for further analysis of the mechanism of its action on myeloma cells and careful analysis of its clinical impact in MM patients undergoing MRI evaluation. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 1804 Poster Board I-830 Introduction MicroRNAs (miRNAs) are non-coding RNAs that regulate mRNA expression. miRNAs often act synergistically to repress target genes and their deregulation can contribute to the initiation and progression of a variety of cancers. The clinical relationship between global expression miRNA and mRNA in cancer has not been studied in detail. Methods We used whole genome microarray analyses of CD138-enriched plasma cells from 52 newly diagnosed cases of multiple myeloma (MM) to correlate miRNA expression profiles with a validated mRNA-based risk stratification, proliferation index, and pre-defined gene sets. Results In stark contrast to mRNAs, we discovered that all tested and expressed miRNAs were significantly up-regulated in high-risk disease as defined by a validated 70-gene risk score (P

Description: Abstract 1786 Poster Board I-812 Background Multiple Myeloma (MM) is characterized by a clonal proliferation of antibody producing malignant plasma cells. Complete or partial monoallelic deletion of chromosome 13, is commonly observed in tumor cells of patients with monoclonal gammopathy of unknown significance and in over 50% of MM patients, as well as chronic lymphocytic leukemia (CLL) and mantle cell lymphoma. Recurrent loss of a minimal common region (MCR) of 10 megabases at 13q14, in MM and CLL suggests the MCR harbors a tumor suppressor gene(s) (TSG) with biological and clinical relevance. Within this MCR resides the Ret Finger Protein 2 (RFP2) encoding gene, which produce an E3 ubiquitin ligase located in the endoplasmic reticulum (ER). Because of its copy number-dependent expression, its strong and unique promoter, and its associated inferior survival with reduced expression in MM, RFP2 represents a candidate TSG. Nevertheless, its role and targets have not yet been established. Here we describe a functional analysis of RFP2 in MM cells. Methods: The MMS1 MM cell line lacks chromosome 13 deletion. To study the effects of loss of RFP2 in this line we used the PLKO- GFP lentiviral vector to stably transduce a RFP2 shRNA. Flow cytometer selected cell lines exhibit significantly reduced expression of RFP2 relative transduced shRNA controls or to the parental line. Cell growth rate was measured using trypan blue counting, soft agar colony formation and thymidine incorporation. Cell cycle analysis and apoptosis were measured by flow cytometry after staining with PI or Annexin-V PE and 7AAD, respectively. Intracellular signal modulation was demonstrated by Western blotting. Results At day six post transduction, 75-95% of MMS1 cells were GFP positive. RFP2 downregulation induced an impairment of cell growth with a G2 phase arrest and a profound apoptosis (over 50% at day six as compared with less than 15% of controls). This effect was mediated through ER stress evidenced by upregulation of p-eIF2a and Bip, and the induction of Caspase-8, 9 and 3 cleavage. RFP2 complementation did not produce by itself a significant growth promoting effect, but was able to rescue the knockdown-induced growth retardation. The above described presence of ER stress, combined with the previous reports that RFP2 has E3 ubiquitin ligase activity prompted us to assess total protein ubiquitination. Concordant with its effects on ER stress, RFP2 downregulation was associated with significantly higher levels of poly-ubiquitinated proteins. Subsequently, we were able to document a significant reduction (60% inhibition) in 20S proteasome activity in RFP2 down regulated cells. Proteasome inhibition by RFP2 down regulation was confirmed in other MM cell lines and was partially abrogated by restoring RFP2 levels by overexpression. Importantly, RFP2 down regulated cells were more sensitive to bortezomib; indeed proteasome inhibition was synergistic with RFP2 downregulation in MM cells. The above results prompted us to study the mechanism whereby RFP2 impacts survival and proliferation of MM cells. Inhibition of the NF-kappa-B (NFκB) pathway is a hallmark of proteasome-related growth retardation and apoptosis and is a key pathway in MM. We show that NFkB luciferase reporter assay was associated with significant activity reduction with RFP2 downregulation. To define the mechanism of this process, we examined the level of NFkB related proteins in nuclear and cytoplasmic fractions. Interestingly, the most prominent effect observed in RFP2 down regulated cells was increased levels of IkBá in the nucleus. Altogether, these results support our supposition that the effects of RFP2 downregulation are mediated through an inhibition of the NFkB pathway that is associated with increased nuclear IkBa as well as a decrease in 20S proteasome activity. Conclusions RFP2 is a gene mapping to a deletion hotspot at 13q14 and reduced RNA expression is associated with poor survival in MM. Functional studies revealed that shRNA mediated knockdown of RFP2 in MM causes growth retardation and apoptosis, mediated by ER stress and a G2 arrest, mediated by proteasome inhibition and reduced NFkB activity. Although RFP2 did not prove itself to be a tumor suppressor gene in our studies, targeting RFP2 may represent a novel therapeutic approach in MM and other lymphoid malignancies. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 176 Identification of mutations in a number of ribosomal genes including RPS19, RPL5 and RPL11 in Diamond-Blackfan anenia has established it as a disease of aberrant ribosome biogenesis. To date, it has not been possible to determine if a common cellular mechanism accounts for the erythroid defect in DBA in conjunction with various ribosomal gene mutations identified. To address this issue, we infected normal CD34+ cells from cord blood with specific short hairpin (sh) RNA against RPS19 (shRPS19C), RPL5 (shRPL5A, B, C) and RPL11 (shRPL11A, B, C) and determined their ability to undergo erythroid differentiation in a liquid culture system. Efficiency of each shRNA was verified at the RNA level in UT7 cell lines and CD34+. They all decreased dramatically mRNA expression of RPS19, RPL5 and RPL11 from 90% to 50% depending on the shRNA and the cells, except shRPL11B and C, which reduced RPL11 mRNA expression from 40% to 20%. Erythroid precursors after sh RNA infection were harvested at D7, D9, D11, D14 and D16 and analyzed for cell clonogenicity, erythroid cell differentiation (May Grünwald Giemsa or flow cytometry), apoptosis (Tunel assay and flow cytometry), and mRNA and protein expression. During in vitro erythroid differentiation, we noted a decrease in the extent of cell amplification, from D0 (CD34+ cells) to D7 (CFU-e/proerythroblasts), to D9 (basophilic erythroblasts), to D11, D14, D16 (orthophilic erythroblasts) for all the shRPS19C, shRPL5 (A, B, C) and shRPL11A infected cells compared to uninfected or scramble infected cells. The decrease in erythroid proliferation was less important (50%) in shRPS19 infected cells compared to shRPL5A,B,C and shRPL11A infected CD34+ cells (90–95%). In association with documented decrease in expression of RPS19 mRNA after shRPS19 CD34+ infection, we did not find either an alteration in erythroid differentiation or increased apoptosis at any stage of cell differentiation. In marked contrast, CD34+ cells infected with either shRPL5A,B,C or shRPL11A exhibited importantly a delayed erythroid differentiation with a marked increase in apoptosis. These findings have enabled us to document that while decreased cell proliferation is a feature of all CD34+ cells with decreased expression of different ribosomal proteins, defective differentiation and increased apoptosis of erythroid cells is a distinguishing feature of only CD34+ cells with decreased expression of RPL5 and RPL11. To obtain mechanistic insights into the observed differences in apoptotic phenotype, we analyzed p53 and apoptosis pathways of CD34+ following infection with shRPS19, shRPL5A-B-C, and shRPL11A. All the proteins tested: p53, p21, caspase 3, Bax, Noxa exhibited a decreased expression levels following infection with shRPL5A,B,C and shRPL11A, while exhibiting an increased expression at the mRNA level, suggesting a general inhibition of protein synthesis following RPL5 and RPL11 mRNA depletion. Strikingly, RPS19 depletion resulted increased levels of p53 and p21 expression at both mRNA and protein levels, while Bax and Noxa (proapoptotic) mRNA were as the same level compared to the controls. These different patterns of alteration in p53 and apoptotic protein levels can account for different apoptotic phenotype observed following depletion of RPS19 and of RPL5 and RPL11. In summary, we identified for the first time distinct erythroid proliferation and differentiation defects in conjunction with different ribosomal protein defects. These findings may have implications for future genotype-phenotype relationships in DBA patients. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 1744 Poster Board I-770 CD37 is a tetraspanin transmembrane family protein that is strongly expressed on the surface of mature human B-cells and transformed mature B-cell lymphoma and leukemia cells, including CLL cells. It is expressed minimally or is absent on normal T-cells, natural killer cells, monocytes, and granulocytes. Predominant expression of CD37 on CLL cells makes it an ideal candidate to target with potential agents for treatment of CLL. TRU-016, a Small Modular ImmunoPharmaceutical protein (SMIP) targeted towards the extracellular region of CD37, is presently in clinical trials in CLL patients. TRU-016 consists of variable regions (scFv) and engineered constant regions encoding the human IgG1 domains. We have previously reported that SMIP-016, the chimeric precursor of the fully humanized TRU-016, induced apoptosis in CLL B cells in the presence of goat anti-human Fc ab cross-linker through a novel, caspase-independent pathway. Furthermore, SMIP-016 showed potent in-vivo activity in a SCID xenograft mouse model. Aside from direct cytotoxicity, SMIP-016 mediates antibody-dependent cellular cytotoxicity (ADCC) by NK cells both in vitro and in vivo. Recently, in an attempt to enhance the ADCC function, a new variant of SMIP-016, Tru-ADhanCe SMIP-016, has been created with a modification of the glycosylation of the Fc portion of the molecule. TRU-ADhanCe SMIP-016 has been shown to exhibit enhanced binding to both low- and high-affinity molecular variants of human CD16 (FcRIII) and augmented ADCC potency when compared to SMIP-016. In this study, we compared TruADhanCe SMIP-016 and SMIP-016 in direct cytotoxicity and ADCC experiments using CLL B-cells. While SMIP-016, and TruADhanCe SMIP-016 mediated comparable direct cytotoxicity at 24, 48 and 72 hrs in the presence of anti-human Fc crosslinker, the TruADhanCe SMIP-016 resulted in 2 to 4 fold increased NK cell mediated ADCC function. Consistent with the comparable direct cytotoxic effects, the early phosphorylation patterns were similar in cells treated with TruADhanCe SMIP-016 or SMIP-016 in the presence of anti-human Fc cross linker. Ongoing studies are aimed to define the mechanistic basis of the enhanced ADCC function by TruADhanCe SMIP-016 and to determine if use of soluble CD16.Fc as a cross-linker, an in vitro model of in vivo Fc receptor binding, may reveal enhanced apoptotic-signaling of TruADhanCe SMIP-016. These results suggest potential use of TruADhanCe versions of TRU-016 with enhanced ADCC function as an alternate for TRU-016 in B cell malignancies including CLL therapy. [This work was supported by D. Warren Brown Foundation, Leukemia and Lymphoma Society and National Cancer Institute.] Disclosures Thompson: Trubion Pharmaceuticals: Employment. Siadak:Trubion Pharmaceuticals: Employment. Algate:Trubion Pharmaceuticals: Employment. Cerveny:Trubion Pharmaceuticals: Employment.

Description: Abstract 1742 Poster Board I-768 Introduction In the randomized Phase III study REACH, the combination of rituximab (R) (375 mg/m2 cycle 1, 500 mg/m2 cycles 2-6) and fludarabine (F) (25mg/m2 X 6 cycles) and cyclophosphamide (C) (250 mg/m2 X6 cycles) was shown to improve clinical response and prolong PFS in patients with relapsed/refractory Chronic Lymphocytic Leukemia (CLL) compared with F and C alone. The use of 500 mg/m2 as the dose of R in R-FC was guided by previous published data in CLL patients treated with R monotherapy demonstrating a probable dose-response relationship of a higher response rate at the higher dose levels (O'Brien JCO 2001, Byrd JCO 2001) and also by the data of high number of circulating malignant cells in CLL population (characteristic of CLL) which indicated that R might exhibit a higher clearance rate in CLL compared to observed clearance rates in NHL. Prior to the REACH study, the pharmacokinetics (PK) of R have not been thoroughly studied in the CLL population. As sub-study in REACH trial, a complete PK analysis of R was performed in CLL patients using a population PK analysis. This approach allowed not only the characterization of R PK in CLL patients, but also allowed for an opportunity to perform comparison of the PK differences between indications (CLL and NHL) and provided data-driven validation for the need of high R in CLL patients. Patients and Methods The PK of R were described with plasma concentrations from 21 CLL patients who received R-FC, using nonlinear mixed-effects modeling (NONMEM VI) software. A two-compartment model with time-varying clearance was validated using a bootstrap and visual predictive check method. The concentration vs. time profiles after given different dosages of R in NHL and CLL patients were predicted using the final models based on the observed data. Results R concentration data in CLL patients were well described by a two-compartment model with time-varying clearance, which has been used to describe R concentration data in NHL. Total clearance is comprised of two terms, a non-specific clearance pathway (CL1), which remains unchanged throughout treatment, and a specific clearance pathway (CL2) that decreases following a first-order decay rate from its initial value following the first infusion. The term Kdes represents the actual rate of change from the specific clearance (mediated by CD20) to the non-specific clearance (mediated by IgG1). The typical population estimates of R nonspecific clearance (CL1), and central compartment volume of distribution (V1) are similar between CLL and NHL (171 vs. 138 mL/day; 2310 vs. 2710 mL, respectively). However, the specific clearance (CL2) in CLL was much faster than that in NHL (1280 vs. 577 mL/day), and the rate of change (Kdes) from the specific clearance (mediated by CD20) to the non-specific clearance (mediated by IgG1) is two times lower for CLL patients compared to NHL patients (0.024 vs. 0.046 /day) and this suggests that it takes longer time for receptor saturation for CLL patients compared to NHL patients. The results of the simulation exercise showed that in the early cycles of the R-FC regimen, trough concentrations (Ctrough) and drug exposure (AUC) in CLL patients given 500 mg/m2 would be lower than those for NHL patients given 375 mg/m2 dose regimen. By the final cycles, the Ctrough and AUC of R are similar in NHL given 375 mg/m2 and CLL given 500 mg/m2. Conclusions Retrospective population PK analysis of R in CLL patients using non linear mixed effect modeling confirmed an increased R clearance during the early cycle of treatment as compared to NHL patients. This increased clearance is potentially due to a higher number of malignant cells in circulation for CLL patients, thus a larger dominance of the faster receptor-mediated clearance component in these patients, which overcome the lower CD20 density in CLL. The dose regimen of 500mg/m2 in CLL patients allows for reaching steady state AUC which is similar to the steady state AUC achieved with doses of 375mg/m2 given in NHL patients. Disclosures Li: Genentech: Employment. Zhi:Hoffmann-La Roche Inc.: Employment. Wenger:F. Hoffmann-La Roche Ltd: Employment. Valente:Genentech: Employment, Equity Ownership. Visich:Genentech: Employment.

Description: Abstract 1741 Poster Board I-767 Background In contrast to most normal cells, cancer cells typically produce energy predominantly by glycolysis as demonstrated by O. Warburg more than 50 years ago. Methyljasmonate (MJ), a hormone produced by plants in response to biotic & abiotic stresses such as herbivory and wounding, has been shown to prevent the interaction of hexokinase (Hxk) and voltage dependent anion channels (VDACs), thereby significantly impacting the onset of glycolytic energy production. This may explain promising preclinical results observed with MJ against a variety of cancer cells, including myeloid leukemia and B-cell lymphoma cell lines. Methods and Results We tested the potential of MJ against Multiple Myeloma (MM) cells. We first evaluated the response of 16 different MM cell lines to 24 h of exposure to MJ concentrations of 0.5 – 3.5 mM using MTT assays. 15/16 of the MM cell lines tested displayed an IC50 of 〈 1.5 mM. In contrast, HS-5 stroma cells and peripheral blood mononuclear cells (PBMCs) did not respond to that MJ concentration, and even at a concentration of 2.5 mM MJ showed a maximal reduction of cell viability of 40%. Similarly to MM cell lines, purified CD138+ primary tumor cells of 3 MM patients displayed an IC50 of 〈 1.5 mM, suggesting that the differential sensitivity of MM vs. normal cells to MJ is not restricted to cell lines, but is also observed with primary tumor cells. Importantly, neither co-culture with HS-5 stroma nor IL-6 protected MM cells against MJ. Cell death commitment assays revealed that 1h exposure of 1.5 mM MJ induced cell death. Annexin V/PI FACS analysis of MJ-exposed MM cells showed that the cell death is mainly driven by apoptosis, evidenced by cleavage of caspases 3, 8 and 9 as well as of PARP. However, pre-incubation of MM cells with specific caspase inhibitors such as 10 mM of AC-DEVD-CHO, Z-IETD-fmk, Z-LEHD-fmk or 50 mM of Z-VAD only minimally protects the cancer cells from MJ exposure. Therefore, the impact of the MJ is not solely due to caspase triggered proteolytic cascades. Measurements of cellular ATP content by cell titer glow (CTG; Promega, Madison, WI) assay showed rapid depletion of ATP triggered by MJ action in sensitive MM cell lines. Additionally, we observed that 1 h exposure to 2 mM MJ modulated signaling pathways including IRS1/PI3K/AKT, MEK1/2, as well as Stat3 and JNK. FACS-based cell cycle analysis after propidium iodide staining did not show cell cycle arrest, but rather a rapid transition of cells to G0/G1 No correlation of sensitivity of MM cell lines and the number of mitochondria per cancer cell, as determined by Mitotracker Green (Invitrogen, Carlsbad, CA) -based flow analysis, was observed. We next examined if MJ exhibits either significant antagonism or synergy with established or novel anti-MM agents, including Bortezomib, Lenalidomide, Doxorubicin, Rapamycin or Dexamethasone, but discovered neither. However, MJ displayed synergy when combined with 2-Deoxyglucose. Finally, MJ was tested in vivo in scid/nod mice irradiated with 150 rads, injected with 1× 106 MM1S cells, and then, treated at 500 mg/kg by IP administration on a 5 days on / 2 days off schedule starting two weeks after tumor cell injection, There was an overall survival advantage of MJ-treated animals over the respective controls, with all treated mice (n=10) still alive but 6/10 control mice dead after 27 d. Conclusions Based on its rapidity of anti-MM action, favorable safety profile in preclinical models, distinct pattern of molecular sequelae, and compatibility with established anti-MM agents, MJ represents a promising investigational anti-MM agent. Disclosures Laubach: Novartis: Consultancy, Honoraria. Richardson:Millennium: (Speakers Bureau up to 7/1/09), Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: (Speakers Bureau up to 7/1/09), Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Anderson:Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Mitsiades:Novartis Pharmaceuticals: Consultancy, Honoraria; Milllennium: Consultancy, Honoraria; Bristol-Myers Squibb : Consultancy, Honoraria; Merck &Co.: Consultancy, Honoraria; Kosan Pharmaceuticals : Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; PharmaMar: Patents & Royalties; Amgen: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis Pharmaceuticals: Research Funding.

Description: Abstract 1737 Poster Board I-763 We previously reported the efficacy and B-cell selectivity of the natural product silvestrol in acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL), using both primary cells and B-cell lines. We also showed that silvestrol inhibits translation, resulting in rapid depletion of the short half-life protein Mcl-1 followed by mitochondrial damage and apoptosis. Cencic et al. reported that silvestrol directly blocks translation initiation by aberrantly promoting interaction of eIF4A with capped mRNA (PLoS One 2009; 4(4):e5223). However, the loss of Mcl-1 in breast and prostate cancer cell lines is delayed relative to what we observe in B-leukemias (48 hr vs. 4-6 hr in CLL and ALL cells). Additionally, silvestrol does not reduce Mcl-1 expression in normal T-cells to the same extent that it does in B-cells, potentially explaining in part the relative resistance of T-cells to this agent. We therefore investigated cell-type differences, as well as the importance of Mcl-1, in silvestrol-mediated cytotoxicity. We incubated the ALL cell line 697 with gradually increasing concentrations of silvestrol to generate a cell line (697-R) with resistance to 30 nM silvestrol (IC50 of parental 697 〈 5 nM). No differences between 697-R and the parental line were detected upon detailed immunophenotyping. However, cytogenetic analysis revealed a balanced 7q;9p translocation in 697-R not present in the parental 697 cell line that may be related to the emergence of a resistant clone. We also detected no difference in expression of multi-drug resistance proteins MDR-1 and MRP, which can contribute to resistance to complex amphipathic molecules such as silvestrol. In contrast, we found that baseline Mcl-1 protein expression is strikingly increased in 697-R cells relative to the parental line, although these cells still show similar percent-wise reduction in Mcl-1 upon re-exposure to 80 nM silvestrol. To investigate whether this resistance to silvestrol is reversible, 697-R cells were maintained without silvestrol for 6 weeks (∼18 passages). During this time, viability remained near 99%. Cells were then treated with 30 nM silvestrol. Viability was 94% at 48 hr post-treatment and returned to 99% within a week, while parental 697 cells with the same treatment were completely dead. Baseline Mcl-1 levels remained elevated in 697-R even with prolonged silvestrol-free incubation. These results indicate that the resistance phenotype is not rapidly reversible, as is seen with transient upregulation of multi-drug resistance or stress-response proteins. Additionally, silvestrol moderately induces the transcription of several pro-apoptotic Bcl-2 family members and results in elevated levels of these proteins despite its translation inhibitory activity. Interestingly, no such activity is detected in silvestrol-treated normal T-cells. Together, these results support the hypothesis that in B-cells, silvestrol induces cell death by altering the balance of pro- and anti-apoptotic factors, and that increased Mcl-1 protein can force the balance back toward survival. This work further underscores the importance of Mcl-1 in silvestrol-mediated cytotoxicity. We are now investigating the mechanism of Mcl-1 upregulation in 697-R cells to identify a factor or pathway that can be targeted therapeutically to circumvent resistance. Silvestrol is currently undergoing preclinical pharmacology and toxicology investigation by the U.S. National Cancer Institute Drug Development Group at the Stage IIA level to facilitate its progression to Phase I clinical testing. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 1730 Poster Board I-756 The sonic hedgehog (SHH) pathway, associated with proliferative stem cell niches of many organs, is frequently deregulated in diverse cancers. We have previously shown that the SHH pathway augments the survival of tumor cells by inducing antiapoptotic molecules including bcl-2 and provides resistance to a number of conventional cancer therapies. Aberrant activation of the SHH pathway has been associated with activation and maintenance of lymphoid malignancies. Additionally, our recent data indicates that p63, a p53 family member and an important marker of stem cells has multiple interacting nodes with the SHH pathway. Based on these observations, we hypothesized i) that there is crosstalk between the SHH and p53/p63 networks in cells and, ii) inhibition of the SHH pathway with simultaneous activation of the p53 pathway would result in increased cell death in cancer cell lines of lymphoid origin. Using SDS-PAGE followed by immunoblotting and RT-PCR we surveyed a panel of 18 leukemia/lymphoma cell lines for components of the SHH pathway and the p53/p63/p73 network. Robust SHH pathway expression was observed in 15 of the 18 cell lines examined. Interestingly, in p53 deficient cell lines there was an increase in p63/p73 expression as compared to cell lines with wild type (WT) p53. A set of the previously analyzed diffuse large B- cell lymphoma (DLBCL) cell lines were selected and were representative of both p53 deficient and WT cell lines and also the activated B-like DLBCL (ABC) and germinal center B-like DLBCL (GCB) subgroups. These cells were treated with cyclopamine, an inhibitor of the SHH pathway and/or nutlin, an HDM2 antagonist. Cell viability (MTS assay) was measured using both compounds at various drug concentrations and time points. In addition we also investigated the effects of the drugs individually and in combination on components of the p53/p63 and SHH axes and their targets. Our findings suggest that treatment of p53 (WT) cell lines with a combination of nutlin and cyclopamine results in reduced cell survival than treatment with either drug alone and at lower drug concentrations and that the p53 status of the cell line may be more important in determining therapeutic response to the selected compounds. In addition the p53/p63 pathway may have a novel role in regulation of specific components of the SHH pathway in cells of lymphoid origin. In conclusion, these observations provide proof of concept that a combinatorial therapeutic approach, targeting both the p53 and SHH axes would provide a more robust and favorable response in large B cell lymphomas. Acknowledgments This work was supported in part by the The Mehta Family Foundation Disclosures No relevant conflicts of interest to declare.

Description: Abstract 1743 Poster Board I-769 Background Molecular targeting drugs, all-trans retinoic acid (ATRA)and arsenic trioxide (ATO), have major advances in the treatment of acute promyelocytic leukemia (APL). However, resistance to these drugs has been also observed in clinical practice. ATRA acts as a ligand for retinoic acid receptor alpha (RAR) and restores the aberrant transcription repression by PML-RARA fusion protein in APL cells. Previous reports demonstrate that amino-acids substitution, resulting from genetic mutations, in ligand binding domain (LBD) of RARA region of PML-RARA were closely related to drug resistance to ATRA therapy. In contrast, for ATO therapy, the molecular mechanisms of the effectiveness and also the resistance are still unclear. Here we identified a PML-RARA that holds double genetic missense mutations in RARA and PML regions, respectively, from an APL patient, who showed clinically resistance to ATRA and ATO therapy. These mutations were observed as his disease progression, and we are interested in the relationship between these mutations with drug resistance to ATRA and/or ATO. Aims Analyses of the molecular and clinical significance of the double missense mutations of PML-RARA for disease progression and resistance to ATRA and ATO therapy. Results Eight APL patients were treated with ATO in Nagoya University Hospital, Japan, during ∼5 years from Apr. 1, 2000 to Dec. 31, 2004. One out of 8 patients showed clinically ATO resistance. The patient showing ATO resistance firstly diagnosed as APL (M3 variant) from cytogenetic and chromosomal analyses, and complete remission was obtained after combination chemotherapy with ATRA. Molecular CR was confirmed by RT-PCR analysis, but after 3 month from the induction therapy, ATRA-resistant relapse was observed. After treatment with ATO therapy, response was observed, but the effectiveness was gradually decreased, resulting finally into the resistance. The patient died of disease progression. During his 7 years clinical course, leukemia cells were harvested repeatedly from his bone marrow and peripheral blood. RT-PCR using the total RNA from his tumor cells followed by DNA sequencing was performed, with the result of PML-RARA fusion gene with the bcr3 breakpoint in the intron 3 of PML. When using the tumor cells that were harvested at his terminal stage, a missense point mutation in the LBD of the RARA region of PML-RARA was confirmed. Furthermore, missense point mutation in the PML-B2 domain was also confirmed in the same cDNA clones. Interestingly, these mutations were not observed in the leukemia cells obtained at the onset. These mutations were analyzed in each sample that was obtained as his disease progressed, and some correlation between disease progression and/or the drug resistance and the timing of appearance of these two mutations were suggested. These mutated fusion transcripts were cloned into expression vectors, and we are now analyzing the function relating to the drug resistance and disease progression. Conclusions Double genetic missense mutations in the RARA-LBD and PML-B2 of PML-RARA were confirmed in ATRA and ATO resistant patient. These genetic mutations were confirmed in the leukemia cells during his disease progression, and the relationship between those mutations and drug resistances were suggested from the clinical features. Mutations in the PML-B2 domain has not been reported previously, thus, it may be important to show whether this type of mutations are related to the drug resistance, especially to ATO therapy. Disclosures Kiyoi: Novartis Pharma Co. Ltd.: Research Funding; Kyowa Hakko Kirin Co. Ltd.: Consultancy. Naoe:Kyowa Hakko Kirin Co., Ltd. : Research Funding; Chugai Pharmaceutical Co.,Ltd.: Research Funding; Wyeth K.K.: Research Funding.