ALBERT

Description: Small-molecule drugs that target the B-cell antigen receptor (BCR) signalosome show clinical efficacy in the treatment of B-cell non-Hodgkin lymphoma. These agents, including the Bruton tyrosine kinase (BTK) inhibitor PCI-32765, display an unexpected response in patients with chronic lymphocytic leukemia (CLL): a rapid and sustained reduction of lymphadenopathy accompanied by transient lymphocytosis, which is reversible upon temporary drug deprivation. We hypothesized that this clinical response reflects impaired integrin-mediated adhesion and/or migration. Here, we show that PCI-32765 strongly inhibits BCR-controlled signaling and integrin α4β1-mediated adhesion to fibronectin and VCAM-1 of lymphoma cell lines and primary CLL cells. Furthermore, PCI-32765 also inhibits CXCL12-, CXCL13-, and CCL19-induced signaling, adhesion, and migration of primary CLL cells. Our data indicate that inhibition of BTK by PCI-32765 overcomes BCR- and chemokine-controlled integrin-mediated retention and homing of malignant B cells in their growth- and survival-supporting lymph node and bone marrow microenvironment, which results in clinically evident CLL regression.

Description: Abstract 2099 Background: While oral iron is the preferred first-line treatment for patients with iron deficiency anemia (IDA), there are patients who cannot take oral iron, do not tolerate it or do not adequately respond to oral iron. In the US and Canada, the only approved treatment options for these patients are the iron dextrans, which have boxed safety warnings and inconvenient dosing regimens. Therefore, many of these anemic patients do not receive IV iron, and remain inadequately treated and symptomatic. In the EU, several IV irons, including iron sucrose (IS), are approved for second line use. Few studies have evaluated the IV irons in head-to-head studies. Ferumoxytol (FER) is a new IV iron approved for the treatment of IDA in patients with chronic kidney disease (CKD) that is formulated to allow for bolus IV injection. This randomized, controlled trial was designed to investigate the efficacy and safety of FER compared to IS for the treatment of IDA in patients with a history of unsatisfactory oral iron therapy or in whom oral iron could not be used. Methods: The study was designed to demonstrate non-inferiority and consisted of a 14 day screening period, treatment and a 5 week follow-up period. Key inclusion criteria included a Baseline hemoglobin (Hgb) less than 10 g/dL and 〉7 g/dL, and transferrin saturation (TSAT) 〈 20%. Patients were randomized 2:1 to receive either FER, administered as 2 injections of 510 mg 5±3 days apart, or IS, administered as 5 infusions or injections of 200 mg on 5 non-consecutive days over a 14 day period. Results: A total of 605 subjects were randomized to the 2 treatment arms (FER, n= 406; IS, n=199). FER demonstrated non-inferiority to IS in the proportion of subjects with a 〉2.0 g/dL increase in Hgb at any time from Baseline to Week 5 (the primary efficacy endpoint), compared to those treated with IS, (FER, 84%; IS 81%) with the lower bound of the 95% CI [-3.89%] above the predefined non inferiority margin [-15%]. In addition at each post-treatment time point, a higher percentage of FER-treated subjects achieved a 〉2.0 g/dL increase in Hgb compared to those treated with IS. FER also achieved non-inferiority to IS in the mean change in Hgb from Baseline to Week 5 with a robust 2.7g/dL increase in Hgb compared to 2.4g/dL with IS (the lower bound of the 95% CI [0.06g/dL] was above the predefined non-inferiority margin [-0.5g/dL]); this treatment difference (0.3 g/dL) was statistically significant (p=0.0124), and FER actually achieved superiority over IS. The overall rates of adverse events (AEs) and related AEs were lower in the FER group compared to IS-treated subjects. The serious adverse event (SAE) rate was higher in FER-treated subjects (FER, 4.2%; IS, 2.5%), but no pattern or safety trend was observed to suggest a specific safety signal; treatment-related SAEs were reported in 2 (0.5%) FER-treated subjects (1 anaphylactoid reaction and 1 hypertension). Protocol-defined AEs of Special Interest (signs/symptoms of hypotension or hypersensitivity associated with IV iron use) were reported at a higher rate in IS-treated subjects compared to the FER treatment group (IS, 5.0%; FER, 2.7%). Cardiovascular AE rates were comparable in the 2 treatment groups (1.0%). Overall, the safety profile of FER was comparable to that of IS and no new safety signals were identified. Conclusion: In this randomized, controlled trial, the efficacy and safety of 2 doses of FER were shown to be comparable to IS in treating IDA patients with a history of unsatisfactory oral iron therapy or in whom oral iron could not be used. For this IDA patient population, which has limited treatment options in the US and Canada, FER may offer an important, new treatment option with a convenient 2 dose regimen. Disclosures: Off Label Use: Feraheme (ferumoxytol) injection. For treatment of iron deficiency anemia in non-CKD patients. Bernard:AMAG Pharmaceuticals, Inc.: Employment. Strauss:AMAG Pharmaceuticals, Inc.: Employment. Cressman:AMAG Pharmaceuticals, Inc.: Employment. Li:AMAG Pharmaceuticals, Inc.: Employment. Allen:AMAG Pharmaceuticals, Inc.: Employment.

Description: Abstract 4439 Background: Several reports have recently been published documenting the experience of patients with Philadelphia chromosome positive chronic myeloid leukemia in the chronic phase (CML-CP) who were switched from Glivec (IM), the β-crystalline form of imatinib mesylate, to non-identical alternate copies of imatinib mesylate (IMac) including those composed of the α-crystalline form. As a result of pre-clinical tests performed during the early development of IM, the β-crystalline form of imatinib mesylate was selected for further development due to its superior stability. In one case report evaluation, 126 Iraqi patients with CML-CP were switched from IM to an IMac that was the α-crystalline form of imatinib mesylate. At the time of switch to IMac, patients had previously received 400mg IM once-daily for an average of 50 months and were at least in complete hematologic response (CHR). Post-switch, patients were initially placed on the same IMac dose and followed-up on a monthly basis; more frequently in cases of poor response or adverse events. By 3 months post-switch, 22 (17%) patients had lost hematologic response and of these patients 18 (14%) and 4 (3%) had progressed to accelerated phase (AP) and blast crisis (BC), respectively. By 6 months post-switch, an additional 20 patients (16%; 33% total) had lost hematologic response. Safety assessment for IMac in this cohort has not been previously published. Objective: To assess the clinical safety and to estimate the survival of Iraqi CML patients switched from IM to IMac. Methods: Patient case records were retrospectively reviewed for safety findings as assessed by the treating physician. A previously published Markov transition-state model was used to compare projected life-years (LYs), progression-free life-years (PFLY), and quality-adjusted life-years (QALYs) of IM patients switched to IMac vs. patients not switched. Patients entered the model after a mean 50 months of IM therapy. At that time, based on the IRIS trial results, patients were considered to have CHR (4.7%), partial (6.5%) or complete (88.9%) cytogenetic response. Patients remaining on IM transitioned within these 3 responses levels and no hematologic response, AP, BC, and death according to the original model probabilities. For patients switched to IMac, transition rates were based exclusively on response rates observed in the Iraqi study (Scenario 1) or on the Iraqi study for the first 6 months, and thereafter based on the transition rates originally in the Markov model (Scenario 2). Utilities were from the original model. Results: Non-hematologic adverse event (AE) rates observed in patients who were switched to IMac are reported (Table). Patients remaining on IM were predicted to experience 15.7 LYs, 14.5 PFLYs, and 13.4 QALYs. Corresponding numbers for patients switched to IMac were 2.4 LYs, 1.1 PFLYs, 1.4 QALYs (in Scenario 1) and 11.4 LYs, 10.2 PFLYs, and 9.6 QALYs (in Scenario 2). Results were also sensitive to response distribution at model entry. Conclusions: The clinical safety, efficacy, and tolerability of IM have been established from more than 10 years of clinical experience. Recent introduction of generic versions of imatinib (including α-crystalline form) allows assessment of whether patients switching from IM to a generic version are able to achieve the same clinical outcomes as with the branded drug. The Iraqi case report is the largest cohort currently available for such review. This case report suggests that switching from IM to an IMac that does not have the safety and/or efficacy may result in substantial loss of LYs, PFLYs, and QALYs. Robust pharmacovigilance programs may need to be established to differentiate safety findings for originator drugs vs. substandard generic versions. Disclosures: Botteman: Novartis: Consultancy. Magestro:Novartis: Employment, Equity Ownership. Manley:Novartis Pharma AG: Employment. Zernovak:Novartis Pharmaceuticals Corp: Employment, Equity Ownership. Woodman:Novaris Pharmaceuticals Corp: Employment, Equity Ownership.

Description: Abstract 2195 Introduction: Eltrombopag (epag), a thrombopoietin receptor agonist (TPO-RA), increases platelet counts in patients with chronic immune thrombocytopenia (cITP). TPO-RAs have been associated with varying degrees of increases in bone marrow reticulin (Brynes 2011; Ghanima 2011). Due to lack of pretreatment evaluations, the incidence and clinical significance of these findings have not been established. Inconsistencies in specimen preparation, staining, and analysis across institutions further confound conclusions. The purpose of this 2-year (y) study (NCT01098487) is to assess for bone marrow fibrosis (reticulin and/or collagen) in patients treated with epag for cITP. Baseline and 1y findings are presented. Methods: Bone marrow biopsies are being collected at baseline (before treatment with epag) and at 1 and 2y of treatment. Specimens are centrally processed and stained for reticulin (silver) and collagen (trichrome) and undergo central independent pathology review of cellularity; megakaryocyte, erythroid, and myeloid quantity and appearance; trabecular bone quality; reticulin grade; and presence of collagen (European Consensus scale-MF; Thiele 2005). Results: Baseline and 1y (10–14 months) data are available for 101 patients. Median age is 42y (18–78); 70 patients are female; 50% are Caucasian/European, 22% are East Asian, and 29% are Central South Asian. Median time since ITP diagnosis is 4.2y (0.2–45.7). All patients had received prior ITP therapy, and 8 patients had received prior TPO-RA treatment (epag [7], romiplostim [1]), the last dose ≥6 months before enrollment. At baseline, 91 patients had reticulin grade 0 (MF-0), 10 MF-1, and 0 MF≥2. At 1y, 59 patients had MF-0, 38 MF-1, 3 MF-2, and 1 MF-3 (Figure). Compared with baseline, there was no change at 1y in MF grade in 61 patients, a decrease by 1 grade in 3, an increase by 1 grade in 35, and an increase in 2 or 3 grades in 1 patient each (Table). Three patients had collagen at 1y (1 patient each with MF-1, MF-2, and MF-3). None of the 4 patients with MF≥2 had adverse events or hematologic abnormalities considered related to impaired bone marrow function, and none withdrew due to bone marrow findings. Among the 8 patients with prior TPO-RA treatment, all had baseline reticulin of MF-0 and none had collagen; at 1y, 6 remained MF-0, 1 was MF-1, and 1 MF-3 (collagen demonstrated). Cellularity was normal in 83% and 80% of patients at baseline and 1y, respectively. Other than normalization of erythroid lineage numbers, no changes occurred in marrow cellular composition. In 3 of 4 patients with MF≥2, cellularity was increased at 1y. Trabecular bone thinning was found at baseline in 28 patients (the majority with prior steroid use) and 51 patients at 1y. Discussion: 10% of patients had MF-1 at baseline. After 1y of treatment, no increase or a mild increase in reticulin was observed in 63% and 35% of patients. No patient with MF≥2 (n=4) had clinical signs or symptoms indicative of bone marrow dysfunction and none withdrew from the study. Results were similar to those reported for EXTEND, an eltrombopag extension study (median treatment duration 〉2 years; Brynes 2011). Conclusion: These data suggest that treatment with epag is generally not associated with clinically relevant increases in bone marrow reticulin or collagen. The potential association of TPO-RAs and increased bone marrow reticulin needs further study. Disclosures: Brynes: GlaxoSmithKline: Research Funding. Orazi:GlaxoSmithKline: Research Funding. Wong:Roche: Research Funding; MSD: Research Funding; Johnson & Johnson: Research Funding; Bayer: Consultancy, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Biogen-Idec: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; GlaxoSmithKline: Research Funding; Bristol-Myers Squibb: Research Funding. Bakshi:GlaxoSmithKline: Employment, Equity Ownership. Bailey:GlaxoSmithKline: Employment, Equity Ownership. Brainsky:GlaxoSmithKline: Employment, Equity Ownership, Patents & Royalties.

Description: Sjögren syndrome (SS) is a systemic autoimmune disease characterized by dry mouth and eyes, and the cellular and molecular mechanisms for its pathogenesis are complex. Here we reveal, for the first time, that bone marrow mesenchymal stem cells in SS-like NOD/Ltj mice and human patients were defective in immunoregulatory functions. Importantly, treatment with mesenchymal stem cells (MSCs) suppressed autoimmunity and restored salivary gland secretory function in both mouse models and SS patients. MSC treatment directed T cells toward Treg and Th2, while suppressing Th17 and Tfh responses, and alleviated disease symptoms. Infused MSCs migrated toward the inflammatory regions in a stromal cell–derived factor-1–dependent manner, as neutralization of stromal cell–derived factor-1 ligand CXCR4 abolished the effectiveness of bone marrow mesenchymal stem cell treatment. Collectively, our study suggests that immunologic regulatory functions of MSCs play an important role in SS pathogenesis, and allogeneic MSC treatment may provide a novel, effective, and safe therapy for patients with SS. This study was registered at www.clinicaltrials.gov as NCT00953485.

Description: Erythroid (red blood) cells are the first cell type to be specified in the postimplantation mammalian embryo and serve highly specialized, essential functions throughout gestation and postnatal life. The existence of 2 developmentally and morphologically distinct erythroid lineages, primitive (embryonic) and definitive (adult), was described for the mammalian embryo more than a century ago. Cells of the primitive erythroid lineage support the transition from rapidly growing embryo to fetus, whereas definitive erythrocytes function during the transition from fetal life to birth and continue to be crucial for a variety of normal physiologic processes. Over the past few years, it has become apparent that the ontogeny and maturation of these lineages are more complex than previously appreciated. In this review, we highlight some common and distinguishing features of the red blood cell lineages and summarize advances in our understanding of how these cells develop and differentiate throughout mammalian ontogeny.

Description: Histone methylation is thought to be important for regulating Ag-driven T-cell responses. However, little is known about the effect of modulating histone methylation on inflammatory T-cell responses. We demonstrate that in vivo administration of the histone methylation inhibitor 3-deazaneplanocin A (DZNep) arrests ongoing GVHD in mice after allogeneic BM transplantation. DZNep caused selective apoptosis in alloantigen-activated T cells mediating host tissue injury. This effect was associated with the ability of DZNep to selectively reduce trimethylation of histone H3 lysine 27, deplete the histone methyltransferase Ezh2 specific to trimethylation of histone H3 lysine 27, and activate proapoptotic gene Bim repressed by Ezh2 in antigenic-activated T cells. In contrast, DZNep did not affect the survival of alloantigen-unresponsive T cells in vivo and naive T cells stimulated by IL-2 or IL-7 in vitro. Importantly, inhibition of histone methylation by DZNep treatment in vivo preserved the antileukemia activity of donor T cells and did not impair the recovery of hematopoiesis and lymphocytes, leading to significantly improved survival of recipients after allogeneic BM transplantation. Our findings indicate that modulation of histone methylation may have significant implications in the development of novel approaches to treat ongoing GVHD and other T cell–mediated inflammatory disorders in a broad context.

Description: EZH2, a catalytic component of the polycomb repressive complex 2, trimethylates histone H3 at lysine 27 (H3K27) to repress the transcription of target genes. Although EZH2 is overexpressed in various cancers, including some hematologic malignancies, the role of EZH2 in acute myeloid leukemia (AML) has yet to be examined in vivo. In the present study, we transformed granulocyte macrophage progenitors from Cre-ERT;Ezh2flox/flox mice with the MLL-AF9 leukemic fusion gene to analyze the function of Ezh2 in AML. Deletion of Ezh2 in transformed granulocyte macrophage progenitors compromised growth severely in vitro and attenuated the progression of AML significantly in vivo. Ezh2-deficient leukemic cells developed into a chronic myelomonocytic leukemia–like disease with a lower frequency of leukemia-initiating cells compared with the control. Chromatin immunoprecipitation followed by sequencing revealed a significant reduction in the levels of trimethylation at H3K27 in Ezh2-deficient leukemic cells, not only at Cdkn2a, a known major target of Ezh2, but also at a cohort of genes relevant to the developmental and differentiation processes. Overexpression of Egr1, one of the derepressed genes in Ezh2-deficient leukemic cells, promoted the differentiation of AML cells profoundly. Our findings suggest that Ezh2 inhibits differentiation programs in leukemic stem cells, thereby augmenting their leukemogenic activity.

Description: Abstract 45 Background Homoharringtonine-based induction regimens have been widely used in China for patients with acute myeloid leukemia (AML), which have shown to improve the rate of complete remission (CR) and long-term survival. We aimed to further evaluate its efficacy and safety in treatment of de novo AML. Methods This phase 3 study was done in 17 institutions in China. Patients between the age of 14 and 59 with untreated AML were randomly assigned to receive HAA (homoharringtonine 2 mg/m2/day, days 1–7; cytarabine 100 mg/m2/day, days 1–7, aclarubicin 20 mg/day, days 1–7), HAD (homoharringtonine 2 mg/m2/day, days 1–7; cytarabine 100 mg/m2/day, days 1–7; daunorubicin 40 mg/m2/day, days 1–3) or DA (daunorubicin 40–45 mg/m2/day, days 1–3; cytarabine 100 mg/m2/day, days 1–7) regimen as induction therapy. Patients who achieved partial remission or had a decrease of blast ¡Ý60% could receive a same second induction course. All patients who had a complete remission were offered the same consolidation chemotherapy according to the cytogenetic-risk. The primary endpoints were CR and event-free survival (EFS). The trial is registered in Chinese Clinical Trial Register, number ChiCTR-TRC-06000054. Results 620 patients were randomly assigned to receive HAA (n=207), HAD (n=206) and DA (n=207) regimens. HAA or HAD regimen, as compared with DA regimen, resulted in a higher rate of CR in the first course of induction therapy (67.5% vs. 54.0%, P=0.005; 64.9% vs. 54.0%, P=0.026, respectively). The overall CR rate remained significantly higher in the HAA arm as compared with DA arm (75.0% vs. 61.9%, P=0.005). HAA or HAD regimen has similar rates of adverse events as compared with DA regimen, but was associated with significantly increased risk of induction death (5.8% vs. 1.0%, P=0.007; 6.6% vs. 1.0%, P=0.003, respectively). The EFS was greatly improved in the HAA arm (3-year EFS 35.4±3.5% vs.23.1±3.1%, P=0.002), while not significantly in the HAD arm (3-year EFS 32.7±3.5% vs.23.1±3.1%, P=0.078) as compared with the DA arm. Overall survival (OS) and relapse-free survival (RFS) did not differ significantly in the HAA or HAD arm as compared with DA arm, but an OS and RFS advantage of the HAA arm over the DA arm was observed in patients with favorable or intermediate cytogenetic profile (OS: P=0.014; RFS: P=0.022, respectively). Patients in the HAD arm with NPM1 but not FLT3ITD mutations, as compared with the patients in the DA arm, had an improved EFS (P=0.038). In intermediate cytogenetic profile, patients with mutant CEBPA had prolonged RFS in the HAA arm as compared with the DA arm (P=0.045). Conclusions Homoharringtonine-based induction regimens are associated with a higher rate of CR and improved survival as compared with DA regimen in AML. The toxicity is mild with the exception of a higher rate of induction death. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3641 Background: Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of lymphoproliferative disorders, and most subtypes have a poor prognosis even with aggressive chemotherapy. Romidepsin is a potent class 1 histone deacetylase inhibitor approved by the US Food and Drug Administration for treatment of patients with PTCL who have received at least 1 prior therapy and patients with cutaneous T-cell lymphoma who have received at least 1 prior systemic therapy. A phase 2, single-arm, open-label registration study (GPI-06–0002) demonstrated the clinical benefit and tolerability of romidepsin in patients with relapsed or refractory PTCL (data cutoff: Oct 2010). Here, we present an update of the efficacy of GPI-06–0002 and characterize patients who achieved long-term responses (≥ 12 months) as of Dec 2011 (median follow-up: 22.3 months). Methods: Patients with histologically confirmed PTCL (N = 130) who failed or were refractory to ≥ 1 prior systemic therapy received romidepsin 14 mg/m2 as a 4-hour intravenous infusion on days 1, 8, and 15 every 28 days for up to 6 cycles; treatment could be extended for responding patients. The primary endpoint was confirmed/unconfirmed complete response (CR/CRu) determined by an independent review committee (IRC) based on the International Workshop Response Criteria. Secondary endpoints included objective response rate (ORR: CR/CRu + partial response), duration of response (DOR), and time to progression. Disease response was assessed every 2 treatment cycles. Baseline patient characteristics by DOR (≥ 12 months vs 〈 12 months) were examined. Results: The majority of the 130 patients had stage III or IV disease (70%); 28% had bone marrow involvement. PTCL not otherwise specified (53%) and angioimmunoblastic T-cell lymphoma (21%) were the most common subtypes. Patients received a median of 2 prior systemic therapies (range, 1–8); 38% of patients were refractory to their last line of therapy. The ORR was 25% (33 of 130 patients), including CR/CRu in 15% (19 of 130) of patients. The median duration of objective response was 28 months, with the longest response ongoing at 48 months (Figure). Of the 19 patients who achieved CR/CRu, 13 (68%) had not experienced disease progression per the IRC at a median follow-up of 25.8 months. The median duration of CR had not yet been reached (range, 1–48+ months; Figure). Of the 19 patients who achieved CR/CRu, 10 were long-term responders (responses ≥ 12 months). Interestingly, heavy pretreatment (≥ 4 prior systemic therapies) did not preclude patients from achieving long-term CR/CRu: 5 of 10 patients (50%) who maintained CR/CRu for ≥ 12 months were heavily pretreated vs 1 of 9 (11%) patients with CR/CRu maintained for 〈 12 months. Long-term CR/CRu was achieved regardless of response to last prior therapy; only 2 of 10 (20%) long-term responders had an objective response on their last treatment. In contrast, 6 of 9 (67%) patients with CR/CRu for 〈 12 months responded to their last prior therapy. Furthermore, advanced disease did not preclude long-term response to romidepsin: all 10 patients (100%) who maintained CR/CRu for ≥ 12 months had stage III/IV disease vs 55.5% of those who maintained CR/CRu for 〈 12 months. Other characteristics, such as Eastern Cooperative Oncology Group performance status, International Prognostic Index score, age, sex, and race, were similar among patients achieving CR/CRu for ≥ 12 months or 〈 12 months. Conclusions: Single-agent romidepsin induced durable responses in patients with relapsed/refractory PTCL, with responses ongoing at 48 months. None of the examined patient and disease characteristics predicted failure to achieve long-term remissions. These results support the use of romidepsin in relapsed/refractory PTCL. Disclosures: Coiffier: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Pro:Allos: Honoraria; Spectrum : Honoraria; Seattle Genetics : Research Funding; Celgene: Honoraria, Research Funding. Prince:Celgene : Consultancy, Honoraria, Research Funding. Foss:Celgene : Consultancy. Sokol:Celgene : Honoraria, Speakers Bureau. Morschhauser:Celgene : Consultancy, Honoraria. Pinter-Brown:Celgene : Consultancy; Allos : Consultancy. Shustov:Celgene : Honoraria, Research Funding, Speakers Bureau. Nielsen:Celgene: Employment, Equity Ownership. Nichols:Celgene: Consultancy, Employment, Equity Ownership. Horwitz:Celgene: Consultancy, Research Funding; Kyowa Hakko Kirin Pharma: Consultancy; Bristol-Myers Squibb: Consultancy; Allos: Consultancy, Research Funding; Genzyme: Consultancy; Johnson & Johnson: Consultancy; Infinity Pharmaceuticals: Research Funding; Seattle Genetics: Consultancy, Research Funding.

Description: In the present study, we re-annotated von Willebrand factor (VWF), assigned its entire sequence to specific modules, and related these modules to structure using electron microscopy (EM). The D domains are assemblies of smaller modules visible as lobes in EM. Modules in the D-domain assemblies include von Willebrand D, 8-cysteine, trypsin inhibitor-like, E or fibronectin type 1-like domains, and a unique D4N module in D4. The D1-D2 prodomain shows 2 large connected assemblies, each containing smaller lobes. The previous B and C regions of VWF are re-annotated as 6 tandem von Willebrand C (VWC) and VWC-like domains. These 6 VWC domains correspond to 6 elongated domains that associate in pairs at acidic pH in the stem region of VWF dimeric bouquets. This correspondence is demonstrated by binding of integrin αIIbβ3 to the fourth module seen in EM, VWC4, which bears the VWF Arg-Gly-Asp motif. The C-terminal cystine knot domain dimerizes end-to-end in a manner predicted by homology to TGF-β and orients approximately perpendicular to the VWC domains in dimeric bouquets. Homologies of domains in VWF to domains in other proteins allow many disulfide bonds to be tentatively assigned, which may have functional implications.

Description: The Pediatric Hydroxyurea Phase 3 Clinical Trial (BABY HUG) was a phase 3 multicenter, randomized, double-blind, placebo-controlled clinical trial of hydroxyurea in infants (beginning at 9-18 months of age) with sickle cell anemia. An important secondary objective of this study was to compare clinical events between the hydroxyurea and placebo groups. One hundred and ninety-three subjects were randomized to hydroxyurea (20 mg/kg/d) or placebo; there were 374 patient-years of on-study observation. Hydroxyurea was associated with statistically significantly lower rates of initial and recurrent episodes of pain, dactylitis, acute chest syndrome, and hospitalization; even infants who were asymptomatic at enrollment had less dactylitis as well as fewer hospitalizations and transfusions if treated with hydroxyurea. Despite expected mild myelosuppression, hydroxyurea was not associated with an increased risk of bacteremia or serious infection. These data provide important safety and efficacy information for clinicians considering hydroxyurea therapy for very young children with sickle cell anemia. This clinical trial is registered with the National Institutes of Health (NCT00006400, www.clinicaltrials.gov).

Description: Abstract 578 Autologous stem cell transplantation (ASCT) for multiple myeloma (MM) offers a unique setting to explore the role of immunotherapeutic strategies in eradicating residual disease. A fundamental challenge to developing an effective anti-tumor immune response is overcoming the immunosuppressive milieu by which tumor cells evade host immunity. Key elements contributing to tumor-mediated immune suppression are the increased presence of regulatory T cells in patients with malignancy, and upregulation of the PD-1/PDL1 pathway. Tumor expression of PD-L1 promotes T cell tolerance by binding PD-1 on activated T cells and suppressing their capacity to secrete stimulatory cytokines. In addition, the PD-1/PDL-1 pathway has been shown to inhibit T cell-mediated lysis of tumor cells, potentially preventing a clinically meaningful immunologic response to tumor vaccines. We are conducting a clinical trial in which patients with MM are treated with an anti-PD1 antibody (CT-011) alone (Cohort 1) and in combination with a dendritic cell/myeloma fusion cell vaccine (Cohort 2) following ASCT. To date, 27 patients have been enrolled into Cohort 1, in which patients receive three infusions of CT-011 at doses of 3mg/kg given at 6 week intervals beginning 1–3 months following ASCT. Mean age of the patients is 57 years; 61% are male. 11 patients have received at least two infusions of CT-011. The remaining patients are undergoing pre-transplant therapy/transplant. CT-011 has been well tolerated, with possibly related adverse events consisting of transient grade 1–2 leukopenia, diarrhea, fatigue, arthralgia, rash, and peri-orbital edema. One patient developed grade 3 neutropenia, which resolved after two days without growth factor. Immunologic response was determined by quantifying circulating tumor reactive T cells prior to each dose of CT-011 and at 1, 3, 6 months following the last infusion, as defined by the percentage of T cells expressing IFNg in response to ex vivo exposure to autologous tumor lysate. 4 patients have completed 6 months of follow up after the third dose of CT-011, and are evaluable for immune response. CT-011 therapy was associated with the dramatic expansion of myeloma specific T cells. Mean percentage of circulating tumor reactive CD4+ and CD8+ T cells increased from 1.5 and 1.96 respectively prior to the first infusion of CT-011, to 4.26 and 8.28 respectively 1 month following the third infusion. As determined by tetramer staining in the subset of patients who are HLA A2.1, infusion of CT-011 resulted in a mean 9 fold expansion of T cells specific to the MUC1 antigen, which is aberrantly expressed by myeloma cells. Notably, immunologic response to CT-011 persists at 6 months following completion of therapy. Clinical response, as determined by time to disease progression, will be determined with longer follow up, as the median time from transplant is presently 8 months. We are initiating enrollment to Cohort 2, in which patients will be vaccinated with an autologous DC/myeloma fusion vaccine 1 week prior to each dose of CT-011. These data demonstrate that CT-011 results in the expansion of tumor reactive lymphocytes in the early post-transplant period, providing an ideal platform for combination with a tumor vaccine. Disclosures: Rosenblatt: CureTech Ltd.: Research Funding. Schickler:CurTech Ltd.: Employment, Research Funding. Rotem-Yehudar:CureTech Ltd: Employment, Research Funding. Avigan:CureTech Ltd: Research Funding.

Description: Abstract 687 Background: A persistently positive PET scan after just a few cycles of therapy is predictive of a poor clinical outcome in diffuse large B-cell lymphoma (DLBCL). Prior data suggested that about one third of patients remain PET positive after 2–4 cycles, with ≤ 20% 2 year progression-free survival (PFS) for such patients. A response-adapted strategy was studied in E3404 to test the hypothesis that an early treatment change to four cycles of R-ICE might reduce the treatment failure rate of patients whose PET scan remained positive after an initial 3 cycles of R-CHOP. Study Design: Previously untreated patients with DLBCL stage III, IV, or bulky II, with measurable disease, HIV negative, and with adequate organ reserve, were eligible. PET/CT scan was performed before treatment and again after 3 cycles of R-CHOP. A fourth cycle of R-CHOP was given while the scan was centrally reviewed and scored as either positive or negative for FDG-avid tumor by a single reviewer using criteria based on modifications of the Harmonization Criteria. Persistently PET-positive patients received 4 cycles of R-ICE, while PET-negative patients received 2 more cycles of R-CHOP, for a total of 6 cycles. PET/CT was performed again at the end of treatment. A ≥45% 2 year PFS for mid-treatment PET- positive patients was viewed as a promising result, with 88% power if 33 such patients were accrued. Total accrual of 99 patients was therefore planned. Results: Of 100 patients accrued, 78 were eligible; all but 1 ineligibility was based on central pathology review. Fifty-eight were male; median age was 62 years (20–74); 13% IPI 0–1, 31% IPI 2, 37% IPI 3, and 19% IPI 4–5. Seventy-four of 78 (95%) patients completed the first 3 cycles of R-CHOP. Of 72 patients continuing treatment, 67 (93%) completed protocol treatment: 83% of mid-treatment PET-positive and 93% of PET-negative patients. Of 74 patients undergoing mid-treatment PET scan, 12 (16%) were scored as positive, and 62 (84%) as negative. At the end of treatment, 13% were scored as positive, and 87% as negative. Two-year PFS, from the time of study entry, was 72% among all eligible patients. Two year PFS from the time of mid-treatment PET scan was 45% (90% CI, 21–67%) for patients scored as mid-treatment PET-positive, and 77% (90% CI 67–85%) for patients scored as mid-treatment PET-negative. The 80% confidence interval (corresponding to a test with a one-sided type I error of 10%) did not include the null hypothesis of 25%, implying that the results met the pre-specified threshold. Among all 78 eligible patients, 10 have died (13%); 5-year overall survival was 87% (90% CI 78–92%) Three-year overall survival was 67% (90% CI 40–84%) for mid-treatment PET-positive patients, and 93% (90% CI 85–97%) for mid-treatment PET-negative patients. Conclusions: The 2-year PFS for mid-treatment PET-positive patients met the threshold to be considered promising, but the confidence interval was wider than expected due to the small patient number. In addition, the inter-observer variability in the interpretation of mid-treatment PET scans as a binary variable in this study (studied and reported separately in Horning SJ et al. Blood 2010) implies that treatment modification based on early PET scanning should remain confined to clinical trials. Disclosures: Swinnen: Celgene: Consultancy; Genentech: Research Funding. Quon:Genentech: Research Funding. Advani:Pharmacyclics: Research Funding. Kahl:Roche/Genentech: Consultancy; Celgene: Consultancy; Cell Therapeutics: Consultancy; Janssen: Consultancy; GSK: Consultancy; Gilead: Consultancy. Horning:Genentech: Employment; Roche: stock, stock Other.

Description: Cancer patients often have an activated clotting system and are at increased risk for venous thrombosis. In the present study, we analyzed tissue factor (TF) expression in 4 different human pancreatic tumor cell lines for the purpose of producing derivative tumors in vivo. We found that 2 of the lines expressed TF and released TF-positive microparticles (MPs) into the culture medium. The majority of TF protein in the culture medium was associated with MPs. Only TF-positive cell lines activated coagulation in nude mice, and this activation was abolished by an anti–human TF Ab. Of the 2 TF-positive lines, only one produced detectable levels of human MP TF activity in the plasma when grown orthotopically in nude mice. Surprisingly, 〈 5% of human TF protein in plasma from tumor-bearing mice was associated with MPs. Mice with TF-positive tumors and elevated levels of circulating TF-positive MPs had increased thrombosis in a saphenous vein model. In contrast, we observed no difference in thrombus weight between tumor-bearing and control mice in an inferior vena cava stenosis model. The results of the present study using a xenograft mouse model suggest that tumor TF activates coagulation, whereas TF on circulating MPs may trigger venous thrombosis.

Description: Cancer cells frequently overexpress tissue factor (TF) and become procoagulant. This conversion may be driven by genetic transformation, including through the expression of the oncogenic epidermal growth factor receptor (EGFR) and its mutant, EGFRvIII, present in glioblastoma multiforme (GBM). Here we show that the EGFRvIII-dependent GBM cell transformation is associated with the onset of the simultaneous overexpression of TF, protease-activated receptors 1 and 2 (PAR1 and PAR2), and ectopic synthesis of factor VII (FVII). Efficient generation of factor Xa by these cells still requires exogenous FVIIa. However, as a result of EGFRvIII-dependent transformation, GBM cells become hypersensitive to TF/PAR-mediated signaling and produce ample angiogenic factors (vascular endothelial growth factor and interleukin-8) on exposure to FVIIa and PAR1- or PAR2-activating peptides. Thus, oncogenes may cause complex changes in the ability of GBM cancer cells to interact with the coagulation system, thereby exacerbating its influence on angiogenesis and disease progression.

Description: Natural killer (NK) cells can mediate the rejection of bone marrow allografts and exist as subsets based on expression of inhibitory/activating receptors that can bind MHC. In vitro data have shown that NK subsets bearing Ly49 receptors for self-MHC class I have intrinsically higher effector function, supporting the hypothesis that NK cells undergo a host MHC-dependent functional education. These subsets also play a role in bone marrow cell (BMC) allograft rejection. Thus far, little in vivo evidence for this preferential licensing across mouse strains with different MHC haplotypes has been shown. We assessed the intrinsic response potential of the different Ly49+ subsets in BMC rejection by using β2-microglobulin deficient (β2m−/−) mice as donors. Using congenic and allogeneic mice as recipients and depleting the different Ly49 subsets, we found that NK subsets bearing Ly49s, which bind “self-MHC” were found to be the dominant subset responsible for β2m−/− BMC rejection. This provides in vivo evidence for host MHC class I–dependent functional education. Interestingly, all H2d strain mice regardless of background were able to resist significantly greater amounts of β2m−/−, but not wild-type BMC than H2b mice, providing evidence that the rheostat hypothesis regarding Ly49 affinities for MHC and NK-cell function impacts BMC rejection capability.

Description: Although much is known about extrinsic regulators of platelet function such as nitric oxide and prostaglandin I2 (PGI2), considerably less is known about intrinsic mechanisms that prevent overly robust platelet activation after vascular injury. Here we provide the first evidence that regulators of G-protein signaling (RGS) proteins serve this role in platelets, using mice with a G184S substitution in Gi2α that blocks RGS/Gi2 interactions to examine the consequences of lifting constraints on Gi2-dependent signaling without altering receptor:effector coupling. The results show that the Gi2α(G184S) allele enhances platelet aggregation in vitro and increases platelet accumulation after vascular injury when expressed either as a global knock-in or limited to hematopoietic cells. Biochemical studies show that these changes occur in concert with an attenuated rise in cyclic adenosine monophosphate levels in response to prostacyclin and a substantial increase in basal Akt activation. In contrast, basal cyclic adenosine monophosphate (cAMP) levels, agonist-stimulated increases in [Ca++]i, Rap1 activation, and α-granule secretion were unaffected. Collectively, these observations (1) demonstrate an active role for RGS proteins in regulating platelet responsiveness, (2) show that this occurs in a pathway-selective manner, and (3) suggest that RGS proteins help to prevent unwarranted platelet activation as well as limiting the magnitude of the normal hemostatic response.

Description: Constitutive expression of tissue factor (TF) by cancer cells triggers local activation of the coagulation cascade and promotes breast cancer progression through cell signaling involving protease activated receptor (PAR)2. In human breast cancer, TF and PAR2 are up-regulated and TF cytoplasmic domain phosphorylation is correlated with relapse. Here we show that cancer cell PAR2 signaling promotes angiogenesis independent of PAR2 phosphorylation at the recognized β-arrestin recruitment site. Similar to PAR2−/− mice, TF cytoplasmic domain–deleted (TFΔCT) mice have delayed spontaneous breast cancer development in the polyoma middle T model. Simultaneous deletion of PAR2 in TFΔCT mice did not further delay tumor appearance, consistent with overlapping roles of TF and PAR2 in promoting the angiogenic switch in early stages of breast cancer. In advanced carcinomas, tumor-associated macrophages were reduced in TFΔCT and TFΔCT/PAR2−/− mice, and increased tumor vessel diameters of TFΔCT mice were partially reversed by PAR2-deficiency, indicating that the TF cytoplasmic domain has additional roles that are interdependent with PAR2 signaling in regulating host angiogenic responses. These experiments demonstrate a crosstalk of tumor cell TF cytoplasmic domain and PAR2 signaling and provide a possible mechanism for the close correlation between TF phosphorylation and cancer recurrence of TF and PAR2-positive clinical breast cancer.

Description: Abstract 2237 Introduction: von Willebrand disease (VWD) has clinically heterogeneous phenotype. Routine measurements of von Willebrand factor (VWF) antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo) and FVIII activity (FVIII:C) do not always reflect clinical severity, especially in type 1 VWD. These assays evaluate VWF function under non-physiological static condition - lacking blood flow. We had reported that a new microchip flow chamber system, total-thrombus-formation analysis system (T-TAS®, Fujimori Kogyo, Tokyo) would be a clinically useful flow assay for VWD (ASH 2011). In this study, we extended this study for application to evaluation and hemostatic monitoring for type 1 VWD. Methods: Citrated or hirudin-added blood from 15 patients with type 1 VWD was utilized. Re-calcified citrated blood added corn trypsin inhibitor was injected to a microchip in T-TAS at a constant flow rate (240 s−1), which flow surface was coated by collagen and tissue factor (AR chip). Hirudin-added blood was injected to a microchip in T-TAS at higher shear rate (1,000 s−1) which surface was coated by collagen (PL chip). Flow pressure curve was visualized and time until reach to 10 kPa (T10) was evaluated. AR chip promoted thrombus formation by both platelet aggregation and fibrin generation, whilst PL chip promoted thrombus formation by platelet alone. Standard laboratory tests for VWD were also performed. Clinical severities of VWD patients were evaluated by using a quantitative bleeding score (BS, from −3 without any symptoms to +45 with all major symptoms) previously reported by Tosetto (JTH, 2006). Results: Fifteen patients with type 1 VWD showed low levels of VWF:Ag [median 14% (range 1.3–51%)], VWF:RCo [8% (1.6–32%)], and FVIII:C [31% (3.0–68%)]. T10 in AR chip or PL chip was 17.7 min (11-〉30) or 7.1 min (3.3-〉10) [normal control (n=20); 12.2 min (8.6–16.6) or 3.5 min (2.4–6.6), respectively], showing delayed thrombus formation in type 1 VWD. Correlations between VWF:Ag and VWF:RCo (r2=0.80, p

Description: Abstract 3783 Introduction: Dengue fever is the most prevalent mosquito-borne viral disease, and its clinical signs and symptoms can vary widely. Since hemorrhagic manifestations are common, hematologists are often included in the care of these patients, and face a difficult challenge trying to discriminate dengue fever from other more common viral infections. Laboratory tests used in this context are less than optimal. The expected findings of leukopenia and thrombocytopenia are absent in many cases, thus delaying the suspicion for dengue and the ordering of confirmatory serological tests. Leukocyte morphology changes in numerous medical conditions, including infections. The VCS technology available in the LH and DxH hematology analyzers is capable of automatically quantifying leukocyte morphologic characteristics: cell volume by voltage impedance (V); cytoplasmic and nuclear density by radio frequency conductivity (C); and cytoplasmic granularity and nuclear complexity by laser light scatter (S). The mean and standard deviation of each parameter is calculated. This data is collected for neutrophils, lymphocytes, monocytes and eosinophils separately. Previous studies have demonstrated the significant value of these VCS parameters in improving the laboratory diagnosis of malaria and septicemia, both in adults and neonates. The objective of this study was to compare the performance of the VCS parameters with that of traditional hematological tests used in the diagnosis of dengue fever. Methods: We included in this study 174 patients who were clinically suspected to have dengue fever, as indicated by the clinicians ordering serological testing. Of these, 92 patients were positive and 82 negative by serology. Using the Mann-Whitney U test, we compared the mean VCS values, as well as total leukocyte counts, leukocyte differential counts and platelet counts, between both groups. For those tests that showed a statistically significant difference between dengue positive and dengue negative patients, their diagnostic performance was compared by ROC curve. Finally, we separated patients with normal platelet and WBC counts, likely to be misdiagnosed based on these traditional laboratory tests, and evaluated the diagnostic performance of the VCS parameters in this subgroup. Results: Tests that showed a statistically significant difference (p

Description: FPD/AML is a familial platelet disorder characterized by platelet defects, predisposition to acute myelogenous leukemia (AML) and germ-line heterozygous RUNX1 alterations. Here we studied the in vitro megakaryopoiesis of 3 FPD/AML pedigrees. A 60% to 80% decrease in the output of megakaryocytes (MKs) from CD34+ was observed. MK ploidy level was low and mature MKs displayed a major defect in proplatelet formation. To explain these defects, we focused on myosin II expression as RUNX1 has been shown to regulate MYL9 and MYH10 in an inverse way. In FPD/AML MKs, expression of MYL9 and MYH9 was decreased, whereas MYH10 expression was increased and the MYH10 protein was still present in the cytoplasm of mature MKs. Myosin II activity inhibition by blebbistatin rescued the ploidy defect of FPD/AML MKs. Finally, we demonstrate that MYH9 is a direct target of RUNX1 by chromatin immunoprecipitation and luciferase assays and we identified new RUNX1 binding sites in the MYL9 promoter region. Together, these results demonstrate that the defects in megakaryopoiesis observed in FPD/AML are, in part, related to a deregulation of myosin IIA and IIB expression leading to both a defect in ploidization and proplatelet formation.

Description: MicroRNAs are small noncoding RNAs that regulate cellular development by interfering with mRNA stability and translation. We examined global microRNA expression during the differentiation of murine hematopoietic progenitors into megakaryocytes. Of 435 miRNAs analyzed, 13 were up-regulated and 81 were down-regulated. Many of these changes are consistent with miRNA profiling studies of human megakaryocytes and platelets, although new patterns also emerged. Among 7 conserved miRNAs that were up-regulated most strongly in murine megakaryocytes, 6 were also induced in the related erythroid lineage. MiR-146a was strongly up-regulated during mouse and human megakaryopoiesis but not erythropoiesis. However, overexpression of miR-146a in mouse bone marrow hematopoietic progenitor populations produced no detectable alterations in megakaryocyte development or platelet production in vivo or in colony assays. Our findings extend the repertoire of differentially regulated miRNAs during murine megakaryopoiesis and provide a useful new dataset for hematopoiesis research. In addition, we show that enforced hematopoietic expression of miR-146a has minimal effects on megakaryopoiesis. These results are compatible with prior studies indicating that miR-146a inhibits megakaryocyte production indirectly by suppressing inflammatory cytokine production from innate immune cells, but cast doubt on a different study, which suggests that this miRNA inhibits megakaryopoiesis cell-autonomously.

Description: RUNX1 gene alterations are associated with acquired and inherited hematologic malignancies that include familial platelet disorder/acute myeloid leukemia, primary or secondary acute myeloid leukemia, and chronic myelomonocytic leukemia. Recently, we reported that RUNX1-mediated silencing of nonmuscle myosin heavy chain IIB (MYH10) was required for megakaryocyte ploidization and maturation. Here we demonstrate that runx1 deletion in mice induces the persistence of MYH10 in platelets, and a similar persistence was observed in platelets of patients with constitutional (familial platelet disorder/acute myeloid leukemia) or acquired (chronic myelomonocytic leukemia) RUNX1 mutations. MYH10 was also detected in platelets of patients with the Paris-Trousseau syndrome, a thrombocytopenia related to the deletion of the transcription factor FLI1 that forms a complex with RUNX1 to regulate megakaryopoiesis, whereas MYH10 persistence was not observed in other inherited forms of thrombocytopenia. We propose MYH10 detection as a new and simple tool to identify inherited platelet disorders and myeloid neoplasms with abnormalities in RUNX1 and its associated proteins.

Description: This systematic review was designed to provide more precise effect estimates of inhibitor development for the various types of F8 gene mutations in patients with severe hemophilia A. The primary outcome was inhibitor development and the secondary outcome was high-titer-inhibitor development. A systematic literature search was performed to include cohort studies published in peer-reviewed journals with data on inhibitor incidences in the various F8 gene mutation types and a mutation detection rate of at least 80%. Pooled odds ratios (ORs) of inhibitor development for different types of F8 gene mutations were calculated with intron 22 inversion as the reference. Data were included from 30 studies on 5383 patients, including 1029 inhibitor patients. The inhibitor risk in large deletions and nonsense mutations was higher than in intron 22 inversions (pooled OR = 3.6, 95% confidence interval [95% CI], 2.3-5.7 and OR = 1.4, 95% CI, 1.1-1.8, respectively), the risk in intron 1 inversions and splice-site mutations was equal (pooled OR = 0.9; 95% CI, 0.6-1.5 and OR = 1.0; 95% CI, 0.6-1.5), and the risk in small deletions/insertions and missense mutations was lower (pooled OR = 0.5; 95% CI, 0.4-0.6 and OR = 0.3; 95% CI, 0.2-0.4, respectively). The relative risks for developing high titer inhibitors were similar.

Description: Severe bacterial sepsis often leads to a systemic procoagulant and proinflammatory condition that can manifest as disseminated intravascular coagulation, septic shock, and multiple organ failure. Because activation of the contact proteases factor XII (FXII), prekallikrein, and factor XI (FXI) can trigger coagulation and inflammatory responses, the contact factors have been considered potential targets for the treatment of sepsis. However, the pathogenic role of contact activation in severe infections has not been well defined. We therefore investigated whether an anticoagulant antibody (14E11) that selectively inhibits prothrombotic FXI activation by activated FXII (FXIIa) modifies the course of bowel perforation-induced peritoneal sepsis in mice. Early anticoagulation with 14E11 suppressed systemic thrombin- antithrombin complex formation, IL-6, and TNF-α levels, and reduced platelet consumption in the circulation and deposition in the blood vessels. Treatment with 14E11 within 12 hours after bowel perforation significantly improved survival compared with vehicle treatment, and the saturating dose did not increase tail bleeding. These data suggest that severe polymicrobial abdominal infection induces prothrombotic FXI activation, to the detriment of the host. Systemic anticoagulation by inhibiting FXI activation or FXIIa procoagulant activity during sepsis may therefore limit the development of disseminated intravascular coagulation without increasing bleeding risks.

Description: Therapeutic targeting of virus-encoded proteins using cellular immunotherapy has proved successful for Epstein-Barr virus (EBV)–associated posttransplant lymphoproliferative disease. However, the more limited repertoire and immunogenicity of EBV-encoded proteins in other malignancies such as Hodgkin lymphoma and extranodal natural killer (NK)/T lymphoma has been more challenging to target. The immunosubdominant latent membrane protein 2 (LMP2) is considered the optimal target in such Latency II tumors, although data relating to its expression in T/NK malignancies are limited. In addressing the validity of LMP2 as an immunotherapeutic target we found that LMP2-specific effector CD8+ T cells recognized and killed EBV-positive NK- and T-cell tumor lines, despite an apparent absence of LMP2A protein and barely detectable levels of LMP2 transcripts from the conventional LMP2A and LMP2B promoters. We resolved this paradox by identifying in these lines a novel LMP2 mRNA, initiated from within the EBV terminal repeats and containing downstream, epitope-encoding exons. This same mRNA was also highly expressed in primary (extra-nodal) NK/T lymphoma tissue, with virtually undetectable levels of conventional LMP2A/B transcripts. Expression of this novel transcript in T/NK-cell lymphoproliferative diseases validates LMP2 as an attractive target for cellular immunotherapy and implicates this truncated LMP2 protein in NK- and T-cell lymphomagenesis. This study is registered at clinicaltrials.gov as NCT00062868.

Description: There is increasing evidence that miRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative polymerase chain reaction, we identified miRNA-494 and miRNA-320a to be up-regulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments, we demonstrate that survivin is a target of the 2 miRNAs. miRNA-494 and miRNA-320a were introduced to the cells by transfection and survivin expression determined by Western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be Dicer-dependent. miRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared with immunophenotype-matched nonTEL-AML1 acute lymphoblastic leukemia subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its antiapoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.

Description: Abstract 964 Background: High dose immunosuppressive therapy and hematopoietic stem cell transplantation (HSCT) has shown efficacy in severe or rapidly progressive systemic sclerosis (SSc) in phase 1 and 2 trials with durable responses in two thirds of patients (pts), while a recent phase 2 randomised trial in 19 SSc pts showed superior benefit of HSCT over iv pulse cyclophosphamide (Cy) on skin score and lung function. Methods: The ASTIS-trial (Autologous Stem cell Transplantation International Scleroderma trial) is a multinational prospective randomized controlled phase 3 trial, comparing safety and efficacy of HSCT versus Cy in early progressive dcSSc pts with disease duration of a) 4 years or less and evidence of organ involvement or b) of 2 years or less and evidence of systemic inflammation with or without major organ involvement. Major exclusion criteria were: concomitant severe SSc disease (mean PAP 〉 50 mmHg, DLCO 〈 40% predicted, creatinine clearance (CCl) 3months oral) treatment), liver failure. Pts randomized to the transplant arm underwent mobilization with Cy 2×2 g/m2 + G-CSF 10mcg/kg/d, conditioning with Cy 200 mg/kg, rbATG 7.5 mg/kg, followed by reinfusion of CD34+ autologous HSCT. Controls were treated with 12× monthly iv pulse Cy 750 mg/m2. Crossing over was allowed after 2 years. The primary endpoint was event-free survival (EFS), defined as survival until death or development of major organ failure at 2 yrs. Toxicity according to WHO criteria and progression free survival (defined as worsening of modified Rodnan skin score, functional ability, major organ function) were the main secondary endpoints. The effects of treatment were analyzed on an ITT basis and by comparing EFS using the KM survival curves (using log-rank test) and Cox models. Results: 156 pts (female 59%), from 27 centers were enrolled in 10 countries from March 2001 until October 2009 and randomized to HSCT (n=79) or iv pulse Cy (n=77). Seventy-five pts in each arm started treatment, 70 pts in HSCT and 58 pts in control groups completed treatment. The median time (Interquartile Range (IR)) from randomization to completion of treatment was 93 (43.0) days in the HSCT and 338 (41.75) days in the control groups respectively. Baseline characteristics (mean (SD)) of the pts were: age 44 (11.2) yrs, SSc duration 1.4 (1.3) yrs, BMI 24 (14.4), Rodnan skin score 25 (8), HAQ 1.35 (0.8), prior Cy therapy 22%, creat cl 116 (39.5) ml/min, LVEF 65% (8.5), DLCO 59% (14), with no significant differences between the 2 arms. With data cut at 1 May 2012, median follow-up (IR) are 33 (42.0) and 27 (34.0) months in the HSCT and control groups respectively. Forty two events occurred : 18 in the HSCT group (16 deaths and 2 irreversible renal failures) and 24 in the control group (24 deaths). Event-free survival was time-dependent with a hazard ratio at 84 months of 0.22 (95% CI 0.08–0.58, P= 0.002). Eight deaths (including 1 during mobilization and 1 after conditioning) in the HSCT group were deemed treatment-related by the independent data monitoring committee with heart failure (3), ARDS (2), multiple organ failure (2) and pulmonary oedema (1) as the causes of death. In the control group, none died from treatment causes and most deaths were due to progressive disease. Eight pts in the control arm received rescue HSCT treatment, one of whom later died from secondary acute myeloid leukaemia. Two HSCT pts received rescue iv Cy therapy. Conclusions: The ASTIS-trial is the first international, investigator-initiated, phase 3 HSCT trial in early diffuse cutaneous systemic sclerosis. The data show that despite 10% treatment-related mortality, long term event-free survival and overall survival were better in the HSCT group than in the group treated with iv pulse cyclophosphamide. (Funded by the European Group for Blood and Marrow Transplantation, European League Against Rheumatism, AP-HP, NIHR, DIGR, Imtix-Sangstat, Miltenyi-Biotec, Amgen Europe; Current Controlled Trials number, ISRCTN 54371254). Disclosures: No relevant conflicts of interest to declare.

Description: Human herpes virus 8 (HHV-8) or Kaposi sarcoma-associated herpes virus is the etiologic agent of Kaposi sarcoma, primary effusion lymphoma, and plasma cell-type multicentric Castleman disease (MCD). HHV-8 encodes a viral homolog of human IL-6, called viral IL-6 (vIL-6), which does not require the cellular IL-6 receptor for binding to the ubiquitously expressed gp130 receptor subunit and subsequent JAK-STAT signaling. Thus, in contrast to IL-6, vIL-6 can stimulate virtually all cells in the body. To elucidate the mechanism by which vIL-6 drives human diseases, we generated transgenic mice that constitutively express vIL-6 under control of the MHC class I promoter. The mice were found to exhibit vIL-6 serum levels comparable with those observed in HHV-8–infected patients, to contain elevated amounts of phosphorylated STAT3 in spleen and lymph nodes, where vIL-6 was produced, and to spontaneously develop key features of human plasma cell-type MCD, including splenomegaly, multifocal lymphadenopathy, hypergammaglobulin-emia, and plasmacytosis. Transfer of the vIL-6 transgene onto an IL-6–deficient genetic background abrogated MCD-like phenotypes, indicating that endogenous mouse IL-6 is a crucial cofactor in the natural history of the disease. Our results in mice suggest that human IL-6 plays an important role in the pathogenesis of HHV-8–associated MCD.

Description: Apc, a negative regulator of the canonical Wnt signaling pathway, is a bona-fide tumor suppressor whose loss of function results in intestinal polyposis. APC is located in a commonly deleted region on human chromosome 5q, associated with myelodysplastic syndrome (MDS), suggesting that haploinsufficiency of APC contributes to the MDS phenotype. Analysis of the hematopoietic system of mice with the Apcmin allele that results in a premature stop codon and loss of function showed no abnormality in steady state hematopoiesis. Bone marrow derived from Apcmin mice showed enhanced repopulation potential, indicating a cell intrinsic gain of function in the long-term hematopoietic stem cell (HSC) population. However, Apcmin bone marrow was unable to repopulate secondary recipients because of loss of the quiescent HSC population. Apcmin mice developed a MDS/myeloproliferative phenotype. Our data indicate that Wnt activation through haploinsufficiency of Apc causes insidious loss of HSC function that is only evident in serial transplantation strategies. These data provide a cautionary note for HSC-expansion strategies through Wnt pathway activation, provide evidence that cell extrinsic factors can contribute to the development of myeloid disease, and indicate that loss of function of APC may contribute to the phenotype observed in patients with MDS and del(5q).

Description: Abstract 2825 Mantle cell lymphoma (MCL) constitutes one of the lymphomas with poorest prognosis at relapse and there are no effective salvage. The activity shown by the combination Gemcitabine and Oxaliplatin in several types of limfoma, along with its “in vitro” synergistic effect, made this regimen an attractive regimen for salvaging patients with MCL. Against this background, we performed an off-label pilot study in order to assess efficacy and toxicity of the combination R-GemOx in relapsed or refractory patients with MCL. For this, 27 patients (70% male, median age 70 years) diagnosed with MCL between November 2004 and January 2010 were included in this study. Inclusion criteria were adequate performance status, confirmed diagnosis of MCL and relapse or refractoriness to the previous treatment. The regimen consisted of Rituximab 375 mg/m2 on day 1, Gemcitabine 1000 mg/m2 and Oxaliplatin 100 mg/m2 on day 2, every 14 days, up to 8 cycles. Dose and interval were adjusted according to hematological and extrahematological toxicities. Median number of previous regimens was 1 (range 1 to 3), being EPOCH-R (n=14), R-CHOP (n=6), and RFC (n=3) the most frequently used induction therapies. Twelve patients relapsed after prior CR, 10 progressed after achieving a PR, whereas 5 were refractory to therapy. At inclusion, 85% of patients were in advanced (III/IV) clinical stage, 40% had bone marrow infiltration, 28% gastrointestinal involvement, and 17% cavum infiltration. Median number of cycles administered was 8 (range, 3 to 8). Doses were reduced in 9 cycles and delayed in 15 cycles. Neutropenia grade 3–4 was observed in 9 cycles and thrombocytopenia grade 3–4 in 6. Hepatotoxicity grade 1–2 in 5 pts and grade 3 in 1, sensitive neurotoxicity grade 1–2 in 12 pts, and renal impairment grade 2 in 1 patient. After completion of the treatment, 21 pts (77%) were considered in CR/uCR, 1 (4%) achieved a PR, 1 a SD, whereas 4 PD. Six patients subsequently received a stem-cell transplantation (4 allogeneic, 2 autologous). Thirteen pts are still alive and out of progression. Ten pts have died (8 due to progression and 2 due to acute GVHD). With a median follow-up of 23 months (range: 3–57), PFS and OS at 2 years are 41% and 58%, respectively. The R-GemOx combination showed a significant activity in relapsed or refractory pts with MCL with a very acceptable toxicity profile. These results prompted us to conduct a multicenter phase II clinical trial that is now ongoing. Disclosures: López: Roche Farma: Research Funding, Travel Support. Bosch:Roche Farma: Research Funding.

Description: Abstract 3498 Introduction: Oral mucositis is a complication of conditioning treatment that produces pain and morbidity in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients. The rationale of this study was to evaluate the efficacy of a calcium phosphate mouth rinse (Caphosol) vs standard regimen in 40 adult patients undergoing allo-HSCT. Patients and Methods: 40 patients treated with allo-HSCT (31 from unrelated donors, 9 from siblings) performed in Hematology and BMT center in Katowice in 2009 were randomized and stratified by the conditioning regimen (busulfan-, treosulfan- or TBI- based), type of transplant (unrelated or related) and age into two equal groups. Treatment group received Caphosol washes 4 times daily from first day of conditioning until reaching ANC 0.2 G/l. Control group received standard topical mouth care with salvia, antibacterial and antifungal solutions. During the trial patients subjectively assessed level of pain in mouth and in pharynx using 0–10 scale and swallowing problems using 0–5 scale. Mucositis was judged by experienced physician. Nonparametric Mann-Whitney U-tests were used for statistical analysis. Results: Average oral toxicity in WHO scale in Caphosol vs control group was 0.9 vs 1.8 (p=0.02), duration of mucositis was 3.2 vs 7.1 days (p=0.02). Total parenteral nutrition (TPN) due to mucosits was required in Caphosol vs control group in 0 vs 6 pts, average duration of TPN was 0 vs 1.9 days (p=0.009). Analgetics were required, respectively, in 3 vs 9 pts and analgesy lasted for 1.1 vs 3.4 days (p=0.047). Average subjective peak pain in mouth was 0.85 vs 1.75 (p=0.005) and in pharynx 1.95 vs 2.2 (NS) in Caphosol vs control group, average pain intensity was lower in Caphosol group throughout the whole period of mucositis. Intensity of swallowing problems tended to be lower in Caphosol group (NS). Acute GVHD was observed in 7 vs 9 pts in Caphosol vs control group and its average degree was 0.5 vs 0.9 (NS). Conclusions: Caphosol mouth rinse in the allo-HSCT recipients is associated with decrease of oral toxicity, lower peak pain due to mucositis and its shorter duration. In consequence, comfort of life is improved and the incidence of acute GVHD is reduced, as well as the requirement of TPN and analgetics. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4517 Oral mucositis is a common toxicity associated with many cancer therapies and has been correlated with risk for infection, mortality, and extended hospital stay. Prophylactic use of a supersaturated calcium phosphate mouth rinse (SSCPR, Caphosol..) was found in a phase III study to reduce the frequency, intensity, and duration of oral mucositis in patients (pts) undergoing allogeneic or autologous hematopoietic stem cell transplantation (Papas, et al. Bone Marrow Transpl 2003;31:705). That study also found a faster time to recovery of an absolute neutrophil count (ANC) ≥0.2×109/l, but not for other engraftment endpoints, possibly a result of the mixed pt population studied. We performed a single-center retrospective review of a uniform population of pts

Description: Age-group analyses were conducted of patients in the prophylactic platelet dose trial (PLADO), which evaluated the relation between platelet dose per transfusion and bleeding. Hospitalized patients with treatment-induced hypoproliferative thrombocytopenia were randomly assigned to 1 of 3 platelet doses: 1.1 × 1011, 2.2 × 1011, or 4.4 × 1011 platelets/m2 per transfusion, given for morning counts of ≤ 10 000 platelets/μL. Daily hemostatic assessments were performed. The primary end point (percentage of patients who developed grade 2 or higher World Health Organization bleeding) was evaluated in 198 children (0-18 years) and 1044 adults. Although platelet dose did not predict bleeding for any age group, children overall had a significantly higher risk of grade 2 or higher bleeding than adults (86%, 88%, 77% vs 67% of patients aged 0-5 years, 6-12 years, 13-18 years, vs adults, respectively) and more days with grade 2 or higher bleeding (median, 3 days in each pediatric group vs 1 day in adults; P 〈 .001). The effect of age on bleeding differed by disease treatment category and was most pronounced among autologous transplant recipients. Pediatric subjects were at higher risk of bleeding over a wide range of platelet counts, indicating that their excess bleeding risk may be because of factors other than platelet counts. This trial was registered at www.clinicaltrials.gov as #NCT00128713.

Description: Antiplatelet treatment is of fundamental importance in combatting functions/dysfunction of platelets in the pathogenesis of cardiovascular and inflammatory diseases. Dysfunction of anucleate platelets is likely to be completely attributable to alterations in posttranslational modifications and protein expression. We therefore examined the proteome of platelets highly purified from fresh blood donations, using elaborate protocols to ensure negligible contamination by leukocytes, erythrocytes, and plasma. Using quantitative mass spectrometry, we created the first comprehensive and quantitative human platelet proteome, comprising almost 4000 unique proteins, estimated copy numbers for ∼ 3700 of those, and assessed intersubject (4 donors) as well as intrasubject (3 different blood samples from 1 donor) variations of the proteome. For the first time, our data allow for a systematic and weighted appraisal of protein networks and pathways in human platelets, and indicate the feasibility of differential and comprehensive proteome analyses from small blood donations. Because 85% of the platelet proteome shows no variation between healthy donors, this study represents the starting point for disease-oriented platelet proteomics. In the near future, comprehensive and quantitative comparisons between normal and well-defined dysfunctional platelets, or between platelets obtained from donors at various stages of chronic cardiovascular and inflammatory diseases will be feasible.

Description: To define a role for hematopoietic stem cell transplantation (HSCT) in infants with acute lymphoblastic leukemia and rearrangements of the mixed-lineage-leukemia gene (MLL+), we compared the outcome of MLL+ patients from trial Interfant-99 who either received chemotherapy only or HSCT. Of 376 patients with a known MLL status in the trial, 297 (79%) were MLL+. Among the 277 of 297 MLL+ patients (93%) in first remission (CR), there appeared to be a significant difference in disease-free survival (adjusted by waiting time to HSCT) between the 37 (13%) who received HSCT and the 240 (87%) who received chemotherapy only (P = .03). However, the advantage was restricted to a subgroup with 2 additional unfavorable prognostic features: age less than 6 months and either poor response to steroids at day 8 or leukocytes more than or equal to 300 g/L. Ninety-seven of 297 MLL+ patients (33%) had such high-risk criteria, with 87 achieving CR. In this group, HSCT was associated with a 64% reduction in the risk of failure resulting from relapse or death in CR (hazard ratio = 0.36, 95% confidence interval, 0.15-0.86). In the remaining patients, there was no advantage for HSCT over chemotherapy only. In summary, HSCT seems to be a valuable option for a subgroup of infant MLL+ acute lymphoblastic leukemia carrying further poor prognostic factors. The trial was registered at www.clinicaltrials.gov as #NCT00015873 and at www.controlled-trials.com as #ISRCTN24251487.

Description: Mantle cell lymphoma (MCL) is a mostly incurable malignancy arising from naive B cells (NBCs) in the mantle zone of lymph nodes. We analyzed genomewide methylation in MCL patients with the HELP (HpaII tiny fragment Enrichment by Ligation–mediated PCR) assay and found significant aberrancy in promoter methylation patterns compared with normal NBCs. Using biologic and statistical criteria, we further identified 4 hypermethylated genes CDKN2B, MLF-1, PCDH8, and HOXD8 and 4 hypomethylated genes CD37, HDAC1, NOTCH1, and CDK5 when aberrant methylation was associated with inverse changes in mRNA levels. Immunohistochemical analysis of an independent cohort of MCL patient samples confirmed CD37 surface expression in 93% of patients, validating its selection as a target for MCL therapy. Treatment of MCL cell lines with a small modular immunopharmaceutical (CD37-SMIP) resulted in significant loss of viability in cell lines with intense surface CD37 expression. Treatment of MCL cell lines with the DNA methyltransferase inhibitor decitabine resulted in reversal of aberrant hypermethylation and synergized with the histone deacetylase inhibitor suberoylanilide hydroxamic acid in induction of the hypermethylated genes and anti-MCL cytotoxicity. Our data show prominent and aberrant promoter methylation in MCL and suggest that differentially methylated genes can be targeted for therapeutic benefit in MCL.

Description: The neutrophil nicotinamide adenine dinucleotide phosphate-oxidase is a multisubunit enzyme (comprising gp91phox, p22phox, p67phox, p40phox, p47phox, and Rac) that plays a vital role in microbial killing. The recent discovery of a chronic granulomatous disease patient who expresses a mutant p40phox subunit, together with the development of mouse models of p40phox function, indicate phosphatidylinositol 3-phosphate binding to the PX domain of p40phox is an important signal for oxidase activation. However, the presence of other conserved residues and domains in p40phox suggest further regulatory roles for this protein. To test this, we introduced wild-type and mutated versions of p40phox into fully differentiated mouse neutrophils by retroviral transduction of p40phox−/− bone marrow progenitors and repopulation of the bone marrow compartment in radiation chimaeras. Phosphorylation of p40phox on threonine 154, but not serine 315, was required for full oxidase activation in response to formylated bacterial peptide fMLP, serum-opsonized S aureus, and immunoglobulin-opsonized sheep red blood cells. A functional SH3 domain was not required for oxidase activation, and deletion of the entire domain resulted in enhanced oxidase responses. Phosphorylation of threonine 154 in response to S aureus was mediated by protein kinase Cδ and was required for full translocation of p47phox to phagosomes. These results define an important new element in the physiological activation of the oxidase.

Description: The SHIELD program for Hodgkin lymphoma in patients 60 years of age or older, prospectively evaluated clinical features and outcome in a large patient cohort (n = 175). The central element was a phase 2 study of VEPEMB chemotherapy (n = 103, median age 73 years) incorporating comorbidity assessment. A total of 72 other patients were treated off-study but registered prospectively and treated concurrently with: ABVD (n = 35); CLVPP (n = 19), or other (n = 18). Of VEPEMB patients, 31 had early-stage disease (stage 1A/2A) and received VEPEMB 3 times plus radiotherapy. Median follow-up was 36 months. Complete remission (CR) rate (intention-to-treat) was 74% and 3-year overall survival (OS) and progression-free survival (PFS) were 81% and 74%, respectively. A total of 72 patients had advanced-stage disease (stage 1B/2B/3 or 4) and received VEPEMB 6 times. CR rate was 61% with 3-year OS and PFS of 66% and 58%, respectively. Of patients achieving CR, 13% with early-stage and 5% with advanced-stage disease progressed. Overall treatment-related mortality was 7%. In patients treated with curative intent with VEPEMB, ABVD, and CLVPP (n = 157), CR linked to several factors in univariate analysis. In a Cox regression model only, obtaining CR remained significant for OS and CR plus comorbidity and age for PFS. RS-EBV status had no significant effect on outcome.

Description: Our previous work has shown that axon guidance gene family Nogo-B and its receptor (NgBR) are essential for chemotaxis and morphogenesis of endothelial cells in vitro. To investigate NogoB-NgBR function in vivo, we cloned the zebrafish ortholog of both genes and studied loss of function in vivo using morpholino antisense technology. Zebrafish ortholog of Nogo-B is expressed in somite while expression of zebrafish NgBR is localized in intersomitic vessel (ISV) and axial dorsal aorta during embryonic development. NgBR or Nogo-B knockdown embryos show defects in ISV sprouting in the zebrafish trunk. Mechanistically, we found that NgBR knockdown not only abolished its ligand Nogo-B–stimulated endothelial cell migration but also reduced the vascular endothelial growth factor (VEGF)–stimulated phosphorylation of Akt and vascular endothelial growth factor–induced chemotaxis and morphogenesis of human umbilical vein endothelial cells. Further, constitutively activated Akt (myristoylated [myr]Akt) or human NgBR can rescue the NgBR knockdown umbilical vein endothelial cell migration defects in vitro or NgBR morpholino-caused ISV defects in vivo. These data place Akt at the downstream of NgBR in both Nogo-B– and VEGF-coordinated sprouting of ISVs. In summary, this study identifies the in vivo functional role for Nogo-B and its receptor (NgBR) in angiogenesis in zebrafish.

Description: The development of tools for the prediction of nonrelapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (HSCT) would offer a major guidance in the therapeutic decision. Recently, the Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) has been associated with increased NRM risk in several retrospective studies, but its clinical utility has never been demonstrated prospectively in an adequately sized cohort. To this aim, we prospectively evaluated a consecutive cohort of 1937 patients receiving HSCT in Italy over 2 years. HCT-CI was strongly correlated with both 2-year NRM (14.7%, 21.3%, and 27.3% in patients having an HCT-CI score of 0, 1-2, and ≥ 3, respectively) and overall survival (56.4%, 54.5%, and 41.3%, respectively). There was an excellent calibration between the predicted and observed 2-year NRM in patients having an HCT-CI score of 0 and 1-2, whereas in the ≥ 3 group the predicted NRM overestimated the observed NRM (41% vs 27.3%). HCT-CI alone was the strongest predictor of NRM in patients with lymphoma, myelodysplastic syndrome, and acute myeloid leukemia in first remission (c-statistics 0.66, 064, and 0.59, respectively). We confirm the clinical utility of the HCT-CI score that could also identify patients at low NRM risk possibly benefiting from an HSCT-based treatment strategy.

Description: Telomerase reverse transcriptase (TERT) is a good candidate for cancer immunotherapy because it is overexpressed in 85% of all human tumors and implicated in maintenance of the transformed phenotype. TERT-based cancer vaccines have been shown to be safe, not inducing any immune-related pathology, but their impact on tumor progression is modest. Here we show that adoptive cell therapy with the use of high-avidity T lymphocytes reactive against telomerase can control the growth of different established tumors. Moreover, in transgenic adenocarcinoma mouse prostate mice, which develop prostate cancer, TERT-based adoptive cell therapy halted the progression to more aggressive and poorly differentiated tumors, significantly prolonging mouse survival. We also demonstrated that human tumors, including Burkitt lymphoma, and human cancer stem cells, are targeted in vivo by TERT-specific cytotoxic T lymphocytes. Effective therapy with T cells against telomerase, different from active vaccination, however, led to autoimmunity marked by a consistent, although transient, B-cell depletion in primary and secondary lymphoid organs, associated with alteration of the spleen cytoarchitecture. These results indicate B cells as an in vivo target of TERT-specific cytotoxic T lymphocytes during successful immunotherapy.

Description: Adaptive immune responses are characterized by substantial restructuring of secondary lymphoid organs. The molecular and cellular factors responsible for virus-induced lymphoid remodeling are not well known to date. Here we applied optical projection tomography, a mesoscopic imaging technique, for a global analysis of the entire 3-dimensional structure of mouse peripheral lymph nodes (PLNs), focusing on B-cell areas and high endothelial venule (HEV) networks. Structural homeostasis of PLNs was characterized by a strict correlation between total PLN volume, B-cell volume, B-cell follicle number, and HEV length. After infection with lymphocytic choriomeningitis virus, we observed a substantial, lymphotoxin (LT) β-receptor–dependent reorganization of the PLN microarchitecture, in which an initial B-cell influx was followed by 3-fold increases in PLN volume and HEV network length on day 8 after infection. Adoptive transfer experiments revealed that virus-induced PLN and HEV network remodeling required LTα1β2-expressing B cells, whereas the inhibition of vascular endothelial growth factor-A signaling pathways had no significant effect on PLN expansion. In summary, lymphocytic choriomeningitis virus-induced PLN growth depends on a vascular endothelial growth factor-A–independent, LT- and B cell–dependent morphogenic pathway, as revealed by an in-depth mesoscopic analysis of the global PLN structure.

Description: Abstract 3875 Introduction: Immunologic environment influences progression of lymphoid malignancies. Specifically, shifts in subsets of natural killer (NK) and T cells as well as tumor expression of inhibitory ligands may contribute to ability to evade host detection. Immune dysfunction may be particularly important in CLL/SLL, as prevalent circulating tumor cells engage in persistent, widespread interactions with immune cells; commonly-used mAb therapies (e.g. rituximab, alemtuzumab) rely upon ADCC mediated by NK cells and other innate effectors; and disease course is highly variable and not fully accounted for by tumor-intrinsic prognostic factors. Therefore, to better characterize the immune system in CLL/SLL, we prospectively assessed NK and T cell frequency, phenotype, and function in a series of CLL/SLL patients. Methods: Serial blood samples (up to 3 samples each, 3–6 months apart) were collected from 31 untreated CLL/SLL patients (median age 66) and 15 healthy age-matched controls (HC), and peripheral blood lymphocytes (PBL) analyzed directly ex vivo by multiparameter flow cytometry (160 distinct parameters evaluated, primarily on T and NK cells). NK cell-mediated natural and antibody-dependent cytotoxicity were also assessed by CD107a degranulation assay following PBL co-culture with rituximab, 721.221 EBV-transformed lymphoma cells, or both. Differences in parameters between patients and controls, or between progressors and non-progressors [categorized based on updated NCI-WG criteria (Blood 2008;111:5446)] were analyzed by Wilcoxon rank-sum test. All subjects signed IRB approved informed consent forms. Results: CLL/SLL VS. HC: CLL/SLL samples displayed a marked decrease in the ability of the cytolytic CD56dim NK cells to degranulate in response to tumor, both with or without rituximab (Table 1). CD56dim NK cells from CLL/SLL patients also displayed a more immature phenotype (↓CD57, ↓NKG2D, ↑CD27, ↓KIR) than those from HC, suggesting either a block in differentiation or elimination of the most-differentiated cells. NK cell expression of NKp44, CD69, CD62L, CD137, granzyme B, perforin, or PD-1, as well as tumor-induced NK cell production of IFNγ, did not differ. CLL/SLL patients had increased total T cells with a decreased CD4:CD8 ratio, associated with increased total number of CD8 T cells, greater activation of naive CD4 T cells and transition to a memory phenotype. Treg (CD4+CD25+FoxP3+) frequency was significantly higher in CLL/SLL patients (4.5% vs. 1.8% of CD4 T cells, p=0.005), as was PD-1 expression on both CD4 and CD8 T cells, while CD137 and ICOS expression was similar in both groups. PROGRESSORS VS. NON-PROGRESSORS: With median follow-up of 16.5 months (range 1–37), 7 of 31 patients have met criteria for progression. Compared to non-progressors, progressors showed changes in the CD56bright NK cell compartment suggestive of increased activation and accelerated differentiation, with increased expression of CD69, granzyme B, perforin, CD16, and KIR. However, no significant functional differences in NK cells, or consistent differences in T cell subsets, have been observed to date. Conclusions: CLL/SLL patients have a shift toward less mature NK cells, associated with deficits in NK cell degranulation against tumor targets, compared with healthy donors. Those CLL/SLL patients who progressed had greater CD56 bright NK cell phenotypic aberrancies than non-progressors, though these findings require confirmation with a larger cohort. Taken together, our findings support the hypothesis that immune dysfunction in CLL/SLL may be due in part to a block in NK cell differentiation or loss of more mature cells, and current studies are exploring these possibilities and potential mechanisms. Given these findings, along with the immunosuppressive changes observed in the T cell compartment (↑Tregs, ↑PD-1), these data support therapeutic strategies in CLL/SLL aimed at augmenting NK and/or T cell function. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3562 Aim of the present study was to evaluate the clinical outcome of a large series of younger patients with symptomatic multiple myeloma (MM) who were enrolled in two subsequent clinical trials of thalidomide-dexamethasone (thal-dex) incorporated into double autologous stem-cell transplantation (ASCT) to support high-dose melphalan (200 mg/m2). In both studies, thal (100 mg/day for the first 14 days and then 200 mg/day) and pulsed dex (between 480 and 160 mg per cycle), were administered from the onset until the second ASCT. The analysis was performed on an intention-to-treat basis on a total of 593 patients who were followed for a median of 36 months. The best VGPR and CR rates were 69% and 35%, respectively. The median duration of CR was 66 months. Median TTP and PFS were 53 and 44 months, respectively. The 5-year projected rates of TTP and PFS were 46% and 38%, respectively, while the corresponding value for OS was 67%. More than 80% of the patients were screened at diagnosis for the presence of cytogenetic abnormalities by FISH analysis. Forty-five percent of patients had del(13q), while t(4;14) and del(17p) were found in 16 % and 7 % of patients, respectively. The presence of del(17p) and/or t(4;14) was associated with a significantly shorter 5-year projected TTP, PFS and OS in comparison with the absence of these abnormalities, indifferently from the presence or absence of del(13q) (TTP: 30% vs 53%, respectively P=0.0000; PFS: 28% vs 45%, respectively, P=0.0000; OS: 53% vs 69%, respectively, P=0.0000). OS and PFS curves of patients carrying del(13q) alone were almost superimposable to those of patients without cytogenetic abnormalities, while TTP was significantly shorter for patients with del(13q) alone (5-year projected rates: 40% vs 53%, respectively, P=0.04). Patients carrying del(17p) in the absence of t(4;14) had similar 5-year projected TTP and PFS as compared with t(4;14) positive but del(17p) negative patients. However, OS was significantly shorter for the subgroup with del(17p) and absence of t(4;14) in comparison with that of patients carrying t(4;14) without del(17p) (5 year projected rates: 18% vs 70%, respectively, P=0.03). In a multivariate analysis, presence of del(17p) and high beta2-m at baseline were the most important variables adversely influencing TTP (HR: 2.3, P=0.001 and HR: 1.8, P=0.002, respectively), PFS (HR: 2.0, P=0.001 and HR: 1.9, P=0.001, respectively), and OS (HR: 3.9, P=0.000 and HR: 2.0, P=0.005, respectively). Additional variables predicting for shorter TTP and PFS were the presence of t(4;14) (HR: 1.8, P=0.004) and of del(13q) (HR: 1.6, P= 0.009). Also the quality of best response to the overall treatment program influenced clinical outcomes. In particular, patients achieving CR had a significantly longer PFS and OS than those achieving a VGPR (PFS: median 68 vs 40 months, respectively, P=0.007; 5-year projected OS rates: 84% vs 70%, respectively, P=0.01). In conclusion, incorporation of thal-dex into double autotransplantation failed to overcome the poor prognosis conferred by del(13 q), t(4;14) and del(17p). In a multivariate Cox regression analysis, del(17p) and high levels of serum beta2-m at diagnosis were the strongest variables adversely influencing PFS and OS. In comparison with the presence of t(4;14) but absence of del(17p), patients carrying del(17p) without t(4;14) had a significantly shorter OS, possibly due to their worst outcome after relapse. Presence of del(13q) alone conferred a significantly shorter TTP, but did not have an adverse impact on OS due to the favorable role of effective salvage therapies incorporating either bortezomib or lenalidomide. Disclosures: Off Label Use: use of first line thalidomide in preparation for ASCT. Cavo:Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau, no; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, no; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau, no.

Description: Abstract 2532 Background: The clinical management of patients with pediatric B-lineage acute lymphoblastic leukemia (B-ALL) relies on combinations of multiagent anticancer drugs and risk-stratified treatment. The prognostic significance of minimal residual detection (MRD) in pediatric B-ALL has been demonstrated in multiple cohorts. Allele-specific oligonucleotide PCR (ASO-PCR) amplification of immunoglobulin or T-cell receptor rearrangements, a method for MRD detection, requires the development of patient-specific reagents and cannot detect clonal evolution. ASO-PCR also has limited coverage, with clonal rearrangements being detected in only 90% of patients. We developed the sequencing-based LymphoSIGHT platform to address these limitations. Here we report the results of a pilot study of MRD detection using both the sequencing assay and ASO-PCR in paired diagnostic and end-of-induction samples from 7 B-ALL patients. Analysis of 82 additional patients is ongoing. Methods: Using universal primer sets, we amplified immunoglobulin heavy chain (IgH@) variable (V), diversity, and joining gene segments from genomic DNA in diagnostic and follow-up bone marrow samples. Amplified products were sequenced to obtain 〉1 million reads (20× coverage per B-cell), and were analyzed using standardized algorithms for clonotype determination. Tumor-specific clonotypes were identified in the diagnostic sample of each patient based on high-frequency within the B-cell repertoire. The presence of the tumor-specific clonotype was then assessed in the end-of-induction sample. A quantitative and standardized measure of MRD level among all leukocytes in the sample was determined using internal reference DNA. Following identification of IgH clonal rearrangements and MRD assessment using the sequencing assay, we examined the MRD results obtained at Boston Children's Hospital using ASO-PCR. Among the 7 patients analyzed to date, 6 patients were in complete remission at the time of the second sample; 1 patient had persistent evidence of disease. Sequencing was performed blinded to all clinical and ASO-PCR information on these patients. Results: With the sequencing platform, we detected a high-frequency IgH clonal rearrangement in all 7 diagnostic ALL samples. The leukemic clonotype that was identified at diagnosis was detected in the end-of-induction sample in each of the 7 patients. The quantitative range of the leukemic sequence in MRD samples ranged over 5 orders of magnitude. MRD results were concordant between sequencing and ASO-PCR in 5 of 7 patients. The detected MRD level differed by 〉 10 fold in 2 patients. In patient 1, sequencing detected high MRD, while low MRD was detected by ASO-PCR; this patient relapsed 1 year later while still on therapy. In patient 6, sequencing detected low MRD, while ASO-PCR detected high MRD. This patient remains in complete remission after 7 years. In patient 7, sequencing and ASO-PCR concordantly detected low MRD; this patient relapsed after completion of therapy. Conclusions: Results from the application of a high-throughput sequencing method for MRD detection in childhood B-ALL are shown. The sequencing assay does not require development of patient-specific reagents, which will reduce cost and laboratory turnaround time. This data, along with the laboratory workflow improvements, support the use of the sequencing assay as a next-generation MRD test for B-ALL. Analysis of samples from 82 patients is ongoing. Disclosures: Faham: Sequenta, Inc.: Employment, Equity Ownership, Research Funding. Fang:Sequenta, Inc.: Employment, Equity Ownership, Research Funding. Moorhead:Sequenta, Inc.: Employment, Equity Ownership, Research Funding. Zheng:Sequenta, Inc.: Employment, Equity Ownership, Research Funding.

Description: Abstract 2512 Background: Tremendous progress has been made in the management of acute lymphoblastic leukemia (ALL) in children, in part, through the wide use of minimal residual disease (MRD) monitoring to guide therapeutic intensification before and after allotransplantation. Unfortunately, poor accessibility and the high costs of MRD testing have limited its use in the management of adult ALL. A universally applicable MRD quantification method has the potential to revolutionize the management of ALL in adults. Most B- and T-cell ALL patients exhibit clonal rearrangements of one or more immunoglobulin (heavy chain, IGH; light chain, IGK/IGL) or T-cell receptor (beta, B; delta, D; gamma, G) genes. Such rearrangements may be quantified in a mixture of polyclonal B or T cells by massively parallel high-throughput sequencing (HTS), enabling highly sensitive MRD quantification. Methods: Thirty-six allografted ALL patients were selected for this retrospective study based on availability of a diagnostic sample containing leukemic cells, which was necessary for validating the amplification and sequencing method with each disease clonotype. Using Sequenta's LymphoSIGHT platform, we amplified and sequenced rearranged immunoreceptor (IR) loci from genomic DNA extracted from peripheral blood (PB) or bone marrow aspirates (BM) using V and J segment consensus primers for each IR gene (IGH, TCRB, TCRD, and TCRG) and, in some cases, D segment primers for incomplete IGH-DJ rearrangements. Sequences were analyzed using standardized algorithms for clonotype determination. Tumor-specific clonotypes were identified for each patient based on their high prevalence in a PB or BM sample at a time of high disease burden. MRD levels were then determined in serial samples of PB or BM and quantified using spiked-in reference sequences. A total of 227 samples with a median 442,672 input genomes (range 8,038 – 7,162,715) were evaluated by IR-HTS. Results: A clonal IGH sequence was identified in 17/36 (47%) ALL patients. Amongst patients who did not have a detectable IGH clonotype, 14/19 (74%) had clonal sequences at one or more other loci, including partial IGH-DJ rearrangements (5/14; 36%), TCRB (4/14; 29%), TCRD (3/14; 21%), or TCRG (6/14; 43%). In total, 31 of 36 (86%) ALL patients had a clonal IR sequence suitable for MRD quantification. In 4 of 5 cases without an identified clonal sequence, only PB, but no BM samples, were available. Twenty patients achieved MRD negativity following HCT and 11 did not. In the MRD negative group, 12/20 patients (60%) ultimately relapsed with a median time to clinical progression of 231 days (range 77–889), whereas 11/11 patients (100%) in the MRD positive group relapsed with a median time to clinical progression of 139 days (range 60–304). The 12 patients who relapsed after achieving MRD negativity showed a median time to molecular disease progression of 93 days (range 59–689 days). Of the 8 patients who maintained MRD negativity following HCT, 7 remain alive at a median 1542 days (range 1133–2557 days). All 22 patients with MRD detected following HCT relapsed and 21 (95%) died (median survival 387 days; range 85–1991 days) (Figure 1). The lead time between molecular disease detection by IR-HTS and clinical relapse was a median 69 days (range 0–207 days) with significant likelihood of MRD detection in a PB sample at least one, three, and six months (each p

Description: Abstract 3415 Background: The incidence of venous thrombotic events (VTE) in children has risen substantially over the past decade, resulting in increasing use of anticoagulants and making it imperative that pharmacokinetic (PK) and pharmacodynamic studies be performed in children. Fondaparinux has several advantages over low molecular weight heparins including once-daily dosing, no risk for heparin-induced thrombocytopenia, and possibly reduced effects on bone mineral metabolism. A PK, dose-finding, and safety study of fondaparinux was published; however it only studied relatively short-term outcomes and adverse effects. The purpose of this study was to investigate the long-term safety, dosing, and efficacy of fondaparinux in children. Methods: The study included all children 1–18 years (yrs) old treated consecutively with fondaparinux in a single institution between September 1, 2007 and June 20, 2011. The following data were abstracted from the medical records: demographics, location of initial VTE, fondaparinux dosing and levels, bleeding events, other adverse events, status of VTE at each subsequent imaging study (complete resolution, partial resolution, no change, or progression), and VTE recurrence. Descriptive statistics are used to describe the patients and the outcomes. Results: Data from 22 patients were collected and all were available for the safety analysis while 19 were analyzed for dosing (1 excluded due to only receiving 2 doses secondary to an allergic reaction and 2 excluded for ineligible diagnoses) and 16 for efficacy (1 excluded due to allergic reaction, 1 because fondaparinux was given as prophylaxis, and 4 due to ineligible diagnoses/insufficient data). There were 11 females (F) and 11 males (M) (10 F and 9 M analyzed for dosing; 9 F and 7 M for efficacy). The mean age of the patients was 9 yrs (median: 10 yrs; range: 1–17 yrs). The mean duration of treatment with fondaparinux was 377 days (d) (median: 171 d; range: 6–1566 d). The mean dose of fondaparinux was 0.1 mg/kg/dose (median: 0.1 mg/kg/dose; range: 0.07–1.4 mg/kg/dose). Nine of 16 evaluable patients (56.3%) had complete resolution of their thrombus while 6/16 (37.5%) had partial resolution, and 1/16 (6.3%) had no change in their thrombus. Thus, 15/16 (93.8%) patients had either a complete or partial response and 0/16 had progression. The mean time to best outcome from initiation of fondaparinux was 110.5 d (median: 63 d; range: 4–487 d). Seven patients needed a total of 12 dose adjustments (one subject with 3 adjustments and one with 4) to achieve therapeutic levels. Three patients (18.8%) (2 had prior complete resolution of the initial VTE) had a recurrent VTE. Two patients were on fondaparinux at the time of recurrence and 1 was on warfarin. There were 2 major (intracranial hemorrhage- occurred prior to initiation of fondaparinux and subretinal hemorrhage) and 3 minor (all with blood in stool) bleeding events. One patient had an allergic reaction after starting fondaparinux. Conclusions: In this long-term follow-up study on children treated with fondaparinux for VTE, 95% of patients had either complete or partial resolution while the recurrence rate was in line with previous studies. There were 5 bleeding events (2 major and 3 minor), though only 1 event required the discontinuation of fondaparinux. Given the advantages of fondaparinux over other anticoagulants, this study suggests that fondaparinux could be considered a safe and effective alternative for the management of VTE in children. Disclosures: Off Label Use: fondaparinux: anti-coagulation for the treatment of venous thromboembolic events in children. Young:Biogen Idec: Research Funding; Baxter: Consultancy, Honoraria; Novo Nordisk: Consultancy, Honoraria, Research Funding.

Description: Determining how normal and leukemic stem cells behave in vivo, in a dynamic and noninvasive way, remains a major challenge. Most optical tracking technologies rely on the use of fluorescent or bioluminescent reporter genes, which need to be stably expressed in the cells of interest. Because gene transfer in primary leukemia samples represents a major risk to impair their capability to engraft in a xenogenic context, we evaluated the possibility to use gene transfer–free labeling technologies. The lipophilic dye 3,3,3′,3′ tetramethylindotricarbocyanine iodide (DiR) was selected among 4 near-infrared (NIR) staining technologies. Unfortunately we report here a massive transfer of the dye occurring toward the neighbor cells both in vivo and in vitro. We further demonstrate that all lipophilic dyes tested in this study (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine perchlorate [DiI], DiD, DiR, and PKH26) can give rise to microenvironmental contamination, including when used in suboptimal concentration, after extensive washing procedures and in the absence of phagocytosis or marked cell death. This was observed from all cell types tested. Eventually, we show that this microenvironmental contamination is mediated by both direct cell-cell contacts and diffusible microparticles. We conclude that tracking of labeled cells using non–genetically encoded markers should always be accompanied by drastic cross validation using multimodality approaches.

Description: The Medical Research Council Myeloma IX Trial (ISRCTNG8454111) examined traditional and thalidomide-based induction and maintenance regimens and IV zoledronic acid (ZOL) and oral clodronate (CLO) in 1960 patients with newly diagnosed multiple myeloma. Overall survival (OS) and skeletal-related event (SRE) data have been reported for the overall trial population. The present analysis investigated optimal therapy regimens for different patient populations in Myeloma IX. Patients were assigned to intensive or nonintensive treatment pathways and randomized to induction cyclophosphamide, vincristine, doxorubicin, and dexamethasone (CVAD) versus cyclophosphamide, thalidomide, and dexamethasone (CTD; intensive) or melphalan and prednisolone versus attenuated oral CTD (CTDa; nonintensive). Patients were also randomized to ZOL or CLO. In the nonintensive pathway, CTDa produced better responses and lower SRE rates than melphalan and prednisolone. ZOL improved OS compared with CLO independently of sex, stage, or myeloma subtype, most profoundly in patients with baseline bone disease or other SREs. In patients treated for ≥ 2 years, ZOL improved OS compared with CLO from randomization (median not reached for either; P = .02) and also from first on-study disease progression (median, 34 months for ZOL vs 27 months for CLO; P = .03). Thalidomide-containing regimens had better efficacy than traditional regimens, and ZOL demonstrated greater benefits than CLO.

Description: Neoplastic transformation requires the elimination of key tumor suppressors, which may result from E3 ligase-mediated proteasomal degradation. We previously demonstrated a key role for the E3 ubiquitin ligase E6AP in the regulation of promyelocytic leukemia protein (PML) stability and formation of PML nuclear bodies. Here, we report the involvement of the E6AP-PML axis in B-cell lymphoma development. A partial loss of E6AP attenuated Myc-induced B-cell lymphomagenesis. This tumor suppressive action was achieved by the induction of cellular senescence. B-cell lymphomas deficient for E6AP expressed elevated levels of PML and PML-nuclear bodies with a concomitant increase in markers of cellular senescence, including p21, H3K9me3, and p16. Consistently, PML deficiency accelerated the rate of Myc-induced B-cell lymphomagenesis. Importantly, E6AP expression was elevated in ∼ 60% of human Burkitt lymphomas, and down-regulation of E6AP in B-lymphoma cells restored PML expression with a concurrent induction of cellular senescence in these cells. Our findings demonstrate that E6AP-mediated down-regulation of PML-induced senescence is essential for B-cell lymphoma progression. This provides a molecular explanation for the down-regulation of PML observed in non-Hodgkin lymphomas, thereby suggesting a novel therapeutic approach for restoration of tumor suppression in B-cell lymphoma.

Description: Abstract 4236 Anemia is one of the most common blood disorders in several diseases including cancer, heart failure, chronic kidney disease (CKD) and Myeloid Dysplastic Syndromes (MDS) associated with a negative outcome. Administration of recombinant Erythropoietin (EPO) represents the most common treatment for anemia. However, a significant number of people remain hypo or non-responsive to EPO treatment, and in some cases its use has been linked to tumor growth, cardiovascular disease and poorer survival. The members of TGFβ super family of ligands (Activins, GDFs and BMPs) and receptors (Type I and II) regulate more than 500 target genes transcriptionally by Smad phosphorylation and are involved in many cellular functions including cell growth, adhesion, migration, differentiation and apoptosis in a concentration and context dependent manner. Members of the TGFβ family have also demonstrated a role in erythropoiesis. ACE-536, a non-ESA agent is a soluble human Fc fusion chimera of a modified Activin Type IIb receptor with a mutation in its extracellular domain. Surface Plasmon Analysis (Biacore) analysis and cell based reporter assays revealed that this mutation disrupted its binding to Activin A but not to GDF11 or GDF8. ACE-536 acts as a decoy receptor for TGFβ signaling and demonstrated potent increase in red blood cells in all the tested animals (mice, rats and monkeys). Subcutaneous administration of ACE-536 (10mg/kg) to C57BL/6 mice resulted in a significant increase in hematocrit, hemoglobin and red blood cells (RBC) over the TBS treated vehicle group after 4 days. These observations were seen even in the presence of an EPO neutralizing antibody; suggesting that EPO is not directing the initial RBC response to ACE-536 treatment. There were no increase in BFU-E or CFU-E colony formation from bone marrow and spleen after 48hrs treatment with ACE-536 over TBS treated group demonstrating that it does not have effect on erythroid progenitor population. Differentiation profiling of bone marrow and splenic erythroblasts by flow cytometric analysis revealed that ACE-536 promotes maturation of developing erythroblasts. ACE-536 treatment for 72 hours resulted in a decrease in basophilic erythroblasts and an increase in late stage poly, ortho chromatophilic erythroblasts in bone marrow and spleen compared to the TBS treated mice. Treatment of Sprague-Dawley rats with a murine analogue of ACE-536 (RAP-536; 10mg/kg) increased the reticulocyte formation in peripheral blood over vehicle treated group. ACE-536 (10mg/kg) treatment combined with recombinant human EPO (1800 units/kg) for 72 hours increased RBC, hematocrit and hemoglobin by approximately 23% over TBS treated vehicle group and 12% over EPO treatment alone. Consistent with its role in proliferation, EPO increased splenic basophilic erythroblast formation. However, ACE-536 treatment combined with EPO significantly promoted maturation of late stage erythroblasts; demonstrating a novel mechanism during erythroid differentiation. To gain further insights into its mechanism of action, C57BL/6 mice were administered with or without RAP-536 (10mg/ml twice a week) pre treated for a week with neutralizing anti-Activin A (10mg/kg) or ActRIIa (10mg/ml) or ActRIIb (10mg/ml) (does not bind ACE-536) antibodies. Anti-ActRIIa but not anti-Activin A or anti- ActRIIb antibody pre-treatment inhibited the RBC increase by RAP-536 suggesting that ActRIIa or its ligands are necessary for transducing the signal. To summarize, ACE-536 treatment results in a rapid increase in red blood cells by a novel mechanism promoting maturation of late stage erythroblasts. The efficacy of ACE-536 molecule was tested in several acute and chronic anemia animal models including blood loss anemia, chemotherapy induced anemia, chronic kidney disease (5/6 Nephrectomy) and Myeloid Dysplastic Syndrome (MDS) and found that ACE-536 treatment prevents or decreases anemia in all these models. Furthermore, unlike EPO, ACE-536 did not promote tumor progression (in Lewis Lung Carcinoma model) thus offering strong promise as alternate treatments for anemia. Disclosures: Suragani: Acceleron Pharma: Employment. Cadena:Acceleron Pharma: Employment. Mitchell:Acceleron Pharma: Employment. Sako:Acceleron Pharma: Employment. Davies:Acceleron Pharma: Employment. Tomkinson:Acceleron Pharma: Employment. Devine:Acceleron Pharma: Employment. Ucran:Acceleron Pharma: Employment. Grinberg:Acceleron Pharma: Employment. Underwood:Acceleron Pharma: Employment. Pearsall:Acceleron Pharma: Employment. Seehra:Acceleron Pharma: Employment. Kumar:Acceleron Pharma: Employment.

Description: In patients with multiple myeloma (MM), risk stratification by chromosomal abnormalities may enable a more rational selection of therapeutic approaches. In the present study, we analyzed the prognostic value of 12 chromosomal abnormalities in a series of 354 MM patients treated within the HOVON-65/GMMG-HD4 trial. Because of the 2-arm design of the study, we were able to analyze the effect of a bortezomib-based treatment before and after autologous stem cell transplantation (arm B) compared with standard treatment without bortezomib (arm A). For allanalyzed chromosomal aberrations, progression-free survival (PFS) and overall survival (OS) were at least equal or superior in the bortezomib arm compared with the standard arm. Strikingly, patients with del(17p13) benefited the most from the bortezomib-containing treatment: the median PFS in arm A was 12.0 months and in arm B it was 26.2 months (P = .024); the 3 year-OS for arm A was 17% and for arm B it was 69% (P = .028). After multivariate analysis, del(17p13) was an independent predictor for PFS (P 〈 .0001) and OS (P 〈 .0001) in arm A, whereas no statistically significant effect on PFS (P = .28) or OS (P = .12) was seen in arm B. In conclusion, the adverse impact of del(17p13) on PFS and OS could be significantly reduced by bortezomib-based treatment, suggesting that long-term administration of bortezomib should be recommended for patients carrying del(17p13). This trial is registered at the International Standard Randomised Controlled Trial Number Register as ISRCTN64455289.

Description: Abstract 2287 High throughput genomic testing for blood groups allows large scale antigen typing and assessment of donor pool compatibility with chronic transfusion dependent populations, particularly thalassemia or sickle cell disease (SCD) patients, in order to decrease RBC alloimmunization. Thus, it is crucial to determine if the quantity and antigen diversity of the donor pool meets the demands to sustain these patients on phenotype/genotype extended matched chronic transfusion protocols. We calculated the most common extended RBC predicted phenotypes for the 12 major clinically significant blood group antigens, D, CcEe, K, Jka/b, Fya/b, and Ss, in patients undergoing chronic transfusion for sickle cell disease (n=203) or thalassemia (n=98). The most common phenotypes in each diagnostic group were used to determine the prevalence of these phenotypes in a single day donor inventory (n=5,000) and stratified by ethnic group (70% Caucasian, 10% African-American, 13% Hispanic, 5% Asian, and 2% Other). All patient samples were tested for the presence of the GATA mutation which disrupts erythroid expression of Fy(b), and if present deemed not at risk for Fy(b) alloimmunization. The majority of patients with SCD and thalassemia are RhD positive (97% and 90% respectively), but differ in extended Rh phenotype, with Ro (Dce) prevalent in SCD pa tients (61%), and R1 (DCe) in thalassemia patients (79%). For patients with SCD, the most prevalent antigen-negative phenotypes were 17% C-E-K-,Fy(a-),Jk(b-), S-; 9% C-E-K-, Fy(a-),S-; 5% E-K-,Fy(a-),S-; and 4% C-K-,Fy(a-), Jk(b-), S-. In patients with thalassemia, no minor antigen profile exceeded 5% of individuals. The most prevalent antigen-negative profiles were 5% E-c-K-, Fy(b-),Jk(b-),S-, and 4% E-K-. Comparison of the most prevalent antigen-negative phenotype in patients with SCD with the donors revealed only 0.06% Caucasian (n=2), but 20% of the African-American donors (n=90) were antigen-negative matches. For the second most prevalent phenotype, 0.08% Caucasian (n=3) and 33% of African-American (n=167), 2% of Hispanic (n=13), and 5% other (n=5) were antigen-negative matches. For the third and fourth prevalent phenotypes, 47% of African-American (n=233) and 23% (n=115) respectively, were antigen-negative matches, while only 0.14% (n=5) and 0.06% (n=2) of Caucasians, but 5% (n=31) and 2% (n=13) of Hispanic donors were appropriate matches, respectively. For the thalassemia patients, antigen matches for the most common phenotype were found most often in Asian (13%) and donors identifying as “other” (6%). Matches were present in only 2% of the Caucasians, 2% of Hispanics, and 1.8% of African-American donors for thalassemia patients. These results confirmed the importance and impact of African-American donors for extended antigen-matching for patients with SCD. Less than 1% of our Caucasian donors could serve as extended matching for SCD. Nearly 20% of patients with SCD are negative for a common group of antigens, which allows future donor recruitment efforts focused on extended antigen profiles of the donor. Patients with thalassemia do not have a common antigen-negative profile, but extended matching for these patients can be improved by increase recruitment of Asian donors. High throughput genotyping enables typing of large numbers of donors, and potentially the majority of the donor inventory. Analysis of antigen-negative phenotypes in the donor pool with analysis of patient groups is important for inventory management, focused donor recruitment, and improved transfusion practice by avoiding alloimmunization. Disclosures: Stassinopoulos: Cerus: Employment, Equity Ownership, Patents & Royalties.

Description: The cellular and molecular mechanisms orchestrating the complex process by which bone marrow megakaryocytes form and release platelets remain poorly understood. Mature megakaryocytes generate long cytoplasmic extensions, proplatelets, which have the capacity to generate platelets. Although microtubules are the main structural component of proplatelets and microtubule sliding is known to drive proplatelet elongation, the role of actin dynamics in the process of platelet formation has remained elusive. Here, we tailored a mouse model lacking all ADF/n-cofilin–mediated actin dynamics in megakaryocytes to specifically elucidate the role of actin filament turnover in platelet formation. We demonstrate, for the first time, that in vivo actin filament turnover plays a critical role in the late stages of platelet formation from megakaryocytes and the proper sizing of platelets in the periphery. Our results provide the genetic proof that platelet production from megakaryocytes strictly requires dynamic changes in the actin cytoskeleton.

Description: Abstract 173 One of the most common karyotypic abnormalities identified in myelodysplastic syndromes (MDS) is monosomy 7 (del7) or deletion of the long arm of chromosome 7 (del7q). The presence of del7/del7q carries a poor prognosis in MDS, MDS/myeloproliferative neoplasms (MPN) and acute myeloid leukemia (AML); the impact of these defects appears similar. Recently, a copy-neutral type of loss of heterozygozity (LOH also referred to as a somatic UPD) has been identified on 7q. Microdeletion on 7q corresponding to the EZH2 locus led to identification of inactivating mutations in this gene, though hemizygous EZH2 mutations are only rarely found and do not fully explain del7/7q pathogenesis. We performed a comprehensive analysis of myeloid neoplasms (N=189), using next generation whole exome sequencing technology, including MDS (N=34), MDS/MPN (N=26) or MPN (N=4) and 124 with AML (both primary and secondary). Among them, LOH7, involving del7/del7q were observed in 17% of cases (N=33). To minimize false positives and focus on the most prevalent/relevant somatic events, we implemented a rational bioanalyitic filtering approach, whereby paired DNA (tumor/CD3 lymphocyte) were sequenced and results aligned using Burrows-Wheeler Aligner and variants detected using GATK pipeline (Best Practice Variant Detection from Broad Institute). We focused on searching for del7/7q linked somatic mutational events involved comparisons of mutations in the area of del7q to cases diploid for this locus. We hypothesized that there may be heterozygous mutations of 7q, which could lead to functional haploinsufficiency that is also a result of del7q (haploinsuffcient theory, heterozygous mutations). Conversely, mutations may be either unique to del7q hemizygous inactivation, or shared between 7q diploid and haploid cases. In total, we found alterations in 12 genes located on chromosome 7 (6% of all alterations found). Using filtering strategies we narrowed the focus to “tier 1” mutations to avoid false positives; 11 mutated genes were found in cases with del7/7q and 2 in UPD7q. For example, novel hemzygous (but not heterozygous mutations) of an E3 ubiquitin ligase CUL1 gene were detected only in cases with del7/7q, suggesting that the wild type allele is protective. In cases with diploid 7q, 24 heterozygous alterations were observed (10 genes shared with del7/7q). The previously described EZH2 mutations were seen in heterozygous, homozygous and hemizygous configurations, but were most common in UPD7q (100%), while only 7% of del7/7q cases were positive. Notably, 5/12 mutant genes were located in commonly deleted regions (CDRs) either 7q22, 7q34 or 7q35–36. These CDRs also contain recurrently mutated lesions, including 7q22 (CUX1:n=4; STAG3:n=2), 7q34 (a splicing factor; LUC7L2: n=3) and 7q35–36 (EZH2: n=10). When we investigated the association between haploinsufficiency and heterozygous mutations, among those on del7/7q, cases with wild type forms of corresponding genes showed decreased expression. Similarly, such mutations were occasionally present in diploid configuration; here again the wild type cases showed a decreased expression. These findings suggest that mutated genes located in CDRs can be pathogenic due to both haploinsufficiency of WT genes and heterozygous mutations. EZH2 is a good example of such a gene. We also searched accessory genetic events observed on other chromosomes along with del7/7q and UPD7. By SNP-A, there were clear differences among 3 LOH7 groups, in which del7 was more associated with accessory chromosomal defects than cases with UPD7q or del7. Similarly, mutational patterns were specific to each LOH cohort. For example, while well known frequently mutated genes, such as U2AF1, TET2 and TP53, were commonly found in all 3 LOH7 groups, some specific genes, including the CSMD family, were uniquely observed in monosomy 7, not in del7q or UPD7. Similarly, LOH7q was associated with somatic mutations in SETBP1 and RUNX1. In conclusion, we detected several candidate genes that could be associated with del7/7q and UPD7. Some mutations were heterozygous in cases with diploid 7q and correlated with CDRs on del7/7q without mutation. Certain mutations are specifically observed with del7, while others are commonly observed in all categories of LOH7, including EZH2. Moreover, some genes outside of the chromosome 7 were coincidently mutated with LOH7. Disclosures: Makishima: Scott Hamilton CARES Initiative: Research Funding. Maciejewski:NIH: Research Funding; Aplastic Anemia&MDS International Foundation: Research Funding.

Description: Abstract 2737 Introduction: ATL is prevalent in Japan and has the worst prognosis among T-cell malignancies. PTCL also has a poor prognosis with currently available chemotherapeutic regimens, and both would benefit from better treatment modality. Lenalidomide is an immunomodulatory agent with direct tumoricidal and antiproliferative activity, and is approved for multiple myeloma (MM) in combination with dexamethasone after at least 1 prior therapy and for transfusion-dependent anemia due to low- or intermediate-1-risk myelodysplastic syndromes associated with 5q deletion. We conducted a phase 1 study of lenalidomide in patients with relapsed ATL or PTCL to establish the recommended dose and schedule for a subsequent phase 2 study. Patients and Methods: This multicenter, phase 1, dose-escalation study assessed the safety, maximum tolerated dose (MTD), pharmacokinetics, and efficacy in patients with relapsed advanced ATL or PTCL. Dose-escalation was conducted according to the standard 3+3 design. Up to one PTCL patient was allowed to be included in each cohort of 3 patients. Patients in Cohort 1 received oral lenalidomide 25 mg daily on Days 1–21 of a 28-day cycle. Patients in Cohorts 2 and 3 received 25 and 35 mg/day, respectively, on each day of the 28-day cycle. Dose-limiting toxicity (DLT) was defined as febrile neutropenia lasting 5 or more days; thrombocytopenia (platelets

Description: In neutrophils, the phosphoinositide 3-kinase/Akt signaling cascade is involved in migration, degranulation, and O2− production. However, it is unclear whether the Akt kinase isoforms have distinct functions in neutrophil activation. Here we report functional differences between the 2 major Akt isoforms in neutrophil activation on the basis of studies in which we used individual Akt1 and Akt2 knockout mice. Akt2−/− neutrophils exhibited decreased cell migration, granule enzyme release, and O2− production compared with wild-type and Akt1−/− neutrophils. Surprisingly, Akt2 deficiency and pharmacologic inhibition of Akt also abrogated phorbol ester-induced O2− production, which was unaffected by treatment with the phosphoinositide 3-kinase inhibitor LY294002. The decreased O2− production in Akt2−/− neutrophils was accompanied by reduced p47phox phosphorylation and its membrane translocation, suggesting that Akt2 is important for the assembly of phagocyte nicotinamide adenine dinucleotide phosphate oxidase. In wild-type neutrophils, Akt2 but not Akt1 translocated to plasma membrane upon chemoattractant stimulation and to the leading edge in polarized neutrophils. In the absence of Akt2, chemoattractant-induced Akt protein phosphorylation was significantly reduced. These results demonstrate a predominant role of Akt2 in regulating neutrophil functions and provide evidence for differential activation of the 2 Akt isoforms in neutrophils.

Description: In Burkitt lymphoma/leukemia (BL), achievement of complete remission with first-line chemotherapy remains a challenging issue, as most patients who respond remain disease-free, whereas those refractory have few options of being rescued with salvage therapies. The mechanisms underlying BL chemoresistance and how it can be circumvented remain undetermined. We previously reported the frequent inactivation of the proapoptotic BIM gene in B-cell lymphomas. Here we show that BIM epigenetic silencing by concurrent promoter hypermethylation and deacetylation occurs frequently in primary BL samples and BL-derived cell lines. Remarkably, patients with BL with hypermethylated BIM presented lower complete remission rate (24% vs 79%; P = .002) and shorter overall survival (P = .007) than those with BIM-expressing lymphomas, indicating that BIM transcriptional repression may mediate tumor chemoresistance. Accordingly, by combining in vitro and in vivo studies of human BL-xenografts grown in immunodeficient RAG2−/−γc−/− mice and of murine B220+IgM+ B-cell lymphomas generated in Eμ-MYC and Eμ-MYC-BIM+/− transgenes, we demonstrate that lymphoma chemoresistance is dictated by BIM gene dosage and is reversible on BIM reactivation by genetic manipulation or after treatment with histone-deacetylase inhibitors. We suggest that the combination of histone-deacetylase inhibitors and high-dose chemotherapy may overcome chemoresistance, achieve durable remission, and improve survival of patients with BL.

Description: Abstract 750 The non-malignant immune infiltrate comprises the bulk of pathologic tissue in classical Hodgkin lymphoma (CHL). This microenvironment has the potential to induce both malignant cell suppression and support. Increased macrophage infiltration assessed by CD68 expression has been shown to confer adverse prognostic significance (Steidl et al. N Engl J Med, 2010; 362:875-85) while increased FOXP3 expressing T cells are beneficial in this disease (Tzankov et al. Haematologica, 2008; 93: 193–200). However no histological score routinely leads to modification of treatment. Assessing outcomes by the parameters of overall survival (OS), disease specific survival (DSS) and freedom from first line treatment failure (FFTF) at 5 years in a cohort of patients treated at St Bartholomew's Hospital (Barts), London we developed a prognostic score based upon expression of both FOXP3 and CD68 in the CHL microenvironment which defined poor and good risk groups in both early (Stages I and IIA) and advanced stage disease, including a 'poor risk' early stage group with 25% FFTF and a ‘good risk' advanced stage group with 90% FFTF. Immunohistochemical analysis was performed on tissue microarrays (TMAs) from previously untreated patients' diagnostic lymph node biopsies in whom clinical outcome was available. From all 1056 adult patients with HL diagnosed at Barts between 1972 and 2005, high quality formalin-fixed paraffin-embedded tissue was available for 122 (12%), with characteristics representative of the whole group. Median age of the 122 patients was 30 (range 18–80) years, 35% female, 71% advanced stage with median follow up 16.5 (range 2–40) years. Triplicate cores were made from areas of high cellularity, containing malignant cells and avoiding fibrotic, acellular portions, arrayed onto glass slides and stained immunohistochemically for FOXP3 or CD68. Absolute and proportional numbers of FOXP3+ nuclei and CD68+ cell bodies were counted across all intact cores using an automated image analysis system (Ariol), confirmed by expert histopathologists, and means calculated and corrected to a single high powered field (hpf). Recursive partitioning was used to generate optimal cutoff values discriminating prognostic groups and comparisons performed by the chi-square test. Using cutoffs of 15% to define low, intermediate and high CD68 density, 3 prognostic groups were defined, the favourable group having the lowest CD68+ density. OS for low, intermediate and high groups were 89%, 80% and 65% respectively (p=0.02), with FFTF 82%, 64% and 29% (p=0.001). Prognostic significance was maintained in subgroups presenting with advanced stage (FFTF 73%, 63% and 33%, p=0.03), as well as early stage disease (FFTF 92%, 70% and 20%, p=0.01). Using cutoffs of 50 nuclei/hpf to define low, intermediate and high FOXP3+ cell density, 3 prognostic groups were defined, the favourable group having the highest FOXP3+ density. OS for low, intermediate and high groups were 68%, 80% and 94% respectively (p=0.006), with FFTF 50%, 62%, and 84% (p=0.002). Prognostic significance was maintained for both advanced (FFTF: 48%, 60% and 72%, p=0.04) and early stage disease (FFTF: 57%, 67% and 100%, p=0.04). A combined ‘FOXP3/CD68 score' derived from the patient's prognostic group for both markers, for which suitable cores were available on 98 patients, further improved the predictive value of each individually (See Figure). In this model, favourable, intermediate and unfavourable groups had 5 year FFTF of 93%, 62% and 47% (p=0.0002), DSS 93%, 82% and 63% (p=0.03) and OS 93%, 82% and 59% (p=0.002). The score retained prognostic significance for 5 year FFTF and OS in the subgroup of patients presenting with advanced (FFTF: 90%, 59% and 46%, p=0.008; OS: 90%, 80% and 54%, p=0.004) as well as early stage disease (FFTF: 100%, 71% and 25%, p=0.005; OS: 100%, 82% and 75%, trend only, p=ns). We conclude that FOXP3 and CD68 are important independent factors, which in combination have considerable predictive power and will now be validated prospectively. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 313 Background: While advanced PV and ET patients at high thrombotic risk are managed primarily with HU, patients who are intolerant or refractory to HU have limited therapeutic options. Identification of a dominant gain-of-function mutation in the JAK2 kinase, V617F, in myeloproliferative neoplasms (MPNs), including PV and ET, provided a key rationale for the development of a molecularly targeted therapy for these diseases. Long term follow-up data from an ongoing trial of INCB018424, a selective JAK 1/ JAK 2 inhibitor, in PV and ET patients refractory or intolerant to HU are presented. Methods: Study 18424-256 is an uncontrolled open-label Phase 2 study being conducted at 6 sites in the United States and Italy. An initial 8-week run-in evaluation established 10-mg and 25-mg twice daily as starting doses for expansion cohorts in PV and ET, respectively; dose adjustments for safety and efficacy are allowed so that each subject is titrated to their most appropriate dose. For PV, response is defined based on Hct control in the absence of phlebotomy, improvement or elimination of palpable splenomegaly when present, and normalization of leukocytosis and thrombocytosis. For ET, response is defined based on improvement or normalization of WBC and platelet counts and, when present, elimination of palpable splenomegaly. PV results (n=34; median 108 months from diagnosis): After a median follow-up of 15 months (range 8–21), 97% of enrolled subjects achieved Hct control to 15×109/L was present in 47% of subjects and improved (≤ 15×109/L) or normalized (≤ upper limit of normal) in 88% and 63%, respectively. Thrombocytosis 〉 600×109/L was present in 38% of subjects and improved (≤ 600×109/L) or normalized (≤ upper limit of normal) in 92% and 69%, respectively. 59% of subjects achieved phlebotomy independence, resolution of splenomegaly and normalization of leukocytosis and thrombocytosis. 6 patients discontinued therapy (3 due to AEs, 2 withdrew consent, 1 for no response). Grade 3 AEs potentially related to study medication included thrombocytopenia (2 patients), neutropenia (1), renal tumor (1), asthenia (1), viral infection (1), and atrial flutter (1). No Grade 4 drug-related AEs have occurred. ET results (n=39; median 84 months from diagnosis): After a median follow-up of 15 months (range 4–21), 49% of enrolled subjects normalized platelet counts to ≤ upper limit of normal after a median of 0.5 months and for a median duration of 3.5 months. 82% maintained platelet counts 〈 600×109/L, for a median duration of 9.8 months. Of 14 patients with baseline platelet counts 〉 1000×109/L, 13 have experienced 〉 50% reduction. 88% maintained normal WBC (median duration 14.5 months). Palpable spleens resolved in 3 of 4 subjects; 1 reduced 〉50% from baseline. 49% of subjects achieved normalization of WBC and platelet counts in the presence of non-palpable splenomegaly. 9 patients discontinued therapy (4 due to AEs, 2 withdrew consent, 3 for no response). Grade 3 AEs potentially related to study medication included leukopenia (2 patients), GI disorder (1), and peripheral neuropathy (1). No Grade 4 drug-related AEs have occurred. Both patient groups demonstrated reductions in patient-reported symptom scores for pruritus, night sweats, and bone pain. Of 26 PV patients reporting pruritus at baseline (median score of 6 on a 10-point scale), 24 reported scores of 0 after a median duration of 1 month and for a median duration of 7 months. 42% of PV and 56% of ET patients had at least a 20% decrease in JAK2V617F allele burden; 6% of PV and 12% of ET had 〉50% decrease. Clinical responses were unrelated to the presence/absence of JAK2V617F mutation at entry or to the allele burden changes following treatment. Conclusions: Rapid and durable clinical benefits (normalization of hematological parameters, resolution of splenomegaly and alleviation of symptoms) have been demonstrated in advanced PV and ET patients with 〉1 year of follow-up. In this study, INCB018424 continues to be a well tolerated, effective therapy in patients with PV and ET refractory or intolerant to hydroxyurea. Disclosures: Verstovsek: Incyte Corporation: Research Funding. Levy:Incyte Corporation: Employment, Equity Ownership. Bradley:Incyte Corporation: Employment. Garrett:Incyte Corporation: Employment. Vaddi:Incyte corporation: Employment. Huber:Incyte Corporation: Employment, Equity Ownership. Schacter:Pfizer Corporation: Employment. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees.

Description: Proteasome inhibition has emerged as an important therapeutic strategy in multiple myeloma (MM). Since the publication of the first phase 1 trials of bortezomib 10 years ago, this first-in-class proteasome inhibitor (PI) has contributed substantially to the observed improvement in survival in MM patients over the past decade. Although first approved as a single agent in the relapsed setting, bortezomib is now predominantly used in combination regimens. Furthermore, the standard twice-weekly schedule may be replaced by weekly infusion, especially when bortezomib is used as part of combination regimens in frontline therapy. Indeed, bortezomib is an established component of induction therapy for patients eligible or ineligible for autologous stem cell transplantation. Bortezomib has also been incorporated into conditioning regimens before autologous stem cell transplantation, as well as into post-ASCT consolidation therapy, and in the maintenance setting. In addition, a new route of bortezomib administration, subcutaneous infusion, has recently been approved. Recently, several new agents have been introduced into the clinic, including carfilzomib, marizomib, and MLN9708, and trials investigating these “second-generation” PIs in patients with relapsed/refractory MMs have demonstrated positive results. This review provides an overview of the role of PIs in the treatment of MM, focusing on developments over the past decade.

Description: Cyclic adenosine monophosphate (cAMP)-dependent signaling modulates platelet function at sites of vascular injury. Here we show that thrombospondin-1 (TSP-1) prevents cAMP/protein kinase A (PKA) signaling through a CD36-dependent mechanism. Prostaglandin E1 (PGE1) induced a robust inhibition of both platelet aggregation and platelet arrest under physiologic conditions of flow. Exogenous TSP-1 reduced significantly PGE1-mediated inhibition of both platelet aggregation and platelet arrest. TSP-1 prevented PGE1-stimulated cAMP accrual and phosphorylation of PKA substrates, through a mechanism requiring phosphodiesterase3A. TSP-1 also inhibited VASP phosphorylation stimulated by the nonhydrolyzable cAMP analog, 8-bromo-cAMP, indicating that it may regulate cAMP-mediated activation of PKA. The inhibitory effect of TSP-1 on cAMP signaling could be reproduced with a peptide possessing a CD36 binding sequence of TSP-1, while the effects of TSP-1 were prevented by a CD36 blocking antibody. TSP-1 and the CD36 binding peptide induced phosphorylation of Src kinases, p38 and JNK. Moreover, inhibition of Src kinases blocked TSP-1–mediated regulation of cAMP concentrations and the phosphorylation of VASP, indicating that TSP-1 modulated the cAMP/PKA signaling events through a tyrosine kinase-dependent pathway downstream of CD36. These data reveal a new role for TSP-1 in promoting platelet aggregation through modulation of the cAMP-PKA signaling pathway.

Description: Axl is an oncogenic receptor tyrosine kinase that plays multiple roles in tumorigenesis and metastasis of many cancers. This study is the first to demonstrate that Axl is induced in Kaposi sarcoma and Kaposi sarcoma herpesvirus (KSHV) transformed endothelial cells. Conditionally, expression of one KSHV latency protein vFLIP induces Axl expression in endothelial cells. This induction can be blocked by nuclear factor-κB inhibitor, consistent with the known vFLIP mechanism of action. KS cell lines lacking KSHV also have elevated Axl expression, which probably resulted from hypomethylation of AXL promoter. Axl activation activates downstream phosphoinositol-3 kinase signaling, and Axl knockdown by siRNA impairs phosphoinositol-3 kinase signaling. Furthermore, Axl knockdown inhibits KS cell growth and invasion. To explore the potential for translation of these findings, we generated monoclonal antibodies to block the biologic functions of Axl. MAb173, which induces receptor degradation, showed activity in vitro to inhibit KS cell invasion. Moreover, in vivo xenograft studies with KS cells with or without KSHV infection showed that MAb173 reduced tumor growth, increased tumor cell apoptosis, and markedly decreased Axl protein level in tumors. Axl thus has a potential role in KS pathogenesis and is a candidate for prognostic and therapeutic investigations.

Description: Abstract 1071 Background: Treatment of children with acute myeloid leukemia (AML) is associated with considerable toxicity. Children's Oncology Group (COG) AAML0531 trial adopted a modified AML Medical Research Council backbone and reviewed adverse event reports in real time to maximize accurate toxicity data. As of March 31, 2010, AAML0531 had randomized 968 patients with de novo AML to gemtuzumab ozogamicin (GMTZ) versus no GMTZ. Accurate description of toxicities with the backbone regimen as well as increment toxicities of new agents is important to optimize supportive care. Objectives were to describe hepatic, cardiac and infectious toxicities and duration of neutropenia in all patients, and to compare toxicities between treatment arms. Methods: AAML0531 included those ≥ 1 month to ≤ 30 years with de novo AML and used a 5 cycle chemotherapy regimen: Induction (Ind) I and II: cytarabine, daunorubicin, and etoposide (ADE 10+3+5 and 8+3+5); Intensification (Int) I: cytarabine and etoposide; Int II: mitoxantrone and high-dose cytarabine; and Int III: high-dose cytarabine and L'asparaginase. Subjects were randomized to receive or not receive GMTZ 3 mg/m2 during Ind I and Int II. Common Terminology Criteria for Adverse Events v3.0 toxicities were collected prospectively. Hepatic (ALT, bilirubin and veno-occlusive disease (VOD)), cardiac (left ventricular systolic dysfunction (LVSD)) and infection (sterile site bacterial and fungal) toxicities were targeted. All grades of cardiac and VOD toxicities were captured; all other severe (≥ grade 3) toxicities were recorded. Cumulative incidence (CI) of toxicities was calculated only during protocol chemotherapy. Duration of neutropenia was reported from beginning of cycle to absolute neutrophil recovery ≥ 500/uL for patients alive during the cycle. Results: Table describes the prevalence of severe (≥ grade 3) toxicities and illustrates that severe high ALT occurred in 3–10%, high bilirubin was less common and VOD was reported in ≤ 1% of cycles. Severe LVSD also was rare although compliance with suggested cardiac monitoring ranged from 50–80% per course of treatment. In terms of grade 1 or 2 LSVD there were no differences in any course except for Int II where grade 1 or 2 LVSD was higher with GMTZ (8.0% versus 2.4%; P

Description: Abstract 899 Introduction: The classic definition of acute (aGVHD) and chronic graft-versus-host disease (cGVHD) was based on a cut-off day 100 after transplantation, but this did not reflect that aGVHD can occur later and that symptoms of aGVHD and cGVHD can occur simultaneously. In 2005 a NIH consensus classification was proposed which included 1) classic aGVHD, occurring before day 100, 2) persistent, recurrent or late aGVHD occurring thereafter, 3) classic cGVHD and 4) an overlap syndrome with simultaneous features of aGVHD and cGVHD. Only few studies have evaluated this classification and no studies have determined the differential impact of reduced intensity (RIC) and myeloablative conditioning (MAC). Method: We retrospectively analyzed 202 AML patients who were transplanted between 1999 and 2008. 102 patients received RIC (generally 6×30 mg/m2 FLU, 4×4 mg/kg BU, 4×10 mg/kg ATG) and immunosuppression with CSA/MMF and 100 patients received MAC (generally 6×2 Gy TBI and 2×60 mg/kg CY) and CSA/MTX. Donors were HLA-matched related (n=82), -matched unrelated (n=88) or -mismatched (n=32). Result: Leukocyte recovery was faster after RIC than after MAC (14 vs. 19 days, P

Description: Abstract 1595 Background: Immunohistochemistry for Cyclin D1 (CCND1) expression is routine in cases suggestive of mantle cell lymphoma (MCL). Most MCL are t(11;14)/IGH-CCND1-positive by FISH. PCR based detection of the fusion transcript is hampered by widespread breakpoints. Only few data is available on quantitative real-time PCR (RQ-PCR) for CCND1 expression measurement. Aims: To assess CCND1 mRNA expression and correlate it with t(11;14) in mature B-cell neoplasms. Methods: We established a RQ-PCR assay for CCND1 mRNA measurement and investigated 451 cases: 142 MCL (in all cases IGH-CCND1 confirmed by FISH), 76 chronic lymphocytic leukemia (43 typical CLL, 33 CLL/PL), 20 hairy cell leukemia (HCL), 13 hairy cell leukemia-variant (HCL-v), 20 splenic marginal zone lymphoma (SMZL), 91 other mature B-cell neoplasms. CCND1 background expression was assessed in 29 pts with other hematological neoplasms and 60 healthy individuals. FISH and/or chromosome banding analysis for the t(11;14) was available in 364 pts. Bone marrow (BM, n=267) or peripheral blood (PB; n=184) samples were analyzed by cytomorphology, multiparameter flow cytometry (MFC), FISH, and RQ-PCR. CCND1 mRNA expression was given by RQ-PCR in comparison to ABL1 mRNA expression (%CCND1/ABL1). Limited dilution of high expressers into cDNA of healthy controls revealed a sensitivity of the assay of up to 0.1 %. Results: IGH-CCND1 translocation carriers had higher %CCND1/ABL1 than those without which hold true in the total cohort (mean±SD, 420.4±740.3 vs 17.8±128.3; p

Description: Abstract 2566 The CCAAT enhancer binding protein alpha encoded by CEBPA gene is a transcription factors involved in myeloid lineage differentiation. Somatic CEBPA mutations are associated with a favorable prognosis in patients with normal to intermediate karyotype and lacking the internal tandem duplication in the fms-like tyrosine kinase -3 gene (FLT3/ITD) or mutation in the nucleophosmin gene (NPM1). N-terminal CEBPA mutations typically result in a frame shift encoding a truncated form of the 42-kD CEBPα protein and potentially increase translation of the alternative 30-kD isoform. The 30-kD isoform functions as a dominant negative regulator of the full-length 42-kD isoform of the CEBPα protein. C-terminal mutations are generally in-frame insertion/deletions in the DNA binding or the leucine zipper domains that cause alteration of the dimerization domain (bZIP). Germline mutations in CEBPA gene are recognized as the major cause of familial acute myeloid leukemia (AML). Familial AML is inherited in an autosomal dominant manner with complete penetrance. In contrast to somatic AML, the age onset of familial AML is earlier ranging from 4 to 39 years. The overall survival of the familial AML patients with germline CEBPA mutation is ∼50%–65% better than ∼34%–50% observed with the somatic CEBPA mutations (FLT3/NPM1 negative). In all of the familial AML pedigrees reported, the mutations were frame-shift insertions/deletions in the N-terminal domain resulting in translation of a truncated form of the CEBPα protein. We have identified four novel germline sequence variants in patients with history of familial AML and unknown karyotypes (cases 1–4). The patients' age ranges from 3 to 32 years. Of the four novel variants, one variant was identified in the C-terminal region of the gene. This is the first reported C-terminal variant detected in the proband of a familial AML pedigree. The variant is out of frame insertion/deletion of ∼401 bp in the C-terminal region of the CEBPA gene (there is a deletion ‘∼171bp then an insertion of 401bp). Another novel C-terminal variation was identified in a patient with cytogenetically normal AML undergoing testing for somatically acquired CEBPA mutations (case 5). The detection of this C-terminal variation in a buccal swab sample confirmed the germline origin of the variation. In two additional cases (cases 6 and 7), we observed that one of the two sequence variations identified was no longer present after treatment, suggesting the remaining variation was germline in origin. Our results demonstrate that germline C-terminal CEBPA mutations can cause familial AML and that germline CEBPA mutations may be identified in cytogenetically normal AML patients. The possibility of germline variants should be considered in AML patients since other family members, who may be possible transplant donors for the patient, may have also inherited the same germline variant. Case AML Type Sequence variation CEBPA gene region 1 Familial AML c.142delG; p.Ala48fs N terminal 2 c.168C〉A; p.Cys56* N terminal 3 c.175G〉T; p.Glu59* N terminal 4 c.643_814delins401; p.Thr216fs C terminal 5 Somatic AML c.1073delC; p.Ala358fs C terminal 6 c.68_78del; p.Pro23fs N terminal 7 c. 938T〉G; p. Val328G C terminal Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3045 Background: Lenalidomide is an oral IMiD® immunomodulatory compound with a dual mechanism of action, namely tumoricidal and immunomodulatory activity, and established clinical efficacy and safety in patients with multiple myeloma (MM). Lenalidomide plus dexamethasone (Len + Dex) was well tolerated and demonstrated significant improvements in response and favorable overall survival (OS) compared with Placebo + Dex in 2 pivotal phase 3 registration trials in patients with relapsed/refractory MM (RRMM; Weber et al, NEJM 2007; Dimopoulos et al, NEJM 2007). Previously, in a phase 3, multicenter, single-arm, open-label, expanded-access study (MM-018), Len + Dex demonstrated a predictable safety profile that can preserve patient quality of life (QoL) (Yong et al Haematologica 2010 [abstract #0944]). Here we report efficacy, safety, and QoL data for patients enrolled in the Spanish cohort of MM-018. Methods: Patients with progressive disease after 〉 2 cycles of antimyeloma treatment, or after relapse from treatment, with ECOG performance status ≤ 2 received 28-day cycles of Len (25 mg/day, D 1–21) plus Dex (40 mg/day, D 1–4, 9–12, and 17–20 for cycles 1–4; D 1–4 in subsequent cycles). Endpoints included overall response (≥ partial response [PR] by European Group for Blood and Marrow Transplantation criteria) and QoL assessments measured by EORTC QLQ C-30 and EORTC QLQ MY-20 questionnaires at baseline and week 24. All prophylaxis was administered at the investigator's discretion. Results: Sixty-three patients receiving ≥ 1 dose of Len + Dex were evaluated for efficacy, safety, and QoL. Median age was 62 years (21 [33.3%] were 〉 65 years). Prior therapies included thalidomide (n = 15, 24%) and bortezomib (n = 37, 59%). Additionally, 5 (8%) patients had a history of deep vein thrombosis (DVT), and 23 (37%) had a history of peripheral neuropathy. A PR or better was observed in 49 (78%) patients, including complete response (CR) in 13 (21%), very good partial response (VGPR) in 13 (21%), and PR in 23 (37%) patients. Median time to first response and best response was 2.7 and 4.5 months, respectively. Median duration of response was 18.4 months. Response depth improved after long-term treatment with Len + Dex, and 32/63 (51%) patients received 〉12 cycles of therapy. Beyond 12 cycles of therapy, 8 patients achieved VGPR and 12 patients achieved CR; compared with 5 patients and 1 patient, respectively, prior to 12 cycles. Median time to progression and progression-free survival were both 13.3 months; median OS has not yet been reached. Forty-two (67%) patients remained on study at 6 months. Compliance to QoL assessment questionnaires was ≥ 80%. Patient-reported improvements in QoL and disease symptoms measured by both questionnaires were observed in nearly all scales. EORTC QLQ C-30 scores revealed clinically meaningful improvement (〉 5 points) for global QoL (n = 15, 40%), fatigue (n = 16, 42%), emotional function (n = 15, 40%), physical function (n = 12, 32%), role function (n = 11, 29%), social function (n = 11, 29%), cognitive function (n = 10, 26%), and pain (n = 9, 24%) at 6 cycles compared with baseline. Preservation of QoL in role function, emotional function, social function, and pain scores was observed at 6 cycles when compared with baseline in responders (≥ PR). EORTC QLQ MY-20 results revealed no relevant median change (〉 5 points) from baseline in all scales for all patients completing questionnaires at baseline and 6 cycles, except for a meaningful improvement in future perspective scores (median 11.1-point change). Adverse events observed in this study were consistent with those previously reported with Len + Dex. Grade 3/4 hematologic events were experienced by 40 (64%) patients, and included neutropenia (n = 32, 51%), thrombocytopenia (n = 11, 17%), anemia (n = 10, 18%), and febrile neutropenia (n = 4, 6%). DVT (all grades) was experienced by 5 (8%) patients, and only one grade 3/4 new-onset peripheral neuropathy was observed after 6 cycles of treatment. Conclusions: Len + Dex treatment in this expanded-access study demonstrated efficacy and predictable safety, consistent with that of previously published trials for patients with RRMM. More patients achieved VGPR and CR after long-term therapy compared with those receiving 〈 12 cycles of therapy. Furthermore, QoL assessments at baseline and 6 months revealed that patients treated with Len + Dex showed meaningful improvements in certain QoL and symptom scores. Disclosures: Oriol-Rocafiguera: Celgene: Consultancy; Janssen-Cilag: Consultancy; Novartis: Consultancy. García-Laraña:Celgene: Consultancy; Janssen-Cilag: Consultancy. Mateos:Celgene: Honoraria. Cibeira:Celgene: Honoraria for Lectures; Janssen-Cilag: Honoraria for Lectures; Pharmion: Honoraria for Lectures. Knight:Celgene: Employment. Rosettani:Celgene Corporation: Employment.

Description: Only 30% of patients who require an allogeneic hematopoietic cell transplant will have an HLA-matched sibling donor. A search for an unrelated donor will be undertaken for patients without a matched family donor. However, many patients, particularly patients of diverse racial and ethnic backgrounds, may not be able to rapidly identify a suitably matched unrelated donor. Three alternative graft sources, umbilical cord blood (UCB), haploidentical (haplo)–related donor, and mismatched unrelated donor (MMUD) are available. UCB is associated with decreased GVHD, but hematologic recovery and immune reconstitution are slow. Haplo-HCT is characterized by donor availability for transplantation and after transplantation adoptive cellular immunotherapy but may be complicated by a high risk of graft failure and relapse. A MMUD transplant may also be an option, but GVHD may be of greater concern. Phase 2 studies have documented advances in HLA typing, GVHD prophylaxis, and infection prevention, which have improved survival. The same patient evaluated in different transplant centers may be offered MMUD, UCB, or haplo-HCT depending on center preference. In this review, we discuss the rationale for donor choice and the need of phase 3 studies to help answer this important question.

Description: Inappropriately low expression of the key iron regulator hepcidin (HAMP) causes iron overload in untransfused patients affected by β-thalassemia intermedia and Hamp modulation provides improvement of the thalassemic phenotype of the Hbbth3/+ mouse. HAMP expression is activated by iron through the bone morphogenetic protein (BMP)–son of mothers against decapentaplegic signaling pathway and inhibited by ineffective erythropoiesis through an unknown “erythroid regulator.” The BMP pathway is inactivated by the serine protease TMPRSS6 that cleaves the BMP coreceptor hemojuvelin. Here, we show that homozygous loss of Tmprss6 in Hbbth3/+ mice improves anemia and reduces ineffective erythropoiesis, splenomegaly, and iron loading. All these effects are mediated by Hamp up-regulation, which inhibits iron absorption and recycling. Because Hbbth3/+ mice lacking Tmprss6 show residual ineffective erythropoiesis, our results indicate that Tmprss6 is essential for Hamp inhibition by the erythroid regulator. We also obtained partial correction of the phenotype in Tmprss6 haploinsufficient Hbbth3/+ male but not female mice and showed that the observed sex difference reflects an unequal balance between iron and erythropoiesis-mediated Hamp regulation. Our study indicates that preventing iron overload improves β-thalassemia and strengthens the essential role of Tmprss6 for Hamp suppression, providing a proof of concept that Tmprss6 manipulation can offer a novel therapeutic option in this condition.

Description: Iron-refractory, iron-deficiency anemia (IRIDA) is a familial disorder characterized by iron deficiency anemia unresponsive to oral iron treatment but partially responsive to intravenous iron therapy. Previously, we showed that IRIDA patients harbor loss-of-function mutations in TMPRSS6, a type II transmembrane serine protease primarily expressed by the liver. Both humans and mice with TMPRSS6 mutations show inappropriately elevated levels of the iron-regulatory hormone hepcidin, suggesting that TMPRSS6 acts to negatively regulate hepcidin expression. Here we investigate the relationship between Tmprss6 and the bone morphogenetic protein (BMP)–Smad signaling pathway, a key pathway promoting hepcidin transcription in hepatocytes. We show that livers from mice deficient for Tmprss6 have decreased iron stores and decreased Bmp6 mRNA, but markedly increased mRNA for Id1, a target gene of Bmp6 signaling. In contrast, mice deficient for both Tmprss6 and hemojuvelin (Hjv), a BMP coreceptor that augments hepcidin expression in hepatocytes, showed markedly decreased hepatic levels of hepcidin and Id1 mRNA, markedly increased hepatic Bmp6 mRNA levels, and systemic iron overload similar to mice deficient for Hjv alone. These findings suggest that down-regulation of Bmp/Smad signaling by Tmprss6 is required for regulation of hepcidin expression and maintenance of systemic iron homeostasis.

Description: Neutrophil recruitment and extravasation at sites of inflammation provide a mechanism for host defense. We showed previously that heparan sulfate, a type of sulfated glycosaminoglycan, facilitates neutrophil recruitment based on the reduction of neutrophil infiltration in mice in which the overall sulfation of the chains was reduced by selective inactivation of N-acetylglucosamine N-deacetylase-N-sulfotransferase (Ndst1) in endothelial cells. Here we show that inactivation of uronyl 2-O-sulfotransferase in endothelial cells (Hs2st), an enzyme that acts downstream from Ndst1, results in enhanced neutrophil recruitment in several models of acute inflammation. Enhanced neutrophil infiltration resulted in part from reduced rolling velocity under flow both in vivo and in vitro, which correlated with stronger binding of neutrophil L-selectin to mutant endothelial cells. Hs2st-deficient endothelial cells also displayed a striking increase in binding of IL-8 and macrophage inflammatory protein-2. The enhanced binding of these mediators of neutrophil recruitment resulted from a change in heparan sulfate structure caused by increased N-sulfation and 6-O-sulfation of glucosamine units in response to the decrease in 2-O-sulfation of uronic acid residues. This gain-of-function phenotype provides formidable evidence demonstrating the importance of endothelial heparan sulfate in inflammation and suggests a novel enzyme target for enhancing the innate immune response.

Description: Carfilzomib is a selective proteasome inhibitor that binds irreversibly to its target. In phase 1 studies, carfilzomib elicited promising responses and an acceptable toxicity profile in patients with relapsed and/or refractory multiple myeloma (R/R MM). In the present phase 2, multicenter, open-label study, 129 bortezomib-naive patients with R/R MM (median of 2 prior therapies) were separated into Cohort 1, scheduled to receive intravenous carfilzomib 20 mg/m2 for all treatment cycles, and Cohort 2, scheduled to receive 20 mg/m2 for cycle 1 and then 27 mg/m2 for all subsequent cycles. The primary end point was an overall response rate (≥ partial response) of 42.4% in Cohort 1 and 52.2% in Cohort 2. The clinical benefit response (overall response rate + minimal response) was 59.3% and 64.2% in Cohorts 1 and 2, respectively. Median duration of response was 13.1 months and not reached, and median time to progression was 8.3 months and not reached, respectively. The most common treatment-emergent adverse events were fatigue (62.0%) and nausea (48.8%). Single-agent carfilzomib elicited a low incidence of peripheral neuropathy—17.1% overall (1 grade 3; no grade 4)—in these pretreated bortezomib-naive patients. The results of the present study support the use of carfilzomib in R/R MM patients. This trial is registered at www.clinicaltrials.gov as NCT00530816.

Description: Abstract 2223 Disseminated intravascular coagulation (DIC) represents a complex pathophysiologic syndrome where marked alterations in the hemostatic system are manifested. As a result several inflammatory mediators are up regulated through multiple mechanisms. The up regulation of inflammatory mediators such as anaphylatoxin C5a (C5a), procalcitonin (PCT), interleukin 6 (IL-6), interleukin 10 (IL-10), myeloperoxidase (MPO), C reactive protein (CRP), and circulating levels of hemostatic markers including protein C inhibitor (PCI), plasminogen activator inhibitor 1 (PAI-1), and protein C (Pr C) were evaluated in 758 subjects enrolled in a randomized, double-blind, placebo-controlled, Phase-2B study evaluating the safety and efficacy of recombinant thrombomodulin (ART-123) in subjects with sepsis and suspected DIC. Thirty healthy male and female volunteers served as the control group. Commercially available ELISA methods were used to measure the various mediators. Marked deviations in the circulating levels of these markers, as compared to controls, were noted as shown in the following table. Compared with controls, subjects in DIC showed an increase in the circulating levels of most inflammatory markers. The levels of PCT, IL-6 and CRP, where considerably higher in the DIC subjects whereas PCI, Pr C and AT exhibited slight decreases. Wide individual variations were present. The PAI-1 levels were also increased in the DIC subjects. These results are tabulated below. These results clearly indicate that inflammation and impairment of fibrinolysis play a key role in the pathogenesis of DIC Parameter Nomal (NHP Mean+SEM) DIC (Baseline Mean+SEM) % Change Protein C (% Ag) 82.5 ± 13.6 47.6 ± 23.7 −42.2% Functional Protein C (%) 83.4 ± 13.2 46.2 ± 29.8 −44.6% PCI (% Inhibition) 130.0 ± 24.6 79.4 ± 105.5 −38.9% PAI-1 (ng/ml) 35.4 ± 10.8 140.6 ± 165.6 297.1% CRP (ug/ml) 2.6 ± 0.4 48.0 ± 14.2 1736.9% C5a (ng/ml) 9.2 ± 3.2 17.2 ± 13.3 85.1% IL-6 (pg/ml) 9.3 ± 3.7 620.3 ± 1883.4 6583.9% IL-10 (pg/ml) 13.9 ± 13.1 130.2 ± 118.6 836.1% MPO (ng/ml) 16.0 ± 4.2 108.1 ± 68.6 574.6% PCT (ng/ml) 0.2 ± 0.13 21.9 ± 43.3 14514.5% Disclosures: Osawa: Asahi Kasei Pharma America Corporation: Employment. Kaul:Asahi Kasei Pharma America Corporation: Employment.

Description: Protein vaccines for T-cell immunity are not being prioritized because of poor immunogenicity. To overcome this hurdle, proteins are being targeted to maturing dendritic cells (DCs) within monoclonal antibodies (mAbs) to DC receptors. To extend the concept to humans, we immunized human immunoglobulin-expressing mice with human DEC205 (hDEC205) extracellular domain. 3D6 and 3G9 mAbs were selected for high-affinity binding to hDEC205. In addition, CD11c promoter hDEC205 transgenic mice were generated, and 3G9 was selectively targeted to DCs in these animals. When mAb heavy chain was engineered to express HIV Gag p24, the fusion mAb induced interferon-γ– and interleukin-2–producing CD4+ T cells in hDEC205 transgenic mice, if polynocinic polycytidylic acid was coadministered as an adjuvant. The T-cell response was broad, recognizing at least 3 Gag peptides, and high titers of anti-human immunoglobulin G antibody were made. Anti-hDEC205 also improved the cross-presentation of Gag to primed CD8+ T cells from HIV-infected individuals. In all tests, 3D6 and 3G9 targeting greatly enhanced immunization relative to nonbinding control mAb. These results provide preclinical evidence that in vivo hDEC205 targeting increases the efficiency with which proteins elicit specific immunity, setting the stage for proof-of-concept studies of these new protein vaccines in human subjects.

Description: Abstract 4013 Background: In recent years, azacytidine (AZA) has become the standard of treatment for high risk myelodysplasia (MDS). The approved schedule of AZA uses a 75mg/m2/d s.c. regimen for 7 days based on the CALGB-9221 (Silverman, JCO 2002) and the AZA-001 studies (Fenaux, Lancet Oncol 2009). The clinical response rates after AZA have been extensively presented but there is only limited data on the rates of cytogenetic response (CyR). Based on the review of the literature, there are no specific cytogenetic data published on prospective trials. Methods: We based our analysis on a randomized phase 2 study from the US Leukemia Intergroup (E1905 study, NCT00313586) testing 10 days of AZA (50mg/m2/d s.c.) vs 10 days of AZA+ the histone deacetylase inhibitor entinostat (4 mg/m2/d PO days 3 and day 10). MDS, CMML, and AML with myelodysplasia-related changes were included. This analysis includes all patients with cytogenetic abnormalities (at baseline or acquired following treatment) with available cytogenetic follow-up (cycle 6). Of 150 patients, 70 demonstrated baseline cytogenetic abnormalities. To date, forty patients (27 MDS and 13 AML) were evaluable for both time points. Karyotypes were performed at local laboratories, and reviewed centrally (RPK and GH). Cytogenetic response was assessed using IWG 2000 (Cheson et al, Blood 2000) criteria. Results: The clinical response rate (CR+PR+ trilineage HI) according to IPSS cytogenetic risk stratification were of 20%, 33%, and 35% for favorable, intermediate and poor cytogenetic risk groups respectively (p=NS). Patients with Chr 7 abnormalities (i.e. -7 or -7q, n=18) had a response rate of 28% including 17% CR. Of patients with complete cytogenetic data, the rate of overall CyR was 52% (n=21): 22% (n=9) complete CyR, 30% (n=12) partial CyR. This represents a complete CyR of 13% and a partial CyR of 23% as a proportion of all treated patients with initial cytogenetic abnormalities (including those who did not receive six cycles of therapy). To date, confirmatory FISH analyses were available for 4 patients with CyR (2 CCyR and 2 PCyR). All four had complete clearance of their cytogenetic clone. Among the cytogenetic responders, 15 had MDS and 6 had AML (p=NS). CyR did not differ between the two treatment arms. CyR and clinical response were highly correlated (p

Description: Abstract 44 CALGB (now part of the Alliance for Clinical Trials in Oncology) performed a non-randomized phase II study testing one year (yr) of investigational maintenance therapy with decitabine for newly diagnosed adult AML patients (pts) 1 × 109/L, platelets 〉75 × 109/L, and be within 90 days after day 1 of the final consolidation. Decitabine 20mg/m2 was given IV over 1 hour for 4–5 days, every 6 weeks, for 8 cycles. 546 pts enrolled with a median age of 48 yrs (range, 17–60) and median presenting white blood count (WBC) of 12.6 × 109/L (range, 0.3–380 × 109/L). 75% achieved CR (412/546). Reasons for CR pts not receiving maintenance were mainly early relapse, alloHCT in 1st CR, inadequate count recovery, and patient refusal (Blum et al. ASH 2011). 33% of CR pts (134/412) received investigational maintenance. Of these, 46 (34%) were favorable risk; among the remaining 88 pts, 73 were consolidated with autoHCT, and 15 received HiDAC-based consolidation. The median time from initial study registration to initiation of maintenance therapy was 6.3 months. Pts receiving decitabine had a median age of 45 yrs (range, 18–60) and presenting WBC of 13.5 × 109/L (range, 0.4–221 × 109/L). Treatment with decitabine maintenance was feasible and reasonably well tolerated; the primary toxicity was myelosuppression. Preplanned dose reduction criteria for neutropenia were met after the first 20 pts had been treated. After this early timepoint, all subsequent pts who had been consolidated with autoHCT received only 4 days of decitabine per cycle (HiDAC consolidated pts continued to receive 5 days per cycle). The median number of cycles of decitabine received was 7 (range, 1–8); 46% of pts (62/134) received all 8 cycles, and 75% completed at least 4 cycles. Reasons for discontinuation of decitabine before completing 8 cycles included relapse (28%, 38/134), pt refusal (13%), adverse events (4%), and others. In this selected cohort of pts who received post-CR maintenance with decitabine, 1-yr and 3-yr overall survival (OS) were 96% and 66%; 1-yr and 3-yr disease-free survival (DFS) were 80% and 53%. 1-yr “failure-free survival” calculated from the time of registration to decitabine was 68% (70% for favorable risk, 68% for others). These results are similar to the outcomes for comparable pts enrolled on our prior CALGB study 19808 who received identical chemotherapy for induction and consolidation and then were randomized to observation or maintenance with interleukin-2 (3-yr OS 61% and 68%, 3-yr DFS 45% and 56%, for observation and IL-2 respectively). Post-consolidation maintenance with decitabine appears to provide only modest, if any, benefit overall. Correlative studies for CALGB 10503 are ongoing, including investigations into the impact of decitabine in unique molecular and cytogenetic subsets of disease, the prognostic/predictive value of aberrant methylation and other molecular markers, and assessment of minimal residual disease. Supported by CA33601 and CA128377. Disclosures: No relevant conflicts of interest to declare.

Description: Single nucleotide polymorphism arrays (SNP-A) have recently been widely applied as a powerful karyotyping tool in numerous translational cancer studies. SNP-A complements traditional metaphase cytogenetics with the unique ability to delineate a previously hidden chromosomal defect, copy neutral loss of heterozygosity (CN-LOH). Emerging data demonstrate that selected hematologic malignancies exhibit abundant CN-LOH, often in the setting of a normal metaphase karyotype and no previously identified clonal marker. In this review, we explore emerging biologic and clinical features of CN-LOH relevant to hematologic malignancies. In myeloid malignancies, CN-LOH has been associated with the duplication of oncogenic mutations with concomitant loss of the normal allele. Examples include JAK2, MPL, c-KIT, and FLT3. More recent investigations have focused on evaluation of candidate genes contained in common CN-LOH and deletion regions and have led to the discovery of tumor suppressor genes, including c-CBL and family members, as well as TET2. Investigations into the underlying mechanisms generating CN-LOH have great promise for elucidating general cancer mechanisms. We anticipate that further detailed characterization of CN-LOH lesions will probably facilitate our discovery of a more complete set of pathogenic molecular lesions, disease and prognosis markers, and better understanding of the initiation and progression of hematologic malignancies.

Description: Red blood cell transfusions have reduced morbidity and mortality for patients with sickle cell disease. Transfusions can lead to erythrocyte alloimmunization, however, with serious complications for the patient including life-threatening delayed hemolytic transfusion reactions and difficulty in finding compatible units, which can cause transfusion delays. In this review, we discuss the risk factors associated with alloimmunization with emphasis on possible mechanisms that can trigger delayed hemolytic transfusion reactions in sickle cell disease, and we describe the challenges in transfusion management of these patients, including opportunities and emerging approaches for minimizing this life-threatening complication.

Description: Abstract 3240 The role of pulmonary hypertension as a common and attributable cause of mortality in patients with sickle cell disease remains controversial. To assess this question and explore risk factors for death in patients with sickle cell disease we evaluated 632 patients in the Walk-PHASST pulmonary hypertension screening cohort, recruited from nine different study sites in the United States and one site in the United Kingdom. Methods: Patient characteristics and their associations with mortality were analyzed with Cox proportional hazards regression analysis. Based on data from three right heart catheterization screenings studies that have recently been published, we defined the presence of pulmonary hypertension for this analysis by a Doppler-echocardiographic measurement of the tricuspid regurgitant jet velocity (TRV) ≥ 3.0 m/s, which has a 67–75% positive predictive value for a mean pulmonary artery pressure ≥ 25 mm Hg by right heart catheterization. This therefore represents a very conservative threshold for a large population screening study. Among subjects with a measurable TRV (n=572), 64 (11.2%) had measurements of ≥ 3.0 m/sec. Among those with measurable NT-proBNP (n=582), 140 (24.1%) had measurements ≥160 pg/mL, a value associated with both pulmonary hypertension and mortality. A total of 39 (7.4%) had both high TRV (≥3.0 m/sec) and high NT-proBNP (≥160 pg/mL). Results: Over a median follow-up time of 29 months, we observed 22 deaths. 50% (N=11) of these patients had a TRV≥ 3.0 m/sec. At 24 months the cumulative survival was 83% for patients with TRV ≥ 3.0 m/sec and 98% for patients with TRV 〈 3.0 m/sec (p

Description: Abstract 2801 Background: Recommendations for use of erythropoiesis-stimulating agents (ESAs) in anemic patients with MDS are based on baseline endogenous erythropoietin levels and red blood cell transfusion requirements, factors which predict the likelihood of a response to ESA treatment. These recommendations for ESA use have been incorporated into quality-of-care treatment guidelines for MDS. We examined whether baseline endogenous thrombopoietin (TPO) levels and platelet transfusion requirements likewise predict response of thrombocytopenic MDS patients to treatment with romiplostim, a TPO receptor agonist. Patients and Methods: In a placebo(PBO)-controlled trial of romiplostim (randomized 2:1) in 250 thrombocytopenic [median (Q1, Q3) baseline platelet count 19.3 (12.5, 30.3) × 109/L] IPSS low/int-1 MDS patients, study drug was discontinued early due to data monitoring committee concerns that the potential small benefit seen in the reduction of bleeding did not outweigh the potential risk for disease progression to AML and that the transient increases in blast cell counts may put patients at risk for diagnosis of and treatment for AML. Hematologic improvement of platelets (HI-P, per IWG 2006) is defined as 8 consecutive weeks of an absolute platelet increase of 30×109/L (for patients with baseline platelet counts 〉20×109/L) or an increase from 20×109/L and by at least 100% (for patients with baseline platelet counts

Description: Abstract 3937 CHOP and CHOP-like chemotherapy programs remain the most commonly used regimens for the treatment of peripheral T-cell lymphomas (PTCLs) despite often sub-optimal results. Histone deacetylase inhibitors (HDACIs) are epigenetic agents known to be active in T-cell lymphoma. Recently romidepsin (R) was approved for patients with relapsed or refractory CTCL. Both R and belinostat (B) are being investigated in patients with relapsed or refractory PTCL. We have previously shown that hypomethylating agents as decitabine (D) produce synergistic interactions with HDACIs in B-cell lymphomas. We investigated the in vitro and in vivo activity of D, R and B alone or in combination in different T-cell lymphoma and leukemia cell lines including CTCL (H9, HH), and T- acute lymphoblastic leukemia (T-ALL) lines resistant to gamma-secretase inhibitors (GSI) (P12, PF-382). For all cytotoxicity assays, luminescent cell viability was performed using CellTiter-Glo™ followed by acquisition on a Biotek Synergy HT. The IC50s for D, B and R were calculated using the Calcusyn software (Biosoft). Drug: drug interactions were analyzed using the calculation of the relative risk ratios (RRR) based on the GraphPad software (RRR 20 uM. In the cytotoxicity assays, the combination of D and B or R at 72 hours showed synergism in all the cell lines studied. The most representative RRRs are showed in table 1. Table 1 D 0.5 uM 1uM B (nM) RRR H9 50 0.7 0.7 70 0.6 0.6 100 0.4 0.5 PF 382 150 0.8 0.7 0.5 uM 1 uM R (nM) RRR H9 0.5 0.9 0.9 1 0.8 0.8 2 0.3 0.3 PF 382 1 0.8 0.7 1.5 0.4 0.4 2 0.1 0.1 When H9, HH, P12 and PF382 cell lines were treated with D and B or R for 72 hours, all the combination groups showed significantly more apoptosis than the single drug exposures and controls. Table 2 displays the range of apoptosis induction for B, R and D or for them used in combination and the RRR value after the analysis for the most significant data. Table 2 B D B + D RRR (% Apoptotic + Dead Cells) H9 100nM (22.9%) 500nM (17.9%) 51.5% 0.7 HH 100nM (42.9%) 1uM (46.9%) 61.3% 0.8 P 12 150nM (16%) 1uM (42.7%) 80.1% 0.4 PF 382 100nM (8.3%) 1uM (27.9%) 40.1% 0.8 R D R + D H9 2nM (22.2%) 500nM (17.9%) 63.6% 0.5 HH 2nM (80%) 1uM (46.9%) 89.7% 0.6 P 12 2nM (9.9%) 10uM (58.7%) 98% 0.03 PF 382 2nM (54.5%) 500nM (17.9%) 88.7% 0.2 Increased acetylation of H3 was observed when H9 cells were treated with R alone and synergistically increased after exposing cells to the combination of D + B and D + R. The expression of phosphorylated Stat3 was decreased after exposure of H9 cells to the combination of D and R. Additional interrogation of the effects of this epigenetic therapy on the JAK-STAT signaling pathway are now underway. An in vivo xenograft study in six to eight weeks old female SCID beige mice injected subcutaneously with 2 × 107 HH cells has also begun and will be reported. Mice were separated into different cohorts and treated with intraperitoneal injections of D or B or their combination according to the following schedules: D alone at 1.5 mg/kg on days 1, 5; B alone at 35 mg/Kg/day for 7 days. Collectively, the data suggest that the combination of a hypomethylating agent like D and a HDACI (B and R) are synergistic in in vitro models of human T-cell lymphoma, and may lead to a new platform for the treatment of these diseases. Disclosures: O'Connor: Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Description: Abstract 285 Background: KW-0761 is a defucosylated, humanized, monoclonal antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC; Potelligent®) that binds to CC chemokine receptor 4 (CCR4). CCR4 is expressed on the surfaces of cells comprising several T-cell malignancies such as ATL, peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL). A phase I study of KW-0761 in patients with CCR4-positive ATL and PTCL demonstrated that 4 weekly intravenous infusions of KW-0761 were well tolerated up to 1.0 mg/kg and it showed encouraging clinical activity with an overall response rate (ORR) of 31.3% (4 of 13 ATL and 1 of 3 PTCL) in 16 patients (J Clin Oncol 2010;28:1591-8). Methods: A multicenter phase II study of KW-0761 has been conducted for relapsed patients with CCR4-positive ATL to evaluate its efficacy, pharmacokinetics (PK), safety and immunogenicity. Patients were planned to receive 8 weekly intravenous infusions of KW-0761 at 1.0 mg/kg. The primary endpoint was ORR. Objective responses were assessed after the 4th and 8th infusions of KW-0761 according to the response criteria for ATL (J Clin Oncol 2009;27:453-9) by each investigator and the independent efficacy assessment committee. The number of patients required was estimated to be 25, for 90% power to detect a lower limit of the 95% confidence interval (CI) exceeding the 5% threshold of ORR, based on the assumptions that the minimum required response ORR to a new drug for relapsed ATL is 5% and the expected ORR to KW-0761 is 30%. Results: Twenty-seven patients (12 males and 15 females) were enrolled and received KW-0761. The median age was 64 years (range: 49–83). The disease subtypes of ATL consisted of 14 acute-, 6 lymphoma-, and 7 chronic-types with unfavorable prognostic factors. Among the 27 patients enrolled, 14 patients (52%) completed the protocol treatment of 8 infusions. Eleven patients (41%) discontinued the protocol treatment because of progressive disease, and the remaining 2 discontinued because of skin rash or the concurrent colon tumor. The treatment-related grade (G) 2 or greater adverse events (AEs) were lymphopenia (96%), leukopenia (56%), skin rash (52%), neutropenia (33%), thrombocytopenia (26%), AST increase (26%), ALT increase (22%), hypoxemia (19%), anemia (15%), pruritus (15%), g-GTP increase (15%) and hypophosphatemia (15%). G2 or greater Infusion-related toxicities were observed in 22 of 27 patients (81%) including 1 G3, but immediately recovered after treatment with systemic steroids. Treatment-related severe AEs (SAEs) were observed in 5 patients, including a Stevens-Johnson syndrome (G3) and 4 skin rashes (each G3). All these AEs also improved by steroids. PK analysis demonstrated that Cmax and trough (C168h) after the 8th infusion was 38,853 ± 11,267 and 25,934 ± 10,193 ng/mL, respectively, and T1/2 after the 8th infusion were 457 ± 144 h. No anti-KW-0761 antibody has been detected. Among the 26 patients evaluable for efficacy, KW-0761 exhibited an ORR of 54% (14/26; 95% CI, 33 to 73) (acute: 6/14 patients, lymphoma: 3/6 patients, chronic: 5/6 patients) including 7 complete responses (CRs) (27%; 95% CI, 12 to 48) and 7 partial responses (PRs). These are remarkable results, considering that the ORR of relapsed or refractory patients with ATL to a single-agent chemotherapy has been reported to be low (7 to 39%). Response rates according to the affected disease lesion were 100% (13 patients, all CR), 71% (5 of 7 patients), and 38% (5 of 13 patients), respectively, for peripheral blood, skin, and lymph node disease. Conclusions: KW-0761 is a highly effective agent with acceptable toxicity profiles in relapsed patients with CCR4-positive ATL who have no standard therapies. A multicenter, randomized study for untreated ATL patients to compare mLSG15 (a dose-intensified multi-agent regimen, J Clin Oncol 2007;25:5458-64) + KW-0761 with mLSG15 alone has been initiated. Disclosures: Ogura: Kyowa Hakko Kirin Co Ltd: Consultancy. Akinaga:Kyowa Hakko Kirin Co Ltd: Employment.

Description: Abstract 3687 Background: Prednisolone at a dose of 1 mg/kg/day (PRD) for 2 to 4 weeks is administered as front-line therapy to most adult patients with immune thrombocytopenia (ITP) who need to be treated. Recent results from 2 large single arm studies suggest high dose dexamethasone (DEX) as first-line treatment may produce a high sustained response rate. Therefore, we conducted prospective randomized trial comparing DEX with PRD as initial treatment of adult patients with newly diagnosed ITP. Methods: We did a randomized multicentre trial based on a 1:1 design. We enrolled treatment-naïve patients, 16 years or older, with a diagnosis of ITP according to the practice guidelines of the American Society of Hematology and a platelet count of 30×109/L or less. Patients with ITP were randomly assigned to receive either DEX 40 mg/day on day 1–4 (If the platelet count dropped below 3×109/L within the first six months, another four-day course of DEX was given) or PRD 1mg/kg/day for 4 weeks. The primary object of this study was the sustained response (platelet count〉30×109/L after 6 months) rate. Second objectives are response rate at 4 weeks, predictors of steroid response, and toxicity. This study is registered at http://clinicaltrials.gov as NCT00451594. Results: From September 2005 to December 2009, 151 adults with ITP were randomly assigned (76 patients in the DEX arm, 75 patients in the PRD arm). Overall demographics were balanced between arms; Median age 44 years old (DEX:PRD 44 years old:44 years old); 69.5% female (DEX:PRD 73.7%:65.3%); median initial platelet count 17×109/L (DEX:PRD 16×109/L:17×109/L). Of 151 enrolled patients, 117 patients (57 patients in the DEX arm, 60 patients in the PRD arm) were evaluable in terms of sustained response. Sustained response rate by intention-to-treat (ITT) and per protocol were 25.0% and 33.3% in the DEX arm, 36.0% and 45.0% in the PRD arm, respectively (p=0.33 by ITT). Eight patients in the DEX arm and 17 patients in the PRD arm had a sustained platelet counts more than100×109/L. Fifteen patients had a sustained response after a single course of DEX and 6 patients among them required no further treatment during two to four year follow up. Median time to relapse in patients who had a sustained response was 1320 days and 1140 days, respectively. The response rate at day 28 was 68.2% in the DEX arm and 81.2% in the PRD arm. Pre-treatment platelet count was higher in patients who achieved sustained response (responder vs. non-responder: 17.1±7.8×109/L vs. 15.9±8.9×109/L). Eleven patients in the DEX arm and 8 patients in the PRD arm received splenectomy. Both treatments were well tolerated. Three patients represented side effects that were severe enough to discontinue the treatment in the PRD arm, including pneumonia (1), hyperglycemia (1), and myalgia (1). Six patients receiving DEX and 5 patients receiving PRD had G3 or more hyperglycemia. Conclusion: One or two courses of DEX were not more effective than PRD in adults with ITP. However, 19.7% of adult ITP had a sustained response with a single course of DEX. Initial treatment with DEX could be useful for identifying patients who may not require prolonged steroid treatment. Disclosures: No relevant conflicts of interest to declare.