ALBERT

Beschreibung: Current management of hemophilia B entails multiple weekly infusions of factor IX (FIX) to prevent bleeding episodes. In an attempt to make a longer acting recombinant FIX (rFIX), we have explored a new releasable protraction concept using the native N-glycans in the activation peptide as sites for attachment of polyethylene glycol (PEG). Release of the activation peptide by physiologic activators converted glycoPEGylated rFIX (N9-GP) to native rFIXa and proceeded with normal kinetics for FXIa, while the Km for activation by FVIIa–tissue factor (TF) was increased by 2-fold. Consistent with minimal perturbation of rFIX by the attached PEG, N9-GP retained 73%-100% specific activity in plasma and whole-blood–based assays and showed efficacy comparable with rFIX in stopping acute bleeds in hemophilia B mice. In animal models N9-GP exhibited up to 2-fold increased in vivo recovery and a markedly prolonged half-life in mini-pig (76 hours) and hemophilia B dog (113 hours) compared with rFIX (16 hours). The extended circulation time of N9-GP was reflected in prolonged correction of coagulation parameters in hemophilia B dog and duration of effect in hemophilia B mice. Collectively, these results suggest that N9-GP has the potential to offer efficacious prophylactic and acute treatment of hemophilia B patients at a reduced dosing frequency.

Beschreibung: Abstract 1144 Protease-activated receptor (PAR) signaling is closely linked to the cellular activation of the pro- and anticoagulant pathways. In contrast to thrombin that directly binds to and activates PAR1, other coagulation factors are dependent on co-receptors for efficient PAR cleavage. The endothelial protein C receptor (EPCR) is crucial for protein C (PC) activation by thrombomodulin-bound thrombin and supports signaling of activated PC through PAR1. EPCR may play additional roles by interacting with procoagulant proteases. EPCR binds the Gla-domain of human coagulation factor VII and conflicting reports exist about the role of EPCR as a receptor for FX. We studied the interaction of murine soluble EPCR extracellular domain (sEPCR) under physiological concentrations of divalent cations Ca2+/Mg2+. BIAcore measurements showed that murine sEPCR bound both human and mouse complexes of soluble tissue factor (TF) with FVIIa, as well as human FX. In a lipid free system measuring only protein-protein interactions, amidolytic activity of soluble TF-FVIIa was not changed by sEPCR. However, sEPCR dose dependently inhibited FX activation by both human and mouse soluble TF-FVIIa, indicating that sEPCR interacted with the TF-FVIIa-FX extrinsic activation complex. On human cells, TF forms two signaling complexes, the non-coagulant TF-FVIIa binary complex that activates PAR2 and the ternary TF-FVIIa-FXa complex that signals through PAR1 or PAR2. Overexpression of PAR2 in HUVECs resulted in PAR2 activation by activated PC, and in these transduced cells TF-FVIIa-FXa ternary complex signaling was inhibited by antibody blockade of EPCR. Human HaCaT keratinocytes constitutively synthesize TF and represent a well characterized model of TF binary and ternary complex signaling through PAR2. FACS analysis showed that EPCR was expressed on the cell surface and antibody blockade of EPCR prevented TF-FVIIa-Xa ternary, but not TF-FVIIa binary complex signaling. Mutation of FVIIa Gla residues had no effect on ternary complex signaling, indicating a primary interaction of EPCR with FX/FXa. To expand these studies to murine cells that constitutively express EPCR and TF, we isolated lung smooth muscle cells (SMC) from wild-type, PAR1-/-, PAR2-/-, and EPCRlow mice. Stimulation of SMC with thrombin, high concentrations of FXa, or FVIIa/FX, but not FVIIa alone induced PAR1-dependent signaling. While thrombin signaling was unaltered, EPCRlow SMC showed no response to the ternary complex measured by ERK1/2 phosphorylation. In order to exclude indirect effects on SMC phenotypes due to prolonged EPCR-deficiency in vivo, we further deleted EPCR in vitro by adenoviral transduction with cre recombinase from EPCRfloxflox SMC or blocked EPCR function with antibodies to murine EPCR. Both approaches inhibited TF ternary complex, but not thrombin signaling. These results show that EPCR interacts with the TF coagulation initiation complex to enable specifically ternary complex signaling and suggest that EPCR may play a role in regulating the biology of TF expressing extravascular and vessel wall cells that are exposed to limited concentrations of FVIIa and FX provided by ectopic synthesis or vascular leakage. Disclosures: Heibroch Petersen: Novo Nordisk: Employment. Persson:Novo Nordisk: Employment. Petersen:Novo Nordisk: Employment. Ruf:Novo Nordisk: Research Funding.

Beschreibung: Hemophilia is treated by IV replacement therapy with Factor VIII (FVIII) or Factor IX (FIX), either on demand to resolve bleeding, or as prophylaxis. Improved treatment may be provided by drugs designed for subcutaneous and less frequent administration with a reduced risk of inhibitor formation. Tissue factor pathway inhibitor (TFPI) down-regulates the initiation of coagulation by inhibition of Factor VIIa (FVIIa)/tissue factor/Factor Xa (FVIIa/TF/FXa). Blockage of TFPI inhibition may facilitate thrombin generation in a hemophilic setting. A high-affinity (KD = 25pM) mAb, mAb 2021, against TFPI was investigated. Binding of mAb 2021 to TFPI effectively prevented inhibition of FVIIa/TF/FXa and improved clot formation in hemophilia blood and plasma. The binding epitope on the Kunitz-type protease inhibitor domain 2 of TFPI was mapped by crystallography, and showed an extensive overlap with the FXa contact region highlighting a structural basis for its mechanism of action. In a rabbit hemophilia model, an intravenous or subcutaneous dose significantly reduced cuticle bleeding. mAb 2021 showed an effect comparable with that of rFVIIa. Cuticle bleeding in the model was reduced for at least 7 days by a single intravenous dose of mAb 2021. This study suggests that neutralization of TFPI by mAb 2021 may constitute a novel treatment option in hemophilia.

Beschreibung: Plerixafor (PXF) is a bicyclam molecule, which acts as a reversible inhibitor of SDF-1 binding to CXCR4. A single injection results in immediate release of CD34+ cells into the peripheral blood. Sofar, PXF has been used for stem cell mobilization only in a limited number of allogeneic donors (Devine et al. Blood.2008;112(4):990) The currently ongoing randomized phase 2 Hovon -107 study of the Dutch hemato-oncology group HOVON (www.hovon.nl) aims to compare the feasibility of intravenous (iv) versus subcutaneous (sc) PXF (Genzyme Europe BV) 320 µg/kg subcutaneously (sc) 9 hours before the planned stem cell collection or intravenously (iv) 4 hours before stem cell collection in healthy adult matched sibling donors. Concurrently, all stem cell products are evaluated for the total number of CD45+; CD34+ cells and other hematopoietic stem cell subsets, including more primitive progenitor cells (MPP/CMP: CD34+/CD45RA-/CD90- and HSC :CD34+/CD45RA-/CD90+). Furthermore, the frequency and absolute numbers of CD3+, CD4+; CD8+;CD19+; CD 3-CD16/CD56+ (NK) cells and several T cell subsets, including Foxp3+, Th1, Th2 and Th17 cells, are assessed. Thereby, the HOVON-107 study enabled us to retrospectively compare lymphocyte and CD34+ HSPC subsets in grafts harvested in healthy donors (n=27) following PXF versus a similar evaluation of those subsets in grafts (n=10) harvested following G-CSF(Neupogen) (2 x 500 ug/kg (sc) for 5 days). Data are presented with respect to the composition of stemcell harvests, obtained after a single gift of PXF (13 iv and 14 sc) followed by 15 liters leucopheresis. For comparison of the stem cell products between the two groups the Mann-Whitney U test was applied. Results: Both groups are comparable with respect to age/sex. Mobilization with PFX resulted in similar WBC numbers as compared to G-CSF mobilization. The total number of CD34+ cells was significantly lower after PFX mobilization: median 200 x106; (range 40-560) vs 400 x106 (360-840) after G-CSF (p=0.000). However after PFX mobilization, the CD34+ cells contained a higher frequency of immature HSC and a lower frequency of MPP as compared to G-CSF mobilized grafts. The lower number of CD34+ HSPC and the higher frequency of HSC within CD34+ HSPC resulted in similar numbers of immature HSC in PXF mobilized grafts (PFX 50;1-218 x106 for G-CSF 90;11-200 x106 p=0.411).Although it is known that Plerixafor can mobilize a higher number of T-cells no data are available about the frequencies of distinct T cell subsets in the grafts. PFX mobilization resulted in higher numbers of CD3+T cells and CD19+B cells. The number of CD3-CD16/56+ NK-cells did not differ between both groups. Within the CD3+ T cell population, the CD4/CD8 ratio did not differ between both groups of mobilized grafts. While absolute numbers of T-cells were significantly increased, the frequencies of IFN-gamma+ Th1 cells, IL-4+ Th2 cells; IL-17+ Th17 cells and Foxp3+ regulatory T cells were not significantly different between both groups, resulting in increased Treg and Th1 after PFX (see Table below) In conclusion, allogeneic stem cell grafts harvested in healthy donors following a single dose of Plerixafor contain higher numbers of primitive progenitor cells, and higher numbers of both effector and regulatory T-cells as compared to grafts harvested following G-CSF. The impact of altered subset numbers on clinical endpoints including graft versus host, engraftment, and overall outcome remain to be established. Abstract 2451. TableCD3 (x 109)CD3/4 (x 109)CD3/8 (x 109)CD19 (x 109)CD3-CD16/56+ (x 109)Treg (x 109)Th1 (x 109)Th2 (x 109)Th17 (x 109)PFXMedian Range22.7 9.8-56,7 13.2 6.3-30.56.6 2.8-22.15.7 0.6-18.11.40.5-4.30.7 0.3-2.52.8 0.3-9.30.2 0.0-1.80.20.0-6.8G-CSFMedian Range12.8 7.6-217.5 4.3-15.43.8 2.0-6.03.1 1.9-4.51.30.5-2.90.4 0.2-1.20.9 0.4-2.70.20.1-0.40.1 0.0-0.5P-value0.0010.0050.0030.0020.7320.0220.0160.2890.129 Disclosures De Greef: Sanofi The Netherlands: Membership on an entity's Board of Directors or advisory committees. Petersen:Sanofi the Netherlands: Membership on an entity's Board of Directors or advisory committees. Visser:Sanofi the Netherlands: Membership on an entity's Board of Directors or advisory committees. Niederwieser:Novartis, Gentium, Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Beschreibung: 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.

Beschreibung: Abstract 794FN2 LBH589 is a novel pan-deacetylase inhibitor (DACi) that has demonstrated clinical activity in phase I/II studies in patients with a variety of hematologic malignancies. Our group has previously presented preliminary results of a phase I study of LBH589 in patients with myelofibrosis (MF) (Mascarenhas et al, ASH 2009, a308) while a phase II trial using higher doses of LBH589 has also been reported (DeAngelo et al, ASH 2010,a630). Both studies identified reversible thrombocytopenia as the DLT and reported evidence of clinical responses. The final results of our phase I study and the effects of extended treatment with LBH589 are reported here. We enrolled 18 patients at 3 dose levels. Fifty-five percent of these patients had PMF, 28% Post-PV MF and 17% Post ET MF; all were intermediate/high risk based on Lille classification. Twenty-five mg PO TIW was determined to be the recommended phase II dose. All patients experienced resolution of their systemic symptoms and 10/11 patients with baseline palpable splenomegaly, who were evaluable after 1 month of therapy, had a median reduction of 30%, range 0–100%. Five patients entered into an extension phase of the trial and received 〉 6 months of therapy with a mean dose of 20mg PO TIW at time of optimal response (Table 1). Of these patients, 2 were initially enrolled in the 20 mg PO TIW cohort, 1 in the 30 mg PO TIW cohort and 2 in the 25 mg PO TIW cohort. Both patients at the lowest dose achieved clinical improvement (CI) by IWG-MRT response criteria at 6 months as did one patient at the 25 mg dose. The remaining 2 patients had SD at 30 and 25 mg. A mean reduction in palpable splenomegaly at 3 and 6 months of 55% and 83%, respectively, was observed in this group. Two of these patients had marked and durable improvement in anemia (patients 1 and 4). Patient 4 achieved a near CR at 16 months with resolution of palpable splenomegaly, elimination of peripheral blood dacrocytes and leukoerythroblastosis, a 4g/dL increase in hemoglobin, improvement in overall marrow cellularity and megakaryocyte atypia with an increase in erythroid precursors and a significant reduction of reticulin/collagen fibrosis. Patient 1 was heavily transfusion dependent requiring RBC transfusions weekly to maintain a mean hemoglobin of 6.5g/dL and after 6 months on LBH589 achieved 〉50% reduction in transfusion dependence maintaining a mean hemoglobin of 9g/dL. Patient 2 had resolution of palpable splenomegaly and leukoerythroblastosis by cycle 6 and the bone marrow at cycle 26 was characterized by a reduction in marrow fibrosis from grade 4 to 1. A phase II study is ongoing, 14 patients are currently enrolled, with a planned goal of 22 patients. Pharmacokinetic and pharmacodynamic studies as well as cytokine profiling of the phase I patients are being analyzed and will be presented at the meeting. We conclude that low doses of LBH589 delivered for greater than 6 months in patients with MF are capable of ameliorating symptoms, improving clinical features and reversing pathologic marrow changes. Disclosures: Off Label Use: Oral histone deacetylase inhibitor that targets epigenetic changes in malignant myelofibrosis cells with an goal to modify the disease process.

Beschreibung: Objectives: In patients with refractory chronic lymphocytic leukemia (CLL), the potential to cure is unique to allogeneic stem cell transplantation (HSCT). Clearance of minimal residual disease by suspected graft-versus-leukemia effects has been described elegantly and documented in several independent patient cohorts. Yet data from large numbers of patients which support the concept of cure by allogeneic transplantation have not been published. With the advent of new targeted therapies for patients with advanced chemo-refractory CLL, this information becomes crucial for clinical decision making and patient counselling. Therefore, we aimed at the description of long-term survival outcomes, and the estimation of excess mortality compared to the age- and sex-matched general population. Patients and Methods: Data from patients with CLL who had received a first allogeneic HSCT from an HLA-identical sibling (SIB) or alternative donor between January 2000 and December 2010, and who were registered with the EBMT database, were analyzed. Patients with Richter's syndrome and with syngeneic donors were excluded from this analysis. Survival probabilities were calculated by means of the Kaplan-Meier estimator both in the total population, and in patients who passed the 2- and 5-year landmark without previous relapse or progression. Excess mortality of the landmark populations compared to an age-, sex- and calendar year-matched general population was estimated with a Cox regression model for relative survival using the R-package relsurv. Results: In total 2589 patients were included into the analysis. The median follow-up of patients alive at the end of follow-up was 4.0 years (range: 1 to 161 months). The median age at HSCT was 55 years (range: 12 to 74 years). One hundred and fifty eight patients (6.1%) were below 40 years of age at the time of transplantation. Seventy-four percent of patients were male. The remission status at the time of transplantation was reported as complete remission in 15%, partial remission in 47%, and stable disease or progressive disease in 32%. Information on the remission status was not available for 6% of the patients. Fifty-one percent of the patients had an HLA-matched sibling donor and seventy-seven percent of patients received reduced-intensity conditioning. For the whole cohort of patients, the 5- and 10-year overall survival (OS), progression-free survival (PFS), and non-relapse mortality (NRM) were 45%, 35%, 36%, and 35%, 28%, 40%, respectively. The cumulative incidence of relapse (CIR) was 21% at two years, 29% at five years, and 32% at ten years. A total of 1023 patients and 394 patients were alive without relapse or progression, and in follow-up at two and five years after HSCT. Five years after patients had passed the 2- and 5-year landmark, OS, CIR and NRM were 73%, 22%, 16%, and 83%, 11%, 10% respectively. Compared to the general population excess mortality of the 5-year landmark population in the subsequent five years was estimated to be 3% for male patients at an age of 45 years, 10% for male patients at an age of 55 years, and 24% for male patients at an age of 65 years (see Figure 1). For female patients in this 5-year landmark population, the corresponding excess mortality rates were 4%, 11%, and 27%. Patients without progression and with CR at any time from HSCT to the two and five-year landmarks had a slightly better outcome than those who had never had CR. Surprisingly, this was not a result of a lower CIR but of a lower NRM. Conclusion: Long-term follow-up data derived from the EBMT registry show a steady decline in hazard of relapse after allogeneic HSCT, yet relapse continues to be a threat. Moreover, even patients alive and disease-free after 5 years are still confronted with substantial NRM. These results show that there is room for improvement of long-term patient care. By comparing mortality of younger patients who passed the 5-year landmark with the general population, only marginal excess mortality was observed, while elderly patients still had substantial excess mortality beyond this landmark. Nevertheless, the results indicate that a significant fraction of patients can be cured by allogeneic HSCT. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Introduction Frail patients with aggressive NHL frequently do not qualify for CHOP-based chemotherapy. Alternatives are required urgently. Bendamustine has been well established as a standard treatment of indolent lymphomas. Its use in high grade lymphoma has been suggested as a promising option. However, which patients benefit most effectively requires further clarification. Methods We retrospectively characterized 51 unselected consecutive patients (39,2% female, 60,8% male, median age 70 years, range 32 - 92 years) with aggressive NHL treated with bendamustine +/- rituximab. They were analyzed for baseline characteristics (histological type, IPI, ABC/GCB-subtypes, age, ECOG, comorbidity (CIRS-G), outcome (ORR, PFS, OS), and toxicity (CTCAE)). Results 21 patients with aggressive NHL received Bendamustin as 1st-line therapy and 30 patients beyond 1st-line. Of the 1st line patients 14 suffered from diffuse large cell B cell lymphoma (DLCBL), 5 from mantle cell lymphoma (MCL), and 2 from other subtypes. In 1st line patients median age was 82 years, ECOG-status was ≥ 2 in 38%. Median international prognostic index (IPI) was 3 (range 1-4). Comorbidity assessment by CIRS-G revealed median 3 (range 1 to 5) severely or very severely affected organs. The overall response rate (ORR) in 1st line treatment was 91%, with a median progression free survival (PFS) of 6 months and a median overall survival (OS) of 15 month. In DLBCL 5 GCB- and 6 ABC-lymphomas were differentiated. GCB-patients showed an ORR of 80% (2 complete remission (CR), 2 partial remission PR)), a median PFS 8 month and OS of 15 months, respectively. ABC-patients had an ORR 67% (no CR, 4 PR, 2 SD), a median PFS of 6 month and OS of 8 months, respectively (n.s.). 7 patients achieved a long term-remission 〉5 years. Univariate analysis of prognostic variables showed significance for ECOG (p

Beschreibung: Abstract 527 Background: Rozrolimupab is the first in-class fully human, recombinant antibody mixture for the treatment of ITP. Rozrolimupab comprises 25 unique human antibodies with documented binding capacity to the Rhesus D antigen on red blood cells, and constitutes a promising, modern counter-part to the blood-derived immunoglobulin products currently used in the treatment of ITP. The antibody mixture constituting rozrolimupab is produced by a novel single batch manufacturing strategy. Objectives and Endpoints: The objectives of the trial were to investigate the safety and efficacy of a single dose of rozrolimupab in RhD positive, non-splenectomized adult patients with primary ITP. The primary endpoint was incidence and severity of Adverse Events (AEs) during the 6-week trial period. Secondary endpoints included identification of the optimal dose of rozrolimupab and percentage of patients responding to treatment at 72 hours, 7 and 15 days. Methods: Patients from 27 sites in 11 countries were enrolled in this dose escalation (75 μg/kg – 300 μg/kg), multicentre, open label trial. Inclusion criteria included confirmed presence of thrombocytopenia with two individual pre-dose platelet counts of 〈 30 × 109/L. The patients received a single iv dose of rozrolimupab, and were followed for 6 weeks with frequent evaluations for safety and efficacy. Response was defined as platelet count ≥ 30 ×109/L and increase in platelet count from baseline by 〉 20 × 109/L. Results: A total of 61 ITP patients were treated with rozrolimupab: 75 μg/kg (11 patients), 100 μg/kg (10 patients), 125 μg/kg (10 patients), 150 μg/kg (5 patients), 200 μg/kg (6 patients), 250 μg/kg (6 patients) and 300 μg/kg (13 patients). Data from the 300 μg/kg cohort were not available for this abstract, but will be included in the final presentation.Given the small size of this study, the dose cohorts differed in a number of baseline characteristics. 60–90% of patients were females in all dose cohorts except in the 75 μg/kg cohort where 73% were males. Median platelet count before trial entry ranged from 11.5 to 22.3 × 109/L, and median time from first ITP diagnosis ranged from 5 to 68 months. In the individual dose groups, up to 83% of the patients responded at day 7. Up to 50% and 60% of the patients responded at 24 and 72 hours, respectively, and some responses lasted for the duration of the 6 weeks follow up period. Platelet responses also included patients who had baseline platelet counts below 10 ×109/L. A total of 51 AEs considered related to trial drug were reported in 20 patients. The most frequently reported adverse reactions were headache (7 events in 5 patients) and pyrexia (5 events in 4 patients). All but 2 of the adverse reactions (one headache, one extravascular haemolysis) were of mild or moderate intensity. Four of the 51 adverse reactions were categorized as Serious Adverse Events: One mild haemoglobin decrease in the 100 μg/kg cohort, one extravascular haemolysis in the 200 μg/kg cohort (mentioned above) and two mild to moderate, transient increases in D-dimer with no clinical symptoms in the 250 μg/kg cohort. Laboratory data showed a mean maximum decrease in haemoglobin ranging from 1.1 g/dL to 2.7 g/dL in individual cohorts with a slight dose dependency. A drop in haemoglobin of ≥ 3 g/dL was seen in 2 patients, one of 3.1 g/dL in the 100 μg/kg cohort and one of 4.5 g/dL in the 200 μg/kg cohort. Conclusions: Rozrolimupab is well tolerated with a favourable safety profile. In the individual dose groups, up to 83% of patients responded at day 7 including patients who had baseline platelet counts below 10 ×109/L. Final safety and efficacy data from all dose groups in the completed Phase II trial of rozrolimupab in primary ITP patients will be presented. Disclosures: Wiktor-Jedrzejczak: Celgene: Honoraria; Janssen-Cilag: Honoraria; Novartis: Honoraria, Research Funding. Flensburg:Symphogen: Employment. Petersen:Symphogen: Employment.

Beschreibung: The natural killer (NK) type of aggressive large granular lymphocytic (LGL) leukemia is a fatal illness that pursues a rapid clinical course. There are no effective therapies for this illness, and pathogenetic mechanisms remain undefined. Here we report that the survivin was highly expressed in both aggressive and chronic leukemic NK cells but not in normal NK cells. In vitro treatment of human and rat NK-LGL leukemia cells with cell-permeable, short-chain C6-ceramide (C6) in nanoliposomal formulation led to caspase-dependent apoptosis and diminished survivin protein expression, in a time- and dose-dependent manner. Importantly, systemic intravenous delivery of nanoliposomal ceramide induced complete remission in the syngeneic Fischer F344 rat model of aggressive NK-LGL leukemia. Therapeutic efficacy was associated with decreased expression of survivin in vivo. These data suggest that in vivo targeting of survivin through delivery of nanoliposomal C6-ceramide may be a promising therapeutic approach for a fatal leukemia.