Verstovšek, Srđan

Abstract Background: Blood eosinophilia results either from autonomous expansion of a myeloid stem/progenitor cell, or as a response to cytokines that promote growth and differentiation of eosinophil progenitors. A subset of patients with hypereosinophilic syndrome/idiopathic eosinophilia (HES/IE) display abnormal T-cell immunophenotype and/or clonal rearrangements of the T-cell receptor (TCR), operationally assigned the term “lymphocyte variant” HES/IE. Information on the prevalence, FIP1L1-PDGFRA status, and clinical course of such patients is limited. Methods: Consecutive patients with eosinophilia were identified by querying our institutional electronic database from 1995 to 2004. Clonal rearrangements of the γchain of the TCR were identified by polymerase chain reaction followed by gel electrophoresis in all cases, and confirmed by Southern Blot analysis of the gene coding for the β chain of the TCR, using standard methods. FIP1L1-PDGFRA was screened by fluorescence in situ hybridization. Results: We studied a total of 205 consecutive patients with eosinophilia defined as an absolute eosinophil count (AEC) of > 600/μL, who also had a bone marrow study performed. Of these, TCR gene rearrangements studies were performed in 99 patients (AEC range of 650 to 38,000/μL) including 3 children and 96 adults (age range 18 to 88 years; 58 males). Among these 99 patients, 14 (~14%) had a demonstrable T-cell clone in peripheral blood, bone marrow aspirate, lymph node, and/or skin. Six of the 14 patients with a demonstrable T-cell clone were found to have a concurrent T-cell malignancy at the time of evaluation including T-cell large granular lymphocytic (T-LGL) leukemia - 1 case and peripheral T-cell lymphoma - 5 cases. The other 8 (~8%) patients otherwise fulfilled the working diagnosis of “lymphocyte variant” HES/IE (median AEC=2045/μL, range 720/μL to 9600/μL). The median duration of eosinophilic prodrome, prior to identification of the occult T-cell clone was 5 years (range 3 months to 11 years), and virtually all had dominant skin involvement presenting as dermatitis (5 cases) or episodic angioedema with eosinophilia (EAE) (2 cases). Five of 7 patients tested had an elevated serum IgE level, and a similar proportion displayed an abnormal T-cell immunophenotype (most commonly, aberrant CD5 and/or CD7 expression). Six of the 8 patients with an occult T-cell clone were evaluated for FIP1L1-PDGFRA and tested negative. Two patients were effectively treated with low-dose oral cyclophosphamide or methotrexate (follow-up duration of 3+ and 6+ years, respectively) whereas imatinib treatment was ineffective in another 2 patients. Two patients (25%) transformed into cutaneous T-cell lymphoma after 3 to 8 years of eosinophilic prodrome. Conclusion: The current study suggests that the presence of a T-cell clone in idiopathic eosinophilia is a marker/harbinger of a primarily skin-based peripheral T-cell lymphoma that responds to T cell-directed therapy but not imatinib therapy, which is consistent with the absence of FIP1L1-PDGFRA in such cases.

Abstract Background Systemic mastocytosis (SM) is characterized by abnormal proliferation and accumulation of neoplastic mast cells. Patients (pts) with SM are treated with recombinant interferon-alpha or cladribine. Responses to these agents are poor. Malignant mast cells in SM carry, in most cases, a mutation involving codon 816 of the c-KIT gene (D816V) resulting in constitutively activated c-kit receptor tyrosine kinase believed to be important for disease progression. Agents that antagonize this mutated form of c-kit may have clinical benefit in SM. Dasatinib is one such agent, proven effective in pre-clinical in vitro and in vivo models of SM. Study Design In pilot Phase II trial for SM, Dasatinib was administered at 70mg PO BID. Response was assessed after minimum of 3 months (3 cycles) of therapy. Therapy was discontinued in pts who showed no response after 6 cycles of therapy. Response was evaluated following guidelines proposed by Valent et al. (Leuk Res. 25;603–625, 2001). In addition, all symptoms related to SM were recorded and monitored. Results Thus far, a total of 30 pts have been treated; 24 are evaluable for response and toxicity, including 6 with aggressive SM (ASM), 4 with SM and associated hematologic non-mast cell disease (SM-AHNMD; 2 with chronic myelomonocytic leukemia and one each with myelofibrosis [SM-MF; JAK2 mutation positive and abnormal cytogenetics] and hypereosinophilic syndrome [SM-HES; FIP1L1-PDGFRa negative]) and 14 with indolent SM (ISM) with uncontrolled symptoms despite optimal supportive care measures. Median age is 57 years (range, 35–73); these were 10 males and 14 females; time from diagnosis to dasatinib therapy 49 months (range, 0–233), performance status 1 in 23 and 2 in 1 pt. Eleven patients were previously treated: imatinib mesylate in 6; denileukin diftitox in 4; and erythropoietin, interferon-alpha, or cladribine in 2 each. One pt, who had undergone splenectomy, had hepatomegaly prior to start of therapy. Median Hb 12.4g/dL (range, 8.5–15.4), WBC 6.7×109/L, (range, 3.5–53.3), and platelets 263×109/L (range, 60–377); no patient was transfusion dependent. Percent bone marrow mast cell varied from <10% in 9 pts, to 60% in 4 pts; blood tryptase level was ≤20ng/mL (not significant) in 7 pts and >200ng/mL (upper limit of the test) in 7 pts. A total of 94 cycles of therapy were administered. The median number of cycles was 4 (range, 1–8). Ten patients stopped therapy: 1 due to progression of AHNMD to acute leukemia, 1 lost a response (symptomatic improvement), 2 had no response after 3 months of therapy, and 6 due to toxicity. No grade 4 toxicity was observed. Twelve patients decreased the dose of dasatinib to 50mg PO BID, of which four to 40mg PO BID. Two patients (8%) achieved complete remission, one with SM-MF, and one with SM-HES. Both were c-KIT mutation negative and had low, not significant tryptase levels. Both were anemic (Hb 9.4g/dL) and failed erythropoietin therapy, and had abnormal WBC differential; one had low platelets (90×109/L). No significant response in % bone marrow mast cells (4 pts are too early in therapy) or blood tryptase levels have been observed in other patients so far. Symptoms related to SM improved significantly in 7 patients (29%). Conclusion Dasatinib is active in SM (overall response rate 37%). Updated clinical and molecular results will be presented.

Abstract PRM-151 (PRM) is a recombinant form of Pentraxin-2, an endogenous human protein that acts at sites of tissue damage, inducing macrophage differentiation to prevent and reverse fibrosis. PRM has broad anti-fibrotic activity in multiple preclinical models of established fibrotic diseases and no dose limiting toxicities in phase 1 trials. Myelofibrosis (MF: primary (PMF), post-essential thrombocythemia (post-ET MF), and post polycythemia vera (Post PV MF)) is a myeloid malignancy characterized by progressive bone marrow (BM) fibrosis with resultant anemia, abnormal platelet and leukocyte counts, extramedullary hematopoiesis, and a well-defined symptom complex. This study investigated the potential of PRM in MF to reduce BM fibrosis and to improve key disease features including abnormal blood counts, symptoms, and splenomegaly. MF patients (pts) with Dynamic International Prognostic Scoring System (DIPSS) intermediate-1, intermediate-2, or high-risk disease and grade ≥ 2 BM fibrosis, either on no current therapy or on a stable dose of ruxolitinib (RUX) for ≥ 12 weeks and no improvement in spleen for ≥ 4 weeks, were eligible for stage 1 of this open-label adaptive trial. Assignment to one of the 4 treatment arms was per investigator and pt choice: PRM 10 mg/kg IV 1-hour infusion days 1, 3, 5, then weekly (QW) or every 4 weeks (Q4W), alone or with RUX, for 24 weeks. Primary endpoint was overall response rate by IWG-MRT (symptoms by MPN-SAF Total Symptom Score (TSS), spleen by palpation) and/or decrease in BM fibrosis by ≥ 1 grade with otherwise stable disease. BM biopsies were obtained at baseline, 3 and 6 months, and were evaluated centrally by two blinded hematopathologists. Pts with clinical benefit were allowed to continue treatment in an extension. At least one response in any arm was required for that regimen to be evaluated in Stage 2. Twenty seven pts were enrolled: 8 PRM QW, 7 PRM Q4W, 6 PRM QW + RUX, 6 PRM Q4W + RUX. Median age 67 years (52-85); 70% DIPSS Int-2 or High Risk; 52% PMF, 15% post-ET MF, 33% post-PV MF; 63% grade 3 BM fibrosis, Hemoglobin (Hgb) < 100 g/L in 56% and < 85 g/L in 26%, platelet count (PLT)< 100 x 109/L in 52% and < 25 x 109/L in 30%; 22% were JAK inhibitor-naive and 52% had received a prior JAK inhibitor (not including ongoing RUX). Twenty pts completed 24 weeks of therapy; 18 continued extension treatment. PRM-151 was well-tolerated alone and with RUX; most adverse events (AEs) were Grade 1/2 and unrelated, with 3 Grade 3 possibly related AEs and 5 possibly related serious AEs. Nine of 26 evaluable pts responded, for an overall response rate (ORR) of 35%, with 4 IWG symptom clinical improvements (CI) and 6 BM fibrosis responses (Table 1), with ≥ 1 response in each arm. One pt had a CI and BM response. Reduction in BM fibrosis was associated with normal erythroid microarchitecture, normal or decreased myeloid:erythroid ratio, and fewer paratrabecular megakaryocytes, all potential surrogates of improved bone marrow microenvironment. IWG stable disease was observed in 77% of pts, with trends of clinical benefit in Hgb, PLT, peripheral blood blasts, spleen, and symptoms (Table 2). In 14 patients (54%), all parameters were stable or improved. Conclusion: PRM-151 was well-tolerated in patients with advanced MF, with no evidence of drug-related myelosuppression and encouraging trends in both clinical and histologic aspects of the disease. Reduction in BM fibrosis, stable to improved hematologic parameters, symptom responses, and stable to reduced spleen size support further development of PRM-151 in MF. Table 1 Two additional subjects had decrease in bone marrow fibrosis but progressive disease. Number of Patients BM Fibrosis Grade at Last Study Timepoint 3 2 1 BM Fibrosis Grade at Baseline 3 8 3 1 2 1 4 2 Abstract 713. Table 2 Outcome Parameter Denominator (n) Clinical Benefit Pts with Improvement (n/%) ORR (primary endpoint) All evaluable pts (26) IWG-MRT CI AND/OR reduction in BM fibrosis by ≥ 1 grade 9 (35%) Hgb Hgb < 100 g/L (15) ≥10 g/L increase from baseline AND no transfusions or 50% reduction in transfusions if transfusion dependent 6 (40%) PLT PLT < 100 x 109/L (13) > 100 x 109/L AND increase of ≥20 x 109/L ; increase of ≥20 x 109/L if baseline < 50, AND/OR increase of ≥ 10 x 109/L with discontinuation of transfusions 8 (62%) Blasts ≥ 1% peripheral blasts (14) No peripheral blasts 3 (21%) Symptoms All evaluable pts (26) ≥ 25% reduction in TSS ≥ 12 weeks 10 (38%) Spleen Palpable spleen (19) ≥ 25% decrease ≥ 4 weeks AND any decrease ≥ 12 weeks 5 (26%) Disclosures Verstovsek: Incyte: Research Funding; Astrazeneca: Research Funding; Lilly Oncology: Research Funding; Roche: Research Funding; Geron: Research Funding; NS Pharma: Research Funding; Bristol Myers Squibb: Research Funding; Novartis: Research Funding; Celgene: Research Funding; Gilead: Research Funding; Seattle Genetics: Research Funding; Promedior: Research Funding; Cell Therapeutics: Research Funding. Mesa:Incyte, CTI, NS pharma, Gilead, Celgene: Research Funding; Promedior: Research Funding. Foltz:Janssen: Consultancy; Promedior: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Gupta:Incyte Corporation: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Promedior: Research Funding. Mascarenhas:Novartis Pharmaceuticals Corporation: Research Funding; Incyte Corporation: Consultancy, Research Funding; Promedior: Research Funding. Ritchie:Celgene, Incyte: Speakers Bureau; Promedior: Research Funding. Hoffman:Geron: Consultancy, Membership on an entity's Board of Directors or advisory committees; All Cells LLC: Consultancy, Membership on an entity's Board of Directors or advisory committees; Promedior: Research Funding. Pozdnyakova:Sanofi: Consultancy; Incyte: Consultancy; Promedior: Consultancy. Hasserjian:Sanofi: Consultancy; Incyte: Consultancy; Promedior: Consultancy. Trehu:Promedior: Employment, Equity Ownership. Kantarjian:ARIAD, Pfizer, Amgen: Research Funding. Gotlib:Novartis: Research Funding, Travel Reimbursement, Travel Reimbursement Other; Sanofi: Research Funding; Gilead: Research Funding; Incyte: Consultancy, Honoraria, Research Funding, Travel Reimbursement Other; Promedior: Research Funding.

Abstract Abstract 1733 Background: Patients with myelofibrosis (MF) suffer from cytopenias, debilitating symptoms, and splenomegaly, all of which may contribute to shortened life expectancy. Cachexia is a common manifestation of MF. Its causes are multifactorial and include elevated inflammatory cytokines and mechanical effects of splenomegaly. It is a predictor of poor survival in patients with MF. Cachexia manifests as weight loss with low body-mass index (BMI; <20–21 kg/m2) (Strasser F. Sixth Research Congress of the European Association of Palliative Care; Wagner PD. Eur Respir J. 2008;31:492–501) and with metabolic indicators of poor nutritional status including hypocholesterolemia (total cholesterol <150 mg/dL or <3.89 mmol/L), which has been linked to poor prognosis in MF (Mesa et al. Blood 2007;110:abstract 2548). In the phase III, placebo-controlled, COMFORT-I study, ruxolitinib treatment significantly reduced spleen volume, improved MF-related symptoms, and exhibited a survival advantage compared with placebo in patients with MF. In this post hoc analysis, we investigated the effects of ruxolitinib treatment on weight and total cholesterol and the association of these changes with survival in COMFORT-I. Methods: Eligible patients in COMFORT-I were randomized to receive placebo (n=154) or ruxolitinib (n=155) at starting doses of 15 and 20 mg PO BID depending on baseline platelet count. Body weight was measured at baseline, and weeks 4, 8, 12, 16, and 24 and then every 12 weeks thereafter. Total serum cholesterol was measured at baseline and weeks 4, 12, 24, and then every 24 weeks thereafter. All patients receiving PBO completed crossover or discontinued within 3 months of the primary data analysis (when all patients completed 24 weeks and when half the patients remaining on study completed 36 weeks of treatment); thus, data for these patients were available for up to week 36 for weight and week 24 for total cholesterol. Kaplan-Meier analyses of overall survival were conducted in patients randomized to ruxolitinib stratified into 2 groups based on the median values separately for maximum weight gain and for maximum increase in total cholesterol during randomized treatment. Results: At baseline, mean body weight was similar between the treatment groups (72 kg, both) and mean total cholesterol was low (<150 mg/dL) in both treatment groups (ruxolitinib: 118 mg/dL; placebo: 115 mg/dL). The proportion of patients with BMI <22 were similar between the treatment groups (ruxolitinib: 23%; placebo: 28%) as was the proportion with total cholesterol <150 mg/dL (82%, both). Patients randomized to ruxolitinib experienced a gradual increase in body weight that stabilized by week 36 of treatment whereas patients receiving placebo experienced decreases in body weight over time (Figure 1). Similarly, total cholesterol increased in patients randomized to ruxolitinib and decreased in patients receiving placebo (Figure 2). Although total cholesterol increased over time in ruxolitinib-treated patients, increases did not exceed the upper limit of normal (199 mg/dL or 5.15 mmol/L). Nearly all patients randomized to ruxolitinib experienced weight gain (96% of patients) or an increase in total cholesterol (97% of patients). In patients randomized to ruxolitinib, weight gain above the median was associated with prolonged survival relative to lesser degrees of weight gain (HR=0.40; 95% CI: 0.18, 0.90; P=0.022; Figure 3). Similarly, increase in total cholesterol above the median was also associated with prolonged survival relative to a lesser degree of total cholesterol increase (HR=0.46; 95% CI: 0.21, 1.01; P=0.048; Figure 4). Meaningful comparisons with the placebo group based on the same stratification criteria could not be conducted as the majority of such patients experienced weight loss and decreases in total cholesterol while on the study; however, overall survival favored both ruxolitinib groups relative to all patients randomized to placebo even for ruxolitinib-treated patients with lower than median levels of weight gain or increase in total cholesterol. Conclusions: Ruxolitinib therapy promotes weight gain and improves total cholesterol in MF patients. These results suggest that the survival advantage exhibited by ruxolitinib over placebo in MF patients may be partly explained by reversal of the catabolic state and cachexia. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Verstovsek:Incyte Corporation: Research Funding. Gupta:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; YM Biosciences: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi#x2610;#x0025; Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Mascarenhas:Incyte Corporation: Consultancy; Novartis: Clinical Trial Support, Clinical Trial Support Other. Atallah:Incyte: Consultancy, Research Funding. Sun:Incyte Corporation: Employment, Equity Ownership. Sandor:Incyte Corporation: Employment, Equity Ownership. Gotlib:Incyte Corporation: Consultancy, Honoraria, Support for travel to meeting for the study or other purposes from Incyte Other.

Abstract Background : Polycythemia vera (PV) is a myeloproliferative neoplasm driven by JAK/STAT activation and is associated with erythrocytosis and a broad symptom burden that may negatively impact patient quality of life (QoL). Hydroxyurea (HU) is often used as first-line therapy for high-risk patients but may not effectively control or reduce symptom burden. RESPONSE is a phase III trial comparing ruxolitinib (RUX) with best available therapy (BAT) in patients with PV who were intolerant of or resistant to HU according to modified European LeukemiaNet (ELN) criteria. The primary study endpoint (a composite of hematocrit control and ≥35% spleen volume reduction at Week 32) was achieved by 21% of patients in the RUX arm vs 1% in the BAT arm (P<0.0001); 77% of patients in the RUX arm achieved at least one component of the primary endpoint. The current analysis was conducted to evaluate the effect of RUX on PV-related symptoms and QoL measures in the RESPONSE trial. Methods : Patients with PV aged ≥18 years, resistant to or intolerant of HU (modified ELN criteria) with splenomegaly, and who required phlebotomy for hematocrit control were randomized 1:1 to receive open-label RUX 10 mg twice daily (BID) or BAT (administered based on investigator judgment). Dose adjustments were permitted (RUX, 5-mg BID increments [25 mg BID max]; BAT was adjusted per investigator judgment). Objectives of this analysis included assessment of improvement in symptom burden as assessed by patient-reported outcomes using the 14-item modified Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF), the Pruritus Symptom Impact Scale (PSIS), the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), and the Patient Global Impression of Change. The 14-item MPN-SAF (graded from 0 [absent] to 10 [worst imaginable]) comprised symptoms related to cytokines (tiredness, itching, muscle ache, night sweats, and sweats while awake), hyperviscosity (vision problems, dizziness, concentration problems, headache, numbness/tingling, ringing in ears, and skin redness), and splenomegaly (abdominal discomfort and early satiety). Changes in total symptom score (TSS; maximum score = 140) and individual symptom scores from baseline to Week 32 were summarized by treatment group. For the EORTC QLQ-C30 Global Health Status/QOL score, the percentage of patients with a minimally important difference (MID) from baseline (10-point change) at Week 32 was summarized. Results : Overall, 222 patients were randomized (RUX, 110; BAT, 112). Median age (range) was similar between arms (RUX, 62.0 [34.0–90.0]; BAT, 60.0 [33.0–84.0]); the RUX and BAT arms were 60% and 71% male, respectively. At Week 32, a higher proportion of patients in the RUX vs the BAT arms had a ≥50% improvement in MPN-SAF TSS (49% vs 5%, respectively) and MPN-SAF symptom cluster scores (cytokine, 64% vs 11%; hyperviscosity, 37% vs 13%; splenomegaly, 62% vs 17%). Median percentage changes in individual symptom scores are presented in the Table. Mean changes from baseline at Week 32 on the 5 items of the PSIS indicated that the severity of pruritus and its interference on daily life improved with RUX (range, −1.5 to −2.2) and was unchanged/worsened with BAT (range, −0.1 to 0.3). Treatment with RUX vs BAT was associated with improved mean changes from baseline at Week 32 on EORTC QLQ-C30 symptom subscales, functional subscales, and Global Health Status/QOL (Table); 46% of RUX patients versus 10% of BAT patients achieved an MID in Global Health Status/QOL (Figure). At Week 32, RUX patients were more likely to rate their global impression of symptom changes as “very much improved” or “much improved” (67%) vs BAT patients (13%). Conclusion : In patients with PV who were resistant to or intolerant of HU, treatment with RUX was associated with greater and clinically meaningful improvements in PV-related symptom burden and QoL measures compared with BAT. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Mesa: Incyte Corporation: Research Funding; CTI: Research Funding; Gilead: Research Funding; Genentech: Research Funding; Eli Lilly: Research Funding; Promedior: Research Funding; NS Pharma: Research Funding; Sanofi: Research Funding; Celgene: Research Funding. Off Label Use: Ruxolitinib is a JAK1/JAK2 inhibitor approved for the treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Verstovsek:Incyte Corporation: Research Funding. Kiladjian:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Masszi:Novartis Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Durrant:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Harrison:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. He:Incyte Corporation: Employment, Equity Ownership. Jones:Incyte Corporation: Employment, Equity Ownership. Parasuraman:Incyte Corporation: Employment, Equity Ownership. Li:Novartis Pharmaceuticals: Employment, Equity Ownership. Côté:Novartis Pharmaceuticals: Employment, Equity Ownership. Habr:Novartis Pharmaceuticals: Employment, Equity Ownership. Vannucchi:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Abstract 2847 Background and Purpose: Myelofibrosis (MF) is a progressive Philadelphia-negative myeloproliferative neoplasm characterized by debilitating symptoms, massive splenomegaly, and anemia, which severely impairs quality of life. When medical therapy is not effective or tolerated, splenectomy may be required to ease symptoms in patients with symptomatic portal hypertension, massive splenomegaly, and/or frequent red blood cell transfusions (Barbui et al. J Clin Oncol. 2011;29:761–770). In a recent study (Tefferi et al. Mayo Clin Proc. 2012;87:25–33) up to 27% of patients diagnosed with MF eventually underwent splenectomy. However, splenectomy is associated with limited duration of symptom response, high rates of perioperative morbidity and mortality, and acceleration of hepatomegaly. Clinical studies in patients with MF have demonstrated that ruxolitinib, an oral JAK1/JAK2 inhibitor, provides significant and durable reductions in splenomegaly, the burden of MF-associated symptoms, and also improved quality of life. In this post hoc analysis of pooled data from these studies, we determined the incidence of splenectomy in patients treated with ruxolitinib and those who received placebo or best available therapy (BAT) to evaluate whether ruxolitinib therapy may affect the need for splenectomy. Methods: This analysis included patients who participated in the ruxolitinib phase I/II trial (N=153; Verstovsek et al. N Engl J Med. 2010;363:1117–1127); COMFORT-I, a phase III, 24-month placebo-controlled trial of ruxolitinib (N=309; Verstovsek et al. N Engl J Med. 2012;366:799–807); and COMFORT-II, a phase III, 48-month randomized trial comparing the effects of ruxolitinib and BAT (N=219; Harrison et al. N Engl J Med. 2012;366:787–798). Incidence of splenectomy while on treatment or during the protocol-specified follow-up period, adjusted for differences in the duration of follow up, was calculated for patients on ruxolitinib, placebo, or BAT. Results: As a result of the crossover rules and a higher discontinuation rate on the comparator arms in the phase III studies, mean follow-up duration for placebo (0.67 years) or BAT (0.95 years) overall was substantially shorter than mean follow-up duration for ruxolitinib (1.78 years). Baseline characteristics of the 14 patients who underwent splenectomy were as follows: median age=63 years; median time since initial diagnosis=7.8 years; median spleen length (n=13): 17.0 cm (range: 0–28.0 cm); median spleen volume (in those with measurement, n=11)=2924 cm3 (range: 1203–6807 cm3); IPSS high risk=50%, intermediate-2 risk=43%, intermediate-1=7%. Among patients originally randomized and treated with ruxolitinib, the incidence of splenectomy was 1.1 events per 100 patient years (Table). For patients treated with placebo or BAT in the phase III studies, the incidence of splenectomy was approximately three times higher at 2.9 events per 100 patient years, despite the fact that patients on placebo or BAT were allowed to crossover to ruxolitinib if they had worsening symptomatic splenomegaly. Conclusions: Although limited by small numbers, results of this analysis suggest that ruxolitinib reduces the need for splenectomy in patients with MF. Because of crossover to ruxolitinib and higher discontinuation rates in placebo and BAT, follow-up duration was shorter in these treatment arms compared with ruxolitinib. Further, ruxolitinib treatment in crossover patients may have prevented progression of symptomatic splenomegaly in some patients who may have otherwise become candidates for splenectomy. Our analysis may underestimate the true incidence of splenectomy among patients not receiving ruxolitinib therapy and therefore, the relative reduction in splenectomy rate in patients receiving this therapy. Longer-term follow up will better define the splenectomy rate in ruxolitinib-treated patients. Disclosures: Verstovsek: Incyte Corporation: Research Funding. Kiladjian:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Shire: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees. Gotlib:Incyte Corporation: Consultancy, Honoraria, Support for travel to meeting for the study or other purposes from Incyte Other. Kantarjian:Incyte: grant support Other. Sirulnik:Novartis: Employment, Equity Ownership. Peng:Incyte Corporation: Employment, Equity Ownership. Sandor:Incyte Corporation: An employee of Incyte and receiving stock options as part of his compensation Other, Employment. Harrison:Novartis: Honoraria, Research Funding, Speakers Bureau; YM Bioscience: Consultancy, Honoraria; Sanofi Aventis: Honoraria; Shire: Honoraria, Research Funding.

Abstract Abstract 1727 Background: Myelofibrosis (MF) is characterized by cytopenias, splenomegaly, and burdensome symptoms that may worsen over time. Ruxolitinib (RUX) has been shown to reduce splenomegaly and improve MF-associated symptoms in 2 phase III studies, including COMFORT-I, a randomized, double-blind, placebo (PBO)-controlled trial, which also showed prolonged survival in favor of RUX. Purpose: In this post hoc analysis of COMFORT-I, the efficacy of RUX in patients with varying degrees of splenomegaly and symptom severity at baseline was evaluated to assess the potential effects of earlier versus later intervention in this progressive disease. Methods: COMFORT-I participants randomized to RUX (n=155) or PBO (n=154) had MF with an International Prognostic Scoring System (IPSS) score ≥2 and a platelet count of ≥100 × 109/L. Patients with protocol-defined worsening splenomegaly were permitted to cross over from PBO to RUX. The primary endpoint was the percentage of patients with ≥35% reduction in spleen volume (SV) at week (wk) 24. Change in Total Symptom Score (TSS) was a secondary endpoint. TSS was the sum of 6 symptom scores (night sweats, itching, abdominal discomfort, pain under ribs on left side, early satiety, muscle/bone pain) assessed with the modified MF Symptom Assessment Form (MFSAF) v2.0 on a scale of 0 (“absent”) to 10 (“worst imaginable”). Patients were stratified by palpable spleen length (SL) (≤ 10 cm, <10 to 20 cm, >20 cm) and TSS tertile (≤11.1, >11.1 to 22.0, >22.0) at baseline. SV and TSS stratified by baseline values as described were summarized over time. To account for PBO crossover, modeling was performed to predict SV after crossover using a nonlinear mixed model that best predicted individual patient data. Last observation carried forward was used to impute missing TSS data. Results: Mean absolute SV and TSS worsened over time in the PBO group regardless of baseline SL and TSS, demonstrating the progressive nature of MF. In patients treated with RUX, mean absolute SV and TSS at wk 24 were lower for patients with smaller SL and less severe TSS at baseline, respectively (Table); absolute differences with PBO were significant within each subgroup. Therefore, patients who initiated RUX therapy with more advanced MF were less likely to achieve the same clinical status experienced by patients initiating therapy with less advanced MF. Notably, even after 24 wks of RUX treatment, SV and TSS reductions in the cohorts with larger SL or greater TSS at baseline did not achieve levels equivalent to baseline of the next lesser baseline severity group (Table; Figure). Although the severity of splenomegaly and symptoms at baseline influenced the absolute SV and TSS achieved at wk 24, RUX treatment resulted in similar percent reductions in SV and improvements TSS across all subgroups, with the exception of the lower TSS tertile (where there is less room for improvement). In contrast, PBO treatment resulted in increases in SV and worsening of symptoms and patients with less severe SV and TSS at baseline experienced the greatest percent increases in SV and TSS at wk 24. Conclusions: RUX therapy was associated with SV reduction and symptom improvement regardless of spleen size or symptom severity at baseline, whereas patients on PBO experienced disease progression across all subgroups. Patients receiving RUX with less advanced disease achieved an overall better clinical status, as defined by lower absolute SV and symptom scores. This analysis suggests that initiation of RUX in patients with less severe splenomegaly and symptoms may contribute to improved patient outcomes. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Gotlib:Incyte: Consultancy. Kantarjian:Incyte: grant support Other. Sun:Incyte: Employment. Verstovsek:Incyte Corporation: Research Funding.

Abstract Background : Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by erythrocytosis, and in many cases leukocytosis and thrombocytosis. PV is driven by activating mutations in the JAK/STAT pathway, primarily JAK2V617F. For high-risk patients, a commonly used first-line therapy is hydroxyurea (HU); however, a subgroup of patients become intolerant of or resistant to HU. The phase 3 RESPONSE trial compared ruxolitinib (RUX) and best available therapy (BAT) in patients with PV who were intolerant of or resistant to HU (modified European LeukemiaNet criteria). Patients randomized in the BAT arm were permitted to cross over to receive RUX from Week 32 of the study. The results of the primary analysis comparing RUX to BAT prior to crossover have been reported, in which RUX was superior to BAT in achieving hematocrit control, reductions in spleen volume, and improvements in PV-related symptoms. This current analysis was conducted to evaluate the efficacy of RUX treatment in patients who crossed over from BAT relative to their original BAT treatment and relative to those originally randomized to RUX. Methods : Enrollment criteria included PV diagnosis, age ≥18 years, resistance to or intolerance of HU, splenomegaly, and phlebotomy requirement to control hematocrit. Patients were randomized 1:1 to receive open-label RUX 10 mg BID or BAT administered based on investigator judgment. BAT may have included HU, interferon/pegylated interferon, pipobroman, anagrelide, immunomodulators (eg, lenalidomide or thalidomide), or no medication. The protocol allowed for dose modifications (RUX, 5-mg BID increments [25 mg BID max]; BAT was adjusted per investigator judgment). Patients in the BAT group could cross over to RUX from Week 32 if they had not met the primary endpoint, or after Week 32 due to protocol-defined disease progression. The primary study endpoint was a composite of hematocrit control and a ≥35% reduction in spleen size at Week 32. Hematocrit was assessed at screening, every 2 weeks from Day 1 to Week 12, followed by every 4 weeks until Week 32, and 2, 4, 6, 8, 16, 24, and 32 weeks following crossover. Spleen volume was assessed by magnetic resonance imaging at screening and study Weeks 16, 32, 48, 64, 80 and every 32 weeks thereafter. The number of phlebotomy procedures was evaluated over time in each group. Results : A total of 110 patients were randomized to RUX and 112 to BAT; study discontinuation by Week 32 (before crossover was permitted) was 11% in both groups. However, most patients in the BAT arm crossed over to receive RUX treatment immediately after the Week 32 visit (84% between Weeks 32 and 48); only 3% of patients remained in the BAT arm compared with 85% in the RUX arm at the time of the data analysis (median 81-week follow-up). With up to 32 weeks on BAT therapy, 25% of patients in this group did not require a phlebotomy; in contrast, with up to 32 weeks on RUX, 79% of patients after crossover and 74% of patients initially randomized to RUX did not require phlebotomy. The number of phlebotomy procedures adjusted for 100 patient-years during BAT therapy was 196.8 vs 38.5 after crossover to RUX and 34.1 on randomized RUX treatment. Reduction in spleen volume from baseline at any visit occurred in 49% of patients receiving BAT, vs 73% of patients after crossover to RUX and 88% of patients initially randomized to RUX. The proportion of patients achieving at least a 35% reduction in spleen volume (best percentage change) was 1.8% during BAT treatment vs 38.5% after crossover to RUX and 60.0% during randomized RUX treatment. Conclusion : Treatment with RUX after crossover from BAT resulted in improved clinical outcomes compared with original BAT treatment. These findings support the primary RESPONSE results and further validate the efficacy of RUX in this patient population. Disclosures Kiladjian: Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: Ruxolitinib is a JAK1/JAK2 inhibitor approved for the treatment of patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis, post polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Vannucchi:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Masszi:Novartis Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Durrant:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Harrison:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Mesa:Incyte Corporation: Research Funding; CTI: Research Funding; Gilead: Research Funding; Genentech: Research Funding; Eli Lilly: Research Funding; Promedior: Research Funding; NS Pharma: Research Funding; Sanofi: Research Funding; Celgene: Research Funding. Jones:Incyte Corporation: Employment, Equity Ownership. He:Incyte Corporation: Employment, Equity Ownership. Li:Novartis Pharmaceuticals : Employment, Equity Ownership. Habr:Novartis Pharmaceuticals: Employment, Equity Ownership. Verstovsek:Incyte Corporation: Research Funding.

Abstract Background: We sought to retrospectively analyze the clinical differences, at diagnosis and throughout the disease course, between patients with primary myeloifbrosis whom undergo blastic transformation (PMF-BP) and those whom expire from PMF complications without undergoing transformation. Methods: An international collaborative database of patients with PMF which progressed to PMF BP, and a control group of individuals with PMF who expired secondary to PMF was created. Data regarding clinical course, bone marrow, karyotypic, quantitative JAK2V617F analysis (when able), laboratory values, and therapy at the diagnosis of PMF, PMF BP and up to 4 return visits (R1-4) in between these milestones was abstracted. Results: COMPARISON AT DIAGNOSIS OF PMF: 136 cases of PMF who eventually underwent PMF-BP were included, with a control group of 42 PMF patients, were analyzed. Both groups of patients had similar demographic (median age at diagnosis 59 years (range 23–83)/ 59.1 (15–93); and disease parameters (median hemoglobin 10 g/dL (range 2–15.7) /9.8 (4.9–14.6); median platelet count 181 x 109/L (range 7–1400)/168 (16–1916)), and Lille PMF prognostic scores (p = n.s.) for PMF-BP vs. PMF control group respectively. Additionally, blasts (peripheral blood /marrow) were a median of 0% (range 0–18%)/ 2% (range 0–16%) for the study group versus 0.25% (range 0–5%)/ 3% (range 0–4%) (p = n.s. for both) for the control group, respectively. Both groups had similar rates of requiring therapy (86%; 93%) and survival from diagnosis (median 34 months (range 2–441); 29 months (1–236)) (p = n.s.). However, lactate dehydrogenase (LDH) (although high in both groups) was higher at diagnosis (median 802 IU/L (range 83–10353) vs. 416 IU/L (124–2197)) (p=0.04), as well as an abnormal marrow karyotype (85% vs. 25%; p<0.001) amongst the PMF BP group. SUBSEQUENT CLINICAL COURSE: Analyzing the clinical evolution between groups demonstrated persistently higher LDH and worsening thrombocytopenia in the PMF-BP cohort (see figure). Decreasing Platelets Approaching PMF BP Decreasing Platelets Approaching PMF BP Peripheral blood blasts increased in both groups, but values above 10% were unique to the PMF BP group. Additionally marrow karyotype displayed clonal evolution developed in 56% of the PMF-BP patients as opposed to 14% of controls (p<0.001). Initial and serial quantitative JAK2V617F mutation analysis (available from 20 /19 patients from the PMF-BP and control group at diagnosis, with 11 / 12 serial samples) showed no difference between the groups, nor a pattern of mutation burden elevation with transformation to leukemia in the study group. Conclusions: Increasing LDH, peripheral blood blast percentages >10%, and clonal evolution are features commonly seen in PMF patients whom evolve to blast phase and may be a harbinger of movement towards PMF BP.

Abstract Background: PAC is an oral kinase inhibitor with specificity for JAK2, FLT3, IRAK1, and CSF1R that has demonstrated significant and sustained spleen volume reduction (SVR) and symptom control vs BAT (excluding JAK2 inhibitors) in MF pts regardless of platelet count (PERSIST-1). The PERSIST-2 study was a randomized, controlled, open-label, phase 3 trial of PAC 200 mg BID and PAC 400 mg QD vs BAT (including JAK1/JAK2 inhibitor ruxolitinib [RUX]) in pts with 10 or 20 MF whose platelet counts were ≤100,000/µL, a recognized adverse prognostic variable. Prior JAK2 inhibitor use was allowed. Methods: Pts were randomized 1:1:1 to PAC BID, PAC QD, or BAT. The co-primary efficacy endpoints were the percentages of pts achieving ≥35% SVR (MRI or CT) and ≥50% reduction in total symptom score (TSS; MPN-SAF TSS 2.0), both from baseline to Week 24. The primary objective was to compare the efficacy of pooled PAC (BID+QD) to BAT and the secondary objectives were to compare PAC BID and PAC QD individually to BAT. PK samples were collected and analyzed for PAC. Safety analyses were based on all pts exposed to study treatment of any duration (safety population); efficacy analyses were based on ITT pts with a randomization date allowing Week 24 endpoint evaluations prior to the full clinical hold* (ITT efficacy population). Results: 311 pts were randomized (107 PAC BID, 104 PAC QD, 100 BAT), 308 received study drug, and 221 were included in the ITT efficacy population (74 PAC BID, 75 PAC QD, 72 BAT). Demographics and baseline disease characteristics were generally balanced among the treatment arms (Table) and analysis populations. A total of 32 (44%) BAT pts in the ITT efficacy population received RUX as treatment at some point on study. Population PK analyses showed that the steady-state plasma levels achieved with BID were higher than with QD, however the Cmax levels were lower. A significantly higher percentage of pts in the pooled PAC arm achieved SVR ≥35% (18% [27/149]) vs the BAT arm (3% [2/72]; p=0.001; Figure 1A). 25% of PAC pts (37/149) had ≥50% reduction in TSS vs 14% of BAT pts (p=0.079; Figure 1B). In secondary analyses vs BAT, PAC BID demonstrated significant improvement over BAT for both efficacy endpoints with 22% achieving SVR ≥35% (BAT=3%; p=0.001) and 32% achieving ≥50% reduction in TSS (BAT=14%; p=0.011). The PAC QD arm had a significant SVR ≥35% (15% v 3%, respectively; p=0.017), but a similar proportion with ≥50% reduction in TSS (17% v 14%, respectively; p=0.652). More PAC pts reduced their red blood cell transfusion dependence at Week 24 (defined as a ≥50% reduction in average transfusions/month for 3 months relative to baseline) with 19% (7/37) in the PAC QD arm, 22% (8/36) in PAC BID, and 9% (3/35) in BAT. There was no significant difference observed in OS across the treatment arms (Figure 2). Hazard ratios for OS (95% confidence intervals) were 0.68 (0.30, 1.53) for PAC BID v BAT, 1.18 (0.57, 2.44) for PAC QD v BAT, and 0.61 (0.27, 1.35) for PAC BID v QD. PAC BID maintained this survival advantage vs BAT across nearly all demographic and MF-associated risk factors. During the course of the study, 10 (9%), 15 (14%), and 15 (14%) died on PAC BID, PAC QD, and BAT, respectively. The most common treatment-emergent adverse events (AEs) associated with PAC were gastrointestinal (diarrhea, nausea, vomiting) and hematologic (anemia and thrombocytopenia), and were generally less frequent for BID vs QD administration. Grade 3/4 cardiac AEs occurred in 7%, 13% and 9% of PAC BID, PAC QD, and BAT pts, respectively, and grade 3/4 bleeding AEs occurred in 14%, 7%, and 7%, respectively. Grade 3/4 bleeding AEs were associated with grade 3/4 thrombocytopenia, which was also more common in the PAC BID group. Nine pts had cardiac failure (2% PAC QD, 4% PAC BID, 3% BAT) and 1 (1%, PAC QD) had intracranial hemorrhage.* Conclusions: The PERSIST-2 study is the only randomized, controlled trial to date in pts with MF and thrombocytopenia (platelets ≤100,000/µL), allowed prior JAK2 inhibitor treatment exposure (including RUX), and allowed RUX as BAT comparator. Irrespective of prior JAK2 inhibitor treatment, both PAC arms were more effective at SVR than BAT; however, PAC BID appeared more active than QD dosing and achieved significance versus BAT for both SVR and TSS. The most frequent AEs with PAC were gastrointestinal and hematologic toxicities. *PAC on full clinical hold by the FDA on 2/8/2016 based on concerns around excess deaths and cardiac and hemorrhagic events in PERSIST-1. Disclosures Mascarenhas: Incyte: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; CTI BioPharma: Research Funding; Janssen: Research Funding; Roche: Research Funding; Promedior: Research Funding. Talpaz:CTI BioPharma: Research Funding; Pfizer: Research Funding; Incyte Corporation: Research Funding; Ariad: Other: Expense reimbursement, travel accomodation expenses, Research Funding; Gilead: Other: Travel, Accommodations, Expenses, Research Funding; BMS - Canada: Consultancy. Gerds:CTI BioPharma: Research Funding; Astra-Zeneca: Research Funding; Roche: Research Funding; Incyte: Research Funding. Stein:Incyte Corporation: Consultancy. Gupta:Incyte Corporation: Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Drummond:CTI BioPharma: Honoraria; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; Roche: Speakers Bureau. Granston:CTI BioPharma Corp.: Employment. Daly:CTI BioPharma Corp.: Employment. Dean:CTI BioPharma Corp.: Employment, Equity Ownership. Al-Fayoumi:CTI BioPharma Corp.: Employment, Equity Ownership. Callahan:CTI BioPharma: Employment. Singer:CTI BioPharma Corp.: Employment, Equity Ownership, Other: Leadership . Gotlib:Novartis: Other: Travel, Accommodations, Expenses; Steering Committee Chairman, Research Funding; Promedior: Research Funding; CTI BioPharma: Research Funding; Gilead: Research Funding; Incyte: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding. Jamieson:GSK: Research Funding; Johnson & Johnson: Research Funding; CTI BioPharma: Research Funding. Harrison:Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; CTI BioPharma: Consultancy, Honoraria, Speakers Bureau; Baxter: Consultancy, Honoraria; Shire: Speakers Bureau; Gilead: Speakers Bureau; Incyte: Speakers Bureau. Mesa:Novartis: Consultancy, Honoraria; Incyte: Research Funding; Gilead: Research Funding; CTI BioPharma: Research Funding; Celgene: Research Funding; Genetech: Research Funding; Promedior: Research Funding. Verstovsek:CTI BioPharma Corp: Research Funding.