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Abstract BACKGROUND: Pomalidomide-dexamethasone (Pom-Dex) represents an important therapeutic advance for the treatment of patients with relapsed/refractory multiple myeloma (MM). Nonetheless, patients with lenalidomide (Len) and bortezomib (double) refractory disease have a median progression-free survival of only 3.7 months with the combination, thus highlighting the need for further progress. Ixazomib, a novel, oral proteasome inhibitor, has pharmacodynamic properties that may allow for improved proteasome inhibition at the tumoral level and has synergistic activity in combination with IMiDs in preclinical MM models. Clinical studies have demonstrated activity as a single agent in relapsed/refractory MM and in combination with Len-Dex in newly diagnosed patients. We therefore evaluated the safety and preliminary efficacy of the combination of Pom, ixazomib and Dex in patients with Len and proteasome inhibitor (PI) refractory MM in the phase I portion of Alliance study A061202. METHODS: Key eligibility criteria included: relapsed or relapsed/refractory disease; ≥2 prior lines of therapy; double refractory disease (progression on or ≤60 days from the last dose of a Len- and PI-based therapy); ECOG performance status (PS) ≤2; absolute neutrophil count ≥1.0 x 109/L, platelets ≥50 x 109/L, creatinine clearance ≥50 mL/min; and ≤grade 2 peripheral neuropathy. Patients were treated with escalating doses of Pom and ixazomib utilizing a standard 3 + 3 dose escalation design in combination with standard dose Dex (Table 1). Patients received 2 - 4 mg of Pom on days 1 - 21; ixazomib 3 - 4 mg on days 1, 8 and 15; and Dex 40 mg (20 mg for those >75 years of age) on days 1, 8, 15 and 22 of a 28-day cycle. Patients were treated until disease progression or the development of unacceptable toxicity. RESULTS: Out of 17 evaluable patients, the median age was 64 (range 47 - 77) and the median time from diagnosis 5.5 years (range 3.3 - 8.3). Sixty-five percent, 24% and 12% had ISS stage 1, 2 and 3 disease at the start of treatment, respectively, and 65% had high-risk cytogenetics (gain of 1q, del[17p] and/or high-risk IgH translocation). All patients had an ECOG PS of 0 or 1 (59% and 41%, respectively). Of 14 patients with complete prior treatment data available, 100% had received prior Len, bortezomib and Dex, 71% alkylating agents (cyclophosphamide or low dose melphalan), 71% autologous stem cell transplant and 29% carfilzomib. Eighty-two percent were refractory to sequential Len- and bortezomib regimens, whereas 6% were refractory to a prior Len/proteasome inhibitor combination (12% not reported). Two dose limiting toxicities have occurred to date, 1 each at dose levels 3 and 4 (Table 1). Grade 3 and 4 neutropenia, thrombocytopenia and lymphopenia attributable to protocol therapy have been seen in 29%/6%, 12%/6% and 29%/0% of patients, respectively. Twelve percent of patients have experienced grade 3 infection, regardless of attribution, but none have experienced ≥grade 4 infection. The incidence of therapy-related peripheral neuropathy was 24%, none of which was ≥grade 3 in severity. Other common, therapy-related adverse events have included fatigue (53%), nausea (24%), constipation (18%), diarrhea (29%), rash (18%), tremor (24%), anxiety (18%), insomnia (29%) and edema (24%), all of which were ≤grade 2 in severity. Fifty-three percent of patients had at least 1 of the 3 medications dose reduced, and 35% experienced dose delays. To date, 1 patient has discontinued therapy due to adverse events and 1 due to refusal of further therapy. Of 13 patients receiving >1 cycle of therapy, the best overall response rate was 62% (7 partial responses, 1 very good partial response). CONCLUSIONS: The Pom, ixazomib and Dex combination has demonstrated an acceptable toxicity profile thus far with encouraging preliminary efficacy. Updated results of the phase I portion of the study will be presented at the meeting, including the maximum tolerated dose that will be used in the randomized, phase II portion of the study, in which the 3-drug combination will be compared with Pom-Dex in double refractory MM patients. ClinicalTrials.gov Identifier: NCT02004275. Supported by U10CA180821, U10CA180882. Table 1. Dose Level Pomalidomide Dose (mg) Ixazomib Dose (mg) DLT Evaluable DLTs 1 2 3 3 None 2 3 3 3 None 3 4 3 6 1 febrile neutropenia 4‡ 4 4 4 1 grade 4 thrombocytopenia lasting 8 days ‡enrollment into dose level 4 is complete. Disclosures Voorhees: Janssen, Celgene, GlaxoSmithKline, Onyx Pharmaceuticals and Oncopeptides: Consultancy, Research Funding; Array BioPharma, Celgene, GlaxoSmithKline, and Oncopeptides: Consultancy; Millennium/Takeda and Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Off Label Use: We will discuss the use of Ixazomib, an agent that is not FDA approved, in combination with pomalidomide and dexamethasone for the treatment of multiple myeloma.. Richardson:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees.

Abstract Introduction : Anecdotal reports of “idiopathic” cardiomyopathy (ICM) in patients receiving anagrelide therapy have surfaced but not formally studied. We undertook a tertiary-center comprehensive study of ICM that was diagnosed in the setting of either polycythemia vera (PV) or essential thrombocythemia (ET). Methods : Standard criteria were used for the diagnosis of both ET and PV. A diagnosis of ICM required echocardiogram documentation of a reduced left ventricular systolic ejection fraction (EF < 50%) as well as the absence of both coronary artery disease and other causes of cardiomyopathy. In order to avoid specific drug selection bias, we queried the entire Mayo Clinic Rochester database first for the diagnosis of ‘polycythemia’, ‘thrombocytosis’, or ‘thrombocythemia’ and subsequently cross-referenced the results with the diagnosis of either ‘cardiomyopathy’ or ‘heart failure’. Results : Initial data inquiry yielded a total of 434 patients whose medical histories were thoroughly reviewed for the presence of an echocardiogram-documented ICM that post-dated a diagnosis of either ET or PV. Nine such patients (7 females; age range 46–78 years) were identified. Anagrelide therapy, at standard doses (median 2 mg/day), was temporally associated with ICM in 4 of the 9 patients while treatment in the remaining 5 patients consisted of either phlebotomy alone (3 patients) or other cytoreductive agents (2 patients). A similar database inquiry at Mayo Clinic Jacksonville identified 2 more patients with ICM that was temporally associated with anagrelide treatment. A normal echocardiogram was documented in 3 of the 6 patients with anagrelide-associated ICM at 2, 15, and 39 months prior to treatment (table 1). Interval (months) Ejection fraction (%) Sex Diagnosis Diagnosis to ICM Anagrelide treatment to ICM Pre-treatment At ICM diagnosis Off-anagrelide therapy for 0.2–16 months F PV 66 60 69 30 and then 18 with continued anagrelide therapy 28 F ET 8 6 N/A 30 N/A F PV 120 36 N/A 20 66 F PV 156 13 73 35 55 F ET 108 10 N/A 35 44 F ET 108 11 58 10 34 Anagrelide therapy was immediately discontinued when ICM was diagnosed in 5 of the 6 patients and after further worsening of EF on continued anagrelide therapy in the sixth patient (first patient in table 1). All 6 patients with anagrelide-associated ICM experienced symptomatic improvement after drug discontinuation but the corresponding improvement in EF, after a period of 0.2–16 months, was often suboptimal (table 1). In contrast, ICM not associated with anagrelide therapy remained unchanged both in terms of symptoms and EF in all 5 cases. Conclusion : Anagrelide-induced cardiomyopathy might occur in some patients with either PV or ET. Prompt recognition and drug discontinuation has the potential to adequately reverse the situation in some but not all patients.

Abstract Background : Polycythemia Vera (PV) is associated with JAK2 mutations. In essential thrombocythemia (ET), ̴ 85% of patients harbor one of 3 "driver" mutations, with frequencies of ̴ 58%, 23% and 4%, for JAK2, CALR and MPL, respectively; ̴ 15% are wild type for all three mutations and are referred to as "triple negative". We applied next-generation sequencing (NGS) with a 27-gene panel of myeloid malignancy-relevant genes, in order to describe the prevalence of "non-driver" mutations and their prognostic relevance in PV and ET. Methods: Targeted capture assays were carried out on bone marrow or whole blood DNA for the following genes: TET2, DNMT3A, IDH1, IDH2, ASXL1, EZH2, SUZ12, SRSF2, SF3B1, ZRSR2, U2AF1, PTPN11, Tp53, SH2B3, RUNX1, CBL, NRAS, JAK2, CSF3R, FLT3, KIT, CALR, MPL, NPM1, CEBPA, IKZF, and SETBP1.Paired-end indexed libraries were prepared using the NEBNext Ultra Library prep protocol (NEB, Ipswich, MA /Agilent Technologies Inc, Santa Clara, CA). Capture libraries were assembled according to Nimblegen standard library protocol (Roche Nimblegen, Inc, Basel, Switzerland). Base-calling was performed using Illumina's RTA version 1.17.21.3. Genesifter® software (PerkinElmer, Danvers, Massachusetts) was utilized to analyze targeted sequence data. Nucleotide variants were called using the Genome Analysis Toolkit (GATK -Broad Institute, Cambridge, MA). Specific variants were deemed as mutations if they are associated with a hematologic malignancy (COSMIC database), or if they have not been associated with a dbSNP. Results: 314 patients with PV (n =133; median age 64 years, 53% females) or ET (n =181; median age 58 years, 59% females) were evaluated. Median follow-up was 9.8 years for PV and 9.2 years for ET. During this time 59 (44%) deaths, 15 (11%) fibrotic and 5 (4%) leukemic transformations were documented for PV and the corresponding percentages for ET were approximately 33%, 8% and 2%. Driver mutation distribution was 98% JAK2 for PV and 52% JAK2, 24% CALR, 20% triple-negative and 4% MPL for ET. Polycythemia Vera Mutations other than JAK2, CALR or MPL were seen in 58 (44%) patients; 29% harbored one, 14% two and one 3 mutations. None of 3 JAK2 -unmutated cases expressed non-driver mutations. Mutational frequencies were 18% TET2, 11% ASXL1, 5% SH2B3, 3% SF3B1 and ≤2% SETBP1, IDH2, DNMT3A, CEBPA, CSF3R and SUZ12, SRSF2, ZRSR2, TP53, CBL, NRAS, RUNX1, KIT, PTPN11 and FLT3. "Number of mutations" significantly affected overall (OS; Figure 1) and myelofibrosis-free (MFS) survival; respective HR (95% CI) were 2.6 (1.3-5.2) and 1.7 (0.97-3.1) and 13.7 (2.9-63.4) and 5.1 (1.5-17.6) for ≥2 mutations and one mutation, respectively. OS was also adversely affected by SRSF2 (p=0.006) and RUNX1 (p=0.04) and borderline affected by TET2 (p=0.06), IDH2 (p=0.08), ASXL1 (p=0.19) and SF3B1 (p=0.19) mutations. In multivariable analysis, SRSF2 and RUNX1 retained significance whereas the others remained borderline significant. In both univariate and multivariable analyses, leukemia-free survival (LFS) was adversely affected by IDH2 and RUNX1 mutations. In univariate analysis, ASXL1, IDH2, RUNX1 and KIT mutations predicted fibrotic progression, whereas SETBP1 was of borderline significance (p=0.07); all, including SETBP1, were significant during multivariable analysis. Essential thrombocythemia Mutations other than JAK2, CALR or MPL were seen in 83 (46%) patients; 35% harbored one, 7% two and 4% three mutations; prevalence in JAK2, CALR, MPL mutated and triple-negative cases was 52%, 43%, 43% and 35%, respectively (p=0.52). Mutational frequencies were: 13% TET2, 11% ASXL1, 6% DNMT3A, 5% SF3B1, 4% CEBPA, 2% TP53, SH2B3, EZH2 and CSF3R and <2% for SETBP1, IDH2, SRSF2, ZRSR2, CBL, NRAS, RUNX1, U2AF1, KIT, PTPN11 and FLT3. "Number of mutations" significantly affected OS (Figure 2) but not MFS or LFS; HR (95% CI) for OS were 6.6 (2.5-17.8) for 3 mutations and 2.2 (1.3-3.9) for one or two mutations. In univariate analysis, survival was adversely affected by CBL, EZH2, SF3B1, SRSF2 and IDH2 mutations. In multivariable analysis, EZH2 and SF3B1 remained significant. Univariate analysis identified SETBP1 and SF3B1 mutations as risk factors for fibrotic progression and EZH2, TP53 and CSF3R mutations for leukemic transformation. Conclusions: "Non-driver" mutations occur in more than 40% of patients with PV or ET; the number of such mutations and presence of certain specific ones likely predict OS, MFS or LFS. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Pardanani: Stemline: Research Funding.

Abstract Background Current risk stratification in Polycythemia Vera (PV), is designed to estimate the likelihood of thrombotic complications. In ECLAP large prospective study of 1638 PV cases diagnosed by Polycythemia Vera Study Group (PVSG) criteria, risk factors were age over 65 years and prior thrombotic events. After the JAK2V617F discovery, diagnosis has undergone substantial revision by the World Health Organization (WHO). Consequently, current risk factors determination should be described in patients diagnosed by the most recent recommendations and requires a large sample size with reliable and sufficiently long clinical course documentation. Accordingly, the current study includes 1545 patients with strictly WHO-defined PV diagnosed and followed-up in seven centers from Italy, Austria and the United States, belonging to the International Working Group for Myeloproliferative Neoplasm (MPN) Research and Treatment (IWG-MRT). Objective and design 1) Describe the rate of thrombosis in this population; 2) Report the sites and frequency of recurrences after a first arterial or venous event; 3) Identify separately risk factors for arterial versus venous thrombosis and develop practically useful prognostic models. Results 1. Presenting features The characteristics of the cohort recruited reflected well the heterogeneity of epidemiologic and clinical features that are found in the routine clinical practice of PV. Arterial and venous thrombosis history before or at diagnosis was documented in 246 (16%) and 114 (7.4%) patients, respectively. The frequencies of arterial and venous thrombosis were lower than those recorded in the ECLAP4 (27% and 11% respectively) but comparable to those reported in the recent Cyto-PV2 (arterial 17%, venous 12%) studies. The discrepancy might be partly related to earlier diagnosis in the post-ECLAP JAK2mutation era. 2. Thrombotic events after diagnosis Median follow-up was 6.9 years and treatment included aspirin (84%) and cytoreductive agents (73%), in addition to phlebotomy. Post-diagnosis total major thrombosis rate was 2.62% pt/yr, lower than reported in the ECLAP trial (4.4% pt/yr) but comparable to the Cyto-PV study (2.7% pt/yr) where management of cardiovascular risk factors was more intensive than in ECLAP. Arterial or venous thrombosis occurred in 184 (12%, rate: 1.59 % pts/yr) and 137 (9%, rate: 1.05 % pts/yr) patients, respectively. In addition, prior arterial events were associated in 75% of cases with subsequent arterial events and in the remaining 25% with venous thrombosis including splanchnic vein events. Moreover, patients with prior venous events had recurrences in venous district in 61% of cases and in the arterial district in 39%. 3. Risk factors for arterial versus venous thrombosis and prognostic models In multivariable analysis, arterial thrombosis was predicted by previous arterial event (HR 1.7, 95% CI 1.2-2.4), and hypertension (HR 1.6, 95% CI 1.2-2.2) while predictors of venous events were previous venous thrombosis (HR 2.6, 95% CI 1.5-4.4), and age ≥ 65 years (HR 1.7, 95% CI 1.2-2.5). We used the above-mentioned risk factors in order to develop prognostic models allowing to identify patients at different probability to develop arterial or venous thrombosis. For arterial thrombosis, the absence of previous arterial thrombosis and hypertension defined lower-risk (rate 1.27 % pts/yr) while the presence of one or both identified higher-risk patients (rate 2.04 % pts/yr). Previous venous event and/or age ≥ 65 years identified patients at higher risk of venous (rate 1.62 % pts/yr) thrombosis and, if absent, patients at lower risk (rate 0.78 % pts/yr). Conclusion The overall rate of thrombosis was half than in ECLAP and should be considered in future clinical trials. Of note, patients with a prior venous thrombosis had a more frequent subsequent recurrence in the venous district but a proportion of them (40%) had also arterial events; conversely, recurrences after previous arterial event were also registered in the leg and non-leg veins in 30 % of cases, indicating that in PV, venous and arterial thrombosis may share some common pathogenetic mechanisms. These findings may have practical implications and suggests antiplatelet therapy and anticoagulant therapy as the favorite choice to prevent arterial and venous thrombosis, respectively, but also suggests studies of antithrombotic drug combination. Disclosures No relevant conflicts of interest to declare.

Abstract Background: NS-018 is an oral, selective, small molecule inhibitor of Janus kinase 2 (JAK2). Pre-clinically NS-018 inhibited JAK2 kinase with an IC50 value in the subnanomolar range and demonstrated splenomegaly reduction at low doses in a JAK2V617F-bearing mouse model (Blood Cancer J 2011; 1: e29.). Methods: This multicenter, Phase 1/2, 3+3 dose-escalation study of NS-018 enrolled patients with IPSS intermediate-1, intermediate-2, or high risk PMF, postPV MF, or postET MF. Patients were ≥ 18 years, had ECOG PS ≤ 2 and required therapy but were not required to have splenomegaly in Phase 1. NS-018 was dosed orally daily (QD) or twice daily (BID) in 28-day cycles. Responses were assessed according to IWG consensus criteria, changes in spleen size by manual palpation and quality of life with the Myelofibrosis Symptom Assessment Form (MF-SAF). The Phase 1 portion of the study completed enrollment and is presented here. Results: Patients: 42 patients were enrolled across 10 cohorts. Patient characteristics: 33 PMF, 5 postPV MF, 4 postET MF; median age (range) 69 yrs (43-83); M/F:28/14; 31 JAK2V617F+, and 17 previously treated with a different JAK inhibitor. Dosing and tolerability: Dose levels included 75, 125, 200, 300 and 400 mg QD and 100, 200, 250, 300 and 400 mg BID. Systemic exposures based on Cmax were approximately dose proportional across the tested range from 75 to 400 mg. The recommended Phase 2 dose (RP2D) was 300 mg BID, based on drug-related neurological adverse events (AEs) at 400 mg BID including dizziness (Grade 2 or 3), dysphagia (Grade 2) or hypoesthesia (Grade 1) in one patient each that led to dose reduction or drug discontinuation. Study drug-related serious AEs (SAEs) included non-cardiac chest pain (Grade 2, 200 and 300 mg BID), lower GI hemorrhage (Grade 3, 300mg BID), paresthesia (Grade 3, 300mg BID), increased lipase (Grade 2, 300mg BID), and dizziness (Grade 3, 400 mg BID) in one patient each. For the 300 mg BID cohort (n=11), the most frequent drug-related AEs across all grades were nausea (Grade 1, 18%), decreased platelet count (≤ Grade 2, 18%), and dizziness (≤ Grade 2, 27%); Grade 3 related AEs included anemia, lower GI bleed, leukopenia, neutropenia or paresthesia (1 patient each, 9%); and no Grade 4 AEs. Overall, 22 patients (52%) discontinued treatment due to AEs (n=7), progressive disease (PD) (n=7), or MD/patient decision (n=8). The AEs leading to discontinuation included thrombocytopenia (Grade 4), transient ischemic attack (Grade 2), muscle contraction involuntary (Grade 2), light headedness (Grade 1), insomnia (Grade 1), hemolytic anemia (Grade 3), dizziness (Grade 2), dysphagia (Grade 2), and hypoesthesia (Grade 1). Nine patients had a hemoglobin decrease ≥ 2 g/dL and 8 patients a platelet decrease ≥ 50%. Responses: Of 33 evaluable patients with baseline splenomegaly ≥ 5 cm and treatment for ≥ 1 cycle, 16 (48%) patients showed ≥ 50% reduction in spleen size (confirmed for ≥ 8 weeks in 11 patients). In addition, 11 patients showed splenic clinical improvement (CI, for ≥ 8 weeks), 3 patients hemoglobin CI, and 2 patients platelet CI. Median (range) time to splenic response and duration of response: 1.5 cycle (1-12) and 4.5 cycles (1-29). Splenic reductions ≥50% are shown in the Table for the specified patient groups. Changes in MF-SAF and PK and PD results will be presented. Table Splenic reduction(in evaluable patients) All doses 16/33 (48%) 300mg BID 3/6 (50%) 300mg QD 4/7 (57%) Prior different JAK inhibitor treated 8/16 (50%) Conclusions: The dose of NS-018 determined to be the RP2D in Phase 1 was 300 mg BID. This dose provided a durable dosing schedule with an acceptable safety profile, and was associated with splenic size reduction and clinical improvements. The Phase 2 portion of the study is ongoing and includes only patients previously treated with a different JAK inhibitor. Disclosures Verstovsek: NS Pharma, Inc: Research Funding. Talpaz:Ariad, BMS, Sanofi, Pfizer, Incyte: Research Funding. Ritchie:Celgene, Incyte: Speakers Bureau. Odenike:Suneisis Pharmaceuticals, Incyte, Sanofi-Aventis, Algeta Pharmaceuticals, Spectrum Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Jamieson:Roche, Johnson&Johnson, CTI: Research Funding. Stein:Incyte Corporation: Honoraria, Speakers Bureau; Sanofi Oncology: Honoraria. Tomonori:NS Pharma, Inc.: Employment. Mesa:Incyte, CTI, NS Pharma, Inc., Gilead, Celgene: Research Funding.

Abstract Abstract 2071 Background: PV and ET are clonal stem cell diseases belonging to the 3 BCR ABL negative myelopoliferative neoplasms. Patients with PV and ET suffer from splenomegaly and disease associated symptoms such as pruritus, night sweats, fatigue, and bone pain. Both diseases, if progressive despite standard therapies, are associated with an increased risk of thrombosis, bleeding, and progression to MF or even acute myeloid leukemia. Literature estimates looking at burden of illness are lacking for these disorders. Hence, real world analyses evaluating economic burden are imperative. The objective of this study was to evaluate the clinical and economic burden of these disorders by describing the patient demographics, prevalence, comorbidities, utilization and costs using large scale databases. Method: The US IMPACT® claims database was used to retrospectively identify unique patients with PV and ET between 1/1/08 and 12/31/10. This database is a fully de-identified, HIPAA compliant national database that captures the complete medical history for over 100M managed care individuals, including patient demographics, disease description, laboratory results, and details of medical, pharmacy, outpatient, and inpatient claims. ICD9 CM codes were used to identify PV and ET. Charlson Comorbidity Index (CCI) was used to assess overall comorbid disease status. Enrollment was restricted to those with a full year of medical and pharmacy benefit. Control group was age and gender matched but without any diagnosis of PV or ET. Medical costs include inpatient, outpatient and ER cost. Result: In 2010, we identified 5752 PV patients from ∼12M enrollees. This corresponds to an age adjusted prevalence of 56.5 cases/100000 patients. Compared with age gender matched control patients, PV patients had higher overall comorbidities (mean CCI 1.2 vs 0.7), were hospitalized more often (16% vs 8%), had higher average number of hospital days spent (1.7 vs 0.8), and had more outpatient visits (31 vs 18). PV patients incurred much higher average annual cost ($14,903 vs $7,913) than age gender matched controls driven by both medical ($12,006 vs $6,188) and pharmacy ($2,897 vs $1,724) cost. In 2010, we identified 5483 ET patients from ∼12M enrollees. This corresponds to an age adjusted prevalence of 56.1 cases/100000 patients. Compared with age gender matched control patients, ET patients had higher overall comorbidities (mean CCI 1.4 vs 0.7), were hospitalized more often (30% vs 9%), had higher average number of hospital days spent (5 vs 0.9 days), and had more outpatient visits (37 vs 19). ET patients incurred much higher average annual cost ($29,553 vs $8,026) than age gender matched controls driven by both medical ($26,287 vs $6,394) and pharmacy ($3,267 vs $1,631) cost. Similar trend was observed in 2008 and 2009. Over a period of 3 years, annual cost of PV ranged from $14,000-$16,000 and those of ET ranged from $29,000-$31,000. The utilization rate and total cost in each of conditions were significantly higher than those of their matched patients in each of the 3 years. Conclusion: PV and ET are associated with significant burden of illness. Healthcare expenditure was twice as higher in PV patients compared with the control group. ET patients incurred more than 3 times the healthcare expenditure than the control group. Our study indicates that PV and ET associated medical resource utilization and the corresponding expenditures for those services are substantive. In order to reduce the burden of illness associated with these diseases, continued efforts in the development of more efficacious treatments for these disorders are needed. Disclosures: Mehta: Sanofi: Employment. Wang:Sanofi: Employment, Equity Ownership. Iqbal:Sanofi: Employment, Equity Ownership. Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding.

Abstract Background Polycythemia vera (PV) is a clonal myeloproliferative disorder characterized by erythrocytosis, splenomegaly and a frequently burdensome symptom profile. Despite current guidelines of aspirin, phlebotomy, and selective cytoreduction, many patients have inadequately controlled PV-related symptoms and/or disease features. We performed a comparison of PV symptom burden/disease feature phenotypes to understand unmet needs in current medical management. Methods Data was collected prospectively amongst an international cohort of PV patients including symptom burden, demographics, and disease features. Subgroups were identified who had previously failed hydroxyurea (PV-HU), required ongoing phlebotomy (PV-P), had palpable splenomegaly (PV-S), or had all 3 features (PV-HUPS). Control groups were derived from the remaining PV patients lacking the specified subgroup trait; patients in whom the trait status was unknown were excluded from each respective control group. All participants completed the MPN specific symptom burden questionnaire (MPN-SAF TSS (MPN-10 – Table 1)) and had no prior history of splenectomy. Surveyed symptoms on the MPN-10 included the patient's perceptions of common MPN-related symptoms and overall quality of life (QOL) on a 0 (absent) to 10 (worst imaginable) scale. PV risk scores were calculated using the 2013 criteria (Leukemia 2013). Comparison of symptoms between groups employed t-tests. Results Patient Demographics and Disease Features Between Phenotypic Groups A total of 1334 PV patients completed the MPN-10, and were assigned to categories of PV-HU (499 [37%]), PV-P (646 [48%]), PV-S (369, [28%]), and PV-HUPS (148 [12%]). The demographics between these groups were similar (comparable age (median range 60-63), PV risk scores (mean risk range: Low 16.4-23.7%; Intermediate 31.4%-36.6%; High 42.8%-47%). Mean hemoglobin was similar among PV subgroups (range 14.4-14.9); PV-HUPS had a higher mean WBC count (20.3 g/dL vs. 8.8-11.8 g/dL) and platelet count (703.5 x 10(9)/L vs. 327.5-462.8 x 10(9)/L), and disease duration (11.5 years vs. 6.4-8.8 years). Prior thrombosis was most common in PV-S patients (28.5% vs. 21.8-25.2%) and prior hemorrhage was most common in PV-HUPS patients (23.8% vs. 13.7-15.8%). Symptom Burden The MPN-10 scores of each problematic PV phenotype (HU, P, S, HUPS) were compared to the remainder of the PV cohort lacking the trait (PV-control; Table 1). Both individual symptom scores and TSS were highest for PV-HUPS patients (mean TSS 32.5 vs. 27.7-29.2). All problematic PV subgroups demonstrated significant differences for individual symptoms and TSS compared to PV-control. Comparing "problematic" subgroup responses, PV-HU patients described more inactivity whereas PV-S patients described more early satiety and pruritus. No statistical differences were noted in PV-HU, PV-P and PV-HUPS patient responses to MPN-10 items of "fever" and "weight loss". Discussion PV patients who have either failed HU, are undergoing phlebotomy and/or have splenomegaly exhibit moderate to severe symptomatology and demonstrate unmet medical need for management. As evidenced in this study, considerable overlap in symptomatology exists in PV-HU, PV-P, PV-S and PV-HUPS. Current randomized trials of JAK inhibitors have demonstrated benefits in a PV-HUPS phenotype. This data suggests that PV patients with any evidence of inadequate control (PV-HU, P, or S) have similarly unmet needs and may be candidates for clinical trials, intensification of medical therapy or perhaps JAK inhibitor therapy. Disclosures Kiladjian: Shire Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Zweegman:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding. Besses:Shire Pharmaceuticals: honoraria for educational lectures Other. Birgegard:Shire Pharmaceuticals: Consultancy, Honoraria, Research Funding. Etienne:Novartis, BMS, Pfizer, Ariad: Honoraria. Roy:Merck: Peg-Interferon provided for academic clinical trial in CML Other. te Boekhorst:Novartis: Consultancy. Griesshammer:Novartis: Honoraria; Shire: Honoraria; Sanofi: Honoraria; Amgen: Honoraria; Roche: Honoraria. Mesa:Incyte Corporation, CTI, NPS Pharma, Inc., Gilead Science Inc., Celgene: Research Funding.

Yacoub et al report excellent responses to pegylated interferon alfa-2a in patients with hydroxyurea-resistant/intolerant polycythemia vera or essential thrombocythemia.