Tefferi, Ayalew

Abstract Abstract 2803 Background: Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder with overlapping features between myelodysplastic syndromes (MDS) and myeloproliferative neoplasms. Ring sideroblasts (RS) represent abnormal mitochondrial iron accumulation in MDS; with ≥15% RS necessary for the conventional diagnosis of MDS-RS. Somatic spliceosome mutations are recurrent in MDS, with SF3B1 mutations being the most frequent in MDS-RS (∼75%) and SRSF2 in CMML (∼28%). The distribution of these mutations in the presence of both RS and monocytosis is unknown and their prognostic relevance, in the particular setting, undetermined. Methods: Using the Mayo Clinic database for myeloid malignancies (1997–2007), we identified patients who met the 2008 WHO criteria for CMML, and who also displayed at least 1% RS in their bone marrow (BM). All patients underwent BM examination and cytogenetic evaluation at diagnosis and the pathology slides, including iron stains, were centrally re-reviewed to accurately quantify BM RS. DNA was interrogated in the three most frequent spliceosome genes with somatic mutations; SF3B1, SRSF2 and U2AF35. Results: Sixty four patients met the above stipulated criteria for CMML with ≥1% RS; 46 (72%) were males and median age was 71 years (range, 17–90 years). Fifty three (83%) had CMML-1 and the remainder CMML-2. The percentage of patients with ≥15% RS was 41%: 30% had 15–49% RS and 11% had >50% RS. Thirty patients (47%) displayed SRSF2 mutations (mutational frequencies were 58% in the presence of <15% RS, 42% with 15–49% RS and 0% with >50% RS), 9 (14%) SF3B1 mutations (3% with <15% RS, 26% with 15–49% RS and 43% with >50% RS), and 5 (8%) U2AF35 mutations (8% with <15% RS, 11% with 15–49% RS and 0% with >50% RS). Mutational hotspots were P95 for SRSF2 (93%), K700 for SF3B1 (67%) and Q157 for U2AF35 (60%). The three spliceosome mutations were mutually exclusive. At a median follow-up of 26 months, 49 (77%) deaths and 11 (17%) leukemic transformations were documented. In univariate analysis, significant risk factors for survival included increased levels of white blood cell (WBC), absolute neutrophil (ANC), absolute monocyte (AMC), absolute lymphocyte (ALC) counts, the Spanish cytogenetics risk stratification system (Haematologica 2011;96:375), and the presence of circulating blasts. Neither the presence of spliceosome mutations (SF3B1/SRSF2/U2AF35) nor the percentage of RS (considered both as a continuous and a categorical variable), had an impact on either overall or leukemia-free survival. Conclusions: Among spliceosome mutations in CMML, those involving SRSF2 are by far the most frequent, even in the presence of ring sideroblasts. However, in patients with >50% RS, only SF3B1 mutations were seen whereas in those with 15–49% RS, SRSF2 mutations were more common. These observations suggest that SF3B1 mutations play a dominant but not exclusive role in the pathogenesis of RS. Regardless, the current study did not suggest prognostic impact from either the presence of the spliceosome mutations studied or the percentage of RS. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2837 Introduction: Treatment with the JAK2 selective inhibitor SAR302503 reduced spleen size, disease-related symptoms, and the JAK2 V617F allele burden, with an acceptable safety profile in patients with primary MF, post-PV MF, or post-ET MF in a Phase I/II study (J Clin Oncol 2011;29:789, ASH 2011; Abs 3838). The objective of this Phase II study is to assess the efficacy, safety, pharmacokinetics (PK), and pharmacodynamics (PD) of 3 doses of SAR302503. Methods: Patients with intermediate-2 or high-risk primary MF, post-PV MF, or post-ET MF were randomized to 1 of 3 dose groups of SAR302503 (300, 400, or 500 mg per day). Eligibility criteria included age ≥18 years, ECOG PS 0–2, and an enlarged spleen (length ≥5 cm). SAR302503 was taken orally, once a day, in consecutive 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint is the absolute change in spleen volume at the end of cycle 3 assessed by MRI with independent central review. Secondary endpoints include spleen response (≥35% reduction in spleen volume vs baseline), safety, symptom response (MPN-SAF), PK, and PD (changes in leukocyte pSTAT3). Results: From August–December 2011, at total of 31 patients were enrolled (n=10 in the 300 and 400 mg groups; n=11 to 500 mg). Risk status (intermediate-2 vs high) was balanced in the 400 mg and 500 mg groups (∼50%), whereas the 300 mg group had more high-risk patients (70%). The majority of patients (88% to 91%) had the JAK2 V617F mutation and most (∼80%) were blood transfusion independent. Mean (median) percentage reductions in spleen volume vs baseline at the end of cycle 3 were 30% (26%) in the 300 mg group, 33% (31%) with 400 mg, and 42% (38%) with 500 mg. A spleen response at the end of cycle 3 was seen in 30% of patients (3/10) in the 300 mg group, 50% (5/10) in the 400 mg group, and 64% (7/11) in the 500 mg group. Patients with constitutional symptoms at baseline in all groups reported a symptom response at the end of cycle 3, with at least a 2-point improvement in or resolution of night sweats in 93% (14/15) of patients, itching in 71% (10/14), early satiety in 56% (10/18), abdominal pain in 56% (10/18), and abdominal discomfort in 50% (10/20). Safety was evaluated in all patients. The most common grade 3–4 hematological adverse event (laboratory) was anemia, with rates across the 300, 400, and 500 mg doses of 33%, 30%, and 55%, respectively. Rates of grade 3–4 thrombocytopenia were 20%, 0, and 9%. There was no grade 3–4 neutropenia. Most common grade 3–4 nonhematological events were diarrhea (10%, 20%, 0), nausea (10%, 10%, 0), and vomiting (10%, 10%, 0). Adverse events in the 300 mg group led to discontinuation in 2 patients: 1 patient had grade 3 anemia, and 1 patient with pre-existing intermittent mild transaminase elevations and polyarthritis had hepatic failure, but completely recovered after discontinuation. No other grade 3–4 increases of AST, ALT, or bilirubin were observed. No deaths were due to an adverse event. Following repeated once-daily oral doses, SAR302503 exposure increased in a dose-dependent manner, with a median time to maximum plasma concentration of 2 to 3 hours. Steady state was achieved by cycle 1 day 15 (C1D15), with a 2.95- to 3.88-fold accumulation of drug. Time-dependent pSTAT3 inhibition was observed at all doses, with the highest mean percentage decreases from baseline (range) occurring at C1D15 (44% to 52%) and C2D1 (40% to 51%). The relationship between PK and PD pSTAT3 suppression can be described by an Emax model. There was also a correlation between percentage of pSTAT3 inhibition and spleen response rate at C1D15 and C2D1 and evidence of a steady state exposure-response relationship for spleen volume reduction at the end of cycle 3. Conclusions: In this Phase II trial, treatment with SAR302503 was associated with clinically meaningful reductions in splenomegaly and improvements in constitutional symptoms. SAR302503 was generally well tolerated in this trial and adverse events were consistent with the known safety profile. Time-dependent decreases in pSTAT3 and exposure-response correlations can be demonstrated across the three doses tested. Sponsored by Sanofi (NCT01420770) Disclosures: Talpaz: Novartis: Research Funding, Speakers Bureau; BMS: Research Funding; ARIAD: Research Funding; Deciphera: Research Funding. Gabrail:Sanofi: Research Funding. Lebedinsky:Sanofi: Employment, Equity Ownership. Gao:Sanofi: Employment, Equity Ownership. Liu:Sanofi: Employment, Equity Ownership. Pardanani:YM BioSciences: Clinical trial support, Clinical trial support Other; BMS: Clinical trial support, Clinical trial support Other; Sanofi: Clinical trial support Other.

Abstract Abstract 178 Background: CYT387 is a potent and selective small molecule inhibitor of JAK 1 and JAK 2 which is in clinical development for the treatment of myelofibrosis. Previously reported preliminary results from a phase I/II multicenter study demonstrated improvements in splenomegaly and constitutional symptoms as well as in RBC transfusion requirements. Enrollment has been completed and all subjects have now reached a minimum of 9 months on study. Updated safety and efficacy results are presented. Methods: Subjects with high or intermediate-risk primary myelofibrosis (PMF) and post-polycythemia vera (post-PV) or post-essential thrombocythemia (ET) myelofibrosis were enrolled. Following an initial dose expansion phase, subjects were treated in a 9 month core study at an initial dose of 150 mg QD, 300 mg QD or 150 mg BID. Continued treatment with CYT387 was permitted in an extension phase for subjects who maintained at least stable disease. Responses were assessed by International Working Group (IWG) criteria with transfusion independence response defined as achieving a minimum 12 week transfusion-free period. Results: Enrollment of 166 subjects was completed at 6 study sites. Initial doses included 52 subjects at 150 mg QD, 60 subjects at 300 mg QD and 42 subjects at 150 mg BID. An additional 12 subjects were enrolled in other dose groups (100 mg QD, 200 mg QD, 400 mg QD) during the initial dose escalation phase. The median duration (range) of follow-up is 16.1 months (0.7 to 31.0 months). Durable transfusion independence responses were observed in more than half of the RBC transfusion dependent subjects with a maximal transfusion-free period exceeding 2 years and ongoing. In addition, the percentage of all subjects requiring RBC transfusions substantially decreased over the treatment period. Treatment with CYT387 resulted in rapid and sustained reductions in splenomegaly with a maximal response duration approaching 2 years. The majority of subjects reporting constitutional symptoms at baseline experienced complete resolution or marked improvement by 6 months with measurable improvement within the first month of therapy. Higher transfusion independence and spleen response rates were seen in the 300 mg dose group compared to the 150 mg QD or 150 mg BID dose groups. For the first 60 consecutively enrolled subjects for whom the most mature data is available, the median follow-up period (range) is 21.5 months (2.9–31.0 months). The anemia and spleen response rates in these subjects, per IWG-MRT, were 59% and 48%, respectively; among 33 of these subjects who were RBC transfusion dependent by IWG-MRT criteria, 70% achieved a minimum 12-week period without transfusions with a maximal transfusion-free period of greater than 2 years and ongoing. While 90% of subjects reported at least one treatment-related AE, the majority were reported as Grade 1. The most common treatment-related AEs were thrombocytopenia, peripheral neuropathy, dizziness, diarrhea, nausea, and headache. Treatment-related peripheral neuropathy was sensory, with almost all events reported as Grade 1. The most common Grade 3–4 treatment-related AEs included thrombocytopenia and hyperlipasemia. Only 5% of subjects reported treatment-related AEs resulting in study drug discontinuation. There were no treatment-related deaths. Conclusions: CYT387 has proven safe and well tolerated even with prolonged administration for over 2.5 years. Treatment with CYT387 results in clinical improvement by effecting a rapid, meaningful and durable reduction of splenomegaly and the achievement of sustained RBC transfusion independence in a substantial number of subjects. CYT387 is also effective in improving constitutional symptoms. These results support the development of CYT387 at a dose of 300 mg QD for the treatment of myelofibrosis. Final analyses of safety and efficacy will be available at the time of the meeting. Disclosures: Pardanani: Bristol-Myers Squibb: Clinical trial support, Clinical trial support Other; YM BioSciences: Clinical trial support, Clinical trial support Other; Sanofi-Aventis: Clinical trial support Other. Off Label Use: Data from the ongoing Phase-1/2 study of CYT387 use in myelofibrosis treatment will be described. Gotlib:YM Biosciences: Research Funding. Gupta:Celgene: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; YM Biosciences: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi-Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Roberts:YM BioSciences: clinical trial support Other. Wadleigh:Incyte: Membership on an entity's Board of Directors or advisory committees. Sirhan:Novartis: Consultancy, Honoraria. Bavisotto:YM BioSciences: Consultancy. Kawashima:YM BioSciences: Employment. Kowalski:YM BioSciences: Employment.

Abstract Background : Cytogenetic abnormalities in PMF have been broadly classified into “favorable” and “unfavorable” risk categories. The latter include +8, -7/7q-, i(17q), inv(3), -5/5q-, 12p-, 11q rearrangements and complex karyotype (Leukemia. 2011;25:82). In a more recent study, we had demonstrated an even worse prognosis for patients with monosomal karyotype (MK), inv(3) and i(17q) abnormalities (Blood. 2011;118:4595). In the current study, we revisited the topic using a larger database. Methods: PMF diagnosis was according to World Health Organization criteria (Blood. 2009;114:937). Cytogenetic analysis and reporting was done according to the International System for Human Cytogenetic Nomenclature (Cytogenetic and genome research. 2013. Prepublished on 2013/07/03 as DOI 10.1159/000353118). Assignment to “normal” karyotype required a minimum of 10 metaphases analyzed. A complex karyotype was defined as the presence of 3 or more distinct structural or numeric abnormalities. MK was defined as 2 or more distinct autosomal monosomies or single autosomal monosomy associated with at least one structural abnormality (JCO. 2008;26:4791). Results : A total of 903 patients (median age 65 years; range 19-92; 63% males) met the above stipulations for study eligibility. Dynamic International Prognostic Scoring System (DIPSS)-plus risk distribution (JCO. 2011;29:392) was high in 344 (38%) patients, intermediate-2 in 334 (37%), intermediate-1 in 128 (14%) and low in 97 (11%). 472 patients were annotated for JAK2/CALR/MPL mutations; 276 (58%) harbored JAK2, 117 (25%) CALR and 33 (7%) MPL mutations. Abnormal karyotype was documented in 437 (48%) patients and included sole abnormalities of 20q- (n=71; 16%), 13q- (n=57; 13%), +8 (n=25; 5%), -7/7q- (n=17; 4%) and +9 (n=16; 3%). 22 (5%) patients displayed MK and 31 (7%) complex karyotype without MK. At a median follow-up time of 3 years, 634 (70%) deaths and 65 blast transformations (BT; 7%) were recorded. A step-wise survival analysis, using “normal karyotype” and “MK/inv(3)/i(17q)” as comparators for “low” and “very high risk” categories, respectively, resulted in four distinct cytogenetic risk designations: very high (MK, inv(3), i(17q), -7/7q-, 11q or 12p abnormalities; n=67), high (complex without MK, two abnormalities not included in very high risk category, 5q-, +8, other autosomal trisomies except +9, and other sole abnormalities not included in other risk categories; n=164), intermediate (sole abnormalities of 20q-, 1q duplication or any other translocation, and -Y or other sex chromosome abnormality; n=133) and low (normal or sole abnormalities of 13q- or +9; n=539); the corresponding median survivals were 0.9, 2.6, 3.8 and 4.6 years, with respective HR (95% CI) of 4.4 (3.3-5.8), 2.0 (1.6-2.4) and 1.3 (1.03-1.6). Very high (HR 6.1, 95% CI 2.9-13.2) and high (HR 2.2, 95% CI 1.1-4.1) risk categories were also associated with higher risk of BT. There was no significant correlation between the revised cytogenetic risk stratification and JAK2/CALR/MPL mutational categories (p=0.22), but none of the triple-negative or MPL-mutated patients displayed “very high risk” karyotype. The revised cytogenetic model was also effective in risk-stratification of JAK2 or CALR mutated patients, when analyzed separately, and its prognostic relevance for survival was generally independent of JAK2/CALR/MPL mutational status (p<0.01), DIPSS (p<0.01) or DIPSS-plus (p<0.01). Comparison of the currently used “favorable” vs “unfavorable” with the revised cytogenetic risk model showed a significant number of patients with “favorable” karyotype (n=213 of total 753) being re-assigned to high (n=82) or intermediate (n=131) risk categories. Conclusions : The currently used cytogenetic risk stratification in PMF is too broad and underestimates prognosis in a significant number of patients with “favorable” karyotype. We have developed a revised four-tier risk model that is independent of conventional risk models and JAK2/CALR/MPL mutational status and is expected to facilitate the development of genetics-based prognostic scoring systems in PMF. Disclosures No relevant conflicts of interest to declare.

Abstract Background: 'Myelodysplastic syndrome (MDS) with isolated del(5q),' as defined by the World Health Organization (WHO) criteria (SwederlowSH, et al, 2008) is a unique pathological entity with favorable outcomes. The 2016 revision to the classification expands this entity to include cases that have an additional cytogenetic abnormality, with the exception of monosomy 7 or del(7q) (Arber DA, et al, Blood 2016). The objective of our study was to evaluate the prognostic impact of an additional cytogenetic abnormality, other than monosomy 7 or del(7q), in patients with 'MDS with isolated del(5q)'. Methods: After due IRB approval, the Mayo Clinic MDS database (n=1067) was utilized for this study. All patients had bone marrow (BM) biopsies and cytogenetic studies performed at diagnosis. The International Society for Cytogenetic Nomenclature guidelines were used for cytogenetic nomenclature, while the 2008 and 2016 WHO criteria were used for morphological diagnosis. Results: Patient Characteristics: 72 patients (7.2%) met the 2016 WHO criteria for 'MDS with isolated del(5q)' of which 60% were female and median age was 74 years (28-90). In 61 (85%) cases del(5q) was the only cytogenetic abnormality, while in 11 (15%), del(5q) was present with an 'additional cytogenetic abnormality' (ACA). One additional case within the database had del(5q) accompanied with monosomy 7, which was not included in the analysis. Risk stratification by IPSS-R was as follows; 24 (29%) 'very low', 44 (64%) 'low' and 4 (6%) 'Intermediate' risk, with no patient classified as 'high' or 'very high' risk. At a median follow up of 43 months, 55 (76%) deaths and 5 (7%) leukemic transformations were documented. del(5q) versus del(5q) with an additional cytogenetic abnormality- phenotypic correlates: In the 'del(5q) with ACA' group, the additional abnormalities included trisomy 8 (n=4), del(20q) (n=3), der(9;18) (n=1), inv(3)(p25,q21)(n=1), -Y (n=1), and i(Xp) (n=1) (Table 1). There was no significant difference between the 'del(5q)' and 'del(5q) with ACA' groups in terms of age, gender, hemoglobin, platelet count, white cell count, absolute neutrophil count, bone marrow blast percentage or transfusion requirement. A greater proportion of the 'del(5q) with ACA' group (27%) had IPSS-R risk in the 'intermediate' category compared to the 'del(5q)' group (2%) (p=0.01). 18 of 42 cases diagnosed after 2004 (43%) were treated with lenalidomide, with no difference in the proportions treated between the two groups (p=1.00). del(5q) versus del(5q) with an additional cytogenetic abnormality- impact on overall survival (OS) and leukemia-free survival (LFS): The median survival of the cohort was 54 months. Survival was not significantly different between the 'del(5q)' group (median 55 months) and the 'del(5q) with ACA' group (median 38 months) (p=.75, Figure 1). This finding was consistent when analysis was restricted to patients in both groups treated with lenalidomide (p=0.29). The incidence of leukemic transformation in the del(5q) group was 5%, compared with 18% for the 'del(5q) with ACA' group (p=0.16), however there was no significant difference in LFS between the two groups (p=0.57). Conclusion : In our cohort of primary MDS patients meeting the 2016 WHO definition of 'MDS with isolated del(5q)', we confirm no significant survival difference between cases with del(5q) as the sole cytogenetic abnormality versus cases where del(5q) was accompanied by an additional cytogenetic abnormality. Table 1 Additional Cytogenetic Abnormalities with del(5q): Table 1. Additional Cytogenetic Abnormalities with del(5q): Figure 1 del(5q) vs del(5q) with an additional abnormality (ACA): Overall Survival Figure 1. del(5q) vs del(5q) with an additional abnormality (ACA): Overall Survival Disclosures Al-Kali: Onconova Therapeutics, Inc.: Research Funding; Celgene: Research Funding.

Abstract Background We have previously shown an independent adverse prognostic effect of lymphopenia (absolute lymphocyte count <1.2 x 10(9)/L) for survival in MDS (Jacobs et al. Am J Hematol 2010;85:160) whereas others have suggested a similar value from lymphocyte-to-monocyte ratio (LMR); patients with LMR ≥5 experienced shorter survival with median 67 vs. 126 months (Mushtaq et al. JCO May 20 Supp. 2016:7062). Whether or not "monocytopenia" also carries a prognostic value in MDS is currently unknown and was the main objective for the current study, which also addresses the prognostic value of LMR. Methods We retrospectively recruited 889 consecutive patients with primary MDS who were untreated at the time of referral to our institution and in whom absolute monocyte count (AMC) and absolute lymphocyte count (ALC) at time of referral were documented. The diagnosis of MDS and leukemic transformation (LT) was made according to WHO criteria (Blood. 2009;114:937). Complete follow-up information was updated in January 2015. For the purposes of the current study, monocytopenia was defined as AMC below the lower limit of the institutional normal range, which was 0.3 to 0.9 x 10(9)/L. Comparisons of survival and other clinical parameters were performed between i) patients with and without monocytopenia and ii) patients with and without LMR ≥5. Conventional methods were used for statistical analysis. Results Patient characteristics: Median (range) values for the 889 study patients (69% males) included: age 72 (18-98), hemoglobin 9.6 g/dL (5.4-15.7), leukocyte count 3.4 x 10(9)/L (0.4-35), platelet count 106 x 10(9)/L (2-1804), circulating blasts 0% (0-18), bone marrow blasts 3% (0-19) and absolute lymphocyte count (ALC) 1.2 x 10(9)/L (.02-8.9). Transfusion need was documented in 33% of patients and abnormal cytogenetics in 49%. Risk stratification by the revised international prognostic scoring system (IPSS-R) was very high in 11%, high in 16%, intermediate in 21%, low in 36% and very low in 16%. The median (range) AMC for the entire study population of 889 patients was 0.22 x 10(9)/L (0.0-1.8).The number of patients with subnormal AMC was 539 (61%). After a median follow-up of 27 months, 712 (80%) deaths and 116 (13%) leukemic transformations were documented. Comparison of patients stratified by absolute monocyte count and LMR Compared to patients with AMC >0.3 x 10(9)/L, MDS patients with monocytopenia displayed younger age (p<0.0001), lower hemoglobin (p=0.005), higher red blood cell transfusion need (p=0.03), lower leukocyte count (p<0.0001), lower platelet count (p<0.0001), lower absolute neutrophil count (p<0.0001), higher circulating (p=0.03) and bone marrow (p<0.0001) blasts, higher incidence of abnormal karyotype (p=0.03), and higher risk distribution in terms of both IPSS-R (p<0.0001) and cytogenetic risk stratification by IPSS-R (p=0.03). In univariate analysis, lower AMC was associated with inferior survival (p=0.002); significance was even more apparent when comparing patients with and without monocytopenia (p=0.0003; HR 1.3, 95% CI 1.1-1.5). Similarly, there was significant association between LMR and survival (p<0.0001) with patients with LMR ≥5 experiencing inferior survival (p=0.03; HR 1.2; 95% CI 1.02-1.4). In multivariable analysis, the adverse effect of monocytopenia was shown to be independent of age (p<0.0001), gender (p=0.0001), anemia (Hemoglobin <10 g/dL; p=0.002), thrombocytopenia (platelets <100 x 10(9)/L; p=0.01), neutropenia (absolute neutrophil count <0.8 x 10 (9)/L; p=0.005), subnormal ALC (p=0.0008), circulating blast percentage (p=0.002), cytogenetic risk stratification by IPSS-R (p=0.006) and LMR (p=0.02) or LMR ≥5 (p=0.002); however, significance was lost when risk stratification by IPSS-R was added to the multivariable analysis (p=0.7). In regards to LMR, it retained its significance (p=0.009) during multivariable analysis that included monocytopenia or subnormal ALC, as covariates; however, significance was lost in the context of IPSS-R (p=0.24 for LMR and 0.8 for LMR ≥5) Conclusions Monocytopenia in MDS clusters with adverse disease features and both monocytopenia and higher LMR were associated with poor survival. Despite the display of prognostic independence from each other and other risk factors considered individually, the survival impact of neither monocytopenia nor LMR was found to be independent of IPSS-R. Disclosures Al-Kali: Novartis: Research Funding; Celgene: Research Funding.

Abstract Background A recent study from the International Working Group on Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) identified prior arterial events and hypertension as risk factors for subsequent arterial thrombosis and prior venous events and age 65 years or older as risk factors for venous thrombosis in polycythemia vera (PV) (Blood 2014;124:3021). In the current single center study, we sought to validate the aforementioned findings from the IWG-MRT and look into further details regarding arterial versus venous thrombosis in PV. Methods Study patients were selected from our institutional database of myeloproliferative neoplasms (MPN) and fulfilled the 2008 World Health Organization (WHO) criteria for the diagnosis of PV (Blood. 2009;114:937). Screening for the two most frequent mutations other than JAK2 (TET2 and ASXL1) were performed according to conventional methods (Leukemia. 2014;28:2206). Statistical analyses considered clinical and laboratory parameters obtained at time of diagnosis. Results Patient characteristics: Analysis was conducted on 587 patients (median age 60 years; 48% males). ASXL1 and TET2 mutational status was available in 133 patients. Among informative cases, 31% had palpable splenomegaly, 34% microcirculatory symptoms, 30% pruritus, 8% erythromelalgia, 42% hypertension, 9% diabetes and 11% were active tobacco users. TET2 and ASXL1 mutations were documented in 18% and 11%, respectively. During follow-up, 224 (38%) patients died and median follow-up for living patients was 109 months. Median survival was 16 years and leukemic or fibrotic transformations were documented in 4% and 14%, respectively. Thrombotic events: A total of 235 (40%) patients experienced at least one thrombotic event before or after diagnosis and included 153 (26%) arterial and 104 (18%) venous events. Thrombotic events were recorded before or at time of diagnosis in 146 (25%) patients and included 97 (17%) arterial and 55 (9%) venous events. Thrombotic events after diagnosis were recorded in 128 (22%) patients and included 82 (14%) arterial and 57 (10%) venous events. Associations for arterial, venous or all thrombotic events occurring at any time before or after time of diagnosis: The occurrence of any thrombotic event before or after diagnosis correlated with active tobacco use (p=0.04), diabetes history (p=0.03), hyperlipidemia (p=0.04) and major hemorrhage (p=0.03). The occurrence of any arterial event before or after diagnosis correlated with advanced age (p=0.006), diabetes history (p=0.005), hypertension history (p=0.004) and hyperlipidemia (p<0.0001). The occurrence of any venous event before or after diagnosis correlated with female sex (p=0.008), younger age (p<0.0001), lower platelet count (p=0.0014) and palpable splenomegaly (p=0.006). TET2 or ASXL1 mutations did not correlate with overall, arterial or venous thrombosis. Risk factors for arterial versus venous events after time of diagnosis: In univariate/multivariable analysis, thrombosis-free survival (TFS) was adversely affected by prior vascular events (p=0.002/0.03 multivariable) and increased leukocyte count (p=0.03/0.03); arterial thrombosis-free survival was adversely affected by prior arterial events (p<0.0001/P<0.0001), hyperlipidemia (p=0.001/0.03), hypertension (p=0.02/NS) and advanced age (p=0.02/NS); venous thrombosis-free survival was adversely affected by prior venous events (p=0.04/0.05), increased leukocyte count (p=0.0009/0.002), and younger age (p=0.02/NS). In addition, major hemorrhage at diagnosis was associated subsequent venous thrombosis in both univariate and multivariable analysis. TET2 or ASXL1 mutations did not affect the risk of overall, arterial or venous thrombosis. Conclusions In contemporarily managed patients with PV, prior vascular events predict future events for both arterial and venous thrombosis; additional risk factors included hyperlipidemia for arterial and increased leukocyte count for venous thrombosis. The current study also identifies association of arterial thrombosis in general with older age and history of hypertension, diabetes or hyperlipidemia whereas venous thrombosis was associated with younger age, female sex and palpable splenomegaly. Additional findings included association of major hemorrhage with thrombosis and higher platelet count with lower risk of venous thrombosis. Disclosures No relevant conflicts of interest to declare.

Abstract Background The International Working Group for Myeloproliferative Neoplasms (MPN) Research and Treatment (IWG-MRT) previously published on 1104 patients with "essential thrombocythemia (ET)" and identified 180 (16%) misdiagnosed cases with early/prefibrotic primary myelofibrosis (PMF); the latter diagnosis was associated with inferior overall (OS), leukemia-free (LFS) and myelofibrosis-free (MFFS) survival (J Clin Oncol. 2011; 29:3179). Among the 891 patients with "true" World Health Organization (WHO)-defined ET, risk factors for OS included age ≥60 years, leukocyte count ≥11 x 10(9)/L and history of thrombosis (Blood2012120:1197). In the current study, we explored the possibility that increased serum lactate dehydrogenase (LDH) level or mild grade-1 reticulin fibrosis might identify occult cases of early/prefibrotic PMF in otherwise WHO-defined ET and contribute to disease prognostication. Methods Study patients were selected from the Mayo Clinic institutional database of MPN based on their meeting the 2008 WHO criteria for diagnosis of ET (Blood. 2009;114:937). The degree of bone marrow (BM) reticulin fibrosis was based on "real life" BM reports from Mayo Clinic hematopathologists and often in accordance with the European consensus scoring system (Haematologica 2005;90:1128). Serum LDH levels were obtained at time of diagnosis or within 12 months of diagnosis, in the absence of any treatment. Information on the two most frequent non-driver mutations seen in ET (i.e. TET2 and ASXL1) was available in a subset of the patients (Blood 2015 126:354). Statistical analyses considered clinical and laboratory parameters obtained at time of diagnosis Results Patient characteristics: 183 patients (57% females) were evaluable for BM reticulin grading; median (range) levels were for age 59 years (15-88), hemoglobin 14 g/dL (9.1-17.1), platelets 812 x 10(9)/L (454-3300) and leukocyte count 8.5 x 10(9)/L (3.1-31.5). Palpable splenomegaly was reported in 27 (15%) patients and 12% displayed leukoerythroblastosis (LES). Driver mutational status was JAK2 in 72%, CALR 17%, MPL 2% and triple-negative in 9%. Thrombosis history at diagnosis was obtained from 13% of the patients and 12% experienced the same post diagnosis. Risk stratification according to the International Prognostic Scoring System for ET (IPSET) was 19% high, 43% intermediate and 38% low (Blood2012120:1197). BM reticulin fibrosis was graded "0" in 113 (62%) patients and "1" in 70 (38%). Serum LDH information was available in 110 patients (median194 U/L; range 135-669) and was increased in 31 (28%) patients. Mutational status for TET2 and ASXL1was available in 76 patients with mutational frequencies of 8% each. Clinical and laboratory correlates for mild reticulin fibrosis and serum LDH: We found no significant correlation between mild reticulin fibrosis (grade-1) and a number of clinical parameters, including age, sex, hemoglobin level, leukocyte count, platelet count, driver mutational status, LES, presence of palpable splenomegaly, thrombosis history or serum LDH (p=0.36). In contrast, increased serum LDH was associated with increased leukocyte count (p=0.002), increased platelet count (p<0.001), presence of palpable splenomegaly (p=0.03) and higher IPSET score (p=0.002); there were no significant correlations with age, sex, hemoglobin level, LES, thrombosis history, driver mutational status or TET2/ASXL1mutations. Survival analysis: After a median follow-up of 91 months, 42 (23%) deaths, 2 (1%) leukemic transformations, 7 (4%) fibrotic progressions and 22 (12%) thrombotic events were documented. In univariate analysis, risk factors for OS included age ≥60 years (p=0.002; HR 10.2, 95% CI 2.3-44.6), male sex (p=0.02; HR 3.2, 95% CI 1.2-8.2), leukocyte count ≥15 x 10(9)/L (p=0.007; HR 4.7, 95% CI 1.5-14.6), and increased serum LDH (p=0.004; HR 3.7, 95% CI 1.5-9.1), but not BM reticulin fibrosis (p=0.17). In multivariable analysis, age, sex and LDH remained significant; serum LDH also remained significant for OS, in the context of IPSET, whereas it did not appear to influence thrombosis-free survival (p=0.58), LFS (p=0.84) or MFFS (p=0.34). Conclusions The current study suggests that serum LDH might supersede leukocyte count as an independent risk factor for overall survival in ET; in contrast, mild reticulin fibrosis was irrelevant in terms of both prognostic value and disease phenotype. Disclosures No relevant conflicts of interest to declare.

Abstract Background In polycythemia vera (PV), abnormal karyotype at diagnosis has been reported in 10% to 20% of patients and some studies have suggested an association with inferior survival (Leukemia2013;27:1874) . In the current study, we examined the prognostic contribution of abnormal karyotype, in general, and specific abnormalities, in particular, in newly diagnosed PV. Methods Study patients were selected from our institutional database of myeloproliferative neoplasms (MPN) and fulfilled the 2008 World Health Organization (WHO) criteria for diagnosis of PV (Blood. 2009;114:937). Cytogenetic analysis and reporting was done according to the International System for Human Cytogenetic Nomenclature (Cytogenetic and Genome Research2013;141:1-6). Assignment as "unfavorable karyotype" was according to criteria established for PMF: favorable = normal + favorable abnormalities; unfavorable = unfavorable abnormalities (Leukemia. 2011;25:82). Screening for the two most frequent mutations in PV, other than JAK2 (i.e. TET2 and ASXL1), were performed according to conventional methods (Leukemia. 2014;28:2206). Statistical analyses considered clinical and laboratory parameters obtained at time of diagnosis. Results Patient characteristics: Median (range) values for the 239 study patients (53% females) included: age 62 (17-94), leukocyte count 11.7 x 10(9)/L (4.3-59.3) and platelet count 479 x 10(9)/L (37-2747). Palpable splenomegaly was present in 26% of the patients, pruritus in 27%, erythromelalgia in in 8%, hypertension in 47%, diabetes in 10% and hyperlipidemia in 28%. Thrombosis history at diagnosis was documented in 33% of the patients and 20% experienced the same after diagnosis. 73% of the patients were "high risk" by conventional risk stratification. Mutation screening for TET2 and ASXL1 was performed in 80 patients and mutational frequencies were 19% and 11% respectively. All study patients provided cytogenetic information, which was abnormal in 46 (19%) patients. The most frequent abnormalities were isolated +9 (n=11; 24% of abnormal karyotype and considered favorable), isolated del(20q) (n=8; 17% of abnormal karyotype and considered favorable), isolated loss of Y chromosome (n=7; 15% of abnormal karyotype and considered favorable) and isolated +8 (n=5; 11% of abnormal karyotype and considered unfavorable). A total of 9 (20% of abnormal karyotype) patients displayed unfavorable karyotype that included +8 in 7 patients, del(11q) in one patient and +20 in one patient. After a median follow-up of 83 months, 70 (29%) deaths, 48 (20%) thrombotic events, 20 (8%) fibrotic progressions and 7 (3%) leukemic transformations were documented. Comparison of patients with and without cytogenetic abnormalities Patients with abnormal cytogenetics were older (p=0.048), displayed lower platelet count (p=0.005) and were more likely to be high risk (p=0.02); there was no significant correlation with TET2 or ASXL1 mutation. In univariate analysis, patients with abnormal cytogenetics displayed inferior leukemia-free (p=0.007; HR 10.6, 95% CI 1.9-58.7), myelofibrosis-free (p<0.0001; HR 7.7, 95% CI 3.1-19.3) and overall (p=0.13; HR 1.6, 95% CI 0.9-2.8) survival. Furthermore, the difference in overall survival became significant when cytogenetic abnormalities were classified into unfavorable (p=0.006) and favorable (p=0.6) categories. On the other hand, inferior leukemia-free and myelofibrosis-free survival was noted in both patients with favorable and unfavorable cytogenetic abnormalities, when compared to normal karyotype. During multivariable analysis that included age and leukocytosis (≥15 x 10 (9)/L) as covariates, the adverse effect of abnormal cytogenetics on leukemia-free (p=0.009) or myelofibrosis-free (p<0.0001) survival and that of unfavorable karyotype on overall (p=0.05) survival were shown to be independent. Finally, patients with abnormal cytogenetics were less likely to experience thrombosis after diagnosis (p=0.04; HR 0.3, 95% CI 0.09-0.97), an effect that was independent of both age and thrombosis history. Conclusions Cytogenetic abnormalities in PV confer an independent adverse prognostic effect on overall, leukemia-free and myelofibrosis-free survival, but not thrombosis-free survival; the adverse effect on leukemia-free and myelofibrosis-free survival was seen with both favorable and unfavorable cytogenetic abnormalities. Disclosures No relevant conflicts of interest to declare.

Abstract Background The International Working Group for Myeloproliferative Neoplasms (MPN) Research and Treatment (IWG-MRT) has previously identified older age, leukocytosis, venous thrombosis and abnormal karyotype as risk factors for overall survival (OS) in polycythemia vera (PV), and older age, abnormal karyotype and leukocytes ≥15 × 109/l as risk factors for leukemia-free survival (LFS) (Leukemia2013;27:1874). Serum lactate dehydrogenase (LDH) is a surrogate quantitative measure of cell turnover and tumor burden. We hypothesized that, compared to leukocyte count, serum LDH might be a biologically more accurate indicator of tumor aggression and sought to examine its potential utility as a prognostic biomarker in PV. Methods Study patients were selected from our institutional database of MPN based on their meeting the 2008 or 2016 World Health Organization criteria for diagnosis of PV (Blood. 2009;114:937; Blood 2016 127:2391) and availability of serum LDH level, obtained within six months of diagnosis. Information on karyotype and targeted next-generation sequencing was available in a subset of the patients (Blood 2015 126:354). Statistical analyses considered clinical and laboratory parameters obtained at time of diagnosis. Age and leukocyte count prognostic categories were based on previously published IWG-MRT study (Leukemia2013;27:1874). Results Patient characteristics: A total of 216 patients (50% females) met the above-outlined criteria: median (10th-90th percentile) levels were for age 63 years (38-81), hemoglobin 18 g/dL (16.6-20.7), platelets 467 x 10(9)/L (237-833), leukocyte count 11.7 x 10(9)/L (7.2-20.3) and spleen size 0 cm (0-2). Pruritus was documented in 28%, microcirculatory symptoms in 31%, erythromelalgia in 6%, hypertension in 45%, diabetes in 7%, active tobacco use in 13%, hyperlipidemia in 25%, palpable spleen in 26% and abnormal karyotype in 15% of informative cases. Grading for bone marrow reticulin fibrosis was documented for 144 patients: 50% grade "0", 42% grade "1", 7% grade "2" and 1 grade "3". Thrombosis history at diagnosis was documented in 26% of patients and occurred after diagnosis in 19%. Mutation analysis was available in 72 patients and revealed TET2 mutations in 18 (25%), ASXL1 in 5 (7%), SRSF2 in 2 (3%) and IDH2 in one (1.4%). Serum LDH levels and correlates: Median serum LDH level was 226 U/L (range 71-1008); the upper normal limit (UNL) for Mayo Clinic was 222 U/L. Increased serum LDH was recorded in 110 (51%) patients that included 26 (12%) patients with LDH ≥1.5 x UNL. A significant correlation was demonstrated between increased serum LDH and older age (p=0.007), female sex (p=0.04), leukocytosis (p=0.01), venous thrombosis history (p=0.005) and, interestingly, absence of active tobacco use (p=0.003); no correlation was noted for bone marrow reticulin fibrosis, presence of palpable splenomegaly, abnormal karyotype or ASXL1 mutation. Survival analysis: After a median follow-up of 77 months, 82 (38%) deaths, 8 (3.7%) leukemic transformations, 13 (6%) fibrotic progressions and 41 (19%) thrombotic events were documented. In univariate analysis, the following adversely affected OS: advanced age (P<0.0001), increased LDH as a continuous variable (p=0.0006), LDH ≥1.5 x UNL (p<0.0001), leukocyte count ≥15 x 10(9)/L (p=0.02) and arterial thrombosis history (p=0.001). In multivariable analysis, only age and LDH remained significant; multivariable HR (95% CI) were 5.4 (2.8-10.4) for age ≥67 years, 3.2 (1.8-6.0) for LDH ≥1.5 x UNL and 2.4 (1.2-4.7) for age 57 to 66 years. In the subset of patients with available information on karyotype and non-JAK2 mutations (n=72), advanced age, LDH ≥1.5 x UNL and ASXL1 mutations remained significantly associated with inferior survival. Serum LDH also predicted leukemic transformation (HR 17.8, 95% CI 4.1-78) and fibrotic progression (HR 11.6, 95% CI 25-53.7); in multivariable analysis, only serum LDH ≥1.5 x UNL (HR 22.3, 95% CI 2.1-234.6) and abnormal karyotype (HR 9.5, 95% CI 1.2-74.7) predicted leukemic transformation and only the former predicted fibrotic progression. Conclusions Serum LDH is a simple and inexpensive biomarker that might supersede leukocyte count as an independent predictor of overall, leukemia-free and myelofibrosis-free survival in PV; advanced age and ASXL1 mutations also retained significance for OS and abnormal karyotype for LFS. Disclosures No relevant conflicts of interest to declare.