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Abstract Background: Acute promyelocytic leukemia (APL) has a favorable prognosis with high complete remission rates of over 90 percent, with relapse occurring in only 10 to 15 percent of patients. Our objective was to describe the characteristics of relapsed patients and review management of relapsed disease. Methods: After institutional review board approval, we searched our institutional electronic database for those 18 years and older with a new diagnosis of acute promyelocytic leukemia between January 1, 2000 and April 30, 2016. We gathered all patient information through electronic chart review. Results: Out of 89 patients reviewed, 59 had complete treatment data through induction therapy. Of the 59 patients, with median follow-up of 51 months (range 1-180 months), 7 (11.9%) had relapsed. The median age at APL diagnosis of relapsed patients was 52 years (range: 30-77 years). 6 relapsed patients were intermediate or low risk, and 1 was in the high risk category. 6 relapsed patients received an ATRA and chemotherapy-based induction regimen, and 1 received an ATRA and arsenic-based regimen. Median time to morphological remission was 32 days (range: 22-83 days). 6 of 7 relapsed patients achieved molecular remission. Consolidation regimens included conventional chemotherapy alone (1 patient), ATRA and conventional chemotherapy (4 patients), and arsenic alone (2 patients). Of the 7 relapsed patients, 4 completed maintenance therapy. The median time to relapse from first morphologic remission was 40 months (range: 3-47 months). 6 patients were treated at our institution, and 1 was treated at an outside institution. 2 patients had a molecular relapse, 2 had systemic and central nervous system (CNS) relapse, and 1 patient had an isolated CNS relapse. Treatment regimens at relapse included ATRA and chemotherapy (1 patient), arsenic alone (2 patients), ATRA and arsenic (2 patients), and intrathecal methotrexate with conventional chemotherapy (1 patient). Complications of treatment included infection (2 patients: 1 treated with ATRA and chemotherapy and 1 with intrathecal methotrexate and chemotherapy), thrombotic events (1 patient treated with ATRA and arsenic), rash (1 patient treated with arsenic), and QTc prolongation (1 patient treated with ATRA and arsenic). 5 of 6 patients achieved a molecular remission. Consolidation regimens after reinduction included ATRA and chemotherapy (2 patients), arsenic alone (1 patient), intrathecal methotrexate (1 patient), and ATRA and arsenic (1 patient). Of the 2 patients who had a second relapse, 1 had an isolated CNS relapse, and 1 had a systemic and CNS relapse. Both patients were treated with intrathecal methotrexate and conventional chemotherapy. Due to persistent CNS disease, 1 patient underwent therapy with systemic methotrexate and craniospinal radiation. 1 patient had a third relapse, which was treated with ATRA and arsenic. 4 of 6 patients underwent hematopoietic stem cell transplant, 2 autologous and 2 allogeneic. Of the 7 relapsed patients, 5 are alive, including all 4 patients who underwent transplant. Table 1 provides a detailed summary of the management of relapse in each of these patients. Conclusion: Our data are consistent with the reported relapse rate of 10 to 15 percent in APL. Patients who relapse are successfully treated with both ATRA and arsenic-containing regimens. In our cohort, relapsed patients had favorable survival. Disclosures No relevant conflicts of interest to declare.

Abstract Background In a seminal report (NEJM 2011;30:2496), ASXL1, TP53, EZH2, ETV6 and RUNX1 mutations in myelodysplastic syndromes (MDS) were shown to carry an adverse prognostic impact that was independent of the international prognostic scoring system (IPSS) (Blood 1997;89:2079). Two recent studies (Leukemia20 May 2016; doi: 10.1038/leu.2016.138; Leukemia. 2014;28:241) have proposed mutation-enhanced prognostic models that include the revised IPSS (IPSS-R) (Blood 2012;120:2454 ). In the current study, we applied targeted next generation sequencing (NGS) in order to examine the prognostic interaction between adverse mutations and IPSS-R. Methods The study population was recruited from our institutional database of patients with primary MDS, based on availability of archived DNA from the time of diagnosis. The diagnosis of MDS and leukemic transformation (LT) was made according to WHO criteria (Blood. 2009;114:937). Targeted capture assays were carried out, on bone marrow DNA specimens, 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.Specific variants were deemed as mutations if they are associated with a hematologic malignancy (as identified by COSMIC database), or if they have not been associated with a dbSNP. Results Patient characteristics and type and number of mutations: 179 patients were evaluated (median age 73 years; 68% males). IPSS-R risk distribution was 11% very high, 18% high, 16% intermediate, 39% low and 16% very low. At least one mutation was seen in 139 (78%) patients including 17% with one mutation, 29% with 2, 20% with 3, 10% with four, 2% with 5 and one patient with 6 mutations. The most frequent mutations were ASXL1 (30%), SF3B1 (20%), TET2 (17%), U2AF1 (16%) and SRSF2 (16%). Mutation clusters and clinical correlates: ASXL1 mutations were associated with the absence of SF3B1 (p=0.007), U2AF1 (p=0.01) and SRSF2 (p=0.003) mutations; SF3B1 with absence of U2AF1 (p=0.004) and SRSF2 (p=0.004) mutations; and U2AF1 with absence of SRSF2 mutations (p=0.01). Clinical correlates of ASXL1 mutations included older age, lower hemoglobin, and lower risk karyotype; SF3B1 with higher leukocyte count, higher platelet count, lower bone marrow blast percentage and lower risk karyotype; TET2 with older age and higher hemoglobin. Univariate overall and leukemia-free survival analysis before and after adjusting for IPSS-R: In univariate analysis, ASXL1, RUNX1 and TP53 mutations adversely and SF3B1 favorably affected survival; only ASXL1 mutations retained significance when analysis was adjusted for IPSS-R (HR 1.5, 95% CI 1.0-2.1; p=0.03). For leukemia-free survival, univariate analysis identified SRSF2, which was near-significant for overall survival (p=0.06), and RUNX1 mutations as adverse and SF3B1 mutations as favorable risk factors; SRSF2 (HR 4.1, 95% CI 1.6-10.2) and SF3B1-unmutated (HR 5.9, 95% CI 1.1-31.5) retained their significance when adjusted for IPSS-R. A borderline significance (p=0.07) indicating inferior survival for patients with three or more mutations was fully accounted for by the significant (P<0.0001) association between the presence of ASXL1 mutations and higher number of mutations. Multivariable analysis with individual IPSS-R variables: When the five IPSS-R variables (hemoglobin, platelets, absolute neutrophil count, bone marrow blast percentage and karyotype) were analyzed (both as continuous and IPSS-R-defined categorical variables) with each one of the aforementioned mutations with significant effect on overall or leukemia-free survival, only ASXL1 retained its significance for overall survival (HR 1.6, 95% CI 1.1-2.3) and SRSF2 (HR 5.2, 95% CI 2.1-13.3) for leukemia-free survival. Other IPSS-R variables that retained their significance for survival, in the presence of ASXL1 mutation status as a covariate, included hemoglobin level, platelet count and karyotype. Conclusions: In our cohort of 179 molecularly-annotated patients with newly-diagnosed primary MDS, ASXL1 and SRSF2 mutations were identified as IPSS-R-independent risk factors for overall and leukemia-free survival, respectively. The current study also suggests the need to re-evaluate currently established risk factors, in the context of prognostically-relevant molecular information. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1476 Background: Monosomal Karyotype (MK) is defined as the presence of two or more autosomal monosomies or one autosomal monosomy and one structural abnormality. MK has been found to be an independent poor prognostic factor in myeloid diseases (Patnaik et al, Leukemia 2011, Haferlach et al, Blood 2012) even in the setting of allogeneic stem cell transplantation (Fang et al, Blood 2011). The prognostic relevance of MK in Acute Lymphoblastic Leukemia (ALL) is unknown. Absolute lymphocyte count (ALC) at diagnosis, on the other hand, has been shown to be prognostic in a variety of lymphoproliferative disorders (Porrata et al, Leukemia 2010). However, the prognosis of ALC at diagnosis in ALL is undetermined Methods: This is a retrospective analysis of the Mayo Clinic leukemia database (1998–2010). The study was approved by the Institutional Review Board. Outcomes analyzed included overall survival (OS), leukemia free survival (LFS) and relapse rate. Clinical characteristics, cytogenetics, therapy and outcomes of patients with Philadelphia negative ALL (Ph-negative ALL) were analyzed. Cytogenetics were classified as follows: standard risk [hyperdiploidy], intermediate risk [Normal, del(11q)-not MLL, del(6q), del(17p), del(9p), del(12p), del(13q), t(14q32), t(10;14), low hyperdiploidy, others], high risk [-7, del(7p), +8, MLL translocations, t(1;19), t(17;19), t(5;14)], and very high [t(4;11), t(8;14), complex (≥5 abnormalities), hypodiploidy, triploidy] (Pullarkat et, Blood 2008). Multivariate analysis was performed using Cox Regression Model. Results: Between 1998 and 2010, a total of 175 consecutive patients with ALL were identified. Of these, 112 (64%) had Ph-negative ALL. The median age was 39.5 (16–88) years and 74 were male (66%). The majority of cases were B-ALL (78 patients, 69%). At presentation, the median hemoglobin was 10 (4.1–18.5) g/dL, platelet count was 61 (3–523) ×10(9)/L, WBC was 7.2 (0.8–377) ×10(9)/L and ALC was 1.9 (0–69.0) ×10(9)/L. The ALC was > 1000 in 75 (71%) patients. Cytogenetics risk categories were as follows: standard risk in 5 (4.4%), intermediate risk in 70 (62.5%), high risk in 8 (7.1%) and very high risk in 29 (25.9%) patients. Twenty-two patients (20.9%) presented with extranodal disease (CNS disease in 13 patients, 11.6%). Six patients (5.4%) had prior exposure to chemotherapy. Treatment involved allogeneic stem cell transplantation (SCT) in 34 (30.4%) patients. The median OS for the whole cohort was 24 (0–206) months and LFS was 18 (0–193) months. Forty four patients (39.3%) relapsed after achieving initial remission with a median time to relapse of 15 (2–73) months In a univariate analysis, low platelet count at diagnosis, poor ECOG performance status (PS), and high or very high risk cytogenetics risk categories were associated with inferior OS. ALC at diagnosis did not impact OS or LFS. On a multivariate analysis, high/very high risk cytogenetics, low platelet counts and poor ECOG PS were independent predictors of inferior outcomes. Nineteen patients (16.9%) had a MK. Of these, 16 (84.2%) fell in the very high risk cytogenetics category regardless of MK status. Three patients (1.6%) presented with extramedullary disease and six (3.2%) underwent SCT. The median OS of these 19 patients was 15 (1–73) months. While MK was associated with inferior LFS and a trend towards worse OS, this was not significant on a multivariate model that included cytogenetic risk categories, thrombocytopenia and the ECOG PS. Conclusions: Our study demonstrates that cytogenetics risk stratification, thrombocytopenia and ECOG performance status are independent prognostic factors in ALL. MK and ALC at diagnosis had no prognostic significance. Disclosures: No relevant conflicts of interest to declare.

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.