Hanson, Curtis A.

Abstract Background The Dynamic International Prognostic Scoring System (DIPSS)-plus currently provides the most comprehensive prognostic model for primary myelofibrosis (PMF) (JCO 2011;29:392). DIPSS-pluse uses eight independent predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocyte count >25 x 109/L, circulating blasts ³1%, constitutional symptoms, unfavorable karyotype, red cell transfusion need and platelet count <100 x 109/L. More recently, type 1/type 1-like CALR driver mutational status and ASXL1 andSRSF2 mutations were identified as additional DIPSS-plus-independent risk factors for survival in PMF (JAMAOncol. 2015;1:97). Based on our earlier preliminary observation (Leuk Res. 2007;31:1503), we conducted the current study to fully examine the additional prognostic relevance of monocytosis (absolute monocyte count ≥1 x 10(9)/L) in PMF. Methods Study patients fulfilled the 2016 WHO criteria for the diagnosis of PMF, including both pre-PMF and overt PMF (Blood. 2016;127:2391). Additional selection criteria included the availability of absolute monocyte count (AMC) and percentage at time of referral. Targeted next generation sequencing was used to screen for prognostically-relevant mutations (Blood 2015 126:354). Statistical analyses considered clinical and laboratory parameters obtained at time of initial referral to the Mayo Clinic. Results Patient characteristics: The study population included 454 patients (median age 64 years; 62% males); 293 (64%) patients harbored JAK2 mutations, 74 (16%) type 1/like CALR, 16 (3%) type 2/like CALR, 24 (5%) MPL and 47 (10%) were "triple-negative". DIPSS-plus risk distribution was 29% high, 38% intermediate-2, 17% intermediate-1 and 15% low; 27% displayed red cell transfusion-dependency, 29% constitutional symptoms, 70% palpable splenomegaly and 36% abnormal karyotype, including 13% with unfavorable karyotype. 301 patients were screened for ASXL1 mutations with 39% mutated, 297 for SRSF2 mutations with 15% mutated, 286 for U2AF1 with 18% mutated, 253 for SF3B1 with 6% mutated, 229 for EZH2 with 5% mutated and 110 for IDH1/2 with 7% mutated. Clinical, cytogenetic and molecular comparisons between PMF patients with and without monocytosis: Among all study patients, 376 (83%) displayed AMC <1 x 10(9)/L; the remaining had either moderate (AMC between 1 and 3 x 10(9)/L; n=65) or marked (AMC >3 x 10(9)/L; n=13) monocytosis. Comparison of these three groups revealed that monocytosis was significantly associated with older age (p=0.0001), higher leukocyte count (p<0.0001), lower platelet count (p=0.01), higher circulating blast percentage (p=0.0002) and higher DIPSS-plus risk distribution (p=0.01). There were no significant differences in the distribution of driver mutations, ASXL1, SRSF2, U2AF, SF3B1, EZH2 or IDH1/2 mutations or incidence of unfavorable karyotype. Survival analysis: After a median follow up of 3.2 years, 265 (58%) deaths and 38 (8%) leukemic transformations were documented. In univariate analysis, all 8 variables included in DIPSS-plus were significantly associated with shortened survival (p<0.001 in all instances). Significant risk factors in univariate analysis also included AMC >3 x 10(9)/L (p<0.0001; HR 5.6, 95% CI 3.1-10.0), AMC 1 to 3 x 10(9)/L (p<0.0001; HR 2.1, 95% CI 1.5-2.9), absence of CALR type 1/type 1-like (p<0.0001) and presence of ASXL1 (p<0.0001) or SRSF2 (p<0.0001) mutations. The significant difference in survival between the three AMC categories (i.e. <1, 1-3 and >3 x 10(9)L) was independent of each one of the eight DIPSS-plus variables, DIPSS-plus, driver mutational status, ASXL1 and SRSF2 mutations (p<0.0001 in all instances). The survival difference between patients with and without monocytosis was evident in both high/intermediate-2 and low/intermediate-1 DIPSS-plus risk groups (Figure). Patients with monocytosis were also more likely to undergo leukemic transformation (HR 3.0, 95% CI 1.4-6.5) and this effect was also independent of karyotype, driver mutational status, ASXL1 or SRSF2 mutations. Conclusion The current study identifies monocytosis as a powerful risk factor for both overall and leukemia-free survival in PMF and the effect was independent of currently established prognostic models and genetic risk factors. It was particularly noteworthy to document similar distribution of driver mutations among the three monocyte categories. Figure Figure. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 3899 BACKGROUND: Although chemoimmunotherapy (CIT) has substantially improved response rates, treatment free survival, and overall survival in patients with chronic lymphocytic leukemia (CLL), only 40–50% of patients achieve a complete remission and the majority have residual disease when evaluated using sensitive assays for minimal residual disease (MRD). While these facts generated interest in consolidation strategies for patients with residual disease, previous trials of alemtuzumab-based consolidation found excess morbidity/mortality. In 2008 we began a trial of lenalidomide-based consolidation for patients with previously untreated CLL who had received 6 cycles of CIT induction. Preliminary analysis suggested that lenalidomide consolidation may improve the quality of response and prolong time to retreatment (Shanafelt; ASH 2010), although follow-up was short (median 16 months). METHODS: Eligible patients were previously untreated and had CLL in need of treatment according to the NCI-WG criteria (Blood 111:5446). Treatment schema consisted of 6 cycles of pentostatin (2 mg/m2), cyclophosphamide (600 mg/m2) and rituximab (375 mg/m2) given every 21 days (Blood 109:405). All patients completing 6 cycles of PCR induction, underwent complete restaging including evaluation for MRD using sensitive flow cytometry. Patients subsequently received 6 months of lenalidomide consolidation by daily administration with a starting lenalidomide dose of 5 mg/day and escalation to 10 mg/day after the first cycle as tolerated. Patients again underwent complete restaging including MRD evaluation after 6 months of lenalidomide. At the time of restaging, MRD negative patients entered observation. Those with residual disease continued on lenalidomide and underwent repeat MRD assessment every 3 months until an MRD negative state was achieved. RESULTS: 45 patients were enrolled at Mayo Clinic between 3/2008 and 12/2009 of whom 44 were eligible. Median age was 65 (range: 44–78) and 71% of patients were male. 61% of patients had intermediate Rai risk and 39% high Rai risk. On prognostic testing 32% were CD38+, 52% Zap-70+, 52% IGHV unmutated, and 16% had high risk FISH (del 17p13; del 11q22). Of the 38 eligible patients who completed 6 cycles of PCR induction, 34 (89%) initiated lenalidomide consolidation. Thus by intent to treat analysis, 34/44 (77%) patients starting CIT with PCR were able to receive consolidation therapy. Among the 34 patients who initiated consolidation, the median number of cycles of lenalidomide received was 6 (range: 1–29). Nine of 34 (26%) patients had the lenalidomide dose increased to 10 mg daily while 18 (53%) required a reduction to 5 mg every other day. Five patients are still on lenalidomide at the time of this report. No cases of tumor lysis syndrome or tumor flare reaction were observed. Adverse events deemed at least possibly related to lenalidomide consolidation included 23 (68%) patients with grade 3+ hematologic toxicity and 5 (15%) with grade 3+ non-hematologic toxicity. Among the 34 patients who received at least 1 cycle of lendalidomide, 6 patients have improved the quality of their response including 3 patients who converted from having residual disease to a MRD- state. After a median follow-up of 29 months, 39/44 patients are alive and the median duration of response has not been reached. To date 8/44 (18%) patients have progressed to require additional treatment. Finally, since the eligibility criteria were nearly identical to our historic trial of PCR without lenalidomide consolidation, we conducted an intent to treat analysis that compared all 44 patients in the present trial (i.e. regardless of whether they received lenalidomide consolidation) to the 64 patients previously treated on our PCR trial (Blood 109:405). The demographic and prognostic characteristics of patients in the two studies were similar. With the caveat it represents a comparison across phase II trials, the proportion of patients free of retreatment at 30 months was 79% (95% CI:67–93) for PCR followed by lenalidomide consolidation vs 66% (95% CI: 54–80) for PCR alone (Figure 1). CONCLUSION: Lenalidomide-based consolidation for CLL patients receiving first-line CIT induction appears to improve the quality of response and prolong time to retreatment. Randomized clinical testing of lenalidomide-based consolidation appears warranted. Disclosures: Shanafelt: Celgene: Research Funding; Hospira: Research Funding; Genentech: Research Funding. Off Label Use: PCR-Lenalidomide (off label use of pentostatin and lenalidomide). Tun:Celgene: Research Funding. Kay:Biothera: Research Funding; Clegene: Research Funding; Cephalon: Research Funding; Genentech: Research Funding; Glaxo Smith Kline: Research Funding; Hospira: Research Funding; Novartis: Research Funding; Supergen: Research Funding; Calistoga: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Emergent Biosolutions (Formerly Trubion): Membership on an entity's Board of Directors or advisory committees.

Abstract Background: The cytoreductive treatment options for myeloproliferative neoplasms, in those who have indications, may be limited to hydroxyurea and interferon. Busulfan has been reported to have some activity, but used less frequently in the management of BCR/ABL negative MPNs (Haanen CM et al Br J Cancer 1981; Brodsky American J of clinical oncology 1998). One study has shown significant JAK2V617F allele burden reduction with busulfan (Kuriakose ET et al; Haematologica 2013). Ruxolitinib was approved by the FDA for intermediate and high risk myelofibrosis; and as second line therapy for polycythemia vera in those who are intolerant or develop side effect to hydroxyurea. Objective: To assess the utility of busulfan, an old drug, in patients with myeloproliferative neoplasms who are intolerant to other forms of therapy. Methods: The mayo clinic data base from 1970 to 2014 was interrogated using the terms myeloproliferative disorder, polycythemia vera (PV), essential thrombocythemia (ET), myelofibrosis (MF) and busulfan. Patients' follow up information was collected till July 2015. Results : Seventy five patients with full demographic, diagnostic and therapeutic information were identified, and those included 37 patients with ET, 22 with PV, 12 with MF, and 4 with myeloproliferative neoplasms unclassifiable. The median age was 64 (range 31-91) years. After a median follow up of 17 years, 40 patients (53 %) died, and leukemic transformation was documented in 4 (5%). The median time for leukemic transformation was 86 months (12-229). 1. Essential Thrombocytopenia (n=37): Twenty nine (79%) were females, and the median (range) age was 67 (33-90) years. At diagnosis the median (range) hemoglobin (Hgb) (gm/dL), white blood cell count (WBC) (X109/L), and platelet count (X109/L) were 13.6 (9.8-16.9), 10.2 (5-231), 1113 (593-2062) respectively. After a median follow up time of 230 months, 15 patients (41%) died, and leukemic transformation was documented in 1 patient who was also treated with radioactive phosphorous (P32). Leukemic transformation was documented 230 months from date of diagnosis. Follow up complete blood count was available in 20 patients and the median (range) Hgb, WBC and platelet count was 12 (9.9-16), 7.4 (3.1-25), and 267 (126-573) respectively. 2. Polycythemia Vera (n=22): Fourteen (61%) were females, and the median (range) age was 64 (46-91) years. At diagnosis the median (range) Hgb, WBC, and platelet count were 17.5 (15.1-20.8), 11.5 (1.2-26.6), and 669 (185-2370) respectively. After a median follow up time of 188 months 13 (57%) patients died, and leukemic transformation was documented in 2 patients and one of them was given P32. Follow up complete blood count was available in 21 patients and their median (range) Hgb, WBC and platelet count was 12.9 (10-15.2), 7.2 (2.8-20), and 303 (124-833) respectively. 3. Myelofibrosis (Primary and Post-PV and Post-ET myelofibrosis) (n=12) : The median age was 52 (31-75) and 5 were females. The median Hgb, WBC, and platelet count were 13.6, 14.5, and 472. Six (50 %) patients did have splenomegaly (and 5 of them have splenic size reduction after busulfan), 3 underwent splenectomy, and 3 have no palpable spleen. At a median follow up of 208 months, and 39 months (range 78-401) from the start of busulfan, 10 (84%) patients died and no leukemic transformation was documented. Conclusion: Busulfan should be considered as alternative therapy in myeloproliferative neoplasms especially in ET and PV that are intolerant to other forms of cytoreductive therapy. Busulfan may be given as pulse therapy in controlling cell counts. Disclosures Off Label Use: Busulfan as alternative therapy in myeloproliferative neoplasms.

Abstract Background Polycythemia Vera (PV) constitutes one of the three BCR-ABL1-negative myeloproliferative neoplasms and is characterized by clonal erythrocytosis and the almost invariable presence of JAK2 mutation. An absolute monocyte count (AMC) of ≥1 x 10(9)/L defines chronic myelomonocytic leukemia (CMML) but can also be seen in other myeloid disorders including myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). The presence or development of monocytosis has previously been shown to confer poor prognosis in both primary myelofibrosis (PMF), which is one of the three BCR-ABL1-negative MPN (Leukemia Research 2007;31:1503, Mod Pathol. 2013 Feb;26(2):204) and MDS (Haematologica. 1997;82:25). In the current study, we examined the clinical, prognostic and molecular correlates of monocytosis in PV. Methods Study patients were selected from our institutional database of MPN and fulfilled the 2008 World Health Organization (WHO) criteria for the diagnosis of PV (Blood. 2009;114:937). Cytogenetic and mutational analyses were performed according to conventional methods (Leukemia. 2014;28:2206) any assignment as unfavorable karyotype was per PMF criteria (Leukemia. 2011;25:82). Mutation screening included TET2, ASXL1 and SRSF2 because of their known association with CMML (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) who met WHO criteria for diagnosis of PV. Amongst them, accurate documentation of AMC was available in 237 patients, cytogenetic information in 239, and ASXL1, TET2 and SRSF2 mutational status in 133 patients. Median (range) values were for AMC 0.6 x 10(9)/L (0-4.7) and leukocytes 11.6 x 10(9)/L (3.8-171.6). 31% of 506 informative patients had palpable splenomegaly, 34% of 551 had microcirculatory symptoms, 30% of 566 had pruritus, 8% of 504 had erythromelalgia, 42% of 581 had hypertension, 9% of 584 had diabetes and 11% of 575 were active tobacco users. 25% of the patients presented with history of thrombosis and 22% developed thrombosis after diagnosis. Cytogenetic findings were abnormal in 19%, of whom 20% were unfavorable. TET2, ASXL1 and SRSF2 mutations were documented in 18%, 11% and 3%, 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. Comparison of patients with and without monocytosis: Among 237 informative patients, 32 (14%) displayed monocytosis (AMC ≥1 x 10(9)/L) at time of diagnosis. PV patients with monocytosis were older (p=0.006) and displayed higher leukocyte count (p<0.0001) and higher incidences of leukocytosis (p=0.024) and unfavorable cytogenetic abnormalities (p=0.02). There was no association between monocytosis and mutations for TET2 (p=0.1), ASXL1 (p=0.7) and SRSF2 (p=0.3) or thrombosis before (p=0.9) or after (p=0.5) diagnosis (p=0.5), palpable splenomegaly (p=0.6), pruritus (p=0.7) or microcirculatory symptoms (p=0.1). Among the 237 PV patients in whom information regarding AMC was available, 70 (30%) died during follow-up and 49 (21%), 23 (10%), 9 (4%) developed thrombosis, leukemic transformation or fibrotic progression, respectively. In univariate analysis, overall (p=0.009; HR 2.0, 95% CI 1.2-3.4) but not leukemia-free (p=0.79), myelofibrosis-free (p=0.13) or thrombosis-free (p=0.48) survivals were different between patients with or without monocytosis. Furthermore, the significant difference in survival was no longer apparent when analysis was adjusted for age (p=0.13), unfavorable karyotype (0.17) or leukocytosis (p=0.06). Conclusions Monocytosis (AMC ≥1 x 10(9)/L) is not infrequent in PV (14%). However, the presence of monocytosis does not appear to represent a significantly different phenotype in terms of molecular characteristics although it is associated with older age, leukocytosis and unfavorable karyotype. The latter associations account for the inferior survival seen in patients with monocytosis. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1756 Background: We hypothesized that surrogate markers of host immune response to clonal myeloproliferation predict survival in myeloid malignancies. Because of immediate applicability to current practice, we chose plasma immunoglobulin free light chain (FLC) concentration (B-cell activation marker) as the biomarker of interest. Patients and Methods: Two independent cohorts of patients with primary myelofibrosis (PMF) or myelodysplastic syndromes (MDS) were studied. Both groups were fully annotated for karyotype. Kappa (κ) and lambda (λ) FLC were measured by a quantitative nephelometric assay. Patients with monoclonal FLC were excluded. Results: Above upper normal-limit values for κ or λ FLC was documented in 33% of 240 study patients with PMF and 46% of 74 patients with MDS. Multivariable analysis revealed significant associations between increased FLC and elevated creatinine, as well as advanced age in PMF (p=0.0004) and hemoglobin <10 g/dL in MDS (p=0.005). Increased FLC predicted shortened survival in both PMF and MDS, independent of age, creatinine, and other conventional risk factors. Receiver-operating characteristic analysis-based cutoff levels for κ plus λ total FLC delineated risk groups with highly significant differences in overall survival (Figure); International Prognostic Scoring System-adjusted HR (95% CI) in PMF was 1.9 (1.3-2.7) and in MDS 6.3 (2.7-16.6). No correlations were seen with leukemia-free survival, karyotype or JAK2, MPL or IDH mutations. Conclusions: Elevated plasma FLC concentration predicts inferior survival in both PMF and MDS. Its lack of correlation with leukemia-free survival and tumor-specific genetic markers suggests a primarily host-driven biological phenomenon that might be applicable to other malignant and non-malignant conditions. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Myeloid sarcoma is a tumor mass consisting of myeloid blasts occurring at anatomical site other than the bone marrow (Arber et al. Blood 2016;127(20):2391-2405). It is a subgroup of acute myeloid leukemia, which can be localized or disseminated and may involve multiple organs. It can present with or without a positive bone marrow. It may precede or follow bone marrow involvement. It may be identified at diagnosis or relapse, and is not uncommon after stem cell transplantation (Koc et al. Cancer 1999;85(3):608-615; Yoshihara et al. Biol. Blood Marrow Transplant 2012;18(12):1800-1807). Objective: To describe the clinical characteristics, cytogenetics, prognosis and outcome of patients with myeloid sarcoma with or without bone marrow involvement. Methods: The Mayo Clinic database was interrogated using the ICD-9 codes 205.0, 205.2, 205.3, as well as terms "myeloid sarcoma," "chloroma," and "extramedullary sarcoma" in clinical notes and pathology reports. Patients' follow up information was collected until July 2016. Results: Ninety six patients with a diagnosis myeloid sarcoma were identified. The diagnosis was based on biopsy results and in some cases imaging studies in addition to bone marrow biopsy. The median age was 53 (range 17-83) years, and 64 (67%) patients were males. Myeloid sarcoma with de novo (primary) and secondary acute myeloid leukemia (with antecedent hematologic malignancy and therapy related) accounted for 64% (61) and 36% of the cases respectively. The sites involved based on their frequency of occurrence included integumentary system (skin and soft tissues) in 37 (38%), lymphatic system in 17 (18%), the gastrointestinal and genitourinary system in 14 (15%), the nervous system in 9 (9%), the breast in 3 (3%) and multiple and other single sites in 16 (17 %). Bone marrow cytogenetics findings were documented in 74 (77%) patients; favorable, intermediate, and poor cytogenetic abnormalities account for 7 (9%), 45 (61%), and 22 (30%) cases respectively. After a median follow up of 135 weeks, 57 (59%) patients died. The median survival of primary and secondary acute myeloid leukemia with myeloid sarcoma was 52 and 11.5 months (P<0.0001); and that of favorable, intermediate and unfavorable cytogenetics abnormalities was 169, 52 and 17.5 months (P=0.04) respectively. Twenty six (27%) patients had no bone marrow involvement; and 18 (69%) of them were primary myeloid sarcoma (without antecedent malignancy or therapy). The median (range) age of those with and without bone marrow involvement was 53 (17-83) and 56 (17-81) years (P=0.6). At diagnosis patients with and without bone marrow involvement have a median (range) hemoglobin (gm/dL) (10.3 (6.2-15.4) vs 13.1 (9.9-15.2) P=0.0002), white blood cell count (X109/L) (21.4 (1.1-182.5) vs 5.8 (2.4-23.2) P<0.0001), and platelet count (X109/L) (71 (8-437) vs 250 (17-561) respectively. Aggressive chemotherapy therapy was given to 58 (83%) and 20 (77%) of patients with and without bone marrow involvement (P=0.6). The median survival was 17 and 20 months with and without bone marrow involvement (P=0.4). Of those with bone marrow involvement, 49 (70%) achieved complete remission, and 26 (53%) of those individuals subsequently relapsed. Conclusion: The treatment outcome of patients with myeloid sarcoma with or without bone marrow involvement seems the same. The conventional risk factors, antecedent hematological neoplasms and cytogenetic findings, have significant impact on survival. Disclosures Al-Kali: Celgene: Research Funding; Onconova Therapeutics, Inc.: Research Funding.

Abstract Background : Refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) is a provisional entity in the MDS/MPN overlap syndromes, with diagnostic features of RARS, along with a platelet count > 450 x 10(9)/L and large atypical megakaryocytes. Mutations involving SF3B1 (~80%), JAK2 (~60%), TET2 (~25%) and ASXL1 (~15%) have been reported. The frequency of thrombotic events in RARS-T is thought to be similar to that of essential thrombocytosis (ET) (3.6 vs 3.9/100 patient years; Hematologica 2012; 1036-41). However, unlike in ET, it remains unclear as to whether thrombotic events in RARS-T impact overall (OS) or thrombosis-free (TFS) survival. Methods : 82 patients with WHO-defined RARS-T were included in the study. All patients had bone marrow (BM) biopsies, iron stains for detection of BM ring sideroblasts (RS) and cytogenetics performed at diagnosis. Mutational analysis for JAK2, CALR, MPL, SF3B1, SRSF2 and ASXL1 was carried out on BM DNA obtained at the time of diagnosis. Details of type of thrombotic event and cardiovascular (CV) risk factors including; hypertension, diabetes, smoking and dyslipidemia were obtained by careful review of the medical record. OS was calculated from time of initial diagnosis to the time of last follow-up or death. TFS was calculated from the time of diagnosis of RARS-T to development of thrombosis in uncensored patients and date of last follow up or death in patients censored for thrombosis. Conventional statistics were utilized for all analyses. Results: Among the 82 study patients, 46 (56%) were males and median age was 72 years (range, 48-93). At a median follow-up of 26.5 months; 48 (59%) deaths and 2 leukemic transformations were documented. Median OS was 44 months. Karyotype was diploid in 61 (74%) and analyzed mutational frequencies were; SF3B1 67% (28/42), JAK2 V617F 40% (25/61), ASXL1 21% (9/41), SRSF2 6% (2/31), MPL 1% (2/41) and CALR 0, respectively. Cardiovascular risk factors were present in 52 (63%). a) Thrombotic events and their impact on thrombosis free survival: Eight (10%) patients had a thrombotic event prior to or at the time of diagnosis of RARS-T (venous-8, arterial-0). Nine (11%) patients developed subsequent thrombotic events (venous-7, arterial-2), with no fatalities. In univariate analysis, lower hemoglobin level (p=0.008), lower BM RS % (p=0.04), history of thrombosis (p=0.02), and absence of SF3B1 mutations (p=0.017) were associated with an inferior TFS. Age (p=0.07), JAK2 mutation status (p=0.56) and CV risk factors (p=0.95) did not have prognostic impact. Given the association between SF3B1 mutations and BM RS, in a multivariable model that included these two as covariates, only the absence of SF3B1 mutations retained prognostic significance (p=0.02). Absence of SF3B1 mutation remained significant when history of thrombosis or lower hemoglobin level were introduced into the multivariable model. b) Risk factors for overall survival: In univariate analysis, hemoglobin <10 gm/dl (p=0.007), presence of circulating blasts (p=0.002) and presence of CV risk factors (p=0.04) were associated with an inferior OS. Neither history of thrombosis (p=0.59) nor SF3B1 (p=0.12) mutations affected OS. In multivariable analysis, hemoglobin <10 gm/dl (p=0.03) [HR 1.9; 95% CI 1.1-3.5] and circulating blasts (p=0.002) [HR 1.3; 95% CI 1.1-1.6] remained significant. Conclusions: In contrast to what is observed in ET, thrombosis history does not appear to affect either overall or thrombosis-free survival in RARS-T. The current study suggests a lower thrombosis risk in SF3B1 -mutated patients with RARS-T, compared to their SF3B1 wild-type counterparts. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1752 Background: Patients with primary (PMF) or post-polycythemia vera/essential thrombocythemia (post-PV/ET MF) myelofibrosis often harbor a JAK2 mutation and also display abnormally increased inflammatory cytokines (J Clin Oncol. 2011;29:1356). Therefore, JAK-STAT is an appealing drug target in such patients. Ruxolitinib (INCB018424) is a small molecule ATP mimetic that inhibits both JAK1 and JAK2 and has been evaluated for its therapeutic activity in MF, in the setting of phases 1, 2, and 3 clinical trials. Methods: The first phase-1/2 MF study using ruxolitinib was conducted at the MD Anderson Cancer Center and Mayo Clinic. A total of 153 patients were included in the study whose first line results were published in September, 2010 (NEJM 2010;363:1117). The current report constitutes a sponsor-independent analysis of long-term outcome in the 51 Mayo Clinic patients who participated in the particular clinical trial. Results I: Baseline characteristics: The 51 patients (37 males) from the Mayo Clinic were enrolled between October, 2007 and February 2009. The median time from treatment initiation is now 3.5 years. MF subtype distributions were PMF 60%, post-PV MF 32% and post-ET MF 10%. Median (range) values were age 61 years (39–79), hemoglobin 10.6 g/dL (7.4-15.3), leukocyte count 15.8 (2.0–136), and palpable spleen size 19 cm (0–32). The proportion of patients with red cell transfusion dependency was 24%, hemoglobin <10 g/dL 38%, unfavorable karyotype 18%, pruritus 24%, night sweats 26%, and JAK2V617F 84%. DIPSS-plus risk distributions were high 18%, intermediate-2 48%, intermediate-1 22% and low 14%. Results II: Response and treatment duration: According to the International Working Group for Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria, spleen response rate was 29% and anemia response rate 21%. Responses were also seen in constitutional symptoms (63%) and pruritus (92%). To date, treatment has been discontinued in 47 (92%) patients. The treatment discontinuation rates at 1, 2 and 3 years were 51%, 72% and 89%, respectively. For the 47 patients who were taken off study, median duration of treatment was 9.2 months (range 1.3–42 months). Reasons for treatment discontinuation included loss or lack of response/disease progression (∼40%), toxicity with and without lack of response/disease progression (∼34%), patient/physician choice often associated with lack of response (13%), and death on study (∼4%). Results III: Toxicity: Grade ≥2 thrombocytopenia and anemia occurred in 26% and 33% of patients and persisted in the majority of afflicted patients after drug discontinuation. To date, 18 deaths (36%) and 5 (10%) leukemic transformations have been recorded. Serious adverse events occurred upon drug discontinuation in 6 cases (13%) and were characterized by immediate relapse of symptoms, rapid and painful enlargement of spleen sometimes associated to splenic infarct, and acute hemodynamic decompensation occasionally leading to a septic shock-like syndrome. Results IV: Survival: There was no significant difference in the survival of the 51 ruxolitinib-treated patients compared to that of a cohort of 410 cases of PMF seen at the Mayo Clinic in the most recent 10-year period: unadjusted (Figure 1; p=0.43) and adjusted for DIPSS-plus (Figure 2; p=0.58). Conclusions: Ruxolitinib is effective in alleviating constitutional symptoms in the majority of patients with MF. Its activity in reducing spleen size is modest and not always durable. It is imperative that patients be alerted about important drug adverse events including potentially irreversible thrombocytopenia, worsening of anemia, and potentially catastrophic withdrawal symptoms. Ruxolitinib therapy does not appear to affect survival in MF. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 4009 Trisomy 8 is the most common among sole cytogenetic abnormalities in both acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). In the very first paper published on isocitrate dehydrogenase (IDH) mutations in AML, 13 of the 16 IDH1 mutations detected were associated with normal karyotype, 2 with trisomy 8 and one with trisomy 13. Trisomy 8 was also recurrent in patients with IDH1/IDH2-mutated post-MDS AML. In the current study we examined the prevalence and disease distribution of IDH1 and IDH2 mutations in a large (n=157) group of patients with hematologic malignancies and isolated trisomy 8. The Mayo Clinic cytogenetic database allowed identification of 157 patients with isolated trisomy 8. Archived bone marrow cell pellets were used to extract DNA for IDH1 and IDH2 mutation analysis. Eighteen IDH mutations were identified: 15 IDH2 (14 R140Q and one R140W) and 3 IDH1 (2 R132C and one R132G). Seventeen of the 18 IDH mutations occurred in myeloid malignancies whereas one (IDH2R140W) occurred in a patient with angioimmunoblastic lymphoma who was not previously exposed to chemotherapy or radiotherapy, and in whom the IDH2 mutation disappeared after effective lymphoma chemotherapy. Among the 17 IDH-mutated myeloid malignancies, disease-specific IDH1/IDH2 mutational frequencies were as follows: 27% (3/11) for post-MDS AML, 25% (3/12) for therapy-related MDS/AML, 15% (8/54) for de novo MDS, 13% (2/15) for de novo AML and 3% (1/32) for myeloproliferative neoplasm (MPN). In contrast, IDH mutational frequencies were significantly lower among 64 additional patients with AML or MDS without isolated trisomy 8: 7% in de novo AML (n=28), 0% in de novo MDS (n=21), 0% in post-MDS AML (n=11) and 0% in therapy-related MDS/AML (n=4). In the 54 patients with trisomy 8-associated de novo MDS, prognosis was similar between IDH mutated (n=8; median survival 14 months) and unmutated (n=46; median survival 16 months) cases (p=0.7). The majority of IDH-mutated cases with de novo MDS belonged to high risk MDS disease category. However, 3 of the 8 IDH-mutated patients with de novo MDS and 2 of the 3 with therapy-related MDS did not display excess bone marrow blasts. The current study suggests a possible association between IDH mutations and trisomy 8 in AML and MDS but not in MPN or MDS/MPN. The fact that the mere presence of trisomy 8 did not result in a more than expected incidence of IDH mutations in MPN or MDS/MPN makes it unlikely that such an association would be secondary to trisomy 8-associated genetic or biologic changes. Instead, it is possible that IDH mutations, which have been shown to cluster with high-risk disease in both MPN and MDS associated with 5q-, promote a selective advantage for the survival of the clone that harbors trisomy 8. Consistent with this contention, we were able to demonstrate in one of our patients with relapsed AML, the presence of IDHR132C both at initial AML diagnosis and time of relapse, whereas the trisomy 8 abnormality was seen only at the time of relapse. Regardless, the presence of molecular heterogeneity among patients with trisomy 8-associated AML or MDS might explain the controversial prognostic influence of the specific cytogenetic abnormality. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 4104 Background: The International Prognostic Scoring System (IPSS) for primary myelofibrosis (PMF) uses five predictors of inferior survival: age > 65 years, hemoglobin < 10 g/dL, leukocytes > 25 × 109/L, circulating blasts ≥ 1% and constitutional symptoms (Cervantes F et al. Blood 2009; 113: 2895). The dynamic IPSS (DIPSS) utilizes the same prognostic variables but can be applied at any time during the disease course (Passamonti F et al. Blood 2010; 115: 1703). IPSS-independent risk factors for survival have since been described and include unfavorable karyotype, red cell transfusion need and platelets < 100 × 109/L. Objectives: i) To determine if the aforementioned IPSS-independent risk factors for survival in PMF (i.e. unfavorable karyotype, red cell transfusion need and platelets < 100 × 109/L) are also DIPSS-independent. ii) To develop and validate a refined DIPSS model that incorporates DIPSS-independent prognostic factors for survival. iii) To establish a prognostic model for leukemia-free survival in PMF. Methods: The Mayo Clinic database for PMF was used to identify patients in whom bone marrow histologic and cytogenetic information was obtained at the time of their referral. WHO criteria were used for PMF diagnosis and leukemic transformation (Vardiman JW et al. Blood 2009; 114: 937). None of the patients in the current study were included in the original group of patients used to describe DIPSS (Passamonti F et al. Blood 2010; 115: 1703). Results: A total of 793 patients met the above-stipulated criteria. The study population was divided into two groups based on whether or not patients were seen at the Mayo Clinic within (n=428; training set) or beyond (n=365; test set) their first year of diagnosis. i) Objective 1: Multivariable analysis that included DIPSS risk category (low, intermediate-1, intermediate-2 and high risk), karyotype (favorable or unfavorable), platelet count (≥ or <100 × 109/L) and transfusion status (independent or dependent) was performed using the training set and all four variables were found to be significant as independent predictors of survival (p<0.0001, <0.0001, 0.0008 and 0.01, respectively). ii) Objective 2: Using the respective hazard ratios (HR) obtained during the multivariable prognostic analysis in the training set, HR-weighted adverse points were assigned: 3 points for high-risk DIPSS, 2 points for intermediate-2 risk DIPSS, and 1 point each for intermediate-1 risk DIPSS, unfavorable karyotype, platelets < 100 × 109/L or transfusion need. Accordingly, a refined DIPSS model (i.e. DIPSS-plus) was devised using the training set (Figure 1) and subsequently validated in the test set (Figure 2): low-risk (0 adverse points), intermediate-1 risk (1 adverse point), intermediate-2 risk (2-3 adverse points) and high-risk (4-6 adverse points). Considering the entire group of 793 study patients, the respective median survivals were 185, 78, 35 and 16 months (p<0.0001). ii) Objective 3: Multivariable analysis identified platelet count (p=0.0007) and karyotype (p=0.04) but not DIPSS or transfusion status as independent predictors of leukemia-free survival. We used these two variables to classify patients into a low (favorable karyotype and platelets ≥ 100 × 109/L) or high (unfavorable karyotype or platelets < 100 × 109/L) risk category for leukemic transformation; the respective 5- and 10-year risk of leukemic transformation were 6% and 12% vs. 18% and 31%, respectively (p<0.0001; HR 3.3, 95% CI 1.9–5.6). Conclusions: DIPSS-plus effectively incorporates prognostic information from karyotype, platelet count and transfusion status into the DIPSS prognostic model for PMF. Unfavorable karyotype or platelets <100 × 109/L is associated with a significantly higher risk of leukemic transformation in PMF. Disclosures: No relevant conflicts of interest to declare.