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Abstract Background : Pre-treatment determinants of survival in adult acute myeloid leukemia (AML) include performance status, age, karyotype, the distinction between primary and non-primary AML and FLT3-ITD/NPM1 mutational status. Current literature on AML natural history and risk factors is often based on information derived from stringent protocol studies. In the current series of 1,123 adult patients seen at the Mayo Clinic between 2004 and 2017, we examined long-term survival specified by a number of primarily established risk factors. Methods: Diagnosis of AML and its sub-classification was according to World Health Organization criteria. Study subjects were recruited from the Mayo Clinic AML database. Conventional response criteria were used for CR and CRi assignment; the latter met all criteria for CR with the exception of platelet count <100 x 109/l or absolute neutrophil cunt <1 x 109/l. Standard statistical methods were used for analysis of overall survival, calculated from the initial diagnosis of AML to date of death or last follow-up; analyses were performed both in the absence and in the presence of censoring of survival at time of allogenic stem cell transplant (ASCT). The JMP® Pro 13.0.0 software from SAS Institute, Cary, NC, USA, was used for all calculations. Results: 1,123 adult patients (median age 65 years, range 18-94; 61% males) with non-APL AML were considered; 61% were age >60 years. 351 (31%) patients were seen between 2004 and 2009 and 772 (69%) between 2010 and 2017. AML subcategories were primary (56%), post-myelodysplastic syndromes (post-MDS; 24%), therapy-related (10%), post-myeloproliferative neoplasm (post-MPN; 8%) and post-MDS/MPN (3%). Cytogenetic risk distribution, according to the European LeukemiaNet classification, was favorable in 47 (4%), intermediate in 650 (58%) and adverse risk in 426 (38%) patients. FLT3, NPM1 and CEBPA mutation information was available in 462 (24% mutated), 393 (27% mutated) and 228 (11% mutated) patients, respectively. Treatment included intensive chemotherapy (IC) in 766 (68%) patients, less aggressive chemotherapy, including the use of hypomethylating agents in 144 (13%) and supportive care alone in 213 (19%) patients. ASCT was utilized in 258 (23%) cases, almost all performed after achieving CR/CRi. Complete remission (CR) and CR with incomplete count recovery (CRi) were listed in 333 (30%) and 248 (22%) patients, respectively; the corresponding rates in IC-treated patients were 43% and 32%. Almost all cases of CR/CRi occurred in IC-treated patients; 2 (1.4%) CRs were listed for less aggressive chemotherapy. After a median follow-up of 11 months, 798 (71%) deaths were recorded. Median survival for all 1,123 patients was 14 months with 1-, 3- and 5-year survival rates of 54%, 29% and 23%, respectively; a slight but significant (p=0.01) improvement in survival was apparent in more recent years (Figure 1a). Figures 1b, 1c and 1d depict analysis stratified by AML subcategories, treatment received and response obtained, respectively. Similarly, figures 2a, 2b and 2c depict analysis stratified by karyotype, use of ASCT and age. Multivariable analysis of pre-treatment parameters evaluable in all 1,123 patients identified age >60 years (HR 2.2, 1.9-2.6), adverse karyotype (HR 2.9, 1.9-4.9), intermediate-risk karyotype (HR 1.6, 1.02-2.6), post-MPN AML (HR 1.9, 1.5-2.4) and other secondary AML (HR 1.3 (1.1-1.6), as risk factors for shortened survival; the inclusion in the model of FLT3/NPM1 mutational status in 392 informative cases confirmed the adverse prognostic effect of age >60 years (HR 1.8, 1.4-2.5), adverse karyotype (HR 3.7, 1.4-15.3), post-MPN AML (HR 2.8, 1.6-4.6), other secondary AML (HR 1.4, 1.0-1.9) and FLT3+NPM1- (HR 2.8, 1.6-4.9) and FLT3-NPM1- (HR 1.7, 1.2-2.7) profile. Results were unchanged when survival was censored at time of ASCT. Additional prognostic interaction with treatment strategy and ASCT is further elaborated in an accompanying abstract to be presented. Conclusions: The current study, the largest coming from a single institution, provides practically useful information that should assist with patient consultation on AML prognosis and treatment. The study confirms the primary prognostic importance of age, karyotype and FLT3/NPM1 mutational status, in real-life practice. Novel observations included comparable value of CRi vs CR and the particularly worse prognosis associated with post-MPN AML. Disclosures Al-Kali: Novartis: Research Funding.

Abstract Background : Thrombosis is a characteristic feature in essential thrombocythemia (ET) and polycythemia vera (PV). Previous studies had focused on thrombotic events occurring after diagnosis and did not always distinguish between arterial and venous thrombosis. Arterial thrombosis in ET has been associated with age >60 years, JAK2 mutations, leukocyte count >11 x 109/l, history of thrombosis and cardiovascular risk factors, and venous thrombosis with male sex (Blood 2011;117:5857). In the current two-enter study, we looked for associations between both driver and other mutations, with first incidences of arterial and venous thrombosis in ET and PV, analyzed together and separately. Methods : Study patients were recruited from the Mayo Clinic, Rochester, MN, USA and the University of Florence, Florence, Italy, based on availability of next-generation sequencing-derived mutation information. Diagnoses were according to the 2016 World Health Organization criteria (Blood. 2016;127:2391). Conventional statistics was employed to examine significance of associations, with separate analysis of arterial vs venous thrombosis, occurring at any time before or after formal diagnosis of ET or PV. For the purposes of the current study, only first events were considered. Results: 906 molecularly-annotated patients (416 from Mayo and 490 from Florence), including 502 ET and 404 PV cases, were included in the current study. The Mayo/Florence cohorts included 270/232 ET (median age 57/54 years, 60%/59% females) and 146/258 PV (median age 63/58 years, 52%/44% females) patients; median follow-up was 9.9/12.9 years for ET and 10.7/12.4 years for PV. Driver mutation distribution in ET was 55% JAK2, 27% CALR, 5% MPL and 13% triple-negative. Most frequent mutations, other than JAK2/CALR/MPL, were TET2 (14%; 11% in ET and 18% in PV) and ASXL1 (13%; 13% in ET and 13% in PV). 301 (33%) patients experienced first time thrombosis, before or after diagnosis, including 152 (30%) in ET and 149 (37%) in PV (p=0.03); arterial events occurred in 174 (19%) patients, including 96 (19%) in ET and 78 (19%) in PV (p=0.9); venous events occurred in 177 (20%) patients, including 82 (16%) in ET and 95 (24%) in PV (p=0.007). The number of vascular events after diagnosis was 174 (19%) for arterial and 154 (17%) for venous thrombosis, with no significant difference between ET and PV. Associations with arterial thrombosis: In multivariable logistic regression analysis that included both ET and PV (n=906), age >60 years (23% vs 16%; OR, 1.6, 95% CI 1.1-2.2) and absence of ASXL1 and RUNX1 mutations (21% vs 9%; OR 2.6, 95% CI 1.4-4.8) were associated with arterial thrombosis; these associations remained significant (or near significant) when ET and PV were analyzed separately; in addition, JAK2 mutations in ET displayed borderline significance (p=0.05). Overall incidence of arterial events in ET was estimated at 27% in the presence of all three risk factors (i.e. older age, presence of JAK2 mutations and absence of ASXL1/RUNX1 mutations), 21% with two risk factors, 13% with one risk factor and 9% in the absence of all three risk factors (p=0.01). Associations with venous thrombosis: In multivariable analysis, including both ET and PV (n=906), JAK2 mutations (p<0.001), higher leukocyte count (p=0.03) and younger age (p=0.04) were identified as being significant. Analysis of ET patients only (n=502) identified JAK2 mutations (p<0.001; OR 2.4, 95% CI 1.4-4.1), absence of SRSF2 mutations (p=0.03) and younger age (p=0.04) as independent risk factors and in PV patients (n=404), higher leukocyte count (p=0.06). Prognostic interaction between JAK2 mutations and age: In ET, the overall frequency of venous events was 27% for young patients with JAK2 mutations vs 13% for older JAK2 mutated cases vs 10% for JAK2 unmutated young patients vs 13% for JAK2 unmutated older patients (p<0.001). The corresponding percentages for arterial events were 20%, 24%, 14% and 19%, respectively (p=0.1). Conclusions: JAK2 mutations contribute to the risk of both venous (younger patients) and arterial (young and older patients) thrombosis, in an age-dependent manner; the association with venous thrombosis might explain the higher incidence of venous thrombosis in PV, compared to ET. Additional studies are required to confirm the observed lower risk of thrombosis in patients with ASXL1, RUNX1 and SRSF2 mutations and provide insight into the underlying biological explanation. Disclosures No relevant conflicts of interest to declare.

Abstract Background: While several population-based studies have reported on adverse outcomes and life expectancy in myeloproliferative neoplasms (MPN) (JCO. 2015;33:2288; AJH. 1999;61:10; Leukemia. 2013;27:1874; JCO. 2012;30:2995), large-scale studies reporting mature data have been rare and important questions remain unanswered. The current study documents the Mayo Clinic (MC) decades-long experience with over 3,000 consecutive MPN patients including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) with the majority of patients followed until death. Herein, we provide mature, and importantly, risk-stratified survival data and disease complication estimates. Methods: Study patients were recruited from MC, Rochester, MN, USA between 10/27/1967 and 12/29/2017. All MPN diagnoses and documentation of fibrotic/leukemic transformations were in accordance with the 2016 World Health Organization criteria (Blood. 2016;127:2391). Clinical and laboratory data were abstracted from medical records. Risk-stratification used conventional risk models considering age, leukocytes, and venous thrombosis for PV (Leukemia. 2013;27:1874), international prognostic score for ET (Blood. 2012;120:1197), and dynamic international prognostic scoring system for PMF (Blood. 2010;115:1703). Statistical analyses were based on parameters obtained at the time of referral to MC which, in the majority of cases, coincided with or was within 1 year of diagnosis. All patients were followed from diagnosis until death or date of last follow-up/contact. Recipients of allogeneic stem cell transplants were censored at the time of transplant. Standard statistical methods and time-to-event curves prepared using the Kaplan-Meier method were used to compare MPN subgroups. Survival data for low-risk ET/PV were compared with age- and sex-matched controls from Olmstead County, MN, USA. JMP® Pro 13.0.0 software (SAS Institute, Cary, NC, USA) was used for all analyses. Results: 3,023 consecutive patients (median age 62 years, range 18-96; 51% males) were considered, including 89% diagnosed within the year: 665 PV, 1076 ET and 1282 PMF. Conventional risk stratification in 2925 evaluable patients revealed low, intermediate, and high-risk status in 26%, 29%, and 45% of PV and 30%, 42%, and 28% of ET patients, respectively, while PMF cases were attributed low (14%), intermediate-1 (38%) -2 (40%) and high (8%) risk (Table 1). After a median follow-up of 8.2 years for PV (range 0-39), 9.9 for ET (range 0-47), and 3.2 for PMF (range 0-31), 1631 (54%) deaths, 183 (6%) leukemic transformations, 244 (14%) fibrotic progressions, and 516 (17%) thrombotic events were recorded (Table 1). Median overall survival (OS) was 18 years for ET, 15 for PV and 4.4 for PMF (p<0.05 for all inter-group comparisons) (Figure 1A). Leukemia-free survival was similar for ET and PV (p=0.22) and significantly worse for PMF (p<0.001) (Figure 1B). PV, compared to ET, was associated with higher risk of fibrotic progression (p<0.001) (Figure 1C). Thrombosis risk after diagnosis was highest in PV and lowest in PMF (p=0.002 for PV vs ET; 0.56 for ET vs PMF; and 0.001 for PV vs PMF) (Figure 1D). Following risk stratification, median OS in low-risk ET (28 years) and low-risk PV (27 years) were superimposed (p=0.89) (Figure 2). Similarly, intermediate or high-risk PV and ET patients had comparable OS within each risk strata (p=0.23 and 0.11, respectively). Low-risk PMF survival was analogous to that of intermediate-risk PV (p=0.06). All other risk-stratified categories disclosed significantly different inter- and intra-group survival patterns (p<0.001) (Figure 2). Despite their categorization as favorable-risk disease, both low-risk ET and low-risk PV displayed excess mortality relative to age- and sex-matched controls with median survival of 26.7 and 28.1 years respectively, compared to the expected 37.5 and 39.2 years (p<0.001) (Figure 3). Conclusions: The current study provides large-scale and uniquely mature survival and outcomes data in MPN and highlights MPN subgroup risk categorization as cardinal in appraising disease natural history. Interestingly, OS was only marginally better in ET, compared to PV, while the latter clearly displayed a higher risk of thrombosis and fibrotic progression. Moreover, data disclosed shortened life expectancy relative to matched controls even in MPN with favorable risk attribution. Disclosures Busque: BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Paladin: Consultancy.

Abstract Backgrounds B cell receptor (BCR) signals and microenvironment protection have been recognized to have key influences on CLL survival and activation. Akt activation is down-stream of the BCR signaling cascade and is critical in the mediation of the bi-directional interactions between CLL B-cells and bone marrow stroma. MK2206 is an allosteric Akt inhibitor previously tested for safety in solid tumor patients. Our preclinical data has demonstrated the synergy of MK2206 with bendamustine (B) to induce CLL apoptosis in vitro. MK2206 also abolished the signal activation and cytokine production induced by BCR ligation in CLL leukemic cells (Ding, ASH 2012). Therefore, we conducted a phase 1 trial testing the safety and efficacy of MK2206 in combination with bendamustine and rituximab (BR) for patients with relapsed/refractory CLL. Methods A phase 1 dose-escalation study was designed to define the maximum tolerated dose (MTD) as well as the safety and efficacy of 3 dose levels (90 mg or 135 mg or 200 mg weekly) of the oral Akt inhibitor MK2206 in combination with bendamustine (70 mg/m2 daily for 2 days in each cycle) and rituximab (cycle 1: 375 mg/m2, cycle 2-6: 500 mg/m2) therapy in relapse/refractory CLL patients. To test the targeting efficacy of MK2206 on Akt and downstream signals, we designed a one-week “run-in” of single agent MK2206 before the initiation of BR during cycle 1. MK2206 was then given along with BR on day 1 of cycles 2-6. Tumor response was evaluated 2 months after the 6th/last cycle of therapy based on IWCLL 2008 criteria. Correlative laboratory studies included assessment of Akt signaling and the plasma cytokine levels (multiplex beads assay (Invitrogen)) at baseline and after one week of first dose of single agent MK2206. Results Nine patients (median age 68) were enrolled in the phase I portion of this trial. All 9 patients had unmutated immunoglobulin heavy chain variable region genes (IGHV) and 4 had del(11q). Six had received prior chemoimmunotherapy (CIT: FCR or PCR or PCO) and 5 had high risk disease defined as early progression within 26 months of the last CIT. Three had received alemtuzumab containing regimen. We have observed potent lymphocyte mobilization in all evaluated patients (n=7) after one-dose of MK2206 during week 1 (mean increase ALC: 35%) as well as reductions of plasma CCL3, CCL4 and CCL2 in the majority of the patients. A single dose-limiting toxicity (DLT) (febrile neutropenia and hemolytic anemia) was observed at dose level 1 (90 mg weekly) among 6 patients treated at this dose. Two patients with dose-limiting toxicities at dose level 2 (135 mg weekly) were observed where one patient had a rash and one patient had dehydration and febrile neutropenia among three patients treated at this dose. Accordingly, the 90 mg once weekly dose was determined to be the MTD for phase 2 trial testing. The most frequent grade 3 or 4 adverse events observed to date were neutropenia (44%) including febrile neutropenia (22%), rash (22%), diarrhea (22%), nausea and vomiting (11%), dehydration (11%), hemolytic anemia (11%) and thrombocytopenia (11%). The frequency of cytopenias was similar to the published German experience with BR (50% grade 3 or 4 hematological toxicities compared to 44% in N1087) in relapsed CLL patients (Fischer, JCO 2011). The median number of cycles received was 6 (range 1-6). Using an intent to treat analysis, two patients achieved complete response (CR, n= 2, 22%), one patient achieved nodular partial response (nPR, n=1, 11%) and five patients achieved a partial response (PR, n=5, 56%). The overall response rate (ORR) is 89%. Conclusion The Akt inhibitor MK2206 in combination with BR is well tolerated in patients with relapsed/refractory CLL. Single dose of MK2206 inhibits Akt phosphorylation, mobilizes leukemic cells and decreases plasma cytokines involved in BCR signals. The preliminary efficacy of this combination demonstrated promising results with a 89% ORR and 22% CR albeit in the small phase 1 cohort. These results compare favorably to BR alone (9% CR and 59% ORR) in relapsed/refractory CLL patients. Phase 2 testing of this combination is now underway. Acknowledgment This work was supported by the funding from NCI grant K23CA160345 (WD), NCI grant CA95241 (NEK) and Alliance for Clinical Trials in Oncology (CA025224 and CA33601). Disclosures: Off Label Use: MK2206, used in a phase 1 trial of relapsed CLL disease. Shanafelt:Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding. Zent:Novartis: Research Funding; GlaxSmithKline: Research Funding; Biothera: Research Funding; Genzyme: Research Funding; Genentech : Research Funding. Reeder:Celgene: Research Funding; Novartis: Research Funding; Millenium: Research Funding.

Abstract Background MBL is a precursor state to CLL, with a prevalence of ~5-8% in the general population and 15-18% in CLL families. To date, 41 single nucleotide polymorphisms (SNPs) have been found to be associated with CLL. We previously showed that a PRS of the weighted average of the number of risk alleles of these SNPs is associated with CLL risk using cases and controls from the International Lymphoma Epidemiology (InterLymph) Consortium. We validated this score in an independent sample of CLL cases and controls from the Genetic Epidemiology of CLL (GEC) Consortium, a cohort of families with ≥2 members with CLL. In the CLL families we also reported an association between the PRS and MBL risk, where 93% of MBLs were low-count MBL. Here we evaluate the PRS in an independent sample ascertained from the Mayo Clinic Biobank. Methods The Mayo Clinic Biobank is a large-scale bio-repository of adult patients assembled to provide a wide array of health-related research studies. Biobank participants (N=2530) were screened for MBL using a highly-sensitive, 8-color (CD38, CD45, Kappa, Lambda, CD19, CD23, CD5 and CD20) flow-cytometry assay on stored cryopreserved peripheral blood mononucleotide cells. Low-count and high-count MBL were defined as those individuals who had <85% and ≥85 clonal B-cells out of total B-cells, respectively. Individuals without MBL ("controls") were frequency matched to MBLs based on age and sex, after excluding non-Caucasian and non-interpretable flow results. Participants were genotyped using the Illumina OmniExpress array. Standard genotyping quality-control metrics were applied. We computed the PRS as previously published and categorized it by quintiles based on values previously used with InterLymph controls. The middle quintile served as the reference category. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CI), adjusting for age at consent, sex, and socioeconomic status. In addition, we compared the median PRS by low-count MBL and high count MBL using the Mann-Whitney U test. Results We identified 276 MBLs overall and 2109 controls; 97% (N=267) of MBLs had low-count MBL and only 3% (N=9) had high-count MBL. We then selected 844 controls frequency matched to the MBL cases on age and sex. Family history of leukemia/lymphoma was 11.3% among MBLs overall and 8.8% among controls. The median PRS was 7.88 and 7.46 (Figure) among MBLs overall and controls, respectively. The continuous PRS had a 1.75-fold increased risk for MBL overall (CI:1.5-2.1, P=2.65x10-12). Compared to the middle quintile, the highest quintile had 2.2-fold increased risk for MBL overall (CI:1.5-3.3, P=1.46x10-4) and the lowest quintile had 0.6-fold decreased risk (CI:0.4-0.96, P=0.03). The median PRS for low-count and high count MBL were 7.86 and 8.04, respectively. The continuous PRS had a 1.75-fold increased risk for low-count MBL (CI:1.5-2.1, P=4.81x10-12) and a 1.89-fold increased risk for high-count MBL (CI:0.8-4.2, P=0.13), however, the effect is not statistically significant between high-count and low-count MBL (P=0.89). Conclusion In this independent sample, we validated our previous findings that the CLL PRS is associated with MBL risk. Although the sample size of high-count MBL was limited (N=9), there is evidence of a weak trend towards a higher PRS compared to low-count MBL and controls Larger sample size of high-count MBL is warranted in order to stratify MBL risk by low-count and high-count MBL. These results may help identify individuals at higher risk of MBL including low-count and high-count MBL, beyond the risk associated with age and family history of CLL. Figure: Polygenic risk score distribution by control and MBL status Figure. Figure. Disclosures Parikh: Janssen: Research Funding; Pharmacyclics: Honoraria, Research Funding; Gilead: Honoraria; Abbvie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; MorphoSys: Research Funding. Cerhan:Nanostring: Research Funding; Celgene: Research Funding; Jannsen: Other: Scientific Advisory Board. Kay:Janssen: Membership on an entity's Board of Directors or advisory committees; Acerta: Research Funding; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Morpho-sys: Membership on an entity's Board of Directors or advisory committees. Shanafelt:Genentech: Research Funding; Pharmacyclics: Research Funding; GlaxoSmithKline: Research Funding; Jansen: Research Funding.

Abstract This study evaluated the contributing roles of flow cytometric immunophenotyping of blood and bone marrow and immunohistochemical paraffin section staining of bone marrow biopsies in the staging of B-cell malignant lymphoma. Flow immunophenotyping was performed on a marrow specimen in 175 cases; a corresponding blood specimen was also immunophenotyped in 135 of these cases. Morphologic marrow involvement by lymphoma was found in 59 cases; flow immunophenotyping identified 54 cases with a monoclonal B-cell process: morphology-positive/flow-positive (n = 49), morphology-positive/flow-negative (n = 10), morphology-negative/flow-positive (n = 5), and morphology-negative/flow-negative (n = 111). The 10 morphology-positive/flow-negative cases included 5 follicular and 5 large-cell lymphomas with minimal marrow involvement. All 5 morphology-negative/flow-positive cases were from patients with large-cell lymphomas and bulky clinical disease. Because the blood contained the same B-cell clone in 2 of 2 morphology-negative/flow-positive cases studied, blood contamination of marrow may account for these findings. Blood flow cytometric immunophenotyping studies were positive in 32 cases; 30 had marrow involvement by morphology and were from patients with follicular, mantle cell, lymphoplasmacytic, small lymphocytic, or marginal zone lymphomas. From our results, we conclude that (1) bone marrow flow cytometric immunophenotyping is not a cost-effective replacement for good morphologic evaluation in lymphoma staging and that (2) a positive peripheral blood flow cytometric immunophenotyping study when performed in low-grade lymphomas correlates with marrow involvement.

Abstract Abstract 2835 Background: Extrinsic growth and survival signals provided by nonneoplastic cells present within the tumor microenvironment promote the growth and survival of CLL cells. For example, bone marrow stromal cells, blood-derived “nurse-like” cells and follicular dendritic cells have been shown to promote the survival of CLL cells via the provision of both soluble and cell-contact dependent factors. More recently, monocytes were convincingly shown to support the survival of CLL cells during in vitro culture, and many of the factors (e.g. BLyS/BAFF, SDF-1, CD14) previously implicated in supporting the growth and survival of CLL cells are produced by monocytes. To explore the potential clinical implications of these in vitro findings, we evaluated the relationship between the absolute monocyte count (AMC) at diagnosis and disease progression in a well defined cohort of CLL patients. We hypothesized that the presence of a relative monocytosis at presentation in patients newly diagnosed with CLL may create a nurturing environment for CLL cells and be associated with more rapid disease progression. Methods: Previously untreated patients diagnosed with CLL/SLL within 12 months of presentation to the Mayo Clinic (from 1/1/2000-8/31/2010) were identified (n=1396). The AMC was obtained from routine complete blood counts (CBC) with automated or manual differentials that were performed within 3 months of diagnosis (n=947). The primary study objective was to determine whether the AMC is associated with time to first treatment (TTFT) in CLL. The secondary objective was to determine whether the AMC had independent prognostic value after adjusting for CD38/CD49d/Zap-70 expression, IGHV gene mutation status, and cytogenetic (11q-, 17p-) findings by FISH analysis. Results: The median age was 66 years and the median AMC was 550/μL (380–812/ μL, 1st-3rd quartile) at diagnosis (normal range: 300–900/μL). No significant difference in the median AMC was observed by age, gender; CD38, CD49d, or Zap-70 expression; IGHV gene mutation status or cytogenetic findings. Patients were followed for a median of 3.2 years (range: 0–10.3), with disease progression requiring the initiation of treatment observed in 268 (28%) patients. On multivariate analysis using a Cox proportional hazards model which incorporated age, gender and Rai stage, the AMC (as a continuous variable) was associated with TTFT with a hazard ratio (HR) of 1.099 (per unit change; 95% CI, 1.003–1.205; p=0.04). The optimal cutpoint for the association between AMC and TTFT was determined to be ≥1, 170/μL, a threshold that remained an independently significant predictor of TTFT after adjusting for age, gender and Rai stage with a HR of 5.1 (95% CI, 2.56–10.10, p<0.0001). The median TTFT was 1.0 year for patients with an AMC ≥1, 170/μL and 7.4 years for those with an AMC <1, 170/μL (p<0.0001). In order to evaluate whether the AMC had independent prognostic value after adjusting for other prognostic biomarkers, CD38, CD49d, Zap-70, IGHV gene mutation status and cytogenetic findings (11q- or 17p-), were individually incorporated into the multivariate analysis. In each case, the AMC remained an independent predictor of TTFT, with HRs ranging from 4.31 to 5.43 (p<0.0001 for all analyses). Conclusions: The AMC at the time of diagnosis as measured by a routine CBC is associated with accelerated disease progression in CLL/SLL independent of other prognostic biomarkers. These results suggest that the in vitro observation that nonneoplastic cells present in the tumor microenvironment promote CLL cell survival may have direct clinical implications for the prognostic evaluation of CLL patients and further substantiate the pathogenic role of monocytic cells in CLL. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 971 Unlike the case in acute myeloid leukemia, there is limited information on the prognostic impact of IDH mutations in myelodysplastic syndromes (MDS). In the current study of 277 patients with MDS, IDH mutations were detected in 34 (12%) cases: 26 IDH2 (all R140Q) and 8 IDH1 (six R132S and two R132C). Mutational frequency was 4% (2 of 56) in refractory anemia with ring sideroblasts (RARS), 12% (16 of 130) in refractory cytopenia with multilineage dysplasia, 14% (2 of 14) in MDS-unclassifiable, 14% (6 of 42) in refractory anemia with excess blasts (RAEB)-1, and 23% (8 of 35) in RAEB-2. Normal karyotype was noted in all but one IDH1-mutated cases and 13 IDH2-mutated cases. Multivariable analysis identified presence of mutant IDH1 (p=0.0004; HR 4.0, 95% CI 1.9–8.8), revised International Prognostic Scoring System (IPSS-R) risk category (p<0.0001), and red cell transfusion need (p=0.002) as independent predictors of inferior survival (Figure 1). In a similar multivariable analysis, mutant IDH1 was the only variable associated with shortened leukemia-free survival (p=0.001; HR 7.0, 95% CI 2.3–20.8). The presence of IDH2 R140Q did not affect overall (p=0.54) or leukemia-free (p=0.81) survival (Figure 2). The current study suggests a powerful adverse prognostic effect for mutant IDH1 in MDS. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2806 Background: A high degree of prognostic certainty is required to recommend or discourage high risk treatment procedures in primary myelofibrosis (PMF). The Dynamic International Prognostic Scoring System (DIPSS-plus) uses eight risk factors to predict overall survival (OS) in PMF: unfavorable karyotype, peripheral blood (PB) blast count ≥1%, platelet count <100 × 109/L, white blood cell count (WBC) >25 × 109/L, hemoglobin level <10 g/dL, red blood cell transfusion need, constitutional symptoms, and age >65 years (Gangat et al. JCO 2011;29 :392). The presence of four or more of these risk factors defines high-risk disease. purpose: The purpose of the current study was to enhance the prognostic weight of some of the DIPSS-plus risk factors with the intent to identify one or two parameters that can reliably predict death in the first two years of disease. Methods: An updated Mayo Clinic database of 884 karyotypically-annotated patients with PMF was used. Calculations of 2-year mortality rates and variables considered for prognostic value were from time of referral to the Mayo Clinic. Cytogenetic risk categorization per DIPSS-plus was further refined to capture additional prognostic information from monosomal karyotype (MK) (Vaidya et al. Blood 2011;117 :5612) and inv(3)/i(17q) abnormalities (Caramazza et al. Leukemia 2011;25 :82). Receiver operating characteristic (ROC) analysis was employed to define best discriminant levels. Results: To date, 564 (64%) deaths have been documented. Each one of the aforementioned DIPSS-plus risk factors was associated with a 2-year mortality rate that ranged from 42% (PB blast count ≥1%) to 60% (unfavorable karyotype). High-risk disease per DIPSS-plus was associated with 57% two-year mortality. The only risk factors that were associated with >80% two-year mortality were MK (n =19) and inv(3)/i(17q) abnormalities (n =8) and both were associated with significantly worse survival, compared to other unfavorable karyotype (n =102): HR (95% CI) of 5.1 (3.1−8.4) and 3.9 (1.7−8.8), respectively. ROC analysis identified PB blast counts of 2% and 9% (AUC 0.62) and WBC of 43 × 109/L (AUC 0.66) as best discriminant levels for predicting 2-year mortality; OS was significantly worse in the presence of PB blast >9% (HR 4.1, 95% CI 2.8–6.1) vs. 2% to 9% (HR 1.8, 95% CI 1.5–2.2) vs. <2%; the corresponding 2-year mortality rates were 73%, 46% and 25%. OS was also significantly worse in the presence of WBC ≥40 × 109/L (HR 2.8, 95% CI 2.2–3.6) vs. 26–39 × 109/L (HR 1.6, 95% CI, 1.2–2.1) vs. <26 × 109/L; the corresponding 2-year mortality rates were 63%, 42% and 28%. Two-year mortality rates exceeded 80% in the presence of any two of the following: PB blast count >9%, WBC ≥40 × 109/L or unfavorable karyotype other than MK or inv(3)/i(17q). Conclusions: A greater than 80% 2-year mortality in PMF is predicted by the presence of MK, inv(3)/i(17q) abnormalities, or any two of the following: PB blast >9%, WBC ≥40 × 109/L, other unfavorable karyotype. Such patients and those with high DIPSS-plus risk should be referred to allogenic stem cell transplantation earlier than later. Disclosures: No relevant conflicts of interest to declare.

Abstract BACKGROUND: Information regarding risk factors for leukemic transformation (LT) in primary myelofibrosis (PMF) is limited, although both leukocytosis and abnormal cytogenetics have previously been implicated. The current retrospective study examines clinical variables at diagnosis as well as specific treatment modalities for their effect on LT in PMF. METHODS: Diagnoses of PMF and LT were based on World Health Organization criteria. In addition, study inclusion required availability, for review, of bone marrow histology and clinical data obtained at or within 6 months of diagnosis but prior to treatment intervention. Statistical methods used were standard and included Cox regression analysis of leukemia-free survival (LFS). RESULTS: A master database of PMF patients seen at the Mayo Clinic from 1976 through 2006 was queried to identify 311 patients who fulfilled the aforementioned stipulated criteria for study inclusion; median age was 57 years and 41% were females. At presentation, 30% of the patients displayed a hemoglobin level (Hgb) of < 100 g/L, 20% a leukocyte count of < 4 or > 30 x 109/L, 18% a platelet count of < 100 x 109/L, 12% an absolute monocyte count (AMC) of ≥ 1 x 109/L, 28% hypercatabolic symptoms and 35% a peripheral blood (PB) blast percentage of ≥ 1; 27 patients (9%) had a PB blast percentage of ≥ 3. Dupriez prognostic scoring system distribution for high, intermediate, and low risk disease was 30 (10%), 94 (30%), and 187 (60%) patients. Among 182 and 139 evaluable patients, 74 (41%) and 80 (58%) displayed cytogenetic abnormalities and JAK2V617F, respectively. At a median follow-up of 27 months (range 0–282), 27 cases (9%) of LT were documented at a median time from diagnosis to LT of 26 months (range 0.8–266). Effect of clinical and laboratory variables at diagnosis on leukemic transformation By univariate analysis, LFS was negatively affected by anemia (p=0.04), leukocytosis (p=0.04), PB monocyte count ≥ 1 x 109/L (p=0.02), platelet count of < 100 x 109/L (p=0.004), hypercatabolic symptoms (p=0.03) and PB blast percentage of ≥ 3 (p<0.0001); LFS was not affected by PB blast percentage of > 1 but < 3 (p=0.49). By multivariable analysis, significance was sustained only for PB blast percentage of ≥ 3 (p = 0.0002) and platelet count of < 100 x 109/L (p = 0.02) with hazard ratios (HR) of 5.8 and 2.8 and 95% confidence intervals (CI) of 2.3–14.6 and 1.2–6.6, respectively. The presence of JAK2V617F did not affect LFS (p=0.98). Effect of specific treatment on leukemic transformation By univariate analysis, LT was significantly associated with history of splenectomy (p=0.01) and treatment with erythropoiesis stimulating agents (ESA; p=0.004), danazol (p=0.007), and androgens (p=0.03) but not with hydroxyurea (p=0.17), interferon alpha (p=0.95), thalidomide (p=0.26) or other drugs. On multivariable analysis, significance was sustained for both ESA (p = 0.005; HR 3.1, CI 1.4–6.8) and danazol (p = 0.01; HR 3.4, CI 1.3–8.5), even when the aforementioned prognostic indicators at diagnosis were added as covariates to the multivariable model. CONCLUSIONS: The current study identifies PB blast percentage of ≥ 3% and platelet count of < 100 x 109/L, at presentation, as independent risk factors for LT in PMF. Unexpectedly, the study also revealed an association between LT and treatment history with ESA or danazol. These observations are intriguing, considering recent reports on the possible harmful effects of ESA in certain solid tumors.