Patnaik, Mrinal M.

Abstract Background L-asparaginase (LASP) therapy in adults is associated with frequent hepatic and metabolic side effects, often resulting in dose adjustments and omissions. Pegylated asparaginase (PEGASP) substituted for LASP improves convenience of administration with comparable efficacy; however, adverse event (AE) management remains challenging. The incidence and management of LASP- and PEGASP-induced metabolic and hepatic complications in adult ALL patients is not well defined. Methods This single center, retrospective, observational study was approved by the Mayo Clinic Institutional Review Board. Consecutive adult patients with a confirmed diagnosis of ALL receiving LASP or PEGASP containing chemotherapy regimens between January 2000 and October 2012 were evaluated. Patients were followed up to 60 days after the last LASP or PEGASP dose for development of biochemical and clinical pancreatitis, hypertriglyceridemia and hepatotoxicity. Hyperglycemia was not analyzed due to confounding variables, such as concomitant corticosteroid administration. AEs were graded as per the National Cancer Institute Common Terminology Criteria (CTCAE) version 4.03. Analysis was performed using Cox proportional hazard models with odds ratios (with 95% confidence intervals) reported to demonstrate the strength of association between group and AE rate. Results Of 74 adult patients, 54 (73%) met inclusion criteria. History of dyslipidemia, diabetes mellitus, cholelithiasis and coronary artery disease was documented at baseline in 13 (24%), 4 (7%), 4 (7%) and 10 (19%) patients, respectively. Twenty eight (52%) patients received LASP, 22 (41%) received PEGASP and 4 (7%) received both. A total of 399 doses including 335 (84%) LASP and 64 (16%) PEGASP were administered. Distribution based on treatment schedules was as follows; CALGB 9111 (n=20 (37%), Larson et al, 1998), E2993 (n=13 (24%), Goldstone et al, 2008), C10403 (n=9 (17%), NLM: NCT00558519), CCG 1941 (n=7 (13%), Gaynon et al, 2006) and Augmented Hyper-CVAD (n=5 (9%), Faderl et al,2011). Six (11%), 20 (37%), and 53 (98%) patients experienced pancreatic, lipid (hypertriglyceridemia) and hepatic adverse events, respectively. In this group, CTCAE grade 3/4 AEs occurred in 0 (0%), 8 (15%), and 28 (52%) patients, respectively. No deaths were directly related to these complications. Patients receiving PEGASP were more likely to experience AE of any CTCAE grade (OR 11.5, 95% CI 4.4-30.3, p < 0.0001), including grade3/4 AEs (OR 27.9, 95% CI 11.4-68.2, p < 0.0001) in comparison to those receiving LASP. All cases of pancreatitis manifested as biochemical elevation in pancreatic enzymes, and were either grade 1 (n=4, 67%) or grade 2 (n=2, 33%). All patients were managed conservatively. Management of hypertriglyceridemia was heterogeneous across all grades and included observation (n=11, 55%), non-pharmacologic interventions (n=1, 5%), medication management (n=4, 20%) and combined strategies (n=4, 20%). The most common practice was a combination of fibrate derivatives (fenofibrate) and fish oil (n= 5). One patient with a peak triglyceride level of 2285 mg/dL was placed on an insulin/dextrose infusion for 4 days. Hepatic toxicity manifested as CTCAE grade 3/4 transaminitis in 13 (24%) patients, hyperbilirubinemia in 4 (7%) patients and both in 11 (20%) patients. Temporal correlation was used to best distinguish confounding variables including possible hepatoxicity from azole antifungals and other drugs. Management of hepatic toxicity included delay in dosing, subsequent LASP or PEGASP dose reduction and laboratory monitoring until resolution. Overall, deviations in LASP or PEGASP administration were documented in 18 (33%) patients due to metabolic or hepatic AEs. Eight (15%) patients required omission of at least 1 dose, 7 (13%) experienced delays of administration and 7 (13%) needed a dose reduction. Conclusion PEGASP administration resulted in significantly higher AE rates in comparison to LASP and this significance was retained when comparing AEs of CTCAE grade 3 and 4. Given the growing trend of using PEGASP combination chemotherapy in adults with ALL, a detailed analysis looking at the increase in side effects, their consequences (delayed tereatment and dose reductions) and the impact of these factors on disease remission and survival is needed. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Imetelstat is a 13-mer lipid-conjugated oligonucleotide that targets the RNA template of human telomerase reverse transcriptase. A pilot study of imetelstat therapy in myelofibrosis showed the induction of complete (CR) or partial remissions, as well as molecular remissions, in a subset of patients (Blood. 2014;124:634). In the particular study, CR was significantly higher in patients with SF3B1 or U2AF1 spliceosome mutations, which provided the rationale for the current study; spliceosome mutations are closely associated with refractory anemia with ring sideroblasts with (RARS-T) or without (RARS) thrombocytosis (Leukemia. 2013;27:1826). Methods Diagnosis of RARS and RARS-T was according to WHO criteria (Blood. 2009;114:937). Study patients were treated with a 2-hour intravenous infusion of 7.5 mg/kg imetelstat (Janssen Biotech Inc., Horsham, PA, USA) every 4 weeks. Drug activity was monitored by both formal response criteria (Blood. 2006;108:419) and effect on spleen size, thrombocytosis and leukocytosis. Adverse events (AEs) were monitored by Common Terminology Criteria for Adverse Events (Version 4.03). Laboratory correlative studies included analysis of mutations. Results Accrual to this signal study is now complete and median time from study registration, as of 5/10/2015, was 17.1 months (range 16.1-20.1). Among the 9 study patients, 5 had RARS-T, 3 had RARS and one had "MDS/MPN overlap". Median age was 70 years (78% males). 8 (89%) patients were transfusion-dependent. One patient (RARS-T) had marked splenomegaly (palpable at 16 cm). Three patients each had leukocytosis and thrombocytosis. Seven (78%) patients had received prior treatments, including erythropoiesis stimulating agents in 6 (67%). Baseline international MDS prognostic scoring system scores were intermediate-1 (n=7) and intermediate-2 (n=2). Karyotype was normal in all but one patient with loss of Y chromosome. Drug activity Median duration of treatment with imetelstat was 13.7 months (range 6.6-17.9). Three (38%) patients achieved transfusion-independence (TI) during treatment, defined as not requiring transfusions for at least 8 weeks; 2 had RARS and one RARS-T. The median time to TI was 11 weeks (range 9-14) and the median TI duration was 28 weeks (range 9-37). One of the 3 "TI" patients also had resolution of leukocytosis and thrombocytosis. A 4th patient experienced >50% decrease in palpable spleen size as well as a decrease in transfusion need. In addition, imetelstat induced normalization of counts in two additional patients with thrombocytosis and leukocytosis. As of 5/10/2015, 4 (44%) patients remain on active treatment and one death had been recorded (deemed unrelated to imetelstat). The 5 treatment discontinuations were: death during active therapy, discovery of second malignancy, progression into acute leukemia and insufficient response (n=2). Safety Treatment-emergent grade 4 neutropenia and thrombocytopenia were seen in 2 (22%) and 1 (11%) patients, respectively; neutropenia, and thrombocytopenia were seen in 4 (44%), and 2 (22%) patients. Grade 3 anemia was seen in 6 (67%) of the patients, however baseline grade 2 anemia was noted in 2 (22%) and grade 3 in 3 (30%) patients. None of the grade ≥3 hematologic toxicities lasted ≥4 weeks.. The following grade 3 non-hematologic events occurred in 1 subject: aspiration, fatigue, and lipase increase and a patient with pre-existing cardiovascular disease history experienced a grade 5 heart failure. Treatment-emergent liver function test abnormalities affected: ALT (grade 1 56%/grade 2 11%), AST (grade 1 56%/grade 2 11%), ALP (grade 1 33%), and total bilirubin (grade 2 11%). For patients that discontinued treatment with imetelstat, these events were mostly reversible. Mutation studies Patients were screened for mutations involving JAK2, SF3B1, U2AF1 and SRSF2. Three patients were mutated for JAK2, 7 for SF3B1 (4 K700E, 2 H662Q, one K666N) and one for U2AF1 (Q157P). All three patients with "TI" (H662Q, K700E, K666N) and the 4th patient with spleen response (K700E) were SF3B1mutated. Post-treatment analysis showed no effect of imetelstat on mutations. Conclusions Treatment with imetelstat may offer clinical benefit in patients with RARS or RARS-T with generally acceptable safety profile and warrants further clinical investigation. Disclosures Al-Kali: Celgene: Research Funding. Wan:Janssen Research & Development: Employment, Equity Ownership.

Abstract Background Chronic myelomonocytic leukemia (CMML) is a clonal stem cell disorder with overlapping features between myelodysplastic syndromes and myeloproliferative neoplasms. Numerous models exist for CMML prognostication, with more recent studies suggesting (JCO 201; 31:2428) or refuting (Leukemia 2013; 27:1504) the prognostic contribution of ASXL1 mutations. Furthermore, SETBP1 mutations were recently shown to be associated with shortened overall survival (OS) in CMML (Leukemia 2013; 10:1038). In the current international study, we examine these issues in a larger cohort of 431 patients. Methods 431 patients with WHO-defined CMML were included in the study. 235 (55%) were seen at the Mayo Clinic from 1997 through 2012. The remainders were from the French CMML registry (JCO 201; 31:2428). All patients underwent bone marrow (BM) examination and cytogenetic evaluation at diagnosis. DNA analysis for spliceosome component mutations (SRSF2, SF3B1 and U2AF1), ASXL1 and SETBP1 mutations were carried out on BM specimens obtained at diagnosis. In order to address the aforementioned discrepancy regarding the prognostic impact of ASXL1 mutations, relevant analyses in the Mayo cohort were first performed with and without inclusion of missense ASXL1 mutations. ASXL1 mutations from the French cohort did not include missense mutations. We evaluated the prognostic relevance of ASXL1 and SETBPI mutations, as well as several other clinical and laboratory parameters including those previously identified by the MDAPS (Blood 2002;99:840) the Spanish cytogenetic risk stratification (Haematologica 2011;96:375), and the Mayo prognostic model (Leukemia 2013;27;1504). Results Among the 431 study patients, 286 (66%) were males and median age was 73 years (range, 17-93 years). There were 368 (85%) patients with CMML-1 and the remainder had CMML-2. At a median follow-up of 23 months, 260 (60%) deaths and 70 (16%) leukemic transformations were documented. Median survivals were 38 months for CMML-1 and 24 months for CMML-2 (p=0.11). Mutational frequencies were 44% (173/390) for SRSF2, 6% (23/379) for SF3B1, 7% (27/387) for U2AF1, 38% (164/411) for ASXL1 (excluding missense mutations), and 5% (21/431) for SETBP1. Risk stratification was, based on i) Mayo prognostic model: 172 (40%) high, 151 (35%) intermediate and 94 (25 %) low risk, ii) MDAPS: 15 (3%) high, 73 (17%) intermediate-2, 125 (29%) intermediate-1 and 218 (50%) low risk and iii) Spanish cytogenetic stratification system: 316 (73%) low, 43 (10%) intermediate and 50 (12%) high risk. In the Mayo cohort, univariate analysis revealed that the exclusion of missense mutations changed the prognostic impact of ASXL1 mutations from non-significant (p=0.08) to significant (p=0.001). Accordingly, all subsequent analyses excluded missense ASXL1 mutations. In univariate analysis, lower hemoglobin (p<0.0001), lower platelet count (p=0.0027), higher absolute monocyte count (AMC) (p<0.0001), higher absolute lymphocyte count (ALC) (p=0.0002), circulating immature myeloid cells (IMC) (P<0.0001), cytogenetic risk stratification (p<0.0001) and ASXL1 mutations (p<0.0001) were significant for OS. In multivariable analysis, lower hemoglobin (p=0.0001; RR 2, 99% CI 1.6-2.6), lower platelet count (p=0.002; RR 1.5, 99% CI 1.2-1.9), higher AMC (p=0.0002; RR 2.2, 99% CI 1.6-3.1) and ASXL1mutations (p=0.0009; RR 1.9, 99% CI 1.5-2.4) retained their independent negative prognostic impact. Similarly, in univariate analysis, leukemia-free survival (LFS) was negatively affected by age (p=0.0015), lower hemoglobin (p=0.0002), lower platelet count (p=0.0002), higher AMC (p<0.0001), higher ALC (p=0.0001), circulating IMC (p<0.0001), BM blasts (p<0.0001), and cytogenetic risk stratification (p=.0002). ASXL1 (p=0.17) and SETBP1(p=0.87) mutations were not found to be significant. In multivariable analysis, lower platelet count (p=0.0005), higher AMC (P=0.0042), circulating IMC (P=0.008) and cytogenetic risk stratification (p=0.009) retained their independent negative prognostic impact. Conclusions In the current international study of a large cohort of patients with CMML, we confirm and clarify the independent prognostic relevance of ASXL1 mutations. The relatively high frequency of ASXL1 mutations in CMML warrants its inclusion in contemporary prognostic models. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2976 Poster Board II-955 Background: AT deficiency is classified as type 1 (quantitative), or type 2 (qualitative), based on plasma AT activity and antigen levels. However, such levels can sometimes be only mildly and equivocally reduced. Type 2 deficiency can be subdivided into type 2a (reactive center loop [RCL]), type 2b (heparin binding domain), and type 2c (pleiotropic), usually by molecular analysis, but the role of AT molecular analysis in patient diagnosis and management is uncertain. Objectives: 1) to estimate the frequency of mutation detection in possible hereditary AT deficiency, and 2) to correlate clinical manifestations with AT deficiency type as determined by plasma AT, and by AT genotype. Methods: Mayo Clinic patients (n=16) were categorized as type 1 or 2 by plasma AT, or by molecular analysis for previously reported type 2a-c mutations. Patient characteristics were abstracted from medical records. The SERPINC1 putative promoter region, all exons (n=7) and splice junctions, and the 3'UTR were PCR amplified from leukocyte genomic DNA, and sequenced with both forward and reverse primers. Results: The mean patient age at diagnosis was 32 years (range 18-65); 11 (69%) were women. 12 (75%) patients were type 1 by plasma AT, while 4 were type 2 by molecular analysis (Table). The mean plasma AT (range) activity/antigen for types I and 2 patients were 52% (39-71%)/53% (39-68%) and 58% (43-67%)/85% (60-103%), respectively [normal range=80-130%]. 13 (82%) patients had VTE (8 [61%] idiopathic; 10 [77%] recurrent); 5 (32%) had stroke/TIA, 4 at a young age. Thrombosis “penetrance” appeared greater among type 1 families. Only 2 pregnancy losses occurred in 14 pregnancies among 6 type 1 women, and no losses occurred in 5 pregnancies among 2 type 2b women. Among the 14 (88%) patients with mutations identified, all were heterozygous and 8 patients had 6 novel mutations; 2 patients had no mutation detected. Plasma AT activity/antigen did not always correlate with genotype; 1 patient each with type 2b and 2c by molecular analysis had concordant decreases in plasma AT activity and antigen (i.e., a type 1 plasma phenotype), while amino acid changes (T85K and F239L) predicting reduced plasma AT activity only had a type 1 plasma phenotype. One type 2b (Q118P) patient had extensive recurrent VTE. Conclusion: 88% of patients had a detrimental mutation, suggesting that molecular analysis can be helpful for diagnosis. While our findings should be interpreted with caution, type 1 patients may have a higher prevalence of stroke/TIA at a young age and a higher family thrombosis penetrance compared to type 2. Plasma AT activity and antigen frequently did not correlate with genotype. However, whether molecular analysis is useful for clinical management remains uncertain. Finally, 50% of patients had a novel mutation, suggesting that reported mutations causing AT deficiency have not reached gene saturation. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction L-asparaginase therapy results in systemic depletion of antithrombin (AT) and fibrinogen (FG), resulting in thrombotic (TE) and hemorrhagic events (HE). Prophylactic correction of coagulation disturbances have been inconclusive with regard to cost effectiveness, and specifically cost effectiveness of antithrombin concentrate (ATC) replacement has not been evaluated. (Abbott et al, 2009, Mitchell et al, 2003). Currently, AT repletion is recommended for levels less than 60%. (Stock et al, 2012) Several treatment protocols with distinctly different L-asparaginase (LAS) or pegaspargase (PEG) doses complicate the frequency and intensity of ATC replacement. We carried out this study to evaluate the cost effectiveness of ATC replacement, based on our institutional practice. Methods This single center, retrospective, observational study was approved by the Institutional Review Board and conducted at Mayo Clinic, Rochester, MN. Consecutive adult patients with a confirmed diagnosis of ALL receiving LAS or PEG between January 2000 and October 2012 were evaluated. Patients with hereditary or acquired thrombophilias or pre-existing TE or HE, were excluded. Per institutional guidelines, ATC was administered if levels were less than 70%. The Centers for Medicare & Medicaid (CMS) single drug historical pricing guide was utilized for 2000-2004. ATC cost beginning January 1, 2005, was derived from the CMS average sales price, reported quarterly. To adjust for price differences due to regimen utilization trends, each dose was also calculated at the final 2012 cost of 3.05/unit. ATC repletion practices and estimated expenditures were compared between regimens. Results Fifty four patients were treated with LAS or PEG containing regimens. Of these, 47 (87%) received ATC. Twenty-eight patients received LASP, 22 received PEGASP and 4 received both. Distribution across protocols was; CALGB 9111 (n=20, Larson et al, 1998), E2993 (n=13, Goldstone et al, 2008), C10403 (n=9, NLM: NCT00558519), CCG 1941 (n=7, Gaynon et al, 2006) and Augmented HyperCVAD (n=5, Faderl et al, 2005). PEG and LAS dosing schemes are outlined in table 1 . LAS doses were converted to PEG upon specific protocol revision or at discontinuation of LAS availability in 2012. Regimens specified a dose cap with the exception of C10403. A total of 399 LAS and PEG doses resulted in 378 instances of ATC repletion. The reimbursement price of ATC in 2000 was estimated at 1.50/unit U.S. dollars (USD) and 3.04/unit USD by the fourth quarter of 2012. The total estimated average sales price was 2,471,745 USD over the study period. C10403 resulted in the highest median number of PEG doses per patient (n = 5) and a median of 17 ATC doses per dose of PEG. This resulted in C10403 being the most expensive regimen with the median expense for ATC replacement being 118,064 USD (chart 1). This conclusion was also seen after comparing different regimens using the most recent 2012 cost estimates. The overall incidence of TE or HE was 17% and equally distributed between regimens (please see accompanying abstract). Conclusions Repletion of ATC in patients receiving asparaginase containing chemotherapy regimens is very expensive and continues to add to costs at many centers, without clear benefit, especially with regards to TE and HE. A prospective, randomized, multicenter clinical trial looking to answer this question is the need of the hour. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Chronic myelomonocytic leukemia (CMML) is a clonal hematologic disorder that was classified by the World Health Organization (WHO) as a myelodysplastic/ myeloproliferative overlap disease. Cytogenetic abnormalities have a significant prognostic role in many hematologic neoplasms, but their prognostic value in CMML has been debatable. Recently, monosomal karyotype (MK) has been reported to be a marker of poor prognosis in patients with myelodysplastic syndromes (MDS) and primary myelofibrosis, but its value in CMML is unknown. Aim To study MK effect on clinical outcome for patients diagnosed with CMML Method A retrospective study of all cases diagnosed with CMML at Mayo Clinic Rochester between 1994 to 2011 was performed. Only pts with complete cytogenetic analysis at presentation to our institution were included. MK was defined as the presence of ≥ 2 autosomal monosomies or one autosomal monosomy with at least one structural abnormality (Breems et al, JCO 2008). CK was defined as the presence of at least 3 chromosomal abnormalities. Appropriate IRB approval was obtained in accordance with Helsinki declaration. Comparison between groups’ medians was done using Wilcoxon test, while survival estimates were calculated using Kaplan-Meier curves using JMP V9. Results A total of 262 pts diagnosed with CMML had available cytogenetic data at diagnosis. Median age was 72 years, 176 (67%) were male. Median hemoglobin 10.5 g/dL, white blood cells (wbc) 12 x109/L, platelet 89 x109/L, peripheral blood (PB) blast 0, and bone marrow (BM) blast 4%. CMML2 was seen in 9% while 47% were proliferative (wbc >13). Leukemic transformation was documented in 34 pts (13%). Median overall survival was 513 days. Cytogenetic (CG) analysis was diploid in 167 pts (64%). Trisomy 8 was the most frequent cytogenetic abnormality at 8% (22), followed by complex karyotype (CK) 5% (14), then -7 at 4% (10) and MK 3% (7, six of which were also CK). Comparing pts with diploid CG to other categories indicates: to abnormal CG pts had lower wbc (0.001), PB blasts (p<0.0001), and BM blasts (p=0.0001); to CK pts had lower PB blasts (p=0.003) and higher platelets (p=0.03); to -7 pts had lower wbc (p=0.005), PB blast (p=0.0004), BM blasts (p=0.03) and higher platelets (p=0.03); to +8 pts had lower PB blast (p=0.02) and BM blasts (p= 0.01); no difference was noted when compared to MK. Median OS was statistically significantly worse in MK+ vs MK- (24 vs 527 days, p= 0.002), but not in other comparisons: -7 vs others (250 vs 527 days, p=0.2), CK+ vs CK- (256 vs 527 days, p=0.05), diploid vs others (570 vs 365 days, p=0.1), +8 vs others (312 vs 527 days, p=0.1). Pts with MK+ only or MK+CK+ did worse than CK+ only or other groups (4, 63, 304, 527 days, respectively, p<0.0001). On a multivariate analysis, MK+ (in addition to platelet, BM blast, hemoglobin, and wbc) did have an impact on OS (p=0.0004), while CK+, -7, +8, diploid CG, age, PB blast did not. Conclusion Cytogenetic abnormalities were not frequent findings in pts diagnosed with CMML (36%), but did affect wbc, PB and BM blasts. The most common cytogenetic abnormality was +8 while MK was present at 3% (less than published data in MDS). Only MK predicted statistically significant shorter mOS between all other cytogenetic categories on both univariate and multivariate analysis. This finding needs to be validated by larger cohorts of pts due to its rare occurrence in CMML. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 460 Background: SF3B1 mutations were recently reported to occur in myelodysplastic syndromes (MDS), especially in the presence of ring sideroblasts (RS) (Papaemmanuil et al. Leukemia Research 2011, Volume 35, Supplement 1, page S18). We sought to accurately define the interaction between SF3B1 mutations, bone marrow morphology, karyotype and prognosis in MDS with ≥15% RS (MDS-RS). Methods: Mayo Clinic databases and cell banks were queried to identify patients with MDS and ≥15% RS (MDS-RS). All study patients were required to have undergone bone marrow examination and cytogenetic evaluation at diagnosis. Pathology slides, including iron stains, were centrally re-reviewed to accurately quantify bone marrow RS percentage and confirm World Health Organization (WHO) morphologic categories. Detailed analysis of clinical and cytogenetic parameters was performed to risk stratify patients according to the revised International Prognostic Scoring System (IPSS-R) (Greenberg et al. Leukemia Research 2011, Volume 35, Supplement 1, page S6). All patients were annotated for their mutational status involving JAK2, MPL and IDH. PCR sequencing was used to identify SF3B1 mutations. Results I: Baseline patient information: The study is currently ongoing; to date, results are availab1e in 88 patients (median age 72 years, 69% males) including 36 (41%) patients with refractory anemia with RS (RARS), 36 (41%) with refractory cytopenia with multilineage dysplasia and ≥15% RS (RCMD-RS), 11 (12%) with refractory anemia with excess blasts (RAEB)-1 and ≥15% RS (RAEB1-RS) and 5 (6%) with RAEB2-RS. Median (range) values were 9.1 g/dL (5.8–15.7) for hemoglobin, 4.1 × 109/L (1.2–35.2) for leukocytes and 164 × 109/L (6–585) for platelets. IPSS-R risk categories were 20% very good, 49% good, 11% intermediate, 3% poor and 16% very poor. Karyotype was normal in 60%, other very good/good risk 16%, intermediate-risk 2%, and poor/very poor in 22%; 14% had monosomal karyotype (MK). Six (7%), four (5%) and zero (0%) patients displayed IDH, JAK2 or MPL mutations. Red cell transfusion need was documented in 27 (31%) patients. Results II: Prevalence and distribution of SF3B1 mutations and clinical correlates: SF3B1 mutations (all heterozygous) were detected in 40 (∼46%) of all 88 study patients: 25 (63%) K700E, 6 (15%) K666N/Q/R, 3 (8%) E622D, 2 (5%) H662D/Q, 2 (5%) Y623C, 1 (3%) R625C, and 1 (3%) T663I. One patient each displayed both SF3B1K700E and IDH2R140Q or SF3B1K700E and JAK2V617F. SF3B1 mutational frequencies were 69% for RARS, 36% for RCMD-RS, 18% for RAEB1-RS and 0% for RAEB2-RS (p=0.0007). SF3B1 mutations clustered with normal (59%) and other very good/good risk (57%) karyotype and were infrequent in poor/very poor karyotype (5%; p=0.0004). Additional significant correlations were noted between SF3B1 mutations and lower IPSS-R risk category (p=0.0004), advanced age (p=0.006), higher platelet count (p=0.0003). Results II: SF3B1 mutations and prognostic relevance in MDS-RS: To date, 68 (∼77%) deaths and 10 (∼11%) leukemic transformations have been documented. Median follow-up for living patients was 82 months. Univariate survival analysis considering all 88 study patients identified the following as strongly significant risk factors: IPSS-R (p<0.0001), WHO morphologic categories (p<0.0001), cytogenetic risk categories (p<0.0001), and transfusion need (p=0.0003). In multivariable analysis, only IPSS-R and transfusion need remained significant. In univariate analysis, the presence of SF3B1 mutations was significantly associated with better overall (p=0.04) and leukemia-free (p=0.03) survival; however, in both instances, significance was completely accounted for by WHO morphologic risk categorization and the morphology-adjusted p values were 0.6 and 0.2, respectively. In other words, when RARS and RCMD were analyzed separately, there was no additional prognostic value from the presence or absence of SF3B1 mutations (Figures 1 and 2; p=0.67 and 0.44, respectively). Conclusions: SF3B1 mutations are prevalent in RARS and RCMD-RS but do not provide additional, WHO morphology-independent or IPSS-R-independent, prognostic information. Disclosures: No relevant conflicts of interest to declare.

Abstract Background In routine myelodysplastic syndromes (MDS) practice, physicians do not submit bone marrow (BM) slides for central review. Instead, they rely on available BM reports to assess prognosis and make therapeutic decisions. Such practice is likely to introduce inaccuracies, especially in the diagnosis of MDS-unclassifiable (MDS-U). The objectives of the current study were to describe the natural history of MDS-U that is diagnosed based on routine BM and peripheral blood (PB) smear reports and compare its prognosis to refractory anemia (RA) or refractory cytopenia with multi-lineage dysplasia (RCMD), which were diagnosed in the same manner. Methods Mayo Clinic databases were reviewed to identify consecutive patients who meet current WHO criteria for MDS-U, RA and RCMD (Swerdlow et al. WHO classification of Tumors, Lyon 2008). No central review was required and diagnosis was based on routine Mayo Clinic pathology reports. Included in the current WHO-defined MDS-U are patients with findings of i) refractory cytopenia with unlineage dysplasia (RCUD) or RCMD with 1% blasts in the PB, 2) MDS with unilineage dysplasia and pancytopenia and 3) persistent cytopenia with ≤1% PB blasts, <5% BM blasts, <10% BM myeloid cell dysplasia and cytogenetic abnormalities considered presumptive evidence of MDS. Patients who had exposure to chemotherapy and/or radiotherapy were excluded. Results A total of 382 patients met WHO diagnostic criteria for MDS-U (n=146; 38%), RA (n=26; 7%), and RCMD (n=210; 55%). Presenting clinical characteristics for patients belonging to each one of these three categories are listed and compared in table 1. There was no difference between the three subgroups in age or gender distribution. Similarly, with the exception of thrombocytopenia that was more prevalent in RCMD, complete blood count and transfusion need at diagnosis were not significantly different between the groups. Risk distribution using conventional prognostic models for survival did not reveal significant differences between MDS-U, RCMD and RA. At the time of this analysis, 265 deaths and 25 leukemic transformations were documented. Overall and leukemia-free survival was similar between the three groups (Figure 1). IPSS and IPSS-R karyotypes (Figure 2&3), however delineate patients into distinct category (P=0.001 and P= 0.01) Conclusions Distinguishing between MDS-U, RCMD and RA, in daily practice, has limited clinical relevance. It might be simpler and more practical to consider MDS without excess blasts under one common morphologic category and utilize instead cytogenetic and molecular information for further prognostic stratification and identify patient subgroups with specific therapeutic needs. Myelodysplastic syndrome-unclassifiable (MDS-U) (n=146) compared with refractory anemia (RA) (n=26) and refractory cytopenia with multilineage dysplasia (RCMD) (n=210) Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2705 Background: Due to similar cytomorphological features and treatment strategies, T lineage lymphomas (T-LBL) and lymphoblastic leukemias (T-ALL) are usually grouped together as a single entity. Traditionally, the difference between T-LBL and T-ALL has been based on percentage of blasts found in the bone marrow (BM): >25% BM blasts and/or presence of peripheral blood (PB) blasts consistent with T-ALL. Recent studies, based on immunophenotypic, cytogenetic and molecular differences, emphasize the clinical uniqueness between T-LBL and T-ALL and argue against grouping them as a single entity. Objectives: To perform a clinicopathologic and cytogenetic comparison between patients with T-LBL and T-ALL in order to identify differences between these disease groups. Methods: We utilized the Mayo Clinic Lymphoma database to identify consecutive adult patients (>18 years) diagnosed with T-cell leukemia and lymphoma from 1980 to 2010. The patients were sub-divided into T-LBL and T-ALL based on BM and PB blasts (absence of BM and PB blasts consistent with T-LBL). Clinicopathological and cytogenetic characteristics were retrospectively reviewed. Result: 50 patients met the criteria for T-cell leukemia/lymphoma (29-T-ALL, 21-T-LBL). 50% of patients in each group were females with median age at diagnosis of 32 years for T-LBL and 29 years for T-ALL. Characteristics associated with a statistically significant survival difference for the cohort included: white blood cell count at diagnosis (>100,000/cmm), platelet count (<50,000/cmm), LDH (>500 U/L), presence of BM blasts and an adverse karyotype (hypodiploidy and MLL rearrangements). ECOG performance status, number of lymph node groups involved, extranodal disease, CNS involvement and constitutional symptoms had no impact on survival. Furthermore, no overall survival difference between patients with T-LBL and T-ALL was identified (figure 1). Among patients with T-LBL, 11 (51%) patients with extranodal disease had shortened survival (p=0.02). CNS involvement was seen in 4 (19%) of T-LBL patients and 5 (17%) of T-ALL patients, and did not affect overall survival (p=0.8). 4 (19%) T-LBL patients and 1 (3%) T-ALL patient had pleural involvement at diagnosis. There were no morphologic, flow cytometric, or immunohistochemical differences noted between the two groups. Conclusion: In a large study from a single institution, we confirm no survival difference between T-LBL and T-ALL, which further provides ongoing support that from a therapeutic standpoint these groups can be viewed as a single entity. However, we hope to further clarify clinical differences by performing microarray and chemokine analysis on available tissue specimens. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction: Disease relapse remains one of the major causes of treatment failure in hematopoietic stem cell transplant (HSCT) following reduced-intensity conditioning (RIC) regimens. Donor chimerism assessment early after HSCT may help identify patients at risk for relapse who may benefit from additional therapeutic interventions but its precise role in this setting is unclear. In addition, the differential impact of conditioning regimen is not well studied. Aim: 1. Study the impact of early full T-lymphocyte chimerism (T-lymphocyte chimerism ≥ 90% on day 30 to 60) on relapse incidence (RI) and acute graft versus host disease (aGVHD) in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) following RIC-HSCT. 2. Looking at the tempo of achievement of complete donor T-lymphocyte chimerism based on the two most common RIC regimens, Fludarabine/Melphalan (FM) and Fludarabine/Busulfan (FB). Method: After IRB approval, patients with AML or MDS who underwent RIC-HSCT with FB or FM between 2008 and 2014 at our institution were identified. Post-transplantation CD3 (lymphocyte) and CD33 (myeloid) donor chimerism were measured per protocol using PCR-based analysis of short tandem repeats. Categorical and continuous variables were analyzed using Pearson's chi-squared and Wilcoxon / Kruskal-Wallis, respectively. Survival estimates were calculated using the Kaplan-Meier and log-rank test. RI was estimated accounting NRM on a competing event analysis using Grey's model. Cox proportional regression was used to compute hazard ratios (HR). Results: Baseline characteristics: Out of 134 patients who received FM or FB, 75 patients had evaluable early sorted chimerism data. 42 and 33 patients received FB and FM, respectively. Patient, disease and transplant variables were balanced in both FM and FB (Table 1). The median follow up of the cohort was 37 months (2.4-43) and at last follow up 29.1% of patients relapsed and 59% died. All patients achieved early complete myeloid chimerism whereas T-lymphocyte chimerism was complete in 50 patients and mixed in 25 patients. Characteristics of early lymphocyte chimerism by status are shown in table 1. Notably, likelihood of achieving complete T-lymphocyte chimerism ≥ 90% at 60 days was 100% versus 47% in FM and FB respectively (p <0.0001). Acute graft versus host disease: There was no significant difference in incidence of grade II-IV aGVHD between patients with full early donor T-lymphocyte chimerism in comparison to those with early mixed donor chimerism (46% vs. 48%, p =0.87). Impact of full chimerism and conditioning regimen on RI and overall survival (OS): Among the entire cohort, patients achieving early full T-lymphocyte chimerism had a significantly lower RI compared to those with mixed chimerism with a HR of 0.38 (CI 0.14-0.97; p=0.044) but OS was not significantly different with HR 0.69 (CI 0.33-1.51; p=0.34). In patients conditioned with FB, there was no difference in 2-year RI between complete or mixed early T-lymphocyte chimerism at 38.2% and 40.7% respectively (p = 0.9). After FM conditioning, all patients achieved early T-lymphocyte chimerism and the 2-year RI was 6.9%. Achievement of early complete lymphocyte chimerism post FB in comparison to FM was associated with significantly higher risk of relapse (HR 8.6 CI 2.07-57, p=0.0025). Furthermore, there was a trend towards worse OS with FB vs. FM with a median of 23 vs. 44 months, respectively (p = 0.058). Conclusion: Similar to prior reports, we observed that full T-lymphocyte chimerism is associated with decreased relapse risk without an increase in aGVHD. Our findings also suggest that RIC with FM yields a higher incidence of early complete T-lymphocyte chimerism and is significantly associated with decreased risk of relapse compared to FB. There was a greater risk of relapse in the FB group, even among those achieving early complete donor lymphoid chimerism. This needs further validation given the small sample size. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.