Knudson, Ryan A.

Abstract Abstract 1751 Because IDH mutations are frequent in blast-phase myeloproliferative neoplasms (MPN), they might contribute to leukemic transformation. We examined this possibility in 301 consecutive patients with chronic-phase primary myelofibrosis (PMF). All study patients were fully characterized for karyotype, JAK2 and MPL mutational status, and Dynamic International Prognostic Scoring System-plus (DIPSS-plus) risk status. DNA from bone marrow or peripheral blood was used to screen for IDH1 and IDH2 mutations, by direct sequencing and/or high resolution melting (HRM) assay. Mutant IDH was detected in 12 patients (4%): seven IDH2 (five R140Q, one R140W and one R172G) and five IDH1 (three R132S and two R132C). MPL exon 10 was mutated in 18 patients (6.3%) and constituted W515L in 14 patients, W515K in 3 and a frameshift mutation in 1 patient. JAK2V617F was detected in 169 (56%) patients. Six patients displayed both JAK2V617F and IDH mutations (IDH2R140Q in 2 patients, IDH2R140W in 1 and IDH1R132S in 3); JAK2V617F allele burden was 1%, 7%, 22%, 27%, 30% and 96%, respectively. One patient displayed both IDHR140Q and MPLW515R. One-hundred and seven (36%) patients were negative for all three mutations. The 12 IDH-mutated patients were clinically compared to patients belonging to the three other molecular subgroups: mutated for JAK2 only (n=164), mutated for MPL only (n=18) and unmutated for all three (n=107). The four molecular subgroups were remarkably similar in their phenotype with few exceptions; IDH-mutated patients were significantly older than those with no mutations (p=0.04) whereas age distribution was similar between patients with mutant IDH, MPL or JAK2. In univariate analysis, overall survival (OS) for IDH-mutated patients was significantly shorter than those for JAK2-mutated (p=0.03), MPL-mutated (p=0.047) or unmutated (p=0.0009) patients. IDH-mutated patients also showed significantly shorter leukemia-free survival (LFS), compared to those with mutant JAK2 (p=0.0008), mutant MPL (p=0.02) or no mutations (p=0.001). After accounting for age, the presence of mutant IDH remained a significant disadvantage for both OS (p=0.04) and LFS (p=0.005). Multivariable analysis of OS that included risk categorization per DIPSS-plus confirmed the independent prognostic relevance of mutant IDH (p=0.03): HR for patients with no mutations =0.39, 95% CI 0.2–0.75; HR for JAK2-mutated patients =0.50, 95% CI 0.27–0.95; HR for MPL-mutated patients =0.53, 95% CI 0.23–1.2. A similar analysis for LFS that included risk factors for LT (i.e. unfavorable karyotype and platelet count <100 × 109/L) as covariates also confirmed the prognostic relevance of mutant IDH (p=0.003): HR for patients with no mutations =0.16; 95% CI 0.06–0.46; HR for JAK2-mutated patients =0.18; 95% CI 0.06–0.48; HR for MPL-mutated patients =0.09; 95% CI 0.01–0.76). Further analysis disclosed that the negative OS and LFS effect of mutant IDH was most pronounced in the presence (p=0.0002 and <0.0001, respectively) as opposed to the absence (p=0.34 and 0.64, respectively) of concomitant JAK2V617F expression. Analysis of paired samples obtained during the chronic and blast phases of the disease was possible in 2 IDH-mutated patients and showed the presence of both IDH and JAK2 mutations at both time points. Our observations suggest that IDH mutations in PMF are independent predictors of leukemic transformation and raise the possibility of leukemogenic collaboration with JAK2V617F. 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 Background The median survival (OS) of patients with primary myelofibrosis (PMF; 6.5y) is significantly shortened compared to reference population (Cervantes et al, JCO 2012; 30:2981). OS is predicted by the four risk categories of IPSS, Dynamic-IPSS and DIPSS-plus score, nevertheless pts heterogeneity persists within these categories, necessitating improved risk stratification. We recently reported that pts harboring mutations in any one of the prognostically relevant ASXL1, EZH2, IDH1/2 and SRSF2 genes constitute a IPSS-and DIPPS-plus independent Molecular High Risk category (MHR+) characterized by significant reduction of OS and leukemia free survival (LFS) (Vannucchi et al, Leukemia 2013). The aim of this work was to analyze the impact of the number of prognostically relevant mutated genes on OS and LFS in PMF. Patients and methods Two independent cohorts are included, a “test cohort” from Europe, analyzed at diagnosis, and a “validation cohort” from Mayo Clinic, analyzed at any time after diagnosis. Mutation analysis was performed in DNA from whole blood or granulocytes using RTQ-PCR, HRM and direct sequencing; all mutations were confirmed at least twice. The prognostic value of the molecular variables with regard to OS and LFS was analyzed by Cox regression. Test cohort It included 490 pts (median age 61y; males = 301) risk stratified by IPSS into high (n=74, 15%), intermediate-2 (n=93, 19% ), intermediate-1 (n=147, 30%) and low (n=176, 36%). The median follow-up was 3.63y (95% CI, 0.06-28.33); 161 pts died (33.0%), of whom 76 (15.6%) had progressed to acute leukemia after a median of 3.4y (0.04-28.3) from diagnosis. One hundred forty-six pts (29.8%) presented at least one of the four aforementioned mutated genes and were classified as MHR+. The OS of MHR+ pts was significantly reduced compared to patients with no mutations (n=344): 80.7 vs 148.9 mo (HR 2.2, CI95% 1.6-3.03). One hundred twelve (22.8%) pts had 1 mutation and 34 (6.9%) had 2 or more mutations. In univariate analysis presence of 2 or more mutated genes was significantly more detrimental for OS (29.5mo; HR 4.12, IC95% 2.6-6.4) than having 1 mutated gene (84.2mo; HR 1.8, IC95% 1.2-2.5) compared with having no mutations (148.9mo). Multivariate analysis results adjusted for IPSS indicated that having two or more mutations was an independent prognostic factor for OS (HR 2.9, 95% CI 1.8-4.5). Notably, the prognostic relevance of harboring two or more mutations involved both lower (low and intermediate-1; HR 1.87, 95% CI 1.3-2.6) and higher (intermediate-2 and high; HR 1.6, 95% CI 1.2-2.1) categories of IPSS. Also LFS resulted significantly shorter (129mo; HR 3.1, 95%CI 1.9-4.8) in MHR+ pts compared with pts with no adverse mutations (323mo). Having 2 or more mutations correlated with greater reduction of LFS (79.6mo; HR 7.02, CI95% 3.9-12.6) than having one mutation only (133.9mo; HR 2.2, IC95% 1.3-3.7) as compared with no mutations (323.2mo). Multivariate analysis showed that IPSS high risk category (HR 4.5; 95% CI 2.3-8.8) and two or more mutated genes (HR 5.3; 95% CI 2.9-9.8) predicted independently for a significant reduction in LFS. The negative impact on LFS of having 2 or more mutated genes compared to one or no mutations was maintained in the lower (HR 6.4, 95% CI 2.6-15.2) and higher (HR 5.5, 95% CI 2.3-12.8) risk categories. Validation cohort Validation cohort included 262 patients (median age 64 years; males = 167) risk stratified by DIPSS-plus into high (n=89, 34%), intermediate-2 (n=92, 35%), intermediate-1 (n=46, 18%) and low (n=34, 13%). One hundred forty-six pts (56%) displayed none of the four aforementioned mutations, 93 (36%) harbored one mutation whereas 23 (9%) harbored two or more mutations. In univariate analysis, having two or more mutations (HR 3.7; 95% CI 2.2-6.1) was significantly more detrimental for OS than having no mutations, which is more favorable than having one mutation (HR 1.9; 95% CI 1.4-2.7). When adjusted for DIPSS-plus, the presence of two or more mutations retained its significance (HR 2.1; 95% CI 1.3-3.6) and outperformed ASXL1 mutation alone in its prognostic relevance Conclusions Overall, these results show that the number of prognostically relevant mutated genes correlate with OS and LFS in pts with PMF, suggesting that screening for these mutations might help to improve risk stratification. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2918 Background: Monosomal karyotype (MK) is defined as the presence of two or more distinct autosomal chromosome monosomies or a single autosomal monosomy associated with at least one structural abnormality (Breems DA et al. J Clin Oncol 2008; 26: 4791). In acute myeloid leukemia (AML), MK has been associated with a worse prognosis than otherwise complex karyotype, regardless of the specific type of autosomal chromosome involved (Breems DA et al. J Clin Oncol 2008; 26: 4791). Whether or not these observations also hold true for myelodysplastic syndromes (MDS) is currently unknown. Objective: To determine if MDS with complex karyotype can be prognostically sub-stratified further based on the presence or absence of MK and if prognosis in MDS with MK is in addition affected by the presence or absence of monosomy 7 or monosomy 5. Methods: The Mayo Clinic database for MDS was used to identify consecutive patients with complex karyotype, defined as the presence of three or more numerical or structural cytogenetic abnormalities. World Health Organization (WHO) criteria were used for MDS diagnosis and leukemic transformation (Vardiman JW et al. Blood 2009; 114: 937). Overall and leukemia-free survivals were calculated from the time of initial cytogenetic studies documenting complex karyotype. Results: A total of 127 MDS patients (median age 70 years; 79 males) with complex karyotype were identified. Amongst them, 106 (83%) met the above-stipulated criteria for MK and 21 (17%) had complex karyotype without monosomies. The MK in the 106 patients included monosomy 7 and/or monosomy 5 in 73 cases. The three complex karyotype subsets (i.e. complex without monosomies vs. MK that included monosomy 7 and/or 5 vs. MK excluding monosomy 7 or 5) were not significantly different in terms of age and sex distribution, hemoglobin level, leukocyte or platelet count, bone marrow blast percentage or International Prognostic Scoring System (IPSS) risk score. However, survival was significantly inferior in patients with MK compared to those with complex karyotype without monosomies (p=0.01; HR 1.9, 95% CI 1.1–3.3). Multivariable analysis identified MK (p=0.002), advanced age (p=0.0004), increased bone marrow blast percentage (0.04), but not IPSS risk category (p=0.34), as independent risk factors for survival. Interestingly, there was no difference in survival among MK patients further sub-stratified by the presence or absence of monosomy 7 and/or monosomy 5 (Figure 1). Although not statistically significant, leukemia-free survival was also worse in patients with MK compared to those with complex karyotype (p=0.11; HR 2.7, 95% CI 0.8–9.0); none of the aforementioned variables significantly affected leukemia-free survival. Conclusions: Monosomal karyotype in MDS identifies a prognostically worse subgroup of patients with complex karyotype. Furthermore, in the context of MK, autosomal monosomies other than monosomy 7 or monosomy 5 are prognostically as detrimental. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1887 Poster Board I-910 Background: Chromosomal translocations involving 8p11.2 give rise to diverse oncogenic fusion genes including FGFR1 and MYST3. FGFR1 rearrangements have been associated with the stem cell leukemia/lymphoma (SCLL) syndrome, which is a mixed myeloid-lymphoid malignancy characterized by eosinophilia, monocytosis and rapid disease progression into acute myeloid leukemia or lymphoblastic lymphoma. MYST3 is a histone acetyltransferase whose rearrangement has been associated with acute myeloid leukemia (AML; usually monocytic). Methods: The Mayo Clinic cytogenetic database spanning the years 1988–2009 was screened for 8p11.2 translocations. Bone marrow (BM) pathology and cytogenetic results were re-reviewed and relevant clinical information was retrospectively obtained. Archived BM specimens were analyzed by FISH to identify FGFR1 and/or MYST3 rearrangements. BAC clones used for direct-labeled break-apart FISH probes for FGFR1 were CTC-497A2, RP11-90P5 and RP11-513D5 for the 5' portion and RP11-675F6 and RP11-495O10 for the 3' portion; those used for direct-labeled dual color, dual fusion FISH probes for MYST3 were RP11-589C21, CTD-2532C15, RP11-45I11 and RP11-411A18 and for CREBBP (16p13.3) were RP11-737F1, RP11-136I22, Rp11-962J17 and CTD-2514E9. Results: Out of 24,262 unique patient cytogenetic studies, 8p11.2 translocations were identified in 14 (∼0.06%) patients; 6 constituted sole abnormalities. BM specimens for FISH analysis were available in 13 patients (age range 52–75 years; 8 males). Twelve of these 13 patients had myeloid neoplasms and one had lymphoma; the latter patient had a t(8;10)(p11.2;p13) translocation as a subclone of a 14q32 abnormality and neither FGFR1 nor MYST3 were involved. Among the 12 patients with myeloid neoplasms, FISH analysis revealed abnormalities of MYST3 in 4 patients, FGFR1 in 4 patients, and neither in 4 patients. The MYST3 abnormalities included MYST3-CREBBP in 2 patients, MYST3-EP300 in one patient and MYST3 amplification in one patient; specific diagnoses included AML with or without antecedent chronic myeloid malignancy. Only one of the 4 patients with FGFR1 rearrangements displayed peripheral blood eosinophilia; specific diagnoses included chronic myeloid malignancy and AML. Three of the remaining 4 patients with neither FGFR1 nor MYST3 abnormalities had highly complex cytogenetic abnormalities except one who had sole t(8;13)(p11.2,q12) and presented with lymphadenopathy (precursor-T cell lymphoblastic lymphoma), marked leukocytosis, eosinophilia, monocytosis, and a BM morphology consistent with MPN (marked myeloproliferation with granulocytosis and eosinophilia). Survival was uniformly poor in all 8p11.2 translocations. Conclusions: 8p11.2 translocations are rarely encountered in routine clinical practice and are usually associated with aggressive myeloid malignancies. In the current unselected series of patients, peripheral blood eosinophilia was not a typical feature of the myeloid neoplasm phenotype associated with FGFR1 translocation. Conversely, at least by FISH, FGFR1 was not involved in an 8p11.2-associated myeloid neoplasm that exhibited SCLL-like features. Additional molecular studies are planned to validate the current findings. Disclosures: No relevant conflicts of interest to declare.

Abstract Background The Dynamic International Prognostic Scoring System-plus (DIPSS-plus) uses eight adverse factors to predict survival in primary myelofibrosis (PMF): age >65 years, hemoglobin <10 g/dL, leukocytes >25 x 109/L, circulating blasts 31%, constitutional symptoms, red cell transfusion need, platelets <100 x 109/L and unfavorable karyotype (J Clin Oncol. 2011;29:392). The latter two also predicted leukemic transformation. Most recently, an international study of 879 PMF patients identified ASXL1, SRSF2, EZH2 and IDH1/2 mutations as inter-independent predictors of shortened overall or leukemia-free survival (Leukemia 2013Apr 26 doi: 101038/leu2013119. 2013). Molecular prognostication is now well established for acute myeloid leukemia with normal karyotype (NK). There is currently little information on clinical or molecular prognostication in NK-PMF. Methods Diagnosis of PMF was according to WHO criteria. The study population included all referrals to the Mayo Clinic, Rochester, MN, USA or the University of Florence, Florence, Italy. Information on clinical and laboratory parameters and karyotype was available in all study patients, at time of referral, which coincided with time of sample collection for mutation screening. The current study considered only those patients with NK-PMF. ASXL1, EZH2, SRSF2, IDH1/2 and JAK2 mutations were performed on variable number of patients depending on bone marrow or granulocyte DNA availability. Clinical parameters examined for prognostic relevance included those listed for DIPSS-plus, less unfavorable karyotype. Results A total of 690 patients with NK-PMF patients were studied. Median age was 65 years (14-89). The percentage of patients with age >65 years was 48%, red cell transfusion dependent 35%, hemoglobin <10 g/dL 49%, platelets <100 x 10(9)/L 19%, leukocyte count >25 x 10(9)/L 15%, circulating blasts ≥1% 49% and constitutional symptoms 33%. At a median follow-up of 29 months, 351 (51%) deaths and 39 (6%) leukemic transformations were recorded. Mutational frequencies and clinical correlates The respective frequencies (mutated/number of patients studied) of JAK2V617F, ASXL1, EZH2, SRSF2 and IDH1/2 mutations were 60% (284/473), 34% (72/214), 8% (14/179), 15% (37/249) and 5% (14/262). There was no significant association between JAK2V617F and any one of the aforementioned mutations. Inter-mutation association was evident only between SRSF2 and IDH1/2 (p=0.0005). Each one of the DIPSS-plus risk parameters was examined for correlation with a specific mutation: ASXL1 was associated with leukocyte count >25 x 10(9)/L (p<0.0001) and circulating blasts ≥1% (p=0.0005); EZH2 with leukocyte count >25 x 10(9)/L (p=0.008); and SRSF2 with age >65 years (p=0.0007), transfusion need (p=0.04) and hemoglobin <10 g/dL (p=0.03). JAK2V617F was associated with age>65 years (p=0.003) and leukocyte count >25 x 10(9)/L (p=0.02). Predictors of overall and leukemia-free survival In univariate analysis, all 7 DIPSS-plus parameters, as well as ASXL1, EZH2, SRSF2 and IDH1/2 mutations showed significant association with shortened survival: When each of these analyses was adjusted for age, all except constitutional symptoms and SRSF2 mutations retained their significance. Multivariable analysis of the six age-independent DIPSS-plus variables identified all but transfusion-need as independent predictors of inferior survival. A similar analysis restricted to mutations identified ASXL1 and EZH2 as being independently adverse. When both mutations and DIPSS-plus variables were included in the multivariable model, only four parameters remained significant: age >65 years (HR 4.2; p<0.0001), platelets <100 x 10(9)/L (HR 3.4; p<0.0001), ASXL1 mutations (HR 2.2; p=0.0001) and EZH2 mutations (HR 2.7; p=0.001). A similar analysis identified SRSF2 mutations (HR 5.9; p=0.0003) and platelets <100 x 10(9)/L (HR 4.3; p=0.005) as the only predictors of leukemia-free survival. Conclusions In NK-PMF, molecular markers might be prognostically more useful than conventional models that rely on clinical features. In the current study, thrombocytopenia was the only clinical variable, other than age, with additional value to molecular prediction of survival and leukemic transformation. Disclosures: No relevant conflicts of interest to declare.

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 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 Abstract 1711 Background: Mutations in genes of the splicing machinery, such as SF3B1, SRSF2 and U2AF35 are common in patients with myelodysplastic syndromes [MDS] (Nature 2011;478:64) and chronic myelomonocytic leukemia [CMML] (Haematologica 2012;Epub). In MDS, SRSF2 gene mutations are an independent risk factor for shortened over-all (OS) and leukemia-free survival (LFS) (Blood 2012;119:3578). In MDS with ring sideroblasts (RS), SF3B1 mutations have a high prevalence (∼50%), but do not influence either, the OS or the LFS (Blood 2012;119:569). We carried out this study to evaluate the prevalence, clinical correlates and prognosis of the aforementioned spliceosome mutations in CMML. Methods: The study included 227 patients with WHO defined CMML who were seen at the Mayo Clinic from 1997 through 2007. All patients underwent bone marrow (BM) examination and cytogenetic evaluation at diagnosis. DNA was interrogated in the three most frequent spliceosome genes with somatic mutations; SRSF2, SF3B1 and U2AF35. Results I: Prevalence and clinical correlates Among the 227 study patients, 153 (67%) were male, median age was 71 years (range, 17–90 years) and 192 (85%) met the WHO criteria for CMML-1. Ninety (40%) patients had SRSF2 mutations (86% CMML-1), 13 (6%) had SF3B1 mutations (75% CMML-1) and 20 (9%) had U2AF35 mutations (95% CMML-1). One-hundred and twenty three (54%) patients had at least one of three spliceosome mutations (86% CMML-1). Mutational hot spots were P95 for SRSF2 (P95L-n=36/H-n=32/R-n=13/A-n=1), K700E (n=7) and H662Q (n=2) for SF3B1, and Q157 (Q157R-n=5/P-n=5/G-n=1) and S34F (n=7) for U2AF35. Seven patients (54%) with SF3B1 mutations had ≥1% RS, with 5 (38%) showing ≥15% RS. Mutations involving all three spliceosome genes were mutually exclusive. The cytogenetic distribution based on the Spanish risk stratification system (Haematologica 2011;96:375) was; SRSF2 mutations: 69 (77%) low risk, 11 (12%) intermediate risk, and 10 (11%) high risk (+8-n=3, del/monosomy 7-n=2, monosomal karyotype-n=5); SF3B1 mutations: 8 (62%) low risk and 5 (38%) intermediate risk; U2AF35 mutations: 15 (75%) low risk, 3 (15%) intermediate risk and 2 (10%) high risk (p=0.89). The distribution of mutations according to the MD Anderson prognostic scoring system [MDAPS] (Blood 2002;99:840) was; SRSF2 - low-n=41, intermediate-1-n=26, intermediate-2-n=18, high-n=5, SF3B1- low-n=7, intermediate-1-n=3, intermediate-2-n=2, high-n=1, and U2AF35- low-n=11, intermediate-1-n=5, intermediate-2-n=3, high-n=1 (p=0.73). There was no statistically significant difference, among the three mutation groups, in prognostically relevant parameters, including gender distribution, median age, hemoglobin values, platelet counts, peripheral blood (PB) and BM blast counts, absolute neutrophil counts (ANC) and absolute monocyte counts (AMC). The only notable difference was that patients with the SF3B1 mutation had a lower median white blood cell count (p=0.04) and a lower absolute lymphocyte count (p=0.045). Results II: Prognostic impact of spliceosome mutations At a median follow-up of 15 months, 166 (73%) deaths and 33 (14.5%) leukemic transformations were documented. Median survivals for patients with mutations involving SRSF2, SF3B1 and U2AF35 were 24, 17 and 12 months, respectively. In univariate analysis, the presence of SRSF2 (p=0.67), SF3B1 (p=0.96) or U2AF35 (p=0.49) mutations had no prognostic impact on OS. Similarly, none of the three spliceosome mutations affected LFS; corresponding p values were 0.55 for SRSF2, 0.9 for SF3B1 and 0.38 for U2AF35 mutations respectively. We then examined possible prognostic value of having none of these mutations (n=104) vs otherwise (n=123) and the results were once again negative (p=0.87). Conclusions: SRSF2 is the most frequently mutated spliceosome gene in CMML, but neither it nor SF3B1 or U2AF35 mutations affect overall or leukemia-free survival in CMML. Furthermore, the current study suggests limited genotype-phenotype association, save for the already established association between SF3B1 mutations and RS. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1742 Background Karyotype is one of the most potent and reproducible risk factors for both overall (OS) and leukemia-free (LFS) survival in primary myelofibrosis (PMF) (Blood 2011;118:4595). It is currently not clear if the number of metaphases studied or the abnormal metaphase percentage alters this prognostic impact. Methods: An updated Mayo Clinic database of karyotypically- and DIPSS-plus-annotated patients with PMF was used to identify a consecutive series of patients and their cytogenetic information obtained at time of referral was centrally re-reviewed. Cytogenetic results were interpreted and reported according to the International System for Human Cytogenetic Nomenclature; abnormal karyotype was defined by the presence of at least 2 metaphases with structural abnormalities or monosomy or 3 metaphases with polysomy, regardless of number of metaphases examined. For this particular study, the presence of less than 20 evaluable metaphases did not disqualify patients. “Very high risk” karyotype included monosomal karyotype, inv(3) or i(17q) abnormalities (Blood 2011;118:4595). “unfavorable” karyotype included complex or any sole or two abnormalities that included +8, −7/7q-, -5/5q-, inv(3), i(17q), 12p-, or 11q23 rearrangement (Blood 2011;118:4595). All other cytogenetic abnormalities were considered “favorable” Results: A total of 590 patients (median age 65 years; range 19–89 years) including 424 (72%) males. The DIPSS-plus (JCO 2011;29:392) risk distribution was 40% high, 39% intermediate-2, 12% intermediate-1 and 9% low. Cytogenetic findings included 17 (3%) very high risk, 69 (12%) unfavorable, 165 (28%) favorable and 339 (57%) normal karyotypes. The number of bone marrow metaphases studied to report these cytogenetic findings were ≥20 in 468 (79%) patients, 11 to 19 in 71 (12%) patients and ≤10 in 51 (9%) patients; the proportion of cases studied with ≥20 metaphases were 53% for very high risk, 74% for unfavorable, 83% for favorable and 80% for normal karyotype (p=0.006). Among patients with abnormal karyotype, the abnormal metaphase percentage was ≥75% in 148 (59%) patients, 50 to 74% in 36 (15%) patients, 26 to 49% in 27 (11%) patients and ≤25% in 38 (15%) patients; the proportion of patients with ≥75% was 59% for very high risk, 67% for unfavorable and 56% for favorable karyotypes (p=0.70). As expected, OS was significantly different among very high risk, unfavorable, favorable and normal karyotype patients with respective median survivals of 8, 23, 41 and 57 months (p<0.0001). The number of metaphases studied (p=0.62) or the abnormal metaphase percentage (p=0.12), by themselves, did not affect survival. Similarly, the survival difference among the aforementioned cytogenetic risk groups was equally apparent when patients with ≥20 metaphases studied (n=468; P<0.0001) and those with <20 metaphases studied (n=122; p<0.0001) were separately analyzed. Analysis of patients with very high risk or unfavorable karyotype (n=86) revealed no significant effect of abnormal metaphase percentage on survival (Figure; p=0.80). A similar scenario was demonstrated for patients with favorable karyotype (Figure; p=0.24). Conclusions: Neither the number of metaphases examined nor the abnormal metaphase percentage appear to influence the currently recognized cytogenetic risk stratification in PMF. The current study has implications for both clinical practice and clinical research involving cytogenetic prognostication in hematological malignancies. Disclosures: No relevant conflicts of interest to declare.