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Abstract Hypomethylating agents have changed treatment and outcomes in MDS and are active in AML patients. However a significant number of patients do not respond to 5-Azacytidine or Decitabine and there is no clinically validated assay that predicts response to 5-Azacytidine (5-Aza) or Decitabine (DAC). Clinical parameters and recently TET2 mutations have been identified as genetic predictors of response to 5-Aza. Several recent papers report on the possible predictive value of anti-apoptotic proteins, for example BCL2L10. In previous genome-scale RNA-interference (RNAi) screens anti-apoptotic BCL-2 family members, most potently BCL-XL, were identified as top targets whose down-regulation sensitize to 5-Aza. Results were confirmed with the BCL-XL and BCL-2 inhibitor ABT-737, as well as the BCL-2-specific inhibitor ABT-199, both of which sensitized myeloid cells to 5-Aza. Although it is expected that interfering with anti-apoptotic genes would sensitize to hypomethylating similar to cytotoxics, few of the other >900 genes from our RNAi sensitizer screens, including few of the 571 kinases, sensitized to 5-Aza as potently as inhibition of BCL-XL. Thus BCL-2 family members constitute an especially potent context to modulate the activity of 5-Aza. To assess if protein expression of the top targets BCL-XL, BCL-2 or MCL-1 correlate with and may explain a preferential sensitization, 577 primary AML samples were examined by Reverse Phase Protein Array (RPPA). There was substantial overlap of expression across and within FAB subgroups and cytogenetics, and expression of neither of these genes/proteins could explain the observed effects. This may be expected due to functional redundancies amongst the different anti-apoptotic BCL-2 family members, as well as distinct, yet overlapping binding affinities between anti- and pro-apoptotic BCL-2 proteins and BH3 peptides. Thus, we next aimed to functionally interrogate the overall balance of pro- and anti-apoptotic BCL-2 family members, also described as “primedness” by BH3 profiling. This assay uses peptides derived from pro-apoptotic BH3-only proteins to determine the capacity of cells to initiate apoptosis in response to pro-apoptotic BH3 molecules [anti-apoptotic BCL-2 molecules like BCL-XL and BCL-2 bind and inhibit BH3-only molecules]. This assay is a broad functional readout that incorporates many parameters including the consequences of varying BCL2L10 expression. To establish a proof-of-concept that the functional interrogation of specific apoptotic thresholds may be an optimal readout for 5-Aza response, we first assessed a broad panel of 13 AML-derived cell lines by BH3 profiling and in parallel 5-Aza drug dose response experiments. Several BH3 profiling metrics, including NOXA plus BIM, significantly correlated with 5-Aza sensitivity in vitro (Figure 1). Next, to correlate actual clinical responses to 5-Aza with BH3 profiling, specimens from 28 AML, MDS and MDS/MPN overlap patients treated with 5-Aza or DAC-based regimens and for whom clinical outcome was available, were assayed in BH3 assays. In the clinic, the best BH3 metrics were combined values from NOXA and BIM peptides similar to cell lines. NOXA plus BIM discriminated clinical responses defined as achieving any response (sensitive) versus a patient being resistance/refractory to 5-Aza/DAC based regimens with statistical significance (Mann-Whitney two-tailed p = 0.001). This was true for the entire group of patients (5-Aza- and DAC- regimens) with a Receiver Operating Characteristic (ROC) of an AUC=0.875, with a further increase for patients treated only with 5-Aza based regimens with an AUC=0.95.Figure 1BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM).Figure 1. BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM). In conclusion, due to significant expression overlap and functional redundancies of the BCL-2 family proteins, expression does not correlate with 5-Aza clinical or in vitro responses. However, BH3 profiling as a general functional readout of apoptotic primedness, significantly discriminated responses in patients as well as in vitro. Thus, BH3 profiling incorporates the entirety of pro- and anti-apoptotic molecules (including BCL2L10) and is promising to predict responses to hypomethylating agents. We propose to prospectively validate BH3 profiling as a predictive biomarker assay for 5-Aza or DAC based regimens. Disclosures: Pierceall: Eutropics: Employment, Equity Ownership. Lena:Eutropics: Employment, Equity Ownership. Cardone:Eutropics: Employment, Equity Ownership. Elashoff:Eutropics: Employment. Blake:Noel Blake: Employment, Equity Ownership.

Abstract Background Spliceosome pathway gene mutations are recurrent in myeloid malignancies with the highest frequencies reported for myelodysplastic syndromes associated with ring sideroblasts (MDS-RS; 85%), MDS without RS (44%) and chronic myelomonocytic leukemia (CMML; 55%) (Nature 2011;478:64). SF3B1 mutations were the most frequent (75%) in MDS-RS and SRSF2 mutations in CMML (28%); U2AF1 mutational frequencies were 12% in MDS without RS and 8% in CMML. We have previously described SRSF2 (Blood. 2012;120:4168) and SF3B1 (Leukemia. 2012;26:1135) mutations in 17% and 6.5% of patients with primary myelofibrosis (PMF); prognostic relevance was shown for the former but not the latter. Objectives The objectives of the current study were to i) describe the incidence of U2AF1 mutations in PMF and their correlation with clinical features, karyotype and other mutations and ii) examine the prognostic significance of U2AF1 mutations in PMF, in the context of both conventional prognostic models and other prognostically-relevant mutations. Methods 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. Risk stratification was according to the Dynamic International Prognostic Scoring System (DIPSS)-plus system. U2AF1 and other mutations were analyzed using standard PCR techniques and bidirectional sequencing; for U2AF1, two hot spots that included residues S34 and Q157 were amplified. Results A total of 251 PMF patients (median age 63 years; 160 males) were studied. DIPSS-plus risk distribution was high in 32%, intermediate-2 in 38%, intermediate-1 in 17% and low in 13% of the patients. The frequency of each DIPSS-plus adverse feature was as follows: age >65 years (42%), transfusion need (32%), hemoglobin <10 g/dL (47%), leukocyte count >25 x 10(9)/L, (16%), platelet count <100 x 10(9)/L (22%), ≥1% blasts (57%), constitutional symptoms (35%), and unfavorable karyotype (9%). Karyotype was normal in 156 (63%) patients. At a median follow-up of 48 months, 158 (63%) deaths and 27 (11%) leukemic transformations were recorded. Mutational frequencies Forty-one (16.3%) patients harbored U2AF1 mutations: 16 (39%) Q157P, 10 (24%) Q157R, 8 (20%) S34F, 4 (10%) S34Y and one each for Q157P/E159A, Q157R/S34Y and Q157-Y158insYE. Frequencies for other mutations were 11% for SRSF2, 7.3% for SF3B1, 31% for ASXL1, 5.5% for EZH2, 5% for IDH1/2 and 58% for JAK2V617F. U2AF1 mutations were usually, but not always, exclusive of other spliceosomal mutations: one patient expressed all three spliceosomal mutations. The frequency of any one of the three spliceosomal mutations was 34%. Clinical correlates U2AF1 mutations were significantly associated with older age (p=0.02), JAK2V617F (p=0.002), mutant ASXL1 (p=0.04), transfusion need (p<0.0001), hemoglobin <10 g/dL (p<0.0001), platelets <100 x 10(9)/L (p<0.0001) and normal karyotype (p=0.006). The associations with anemia, thrombocytopenia, JAK2V617F and normal karyotype were inter-independent; the frequency of U2AF1 mutations in the presence of anemia was 29%, transfusion need 36%, thrombocytopenia 35%, JAK2V617F 23% and normal karyotype 21%. Prognostic interactions U2AF1 mutations were associated with inferior overall (p=0.004) but not leukemia-free (p=0.6) survival. However, the survival association was fully accounted for by the above-mentioned clustering of U2AF1 mutations with anemia and thrombocytopenia. Similarly, although multivariable analysis of U2AF1, SRSF2, ASXL1, EZH2 and IDH mutations identified the first three as being independently predictive of poor survival, only ASXL1 and SRSF2 remained significant when either anemia or thrombocytopenia was included as a co-variate. Conclusions U2AF1 mutations are the most frequent spliceosome pathway mutations in PMF, cluster with normal karyotype and JAK2V617F, and are strongly associated with anemia and thrombocytopenia; the latter suggests a pathogenetic contribution to ineffective hematopoiesis in PMF. The current study also suggests that more than one third of patients with PMF carry a spliceosome mutation. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Cost of cancer care is projected to reach $173 billion by 2020, a 39% increase from 2010. Several factors including psychiatric (psych) comorbidities contribute to this increase. Within the oncology setting, 29-38% of the patients (pts) are reported to have mood disorders and 15% have major depression. Depression alone is associated with increased healthcare utilization in pts with breast, colon, lung and prostate cancers. A 2015 report noted that the presence of at least one psychiatric comorbidity in 300 Leukemia pts was associated with an extra $55,000 per pt in just one year. Similarly, in pts treated with systemic steroids, the incidence of neuropsychiatric disorders can be as high as 75%. However, no such data is available for MM, where more than 90% of pts are treated with steroids, likely increasing risk for mood problems and impacting treatment cost. As such, the aim of our study was to analyze the SEER-Medicare database for healthcare utilization trends and acute cost of care (cost incurred during 6 months after MM diagnosis) in MM pts with or without psych comorbidities. Methods: Pts diagnosed with MM between 1991-2010 with continuous Medicare coverage (1 year prior to diagnosis-date of death/end of 2012) were included. Pts were categorized as: MM with any psych disorder (MM+P), MM with depression (MM+D) and MM only. Presence of ³1 inpatient (ipt) or ³2 outpatient (opt) ICD9 diagnosis codes were used to assign pts to the psych categories. Within MM+P and MM+D groups were subdivided by presence of psych or depression diagnosis prior to MM (MM+P PRE or MM+D PRE). Medicare claims adjusted for inflation (2013) within the first 6 months (mth)/total MM care were summed by drug and total charges. Univariate and multivariate logistic regression models (adjusted for age, year, sex, race, and the Charlson Comorbidity Index; CCI) were performed to determine associations with ipt, opt, and any emergency department (ED) charges after MM diagnosis. Associations between psych conditions prior to MM diagnosis and costs of care after MM diagnosis were assessed using univariate and multivariate proportional odds models. Results: The study population included 36,007 eligible MM pts with a median follow-up of 1.8 years. 15168 (42%) pts had a psych condition at any time (MM+P), while 9355 (26%) were diagnosed prior to MM diagnosis (MM+P PRE). Depression was present in 8421 pts (23%), 4546 (13%) of those occurring prior to MM diagnosis. In comparison to MM pts, MM+P and MM+D pts tended to be female, White, and had a higher CCI (all p<0.001). When compared to MM pts, those with MM+P PRE and MM+D PRE had significantly higher incidence of MM-related complications (hypercalcemia, renal dysfunction, anemia, fractures and dialysis) at the time of or after MM diagnosis and also required increased overall care (all p<0.001). Both, MM+P and MM+D had higher odds of ipt visits (OR 1.48 and 1.41, resp., p<0.001), ED care (OR 1.48 and 1.37, resp., p<0.001) and opt visits (OR 1.25 and 1.22, resp., p<0.001) as compared to MM only pts. Cost of care analysis showed that MM+P and MM+D pts had a significantly higher cost of opt (OR 1.36 and 1.39, resp., p<0.001), ipt (OR 1.49 and 1.54, resp., p<0.001) and total care (OR 1.52 and 1.55, resp., p<0.001) as compared to MM only pts during first 6 mth after MM diagnosis (Figure 1). Total costs of care for MM+P and MM+D were also higher than MM only but the differences were less significant. Cost of care differences existed within first 6 mth of MM diagnosis by pt race as well with MM+P among Hispanic and Asian pts being more strongly associated with higher costs than Whites and African-Americans (AA) (p<0.001). MM+D had similar trends but not significant after adjustment for multiple comparisons. Conclusion: Psych comorbidities are associated with significant increase in healthcare utilization and cost of care in MM pts and may contribute to higher MM-related complications. More research is needed to study whether a multidisciplinary approach to identify and manage MM pts with psych conditions may help mitigate these trends. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy.

Abstract Background: Patient (Pt) outcomes have improved significantly in multiple myeloma (MM) due to widespread use of novel therapeutic agents and stem cell transplant (SCT) butoutcome disparities among racial/ethnic groups exist. Differences in access to and utilization of novel therapeutics are likely contributing factors. We performed an analysis of the SEER-Medicare database to explore such differences. Methods: Pts with a confirmed MM diagnosis between 2007-2009 and continuous Medicare coverage from 1 year prior to diagnosis through end of 2012 were included. Medicare Part D data (oral medications) is not available prior to 2007 so utilization analysis of lenalidomide (LEN), thalidomide (THAL) and bortezomib (BORT) was performed from 2007-2009. Demographic/survival data (PEDSAF files) and drug/SCT utilization (NCH, OUTSAF, PDESAF files) were obtained (HCPCS/NCH codes). Categorical and continuous variables were compared using /Fisher tests and Wilcoxon tests, respectively. Gender, age, and year-adjusted p-values were calculated using logistic regression. A proportional odds model was used to detect time-dependent trends in drug usage within 12 months of MM diagnosis across year of diagnosis by race. Separate multivariate models were fit for each drug adjusting for gender, age, drug use and race. Associations between drug use and overall survival (OS) were examined using a time dependent proportional hazards model. Results: A total of 5358 MM pts were included (any Medicare claims) with 2733 (51%) males. Mutually exclusive race categories were White (W; 67%), African-American (AA; 18%), Hispanic (H; 10%) and Asian (A; 5%). Median follow up was 2.4 yrs. Baseline pt characteristics were significantly different for age with AA being the youngest at diagnosis (p<0.001) and for gender (p<0.001) with W having the largest (53.4%) and AA the smallest (45.2%) proportion of males. Medicare claims capture only pts without any supplemental insurance and so drug utilization in this database was much lower than expected for all subgroups. Year-wise comparison showed that LEN use within the first year of MM diagnosis increased from 2007 to 2009 (16.5% to 27.7%; p<0.001) and there was a significant decrease in median days to first dose (p=0.002). Over the same period, use of THAL decreased (26.6% to 14.6%; p<0.001) while use of BORT (7.8% to 15.4%; p<0.001), SCT (3.3% to 6.2%; p<0.001) and more than 1 novel agent (2.5% to 5.7%; p<0.001) increased significantly. Utilization patterns within first year of MM diagnosis were significantly different among racial subgroups for LEN, THAL, BORT, SCT and >1 novel agent use. (Figure 1) No significant difference was seen for days to first dose of LEN/THAL for any race but for BORT, H got first dose in median 117 days after diagnosis as compared to median 46-51 days for other races (p=0.025). During the first year after diagnosis, W and AA had higher BORT only usage while H and A had a higher LEN/THAL only usage (p<0.001). For drug use by year and race, a significant increase in LEN use was seen from 2007 to 2009 in W (p<0.001), AA (p=0.001) and A (p<0.001) but not H (p=0.26) while THAL use decreased significantly for all races. BORT use increased significantly for all except A (p=0.602) and SCT use increased significantly for all except AA (p=0.068). Inferior OS was significantly associated with older age (p<0.001) and males (p<0.001). LEN/THAL use within the first year of diagnosis did not affect OS while BORT use within the first year of diagnosis increased mortality risk (HR 1.18, p=0.021). SCT use improved OS (HR 0.52, p<0.001). Conclusions: In this comprehensive analysis of MM therapeutics utilization, we noted significant variability among different racial groups. The use of LEN, BORT and SCT has increased while THAL has decreased over time but disparities exist in utilization among different races, with lower use of LEN in AA, lower use of BORT in A and significantly delayed use of BORT in H, which are all notable since racial/ethnic minorities are fast growing in the US population mix and seem to have inequitable utilization and/or access. Inferior survival with early BORT use may represent selection bias of pts with more advanced/aggressive disease. These trends need to be examined in larger sample sizes especially from commercial payers to eliminate drug access and utilization disparities and achieve equitable benefit of therapeutic advances across all racial subgroups. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy.

AbstractObjectiveTo evaluate variability in antenatal sonographic prognostication of congenital diaphragmatic hernia (CDH) within the North American Fetal Therapy Network (NAFTNet).MethodsNAFTNet centre were invited to complete a questionnaire and participate in videoconference calls, during which participants were observed while measuring lung area by ultrasound using the anteroposterior (AP) method, longest method, and trace method. Each center identified 1–2 experienced fetal medicine specialist(s) or medical imaging specialists locally to participate in the study. Practices were compared among NAFTNet centre within and without the fetal endoscopic tracheal occlusion (FETO) consortium.ResultsNineteen participants from 9 FETO center and 30 participants from 17 non‐FETO center completed the survey and 31 participants were interviewed and observed while measuring sonographic lung area. All Centres measured observed‐to‐expected lung‐to‐head ratio (o/e LHR) or LHR for CDH prognostication. Image selection criteria for lung area measurement were consistent, including an axial section of the chest with clear lung borders and a 4‐chamber cardiac view. Lung area measurement methods varied across NAFTNet, with most centre using longest (4/9 FETO vs. 13/29 non‐FETO) or trace (3/9 FETO vs. 11/29 non‐FETO) method. Centres differed in expected reference ranges for o/e LHR determination and whether the lowest, highest or average o/e LHR was utilized.ConclusionVariability in antenatal sonographic prognostication of CDH was identified across NAFTNet, indicating a need for consensus‐based standardization.

Abstract Multiple myeloma (MM) is 2-3 times more common among African-Americans compared to non-Hispanic whites. The 2-3-fold increased risk among family members of cases suggests a genetic contribution to risk. Genome-wide association studies (GWAS) in populations of European ancestry have identified seven novel risk loci at 2p23.3 (rs6746082), 3q26.2 (rs10936599), 3p22.1 (rs1052501), 6p21.32 (rs2285803), 7p15.3 (rs4487645), 17p11.2 (rs4273077) and 22q13.1 (rs877529) (Broderick, et al. Nat Genet, 2011, Chubb, et al. Nat Genet, 2013), three of which were replicated in another European series (Martino et al., Br J Haematol, 2012). Here we examined the index signals and conducted fine-mapping for each locus in a case-control study of 1,049 multiple myeloma cases and 7,084 controls of African ancestry to identify better markers of risk and novel independent loci in seven previously reported regions in this high risk population. Incident cases were recruited from 10 clinical centers and SEER cancer registries from 2011 to 2013 and genotyped using the Illumina HumanCore GWAS array. Control data were obtained from previous genome-wide studies of breast and prostate cancer, genotyped using the Illumina 1M-Duo in 4425 male controls from the African Ancestry Prostate Cancer Consortium (consisting of 14 independent studies) and 2632 female controls from a breast cancer GWAS of African-American women (consisting of 9 independent studies). Imputation to 1000 Genomes (March 2012 release) was conducted for regions around six of the previously identified single nucleotide polymorphisms [SNPs] (the HLA region harboring rs2285803 is still being imputed, results will be presented). A case-control analysis of SNPs/indels >1% frequency within 250 kb of each index variant was conducted using unconditional multivariable logistic regression adjusting for age, sex and five leading principal components. Region-specific alpha levels were determined through permutation tests. The minimum alpha level across the six regions was α=0.002. All previously reported risk variants were common in African-Americans (minor allele frequency [MAF] >0.05). For five of the six SNPs, we had ≥94% power to detect the same effect observed in non-Hispanic whites, and 64% power for the less common variant rs10936599 (MAF=0.07). We observed directionally consistent effects (odds ratio [OR]>1) for the six risk variants tested, with three replicating at p≤0.05 (7p15.3, p=1.4x10-7; 17p11.2, p=0.05; 22q13.1, p=0.02). For three of the six regions, we observed better markers of risk in African-Americans that were correlated with the index SNP in Europeans (7p15.3, rs56333627, p=1.5x10-5, r2=0.89; 17p11.2, rs34562254, p=2.9x10-3, r2=0.90; 22q13.1, rs2092410, p=1.1x10-4 r2=.71). The missense variant identified in the 17p11.2 region (rs34562254, Pro251Leu) is located in TNFRSF13B, which encodes the protein TACI, a B cell surface receptor which plays a role in B cell maturation, apoptosis and antibody production by inducing activation of transcription factors including NFAT and NFκβ. In addition, there is evidence suggesting that TACI is involved in MM pathogenesis. Our results demonstrate that many of the risk loci for MM found in European ancestry populations are also risk loci in men and women of African ancestry and that by fine-mapping, we are able to identify variants that better capture risk in populations of African ancestry. Disclosures Terebelo: Celgene Corp: Membership on an entity's Board of Directors or advisory committees. Lonial:Millennium: The Takeda Oncology Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding.

Abstract Abstract 430 Background: The Dynamic International Prognostic Scoring System (DIPSS-plus) uses eight risk factors to predict overall survival (OS) in primary myelofibrosis (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 (JCO 2011;29:392). Among these risk factors, karyotype holds a dominant role in predicting both overall (OS) and leukemia-free (LFS) survival (Blood 2011;118:4595). More recently, certain PMF-associated somatic mutations (IDH, EZH2, ASXL1, SRSF2) have been reported (in print or at recent meetings) to carry prognostic relevance for OS or LFS in PMF while other mutations (JAK2, MPL, TET2, SF3B1) did not. The purpose of the current study was to examine the individual and combined prognostic relevance of the former in the context of cytogenetic risk stratification and DIPSS-plus. Methods: An updated Mayo Clinic database of 1008 karyotypically- and DIPSS-plus-annotated patients with PMF was used to identify study patients in whom DNA at time of referral was available for mutation analysis. OS and LFS were calculated from the time of referral, which was also the time of study sample collection. Results: In an ongoing project, a total of 397 PMF patients have so far been studied for IDH1/2 (n=367), SRSF2 (n=355), ASXL1 (n=260) and EZH2 (n=43) mutations. The corresponding mutational frequencies were 5.4% (20/367), 14.4% (51/355), 31.2% (81/260) and 7% (3/43). These mutations were not exclusive of either each other or JAK2 or MPL mutations and a significant clustering was noted between SRSF2 and IDH mutations; IDH mutational frequency was 21% (10/48) in SRSF2-mutated versus 3% (9/279) in unmutated cases (P<0.0001). Mutational hotspots were P95 in exon 1 for SRSF2 and exons 1, 2 and 5 for ASXL1. OS and LFS effect have so far been examined for ASXL1, SRSF2 and IDH 1/2 mutations; in univariate analysis, all three mutations significantly affected OS (ASXL1 RR 1.9, 95% CI 1.4–2.7; SRSF2 RR 1.7, 95% CI 1.2–2.5; IDH 1/2 RR 1.8, 95% CI 1.1–3.1) whereas only IDH 1/2 (RR 5.5, 95% CI 2.5–11.8) and SRSF2 (RR 3.5, 95% CI 1.7–7.0) but not ASXL1 (p=0.29) mutations affected LFS. The observed prognostic relevance for OS was sustained during multivariable analysis that included ASXL1 with either SRSF2 or IDH mutations, as co-variates, whereas both IDH and SRSF2 mutations remained significant for LFS. Based on the above observations, study patients were classified into two groups: i) unmutated for ASXL1, SRSF2 and IDH1/2 (all unmutated; n=146) and ii) mutated for at least one of the three mutations (one or more mutated; n=130); the latter group constituted 62%, 52%, 18% and 27% of DIPSS-plus high, intermediate-2, intermediate-1and low risk patients, respectively (p<0.0001). The corresponding rates for patients with favorable and unfavorable karyotype were 47% and 43% (p=0.7) and for normal vs. abnormal karyotype were 53% and 36% (p=0.008). The “all unmutated group”, compared to the “one or more mutated group” enjoyed a significantly superior OS (RR 0.5, 95% CI 0.4–0.7) and LFS (RR 0.3, 95% CI 0.2–0.7) that was DIPSS-plus-independent for OS (p=0.03) and karyotype-independent for LFS (p=0.004). The prognostic value of distinguishing “all unmutated” from “one or more mutated” patient groups was most evident for DIPSS-plus intermediate-2 or lower risk groups (p=0.002) and its added value for high-risk group was limited (p=0.23) (Figure). Conclusions: A concomitant analysis strategy reveals that SRSF2, ASXL1 and IDH mutations carry inter-independent prognostic relevance for overall or leukemia-free survival in PMF. Any one of these three mutations is more likely to occur in patients with normal karyotype and such an event predicts shortened survival that is not accounted for by DIPSS-plus and a higher risk of leukemic transformation that is independent of karyotype. The current study suggests that such information might be useful in treatment decisions involving intermediate-2 or lower risk patients. Disclosures: No relevant conflicts of interest to declare.

Objective To compare the outcomes of Aquablation in 30–80 mL prostates with those in 80–150 mL prostates. Surgical options, especially with short learning curves, are limited when treating large prostates for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH). Aquablation (AquaBeam System, PROCEPT BioRobotics Inc., Redwood City, CA, USA) could solve this issue with global reproducibility, independent of prostate volume. Patients and Methods Waterjet Ablation Therapy for Endoscopic Resection of prostate tissue (WATER [W‐I]; NCT02505919) is a prospective, double‐blind, multicentre, international clinical trial comparing Aquablation and transurethral resection of the prostate (TURP) for the treatment of LUTS/BPH in prostates between 30 and 80 mL. WATER II (W‐II; NCT03123250) is a prospective, multicentre, single‐arm international clinical trial of Aquablation in prostates between 80 and 150 mL. We compare baseline parameters and 12‐month outcomes in 116 W‐I and 101 W‐II study patients. Students’ t ‐test or Wilcoxon tests were used for continuous variables and Fisher’s test for binary variables. Results The mean (SD) operative time was 33 (17) and 37 (13) min in W‐I and W‐II, respectively. Actual treatment time was 4 and 8 min in W‐I and W‐II, respectively. The mean change in the International Prostate Symptom Score was substantial averaging (at 12 months) 15.1 in W‐I and 17.1 in W‐II ( P = 0.605). By 3 months, Clavien–Dindo grade ≥II events occurred in 19.8% of W‐I patients and 34.7% of W‐II patients ( P = 0.468). Conclusion Aquablation clinically normalises outcomes between patients with 30–80 mL prostates and patients with 80–150 mL prostates treated for LUTS/BPH, with an expected increase in the risk of complications in larger prostates. Long‐term outcomes of procedure durability are needed.

Abstract Abstract 423 Background: Cytogenetic abnormalities at diagnosis are seen in 20–70% of patients with myelodysplastic syndromes (MDS). The International Prognostic Scoring System -revised (IPSS-R) classifies these cytogenetic abnormalities into five prognostic groups: very good (del(11q), ΠY with overall survival (OS) of 61 months); good (normal, del(20q), del(5q), del(12p) with OS 49 months); intermediate (+8,7q-, i(17q),+19,+21 with OS 26 months); poor (der(3)q21/q26, −7, complex with 3 abnormalities with OS 16 months); and very poor (complex with >3 abnormalities with OS of 6 months) (Schanz J, JCO 2012, Greenberg P, Blood 2012). Monosomal karyotype (MK) is defined as the presence of two or more autosomal monosomies or a single monosomy associated with a structural abnormality. We have previously shown that MK identifies a prognostically worse subgroup of MDS patients with a complex karyotype (Patnaik M, Leukemia 2010). Objectives: Methods: The Mayo Clinic database for MDS was used to identify patients in whom bone marrow histologic and cytogenetic information was obtained at the time of diagnosis. WHO criteria were used for MDS diagnosis and leukemic transformation. Results: i) Patient characteristics: A total of 1,014 patients met the above-stipulated criteria. Median age of the cohort was 71 years (range: 18–98 years) with 684 (67%) males. 819 patients (81%) had primary MDS with 195 cases (19%) of therapy-related MDS. 759 patients (75%) are dead at a median follow-up of 18 months (range: 0–223 months) with leukemic transformation documented in 125 cases (12%). IPSS-R risk distribution was as follows: very low (n=149, 15%), good (n=261, 26%), intermediate (n=221, 22%), high (n=131, 13%), and very high (n=252, 25%). ii) IPSS-R karyotype (Entire cohort; n=1,014): The five cytogenetic groups by IPSS-R were as follows: very good (n=43, 4%), good (n=577, 57%), intermediate (n=187, 18%), poor (n=83, 8%), and very poor (n=124, 12%). We evaluated the prognostic impact of the above groups by Kaplan Meier and Cox proportional hazards analysis. OS for the five cytogenetic groups was as follows: good (36 months), very good (28 months), intermediate (20 months), poor (13 months), and very poor (6 months) (Figure 1). OS of patients with very good karyotype was significantly better than patients with very poor and poor karyotype (p<0.0001, RR 3.2 and p=0.04, RR 1.6 respectively) but similar to patients with intermediate and good karyotype (p=0.22 and 0.28 respectively). iii) IPSS-R karyotype (Primary MDS; n=819): Cytogenetic risk groups by IPSS-R were as follows: very good (n=38, 5%), good (n=512, 63%), intermediate (n=153, 19%), poor (n=46, 6%), and very poor (n=70, 9%). OS of the five groups was as follows: good (39 months), very good (23 months), intermediate (21.5 months), poor (14.5 months), and very poor (6.5 months). OS of patients with very good karyotype was significantly better than patients with very poor karyotype (p=0.0002, RR 2.5) but similar to patients with poor, intermediate and good karyotype (p=0.23, 0.26 and 0.18 respectively). iv) Monosomal karyotype: MK was identified in 153 (15%) cases of which 4 cases were intermediate, 42 poor, and 107 very poor by IPSS-R. OS of patients with MK was similar to those with very poor karyotype (6 months). In addition, OS of patients with very poor without MK was akin to patients with poor without MK (p=0.21). Furthermore, among primary MDS we identified 83 (8%) cases of MK of which 4 were intermediate, 21 were poor, and 58 very poor by IPSS-R. We confirmed that OS of patients with MK was similar to patients with very poor karyotype (6.5 months). Moreover, survival of patients with very poor without MK was similar to patients with poor without MK (p=0.51). Conclusions: In this independent analysis of 1,014 patients with MDS, IPSS-R cytogenetic risk characterization failed to discriminate between very good, good and intermediate prognostic groups. In addition, patients with very poor without MK have a similar prognosis to patients with poor without MK and should be included in the poor category whereas the presence of MK should warrant inclusion into the very poor risk category. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 464 Myeloid-derived suppressor cells (MDSC) are important, albeit incompletely characterized, immune regulatory cells which suppress host anti-tumor immunity in malignancies like melanoma. We sought to address 3 outstanding questions in the present study: i) does tumor burden drive the expansion of MDSC; ii) do MDSC express immunosuppressive B7-H family members,;iii) are MDSC depleted following chemotherapy administration. As MDSC expand in response to tumor-derived factors, including those elevated in melanoma patients, we hypothesized that the frequency of MDSC present in the peripheral blood of melanoma patients may be dependent on tumor stage. Therefore, PBMC were obtained from both normal donors and melanoma patients with all stages of disease (stage I, n=10; stage II, n=10; stage III, n=10; stage IV, n=47). A discreet population of CD14+HLA-DR-/lo MDSC was appreciated in samples obtained from melanoma patients, but was largely absent in normal donors. Approximately 0.5% of PBMC were CD14+HLA-DR-/lo in normal donors. In contrast, the frequency of these cells progressively increased with tumor stage in melanoma. While a two-fold increase in CD14+HLA-DR-/lo MDSC was observed in stage I patients, this difference did not reach statistical significance. In contrast, a significant increase in CD14+HLA-DR-/lo MDSC was observed in patients with stage II-IV disease (2.2% Stage II, p<.01; 3.4% stage III, p<.001; 13.2% stage IV, p<.001). While the observed range (range: 0.8-66.3%) in frequency of CD14+HLA-DR-/lo MDSC was broad in stage IV melanoma, these cells comprised more than 10% of total PBMC in the majority of patients. Various B7 homologues (e.g. B7-H1, B7-H2, B7-H3 and B7-H4) may inhibit T-cell activation, proliferation and cytokine production or promote the induction of T-cell apoptosis and unresponsiveness. Due to their immunosuppressive affects, and expression by tumor cells or immune regulatory cells (e.g. Treg, MDSC), these B7-H members are associated with adverse outcomes in multiple human malignancies. As the expression of these important immunoregulatory molecules on MDSC is unknown, we sought to determine whether CD14+HLA-DR-/lo MDSC in melanoma may express B7-H family members. Therefore, PBMC from patients with metastatic melanoma were stained with either an isotype control or antibodies against B7-H1, B7-H2, B7-H3 or B7-H4. In all cases, B7-H family members were more highly expressed on CD14+HLA-DR-/lo MDSC when compared with the expression observed on CD14+ cells from normal donors. While B7-H1 (p<.01), B7-H2 (p<.001) and B7-H4 (p<.01) were preferentially expressed on HLA-DR-/lo cells in melanoma patients, B7-H3 was more highly expressed on both HLA-DR+ (p<.05) and HLA-DR-/lo (p<.001) CD14+ cells. Serial blood samples, both at baseline and at least 12 weeks after therapy, were availabel for 10 patients with metastatic melanoma undergoing therapy wither either carboplatin and nanoparticle albumin bound paclitaxel (nab paclitaxel; n=6) or carboplatin, paclitaxel and bevacizumab (n=4). The frequency of both CD14+HLA-DR-/lo MDSC and conventional CD14+HLA-DR+ monocytes was determined both before and after chemotherapy. An approximately 50% reduction in the frequency of CD14+HLA-DR-/lo MDSC was observed following chemotherapy (p=.004), with no significant reduction in the frequency of conventional HLA-DR+ monocytes (p=.08). Collectively, the data presented implicates multiple B7-H family members in MDSC-mediated immune suppression and demonstrates that the expansion of B7-H+CD14+HLA-DR-/lo MDSC in melanoma is directly associated with the tumor burden, but may be abrogated by the administration of taxane-based chemotherapy. Disclosures: No relevant conflicts of interest to declare.