Citations

Abstract Multiple myeloma (MM) is characterized by clonal expansion of malignant plasma cells (PCs) and aberrant production of monoclonal immunoglobulin detected as an M spike using serum protein electrophoresis. In the United States, MM represents ~15% of hematologic malignancies and is one of the few cancers increasing in incidence (e.g., 14,400 in 1996 to 30,770 in 2018, from SEER). Previously, a Vk*MYC mouse model was described, in which AID-dependent activation of MYC transgene in germinal center (GC) B cells catalyzes a highly penetrant, indolent MM after a prolonged latency, suggesting that additional genetic mutations are required for the malignant MM progression. Recent sequencing of paired tumor/normal samples from advanced or refractory MM patients identified that constitutive activation of Ras signaling pathway (KRAS: 23%; NRAS:20%; BRAF: 8%) associates with MM progression and therapy resistance. To determine whether oncogenic Nras promotes the progression of Myc-induced indolent MM to a malignant stage, we generated NrasLSL Q61R/+; Vk*MYC; IgG1-Cre (VQ) mice along with single mutant mice Vk*MYC; IgG1-Cre or NrasLSL Q61R/+; IgG1-Cre. To boost NrasQ61R expression in GC B cells, 6-7 weeks old mice were immunized with NP-CGG. A significant fraction of VQ mice developed M-spike after immunization and subsequently died of a highly aggressive MM, which was characterized by high proliferative index, hyperactivation of AKT and ERK pathways, and disease hallmarks (e.g. osteolytic lesions, anemia, and kidney injury). VQ myeloma was readily transplantable into serial syngeneic recipients. In our preliminary study, combined Bortezomib and AZD6244 treatment attenuated MM phenotypes and prolonged the survival of VQ recipients. To facilitate easy molecular or genetic manipulations of VQ MM cells, we established two cell lines from primary cells. These cells could be easily infected (see another abstract from our co-author, Dr. Asimakopoulos's group). The cultured MM cells also express high levels of CD155, a ligand of immune checkpoint TIGIT, which has been recently reported to mediate a significant immune checkpoint blockade in MM patients. We further investigated the transcriptional signature of VQ MM cells (from bone marrow [BM] and from lymph nodes [LN]) vs wild-type (WT) plasma cells using the Illumina Bio-Rad's Single-Cell Sequencing platform. Illumina's Sure Cell app was used to de-multiplex samples, process barcodes and perform single-cell 3' gene counting. The processed data were then analyzed using Seurat R package to yield cluster information and their associated enriched genes. Our results revealed distinct clusters of CD138+ MM and WT cells, and also showed high similarity & overlap between BM & LN MM samples. Consistent with the genetic changes introduced to VQ MM cells, both Myc and Nras expression levels were significantly elevated in MM clusters compared to WT clusters. We also found that transcriptional levels of several potential therapeutic targets were significantly elevated in MM clusters, including Integrin alpha 4 and metabolic enzymes. Currently we are validating the scRNA-Seq results. Taken together, we generated a novel mouse model in which activation of Vk*MYC and oncogenic Nras in GC B cells results in a highly malignant, transplantable MM. The VQ mouse model represents an important innovation that will serve as a platform to investigate pathogenesis of resistant and refractory multiple myeloma and allow for testing the efficacy of novel therapeutic agents. Disclosures No relevant conflicts of interest to declare.

Abstract Background Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) characterised by the frequent presence of driver mutations in genes causing activation of JAK2 signalling pathways (JAK2, CALR and MPL). Additional mutations affecting epigenetic regulators and splicing machinery are common. Anaemia with RBC-transfusion-dependence is common in patients with advanced myelofibrosis and represents a major unmet need. The RESUME study assessed the rates of RBC-transfusion independence (TI) after therapy with Pomalidomide (POM) vs placebo in persons with MPN-associated myelofibrosis and RBC-transfusion dependence. 16% of patients in both the POM and placebo arms became TI. Aims The genetic landscape of strictly confirmed transfusion dependent MF is not fully characterised. Our aim was to analyse the genetics of transfusion-dependent myelofibrosis patients in the RESUME trial and correlate with clinical characteristics, outcome and therapy response. Methods DNA samples were available from 207 of 252 patients and analysed by targeted re-sequencing using a Fluidigm Access Array gene panel followed by next generation sequencing. The panel included JAK2, CALR, MPL, TET2, ASXL1, EZH2, DNMT3A, IDH1/2, CBL, IKZF1, U2AF1, CHEK2, TP53, SF3B1, SRSF2, SH2B3, BARD1, DAP3, HRAS, IRF4, KRAS, KIT, Mir662, NFE2, POLG, SCRIB, SETBP1, TCF12 and VPS45. Results 97% (95-99%) of subjects had a mutation in ≥1 targeted gene. 2 mutations were detected in 41% (34-48%) and ≥3 in 27% (21-33%). 7 had no detectable mutation. Mutations in JAK2V617F, CALR and MPL were identified in 66% (59-72%), 14% (8-19%) and 7% (4-11%) of subjects (Figure 1), with no driver mutation in 27 patients (13%; 9-18%) (triple-negative). 68% (61-74%) had additional non-driver mutations. 42% (35-48%) (N=86) had spliceosome mutations (U2AF1 [21%]; SF3B1 [11%]; SRSF2 [8%]; ZRSR2; [6%]). More spliceosome mutations were detected in men than women (47% [39-55%] vs 27% [15-40%]; p=0.009). Spliceosome mutations were mutually exclusive in 83 subjects and were less common in subjects with prior polycythaemia vera (17% [5-37%]) compared with prior essential thrombocythaemia (39% [22-58%]) and primary MF (46% [38-54%]; p=0.024). Mutations in epigenetic regulators (ASXL1, 28%; TET2, 8%; DNMT3A 5%; EZH2 4%) were detected at similar rates to those previously reported. High molecular risk (HMR) mutations (ASXL1, EZH2, IDH1/2, SRSF2) were detected in 36% [29-43%] of subjects. Only 10 of 105 subjects with an epigenetic regulator gene mutation had ≥1 related mutation. Subjects with JAK2V617F were significantly more likely than subjects with a CALR mutation to have: (1) ≥1 additional mutation (72% [64-79%] vs. 35% [18-54%], p=0.0001); (2) a spliceosome mutation (44% [36-53%] vs. 17% [6-36%], p=0.07), in particular a U2AF1 mutation (24% [17-32%] vs. 0%; p=0.004) and (3) a HMR mutation (38% [30-47%] vs. 21% [8-40%]; p=0.07). Survival at 1.5 years was 62% (55-67%) and was not significantly associated with the presence or number of mutations in this uniformly high-risk cohort. Survival in subjects without an SF3B1 mutation was better than those SF3B1-mutated (80% [56-91%]) vs. 59% [52-65%]; p=0.07). Driver mutation status did not influence the probability of achieving red blood cell (RBC) TI, regardless of therapy. Additional non-driver mutations were more often detected in those failing to achieve RBC-TI than those achieving RBC-TI (70% [63-77%] vs 56% [40-71%], p=0.07). Furthermore, those with additional non-driver mutations were less likely to achieve ≥50% reduction in RBC transfusions (24% [17-32%] vs. 39% [27-51%]; p=0.03). A significant correlation persisted in subjects receiving POM but not in those receiving placebo. There was also a significant correlation between U2AF1 mutations and RBC-TI in POM treated subjects compared with controls; U2AF1-mutated subjects were less likely to achieve RBC-TI (3% [1, 17%]) than U2AF1-unmutated subjects (25% [17, 34%], p=0.008). No other mutations were significantly correlated with response. Conclusion We found a high incidence of spliceosome mutations in persons with MPN-associated MF and RBC-transfusion-dependence. Mutation of U2AF1 correlated with response in subjects receiving POM but not in those receiving placebo. Incorporation of mutation profiling into clinical trial design may help to inform subgroups of patients that may benefit from the intervention. Disclosures Devos: Novartis: Consultancy; Celgene: Consultancy; Takeda: Consultancy. Gisslinger:Shire: Consultancy, Honoraria; Novartis: Honoraria, Research Funding; AOP Orphan Pharmaceuticals AG: Consultancy, Honoraria, Research Funding; Janssen Cilag: Consultancy, Honoraria. Kiladjian:Celgene: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Mesa:Celgene: Research Funding; UT Health San Antonio - Mays Cancer Center: Employment; Pfizer: Research Funding; Gilead: Research Funding; NS Pharma: Research Funding; CTI Biopharma: Research Funding; Incyte Corporation: Research Funding; Novartis: Consultancy; Promedior: Research Funding; Genentech: Research Funding. Ribrag:argenX: Research Funding; BMS: Consultancy, Honoraria, Other: travel; NanoString Technologies: Consultancy, Honoraria; pharmamar: Other: travel; Infinity: Consultancy, Honoraria; MSD: Honoraria; Amgen: Research Funding; Gilead: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Roche: Honoraria, Other: travel; epizyme: Consultancy, Honoraria; Incyte Corporation: Consultancy. Schiller:Celator/Jazz Pharmaceuticals: Research Funding; Pharmacyclics: Research Funding. Vannucchi:Celgene: Membership on an entity's Board of Directors or advisory committees; ITALFARMACO: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Reiser:Celgene: Employment. Zhong:Celgene: Employment. Mead:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; ARIAD: Consultancy; Bristol-Myers Squibb: Consultancy; Cell Therapeutics: Consultancy; Celgene: Research Funding; Elstar: Research Funding; Evotek: Research Funding.

Abstract Monoclonal gammopathies, including multiple myeloma (MM), represent a group of plasma cell (PC) disorders that comprise of mostly incurable hematopoietic malignancies with an increasing incidence in the US. Previous epidemiological studies demonstrated a 2-3 fold higher incidence of monoclonal gammopathy of undetermined significance (MGUS) and a similarly higher incidence of MM along with a ~4-year younger age of onset among African Americans (AA) compared to European Americans (EAs) (Fonseca, Leukemia, 2017). This suggests a possible ancestral-associated genetic predisposition of AAs to the development of monoclonal gammopathies (Landgren, Blood, 2006). When access to care is equal, AAs have a better overall survival compared to EAs suggesting that AAs may have a genetic predisposition that renders them better responders to treatment or have more favorable cytogenetic subtypes of MM (Waxman, Blood, 2010). Previous efforts to understand this disparity have relied on self-reported race rather than genetic ancestry. We hypothesize that quantifying genetic ancestry is necessary to fully understand the genetic mechanisms of racial disparities of monoclonal gammopathies. We describe our study of 881 patients with monoclonal gammopathies who had undergone uniform testing to identify MM-specific cytogenetic abnormalities. DNA from the bone marrow samples was genotyped on the Precision Medicine Research Array. Biogeographical ancestry was assessed using the Geographic Population Structure Origins tool, which provides the ancestral breakdown of 36 admixture components for each individual representing different geographic regions and outputs admixture proportions corresponding to those ancestries (Elhaik, Nat Commun, 2014). We evaluated whether an increase in the percentage of African Ancestry altered the odds of any primary cytogenetic abnormality. We demonstrated that a 10% increase in the percentage of African ancestry was associated with a 6% increase in the odds of detecting either an t(11;14), t(14;16) or t(14;20) (odds ratio = 1.06, 95% CI: 1.02 - 1.11; p-value = 0.05). Although we observed an increase in the odds of each of the individual translocations with 10% increase in African ancestry, l t(11;14) (OR=1.03) t(14;16) (OR=1.11) and t(14;20) (OR=1.10), these three abnormalities were combined to achieve greater statistical power. The differences in cytogenetic abnormalities were most striking among individuals with ≥80.0% African (n=120) compared to individuals with <0.1% African ancestry (n=235). Using these cutoff values comparing the ≥80.0% and <0.1% African ancestry cohorts, there was a higher prevalence of t(11;14), t(14;16) and t(14;20) (51% vs. 33%, respectively, p-value=0.008) and a lower prevalence of trisomies (with or without IgH translocations) (48.3% vs. 61.3%, respectively, p-value=0.066). In addition, the ≥80% African ancestry cohort also displayed a slightly lower prevalence of monosomy 13/13q deletion compared to the cohort with <0.1% African ancestry (34.2% vs. 38.7%, respectively, p-value=0.021). Further, we observed a significantly higher prevalence in the proportion of females with monoclonal gammopathies among the ≥80% African ancestry cohort compared to the cohort with <0.1% African ancestry (56.7% vs. 42.1%, respectively, p-value=0.028). We complement our past studies that relied on self-reported race and characterized patients' demographic and uniformly collected cytogenetic data in relation to genetically defined African ancestry. We demonstrate the prevalence of having one of three specific subtypes (i.e., t(11;14), t(14;16), or t(14;20)) was significantly higher in those with highest (≥80%) compared to lowest (<0.1%) African ancestry demonstrating African ancestry is associated with a subtype distribution of MM that differs from non-African individuals. These differences were only revealed after analysis of individuals with the highest and lowest percentage of African ancestry. Since 38.3% of the individuals with ≥80% African ancestry have the favorable t(11;14) translocation (in comparison to 26.8% of <0.1% African individuals), this finding may explain improved survival with equal access to care. Understanding the genetic mechanisms of this disparity is a fundamental step to understanding differences in incidence and outcomes of patients with monoclonal gammopathies. Disclosures Elhaik: DNA Diagnostics Center: Consultancy. Baird:DNA Diagnostics Center: Employment. Cerhan:Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding; Celgene: Research Funding. Stewart:Amgen Inc., BMS, Celgene, Takeda, Roche, Seattle Genetics, Janssen, Ono: Consultancy; Amgen Inc., Celgene, Roche, Seattle Genetics: Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Kumar:Novartis: Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding.

Abstract Introduction: Determining the optimal post-remission management for elderly patients with acute myeloid leukemia (AML) remains a challenge. AML is primarily a disease of the elderly with >60% of newly diagnosed patients aged 60 years and older. For younger AML patients, post-remission therapy in the form of high-dose cytarabine (HIDAC) consolidation or allogeneic hematopoietic stem cell transplant (HSCT) is critical in maintaining durable disease control and improving survival. However, post-remission HIDAC in elderly AML patients is associated with higher rates of neurotoxicity and decreased survival benefit compared to younger patients. The optimal post-remission therapy for elderly AML patients remains undefined. The objective of this study is to determine the outcomes of using varying doses (0.25-3 g/m2) of cytarabine as post-remission consolidation therapy in an elderly AML population. Methods: We conducted a single-center retrospective analysis of AML patients aged 60 years and older treated with cytarabine as consolidation therapy at UPMC Hillman Cancer Center between January 1, 2005 and December 31, 2014. Patients were excluded if they were not in complete morphologic remission prior to proceeding with cytarabine consolidation or if they proceeded directly to HSCT after consolidation therapy. Relapse-free survival (RFS) was measured from the time of post-induction bone marrow biopsy confirming remission to the date of relapse or death. Overall survival (OS) was defined as the duration from diagnostic bone marrow biopsy confirming AML diagnosis to the date of death. Kaplan-Meier analysis was used to estimate the survival distributions and log-rank test was used to compare survival functions from groups. Multivariate analysis was performed using Cox proportional hazard regression to determine the relationship of RFS and OS to patient's age, cytogenetic risk group, AML type (de novo vs secondary AML), transplant status, cytarabine dosage and number of cycles. All data was analyzed using SAS v9.4 (SAS Institute, Cary, NC, USA). Results: Out of 156 identified patients, 121 were eligible for analysis. Median age at diagnosis was 66 years (range 59-78) with 77 (64%) male patients. Thirty-six patients (30%) had secondary AML. Cytogenetic abnormalities were favorable in 7 (6%), intermediate in 86 (71%), unfavorable in 24 (20%), and unknown in 4 (3%) patients. Cytarabine was administered at a mean dose of 1.44 g/m2 (range 0.25-3.0, SD 0.84) and a median number of cycles of 4 (range 1-4). One patient (0.8%) developed reversible grade 3 neurotoxicity during cycle 2 at a dose of 2 g/m2 with ataxia, dysmetria, and tremors. For all patients, the median RFS was 12.5 months (95% CI 9.7-15.6). Median RFS was significantly different among the cytogenetic risk groups (p=0.0008 via log-rank test): favorable-risk RFS had not been reached because most subjects were in remission and alive at time of analysis, intermediate-risk RFS 13.6 months (95% CI 11.0-17.3), unfavorable-risk RFS 8.3 months (95% CI 3.5-8.9). In this study population, the median OS was 20.5 months (95% CI 16.4-27.1). Median OS was significantly different among the cytogenetic risk groups (p=0.003 via log-rank test): favorable-risk OS 131.3 months (95% CI 12.9-upper limit not reached), intermediate-risk OS 25.1 months (95% CI 18.9-39.4), and unfavorable-risk OS 10.8 months (95% CI 10.4-15.8). Average cytarabine dose did not significantly correlate with RFS or OS in the model. Multivariate analysis revealed a 27% decreased rate of relapse (HR 0.73, 95% CI 0.58-0.92, p=0.008), and 24% decreased mortality rate (HR 0.76, 95% CI 0.59-0.96, p=0.024) with each additional cytarabine cycle given. Conclusions: Our study supports the use of cytarabine as a tolerable and effective option for post-remission therapy in elderly AML patients, particularly those with favorable-risk cytogenetics. Each additional cycle administered was associated with improved RFS and OS rates in this study population. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction B progenitor acute lymphoblastic leukemia (B-ALL) is a leading cause of childhood cancer death. Many chimeric genes have been identified and led to a refined classification of B-ALL and tailored therapies. Still, up to 30% of B-ALL cannot be classified into established subtypes, and the outcome for many is poor. Methods To identify novel subtypes of B-ALL, we performed integrative genomic analysis including transcriptome sequencing (RNA-seq) of 1,988 cases from St. Jude, Children's Oncology Group and adult cooperative group studies and analyzed chromosomal rearrangements, gene-expression profiles (GEP), somatic mutations and chromosome-level copy-number alterations. Cases lacking known or putative subtype-defining alterations underwent whole genome sequencing. Effects on proliferation and transformation of novel lesions were assessed by retroviral expression in cell lines and point-mutation knock-in mice using CRISPR/Cas9 genome editing. Results Using integrated genetic alterations and gene expression profiling, we classified 23 B-ALL subtypes (Table and Figure). Three groups included cases with similar GEP as canonical subtypes (ETV6-RUNX1, KMT2A-rearranged, and ZNF384-rearranged), but lacking the expected drivers (e.g., ETV6-RUNX1-like, n=42). Eighteen cases (0.9%) had rearrangements of BCL2, MYC and/or BCL6 showing a distinct GEP; they were mostly adults (n=16) with very poor outcome. These alterations, rarely seen in ALL, are identical to those observed in "double/triple hit" lymphoma, and are of pre-B immunophenotype. Eight cases with tightly clustered GEP comprised a novel subtype defined by IKZF1 N159Y missense mutation. N159Y is in the DNA-binding domain of IKZF1, and is known to perturb IKZF1 function, with distinct nuclear mislocalization and induction of aberrant intercellular adhesion. We identified two subtypes with distinct GEP characterized by PAX5 alterations. One, herein termed PAX5 altered (PAX5alt), comprised 148 (7.4%) cases, was characterized by diverse PAX5 alterations including rearrangements (n=57), sequence mutations (n=46) and/or focal intragenic amplifications (n=8). These PAX5 alterations were found in 73.6% of PAX5alt cases and different alteration types were mutually exclusive. Other PAX5 alterations, including deletions and large-scale amplifications were also assessed using SNP array, but were not enriched in the PAX5alt group. Clinically, PAX5alt pediatric and adult patients had favorable (96.8±3.2%) and intermediate (42.1±10.2%) 5-year overall survival (OS), respectively. The other GEP distinct subtype comprised 44 cases, all with PAX5 P80R missense mutations. In 30 of these cases, PAX5 P80R was homozygous due to deletion of the wild-type (WT) PAX5 allele or copy-neutral loss of heterozygosity. Of the other 14 cases with heterozygous PAX5 P80R mutations, 13 had a second frameshift (n=7), nonsense (n=2) or deleterious missense (n=4) PAX5 mutation. Four of the remaining 1,944 cases also had the PAX5 P80R mutation, but all were heterozygous with preservation of a WT PAX5 allele, consistent with the notion that homozygous or compound heterozygous PAX5 P80R mutation is the hallmark of this subtype. Adult PAX5 P80R cases (n=14) showed better 5-year OS (61.9±13.4%) than those in PAX5alt subtype (42.1±10.2%). To examine the effects of PAX5 P80R on B-cell maturation, WT PAX5, PAX5 P80R, V26G and P34Q were expressed in Pax5-/- lineage-depleted bone marrow cells. Expression of WT PAX5, PAX5 V26G and P34Q resulted in near complete rescue of B cell differentiation; however, expression of PAX5 P80R blocked the differentiation at the pre-pro-B stage of B-cell maturation. Further, Pax5 P80R heterozygous or homozygous mice developed pre-B-ALL with a median latency of 166 and 87 days, respectively, with heterozygous mice acquiring alterations on the second allele. In contrast, Pax5+/- mice, and those harboring G183S mutation observed in familial leukemia, do not spontaneously develop B-ALL. Conclusions These results show the utility of transcriptome sequencing in defining subtypes and founding genetic alterations in B-ALL, provide a revised taxonomy of the disease across the age spectrum, and reinforce the central role of PAX5 as a checkpoint in B lymphoid maturation and leukemogenesis. Disclosures McKay: ImmunoGen Inc.: Employment. Tallman:Orsenix: Other: Advisory board; AROG: Research Funding; BioSight: Other: Advisory board; Cellerant: Research Funding; AbbVie: Research Funding; Daiichi-Sankyo: Other: Advisory board; ADC Therapeutics: Research Funding. Stock:Jazz Pharmaceuticals: Consultancy. Konopleva:Stemline Therapeutics: Research Funding. Relling:Shire Pharmaceuticals: Research Funding. Mullighan:Cancer Prevention and Research Institute of Texas: Consultancy; Amgen: Honoraria, Speakers Bureau; Abbvie: Research Funding; Loxo Oncology: Research Funding; Pfizer: Honoraria, Research Funding, Speakers Bureau.

Abstract Chronic idiopathic myelofibrosis (MF) is a clonal hematopoietic disorder that leads to progressive marrow fibrosis and peripheral cytopenias. Very little is known about the role of aberrant DNA methylation in the pathobiology of this disease. Whole genome methylation was analyzed by a recently described novel method, the HELP assay (HpaII tiny fragment Enrichment by Ligation-mediated PCR; Khulan et al, Genome Res. 2006 Aug;16(8)) that uses differential methylation specific restriction digestion by HpaII and MspI followed by amplification, two color labeling and cohybridization to quantitatively determine individual promoter methylation. A whole genome human promoter array (Nimblegen) was used to determine the level of methylation of 25626 gene promoters by calculating HpaII/MspI cut fragment intensity ratio. Peripheral blood leucocytes from 9 patients with IMF were compared to 9 age-matched normal and anemic controls. Gene expression analysis was performed using 37K oligo maskless arrays using cDNA from the same samples. Methylation analysis showed that myelofibrosis samples clustered separately from normal and anemic controls when grouped by unsupervised clustering based on Pearson’s correlation coefficient. On the other hand, global gene expression demonstrated no clear cut differences between myelofibrosis and control samples suggesting that methylation profiling has greater discriminatory power when compared to conventional gene expression profiling. A high correlation (r=0.88–0.96) was observed between whole genome methylation profiles of matched sets of bone marrow and peripheral blood leucocyte samples from selected patients demonstrating that peripheral blood leucocytes can act as a valid surrogates for epigenomic analysis. Further analysis showed that genes aberrantly methylated in all myelofibrosis samples included v-myc, histone 2A, TNF, TNF Receptor1, FGF14 and others. Functional pathway analysis by Ingenuity showed that pathways involved in Inflammation and Cell signaling were the most affected by epigenetic silencing. Most interestingly, a large proportion of gene promoters were also aberrantly hypomethylated. These included genes for chemokine CXCL13, APC, IL-3, STAT2 and others. The pathways most activated by hypomethylation were involved in hematopoiesis and cell growth and proliferation demonstrating the biological validity of our analysis. Thus, our data demonstrates that myelofibrosis is characterized by distinct epigenetic aberrations that are preserved in peripheral blood leucocytes. These can be the basis of future studies on pathogenesis and diagnosis for this disease and lead to translational studies with agents targeting DNA methylation.

Abstract Abstract 3931 Poster Board III-867 Extranodal nasal-type Natural Killer/T-cell lymphoma (NKTCL) is a distinct clinicopathologic entity most commonly affecting Asians and Central and South Americans, and characterized by a clonal proliferation of NK or T cells with a cytotoxic phenotype. There is a strong association with Epstein-Barr Virus. The tumor is aggressive with patient usually surviving short duration even with chemotherapy. We performed the first comprehensive genome-wide gene expression profiling (GEP) of extranodal nasal-type Natural Killer/T-cell lymphoma (NKTCL) using formalin-fixed paraffin embedded (FFPE) tissue (n=25) and NK cell lines (n=5) and compared the results to the GEP of normal NK cells using the Illumina DASL whole genome array, with the objective of understanding the oncogenic pathways involved in the pathogenesis of NKTCL and to identify potential therapeutic targets. Quantitative-PCR validation of the GEP findings revealed over-expression of candidate genes BIRC5 (survivin), EZH2 and STMN1 in NK cell lines compared to normal NK cells, consistent with the GEP data. We then extracted a list of genes that are differentially expressed between NKTCL and normal NK cells and tissue controls. We than subjected this list of genes to pathway and network analysis using Metacore. This revealed a significant enrichment for cell cycle related genes and pathways. Furthermore, the network analysis results demonstrated a pro-proliferative and anti-apoptotic phenotype in NKTCL characterized by activation of Myc and nuclear factor kappa B (NF-KB), and deregulation of p53. This was further corroborated using immunohistochemistry on tissue microarray of NKTCL (n=33, including all cases with GEP performed). We observed a significant percentage of NKTCL showing overexpression for c-Myc (45.4%), p53 (87.9%) and NF-KB p50 (67.7%) on immunohistochemistry. Notably, overexpression of survivin was observed in 97% of the cases. Based on our findings, we propose a model of NKTCL pathogenesis where deregulation of p53 together with activation of MYC and NF-KB, possibly driven by EBV LMP-1, result in the cumulative upregulation of survivin. When KHYG and NKYS cell lines were treated with a compound IDR E804 which inhibited survivin, there is significant inhibition of cell growth as assess by MTS assay and induction of apoptosis as measured using Annexin V staining by flow cytometry. This suggests that compounds inhibiting survivin may be a potentially useful novel therapeutic approach in NKTCL. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2477 Background: Aurora A kinase (AAK) is a key mitotic regulator, inhibition of which results in mitotic spindle defects, mitotic delay, and apoptosis. AAK is amplified or overexpressed in a number of heme-lymphatic malignancies. This phase 1, multicenter study (NCT00697346) is the first to assess safety, tolerability, and pharmacokinetics (PK) of the investigational AAK inhibitor alisertib (MLN8237) in patients with advanced hematologic malignancies. Methods: Patients aged ≥18 years with relapsed/refractory hematologic malignancy, confirmed radiographically or clinically evaluable disease, and ECOG performance status 0–2, were eligible for inclusion. Patients with prior allogeneic transplant were excluded; there was no restriction on the number of prior therapies. Patients received escalating doses (standard 3+3 design) of alisertib as either a powder-in-capsule (PIC) or enteric coated tablet (ECT) formulation. Alisertib PIC was administered as a twice-daily (BID) loading dose on Day 1, then once daily (QD) on Days 2–14 or 2–21, followed by 14 or 7 days' rest, respectively, in 28-day cycles. Alisertib ECT administration followed the same scheme in the first dose group, and subsequent groups received divided (BID) doses for 7 days plus 14 days' rest in 21-day cycles. Endpoints included maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, PK, and response. Results: 55 patients were included (PIC n=28, ECT n=27); median age was 61 years (range 27–82), 42% had prior ASCT, and 78% had received ≥3 prior therapies. 60% of patients had non-Hodgkin's lymphoma, 35% multiple myeloma, and 5% chronic lymphocytic leukemia/small lymphocytic lymphoma. Patients received a median of 2 cycles (range 1–14); 8 patients are ongoing. The MTD on the alisertib PIC 14-day + 14 days' rest schedule was 45 mg QD, established following occurrence of DLTs in four patients at higher dose levels: Gr 4 thrombocytopenia, Gr 4 neutropenia (65 mg QD); Gr 3 febrile neutropenia, Gr 4 thrombocytopenia (90 mg QD). In patients receiving alisertib ECT, the MTD was determined as 50 mg BID on a 7-day + 14 days' rest schedule; four DLTs were observed in three patients: at 40 mg QD for 14 days, one patient had Gr 4 febrile neutropenia, and one patient had Gr 4 bullous dermatitis and Gr 4 neutropenia; at 50 mg BID for 7 days, one of nine patients had Gr 4 neutropenia. The most common drug-related adverse events (AEs) were neutropenia (PIC 46%, ECT 63%), thrombocytopenia (39%, 41%), and diarrhea (29%, 41%); most common Gr ≥3 drug-related AEs were neutropenia (PIC 36%, ECT 52%), thrombocytopenia (29%, 26%), and anemia (14%, 26%). 24 patients (PIC n=12, ECT n=12) had serious AEs; the most common was febrile neutropenia (PIC n=1, ECT n=4). Tolerability appeared generally similar between the PIC and ECT formulations. Six patients (PIC n=3, ECT n=3) died during the study (PIC: renal failure, airway obstruction, progressive large cell lymphoma; ECT: progressive myeloma [n=2], hypercalcemia); no deaths were considered to be related to alisertib. Alisertib absorption was rapid with an overall median Tmax of 2 hours. The overall mean terminal half-life following multiple dosing was 19 hours. The mean peak/trough (P/T) ratio was 5 following QD dosing as PIC. The mean accumulation ratio and P/T ratio were 2.5 and 2.1, respectively, following BID dosing as ECT. At data cut-off (29 March, 2011), 42 patients were evaluable for response. Antitumor activity was observed in five patients (PIC n=3, ECT n=2) who had partial responses; 11 patients had a best response of stable disease (PIC n=6, ECT n=5) and 26 had progressive disease (PIC n=14, ECT n=12). Seven patients received ≥5 cycles of therapy, including one patient (PIC group; post-transplant grade 3B follicular lymphoma) with resolution of B symptoms who received alisertib for >1 year. Conclusions: The MTDs of the PIC and ECT formulations of alisertib are 45 mg QD for 14 days (+14 days' rest) and 50 mg BID for 7 days (+ 14 days' rest), respectively, in patients with advanced, non-leukemic hematologic malignancies. AEs were generally manageable and were consistent with inhibition of AAK in highly proliferative tissues (gastrointestinal and hematologic AEs). Current data support further investigation and expansion at the MTDs is ongoing. Data from PK, safety, and tolerability collectively support the progression of ECT formulation at 50 mg BID for 7 days in a 21-day cycle into phase 2 development. Disclosures: Off Label Use: Investigational agent in clinical development for the treatment of advanced hematologic malignancies and solid tumors. Goy:Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Reeder:Millennium Pharmaceuticals, Inc.: Institutional research funding; Novartis: Institutional research funding; Celgene: Institutional research funding. Zhou:Millennium Pharmaceuticals, Inc.: Employment. Danaee:Millennium Pharmaceuticals, Inc.: Employment. Xiao:Millennium Pharmaceuticals, Inc.: Employment. Benaim:Millennium Pharmaceuticals, Inc.: Employment, Equity Ownership. Shea:Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding.

Abstract Abstract 3708 Background: Rituximab maintenance (RM) following induction therapy has been demonstrated to increase PFS in randomized trials in both first-line and relapsed settings (ECOG 1496, EORTC 20981, and most recently, PRIMA), and RM has been frequently used in clinical practice in the U.S. and other countries. We examined the various RM approaches used by practicing physicians in the U.S., factors that predicted whether RM was used, and compared the “real-world” effectiveness of RM to the outcomes of observation (Obs) following front-line R-based induction in FL patients (pts). Methods: The National LymphoCare Study is a prospective, multi-center, longitudinal, observational study that collects data on treatment and outcomes for pts diagnosed with FL in the U.S. from 2004–2007. Pts who achieved complete response (CR), partial response (PR) or stable disease (SD) following initial treatment with R-based therapy and who did not initiate second line therapy during the 215-day period following the date of last dose of initial therapy were categorized as Obs. Pts meeting the same criteria who started maintenance R treatment in the 215-day period comprise the RM group. Multivariable logistic regression analyses were performed to identify characteristics related to receiving RM. We compared RM and Obs groups in progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS) using Cox proportional hazards models controlling for confounding factors of clinical interest (sex, FLIPI risk group, treatment setting [academic vs. community], and induction therapy). PFS was defined as the number of days from the 215 day period following induction that defined the Obs and RM groups up to and including the date of disease progression as assessed by the treating physician or death from any cause. Pts who had not yet experienced a PFS event at the time of analysis were censored at the date of the most recent response assessment. Results: Of the 2,732 pts enrolled in NLCS, 1,536 pts completed R-based induction therapy. Among these,1,236 pts achieved CR/PR/SD and met other criteria described above to be included in analysis. 557 pts started RM treatment in the 215-day post-induction work up period (128 following R and 429 following R-chemo), and 679 pts were observed (125 following R and 554 following R-chemo). The mean duration of RM was 528 days, and the mean number of RM doses received was 13. 23% received Rx4 every 6 months, 20% Rx1 every 2 or 3 months, and 57% received another schedule. 14% of pts discontinued RM early (n=79). The most common reasons for early discontinuations were disease progression (29%), toxicity (11%), or death (7%). Pts who received R induction were more likely to receive RM than those who received R-chemo as induction (51% vs. 44%). Pts treated in community practices were slightly more likely to receive RM compared with those who were treated in academic centers (46% vs. 40%). In multivariable models, the most significant predictors of receiving RM were grade (I/II), stage (III/IV), geographic region (other than West), community practice setting, and R induction treatment (all p<0.05). After adjusting for FLIPI risk group, induction treatment, and clinical factors, RM significantly improved PFS (HR= 0.72; p= 0.010) and TTNT (HR= 0.74; p= 0.03). At 4 years of follow-up, 11% of pts in the combined population have died and there was no significant difference in OS between RM and Obs groups. 22% (n=124) of RM pts had received 2nd line treatment at the time of analysis, of whom 36% received R alone and 31% received R-chemo. The response rate for 2nd treatment was similar between RM and Obs groups (60% CR/PR for both groups). Conclusions: RM following front-line R-based induction was common in this period. However, a large percentage of pts received a RM schedule that was not consistent with standard published schedules reflecting variation among community practices. Nevertheless, RM use in clinical practice produced significant differences in PFS and TTNT compared to Obs. Importantly, response to second-line treatment was similar between RM and Obs groups. Additional followup is needed to determine whether RM produces OS benefits in this context. Disclosures: Sinha: Celgene: Research Funding. Zhou:RTI-HS: Employment; Novartis: Research Funding. Friedberg:Genentech: Consultancy; astellas: ; Lilly: ; Abbott/Trubion: ; Seattle Genetics: Honoraria; Cephalon: Consultancy. Hirata:Genentech Inc/Roche: Employment; Roche: Equity Ownership. Flowers:Spectrum: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Genentech/Roche (unpaid): Consultancy; Novartis: Research Funding; Seattle Genetics: Consultancy.

Abstract Background: Large case-control studies have identified common epidemiologic exposures associated with risk of AML development, including obesity [BMI ≥30 kg/m2] associated with 2-fold increase risk. However it is not known whether individual risk factors are associated with unique AML genetic lesions. We have recently identified a significant association of some common exposures including obesity with unique disease cytogenetic subgroups in a cohort of n=295 consecutive AML patients diagnosed and treated at Mayo Clinic [Cancer Epidemiol 39:1084, 2015]. Aberrant DNA methylation is a hallmark of cancer and has been reported in AML, and we therefore performed an analysis of global DNA methylation in patients in this cohort to determine whether specific epidemiologic exposures are associated with a unique pattern of DNA methylation. Methods: Patients in the initial cohort were previously reported. An available baseline AML bone marrow cytogenetic pellet from diagnosis was identified for n=148 patients (50.2%). Following IRB approval and using previously reported techniques [Leukemia 24:1283, 2010], leukemia DNA was isolated from the remnant diagnostic cytogenetic samples and processed on the HumanMethylation450 BeadChip array (Illumina). Individual CpG dinucleotides were assigned a Beta value (i.e. methylation value) ranging from 0 (unmethylated) to 1 (methylated). We excluded those with minor methylation changes (<0.2 between any two samples), resulting in 383,524 CpG's. For the purposes of this first analysis we have focused only on CpG's with an inter-quartile range (IQR, i.e. difference between 75th and 25th percentiles) of greater than 0.25, comprising a total of 39,657 CpG's. An unsupervised cluster analysis of differential methylation was generated ("Heatmap", Figure). Univariate and multivariable analyses were performed adjusting for age as a continuous variable to determine the association of individual exposures with unique methylation clusters (primary endpoint), and we also evaluated the association of clinical characteristics and clinical outcomes after therapy (secondary endpoint). The median age of patients was 69 yrs (range 19-89), male 65%, and Caucasian 89%. The median BMI was 27.2 (range 16.9-59.9), and n=47 patients (32%) had BMI ≥30. Standard cytogenetic risk groups were applied [favorable (n=8), normal (n=61), intermediate abnormal (n=32) and poor (n=47)]. Results: We identified 4 distinct methylation clusters (Figure: Cluster #1, Black horizontal bar; Cluster #2, Green; Cluster #3, Blue; and Cluster #4, Red). Multivariate analysis of select variables is shown in Table. Patients in cluster #1 were significantly more likely to have a BMI ≥30 [Odds Ratio (OR) 2.49, p=0.017] and more likely to have favorable risk cytogenetics although this was not statistically significant [OR 6.71, p=0.088], while those in cluster #2 were significantly more likely to be have a history of regular NSAID use [OR 3.26, p=0.03] and less likely to have normal [OR 0.40, p=0.044] and possibly intermediate abnormal cytogenetics [OR 0.34, p=0.051]. Those in cluster #3 were significantly younger [median age 48 yrs, p<0.001] and were also more likely to have prior history MDS although this was not statistically significant [OR 3.7, p=0.082]. Cluster #4 was not correlated with any distinct exposure apart from possible decreased alcohol use [OR 0.3, p=0.079]. History of past or current tobacco use, regular acetaminophen use, documented myelotoxin exposure, family history, and secondary AML did not correlate with a unique methylation cluster. There was no independent association of methylation cluster with overall survival (p=0.46), although among patients receiving intensive therapy cluster #2 was associated with lower complete remission rate [OR 0.28 (95% CI 0.09-0.86), p=0.026]. Conclusion: This first analysis of AML molecular epidemiology and clinical outcome suggests that specific disease risk factors (esp. obesity and age) are associated with unique leukemia DNA methylation clusters. In addition, aberrant methylation is associated with some clinical features and with outcome after therapy, suggesting that epidemiologic risk factors may have a prognostic impact. This provides novel insight into leukemogenesis, and will guide prospective studies of AML epidemiology and outcome. Figure. Figure. Disclosures Foran: medscape: Honoraria; pfizer: Honoraria; Millennium Pharmaceuticals, Inc.: Research Funding; novartis: Honoraria; karyopharm: Honoraria; boehringer ingelheim: Research Funding; agios: Research Funding; Cellerant: Research Funding.