ALBERT

Description: Recent studies of the spectrum of somatic genetic alterations in acute myeloid leukemia (AML) have identified frequent somatic mutations in genes that encode proteins important in the epigenetic regulation of gene transcription. This includes proteins involved in the modification of DNA cytosine residues and enzymes which catalyze posttranslational modifications of histones. Here we describe the clinical, biological, and therapeutic relevance of mutations in epigenetic regulators in AML. In particular, we focus on the role of loss-of-function mutations in TET2, gain-of-function mutations in IDH1 and IDH2, and loss-of-function mutations in ASXL1 and mutations of unclear impact in DNMT3A in AML pathogenesis and therapy. Multiple studies have consistently identified that mutations in these genes have prognostic relevance, particularly in intermediate-risk AML patients, arguing for inclusion of mutational testing of these genetic abnormalities in routine clinical practice. Moreover, biochemical, biological, and epigenomic analyses of the effects of these mutations have informed the development of novel therapies which target pathways deregulated by these mutations. Our understanding of the effects of these mutations on hematopoiesis and potential for therapeutic targeting of specific AML subsets is also reviewed here.

Description: The Blood and Marrow Transplant Clinical Trials Network conducted 2 parallel multicenter phase 2 trials for individuals with leukemia or lymphoma and no suitable related donor. Reduced intensity conditioning (RIC) was used with either unrelated double umbilical cord blood (dUCB) or HLA-haploidentical related donor bone marrow (Haplo-marrow) transplantation. For both trials, the transplantation conditioning regimen incorporated cyclophosphamide, fludarabine, and 200 cGy of total body irradiation. The 1-year probabilities of overall and progression-free survival were 54% and 46%, respectively, after dUCB transplantation (n = 50) and 62% and 48%, respectively, after Haplo-marrow transplantation (n = 50). The day +56 cumulative incidence of neutrophil recovery was 94% after dUCB and 96% after Haplo-marrow transplantation. The 100-day cumulative incidence of grade II-IV acute GVHD was 40% after dUCB and 32% after Haplo-marrow transplantation. The 1-year cumulative incidences of nonrelapse mortality and relapse after dUCB transplantation were 24% and 31%, respectively, with corresponding results of 7% and 45%, respectively, after Haplo-marrow transplantation. These multicenter studies confirm the utility of dUCB and Haplo-marrow as alternative donor sources and set the stage for a multicenter randomized clinical trial to assess the relative efficacy of these 2 strategies. The trials are registered at www.clinicaltrials.gov under NCT00864227 (BMT CTN 0604) and NCT00849147 (BMT CTN 0603).

Description: Key Points Serum 2HG analysis by LC-MS can accurately identify patients with AML with and without IDH mutations. Oncometabolite testing of serum 2HG is indicated as a diagnostic, prognostic, and therapeutic monitoring tool in AML.

Description: Intro: Multiple myeloma (MM) is an incurable malignancy that arises from MGUS, however the majority of patients with MGUS do not go on to develop MM. A deeper understanding of the biology of progression from MGUS to MM is needed to identify patients at higher risk of progression and identify potential strategies to prevent development of MM. Altered bone metabolism is common in MGUS with upregulation of the receptor-activator of nuclear kB ligand (RANKL) to osteoprotegrin (OPG) ratio. Vitamin D has a central role in bone metabolism and has recently been associated with progressive disease in several malignancies, including MM. We hypothesized that progressive alterations in the key molecules of bone remodeling would correlate with the risk group of MGUS and that correction of vitamin D deficiency would lead to improved equilibrium of selective cytokines involved in bone remodeling and metabolism. Methods: 43 patients with MGUS or smoldering myeloma were assigned to low (0 or 1 risk factor) or high (2 or 3 risk factors or smoldering multiple myeloma (SMM)) risk of progression to MM based on the IMWG consensus statement (Leukemia. 2010, June; 24(6); 1121-7). We measured 25 hydroxyvitamin D levels, IL-6, and the RANKL/OPG ratio via enzyme linked immunosorbent assay (ELISA). Patients with low levels of 25 hydroxyvitamin D were treated with 6,000 units of cholecalciferol daily for 8 weeks and then 2,000 units daily thereafter. Repeat levels of 25 hydroxyvitamin D, interleukin-6 (IL-6), and RANKL/OPG were repeated after three months of cholecalciferol therapy. Results: Total enrollment was 43 patients, with 26 patients with low risk disease and 17 patients with high risk disease. There was no significant difference in IL-6, OPG, RANKL, or the RANKL/OPG ratio levels between patients with low versus high risk disease. Patients with SMM versus patients with MGUS had higher levels of IL-6 RANKL and the RANKL/OPG ratio. 14 patients were found to have vitamin D deficiency with 25 hydroxyvitamin D

Description: Systemic mastocytosis (SM) is a rare myeloproliferative neoplasm characterized by proliferation and hyperactivation of clonal mast cells. Clinical manifestations are heterogeneous and encompass cutaneous lesions, gastrointestinal alterations, osteoporosis, anaphylaxis and involvement of bone marrow and other organs due to neoplastic mast cells (MC) infiltration. As consequence, diagnosis may be difficult and patients (pts) are often evaluated by different specialists before the disease is recognized. To date, only few studies (Lim 2009, Escribano 2009, Cohen 2014) described relatively large series of pts with SM. We performed a multicentre retrospective study to evaluate clinical and biological features and therapeutic management in a large series of pts from 10 Italian centres experienced in management of SM and organized in multidisciplinary groups of specialists. We collected 455 pts diagnosed with SM according to WHO criteria. Additionally 26 pts with mastocytosis in the skin (MIS) evaluated with BM examination did not fulfil criteria for SM, leading to diagnosis of Cutaneous Mastocytosis (CM); however 2/26 pts with CM had both cKITD816V mutation and CD2/CD25 expression on MC in BM, additional 3 showed either cKITD816V or CD2/CD25. Moreover, we found 22 pts without MIS but with features of monoclonal mast cell activation syndrome. Of the 455 pts with WHO-SM (male 56%), 252 (55%) had MIS: median age at MIS diagnosis (dg) was 37 years (y) (range 0-79), while at SM dg it was 46.5 (range 18-82). Time from onset of MIS to dg of SM was 9 y (range 0-43). In 18/252 pts (7%) MIS occurred before age of 18 y (median 9, range 0-17) and persisted over childhood. Median age at dg of SM without MIS (203/455 pts, 45%) was older: 54 y, range 19-79 (p

Description: Umbilical cord blood (UCB) is of great value by providing transplantable hematopoietic stem and progenitor cells (HSPCs). Compared with HSPCs from adult bone marrow and periferial blood, UCB cells are more primitive with higher proliferation ability, and UCB HSPC transplantation requires less HLA matching. The major problems in UCB transplantation is the limited number of transplantable cells in each unit which are often insufficient for transplantation in adults In order to elucidate the effects of the main components of bone marrow on cord blood CD34+ expansion, freshly enriched cord blood CD34+ cells were cultured in contact with bone marrow stromal cell (BM-MSC) monolayer, BM-MSCs pre-seeded in decellularized Wharton's jelly matrix (DWJM), and in DWJM alone, as well as separated by a transwell preventing the physical contact between CD34+ cells and BM-MSCs in a medium supplemented with a cytokine cocktail including Flt-3 igand, stem cell factor, and thrombopoietin. Expansion patterns were analyzed by CD34+ and CD45+ expansion, as well as colony-forming unit (CFU) assay. We found that the number of CFU increases significantly in cord blood CD34+ cells co-cultured with BM-MSCs in DWJM compared to that of control. Particularly, the increase in CFU-GEMM, BFU-E and CFU-GM number is more significant compared to other colonies. Importantly, DWJM alone is not able to increase CFU numbers compared to that of the control indicating there is a synergistic effect between DWJM and BM-MSCs on cell stemness. Surprisingly, BM-MSCs in DWJM also increses CD34+ cell expansion by 2 to 3 fold after one week culture, presumably from enhanced ablilty of self-renewal from CD34+ cells. Therefore, our data suggest DWJM synergizes with BM-MSCs to increase CD34 cell stemness, which can potentially be used in the clinic therapy. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 4551 Background: In a recent phase IIa open-label, randomized, cross-over design study, we evaluated the pharmacokinetics of Propylene Glycol-Free Melphalan (PG-free Mel) HCL and Alkeran in multiple myeloma patients undergoing transplantation. In this study, we have shown through statistical tests of the geometric means of AUC that PG-free Mel was bioequivalent to Alkeran, and provided marginally higher blood drug levels. Hypothesis: Because this new formulation is associated with marginally higher blood drug levels and because melphalan is associated with a linear dose-response curve, we speculated that patients treated on study would have a better multiple myeloma response compared to matched controls. Goal: To assess day +100 multiple myeloma responses from the study patients (n=24) receiving PG-free Mel conditioning in combination with Alkeran. Responses were assessed based on International Uniform Response Criteria for Multiple Myeloma. Comparison was made to a matched cohort of patients who received conventional melphalan. Methods: We compared the study patient responses to matched controls (n=24) treated exclusively with Alkeran or generic melphalan conditioning within the same time frame in a case-control study design. The controls were matched to study population based on disease stage, age, and pre-transplant response. Results: The study population and the control cohort were well matched in terms of age, gender, disease stage, and pre-transplant response. However, the study population had more patients with high-risk cytogenetics (10 vs 3). Overall response (CR, VGPR, and PR) was higher in the study population (22 vs 19). While no patient on the study progressed within 100 days of transplant, 3 patients in the matched cohort progressed within 100 days. The median duration of follow up of surviving patients was 650 days in the study cohort and 409 days in the matched control cohort. Twenty three study patients and 22 patients in the matched control cohort were reported alive. On the other hand, 7 study patients and 8 patients in the matched cohort progressed during follow up. Conclusion: Compared to matched controls, PG-free Mel, as part of the melphalan conditioning regimen, resulted in higher remission rates and less disease progression at day 100 post autologous transplant for multiple myeloma. Disclosures: Off Label Use: Propylene glycol free melphalan for high-dose therapy and autologous transplant for multiple myeloma.

Description: We recently reported that the induction of polyploidization of malignant megakaryocytes shows great promise as a new therapy for acute leukemia. Polyploidization inducers such as dimethylfasudil (diMF) and MLN8237, both of which target Aurora A kinase (AURKA), induce proliferation arrest, polyploidization, expression of megakaryocyte differentiation markers and apoptosis of leukemic megakaryocytes in vitro and in vivo. Since megakaryocytes in primary myelofibrosis (PMF) show impaired polyploidization and maturation, and likely directly contribute to the disease, we predicted that polyploidization inducers would provide a new therapeutic strategy. To determine the effect of these compounds on the growth of MPN cells, we first treated the JAK2 V617F mutant megakaryocytic SET2 cell line with varying doses of MLN8237 and diMF. Both compounds effectively and dose dependently inhibited proliferation, induced polyploidization and upregulation of lineage specific markers CD41 and CD42, and increased apoptosis. Furthermore, MLN8237 synergized with ruxolitinib to induce apoptosis of the SET2 cells and also potently induced growth arrest of JAK2 inhibitor persistent SET2 cells. We observed a similar polyploidization and differentiating activity of MLN8237 and diMF on megakaryocytes derived from primary human PMF progenitors. The ability of these agents to induce polyploidization was specific, as the non-megakaryocyte fractions of the cultures were not affected. Next, we assayed the activity of polyploidization inducers on progression of MPNs in two mouse models: JAK2V617F conditional knockin mice and mice engrafted with MPLW515L expressing bone marrow progenitors. Of note, spleens from both mouse models displayed a robust increase in both total and phosphorylated forms of AURKA relative to control animals, further suggesting that AURKA is a rational target in this disease. We first assayed the activities of MLN8237 and diMF in the MPLW515L bone marrow transplantation model. Recipient mice develop a rapid MPN characterized by leukocytosis, thrombocytosis and bone marrow fibrosis. Both MLN8237 and diMF reduced the disease burden, as evidenced by significant reductions in the liver and spleen weights, white cell counts and platelet counts. Both compounds also led to a significant decrease of fibrosis in the bone marrow, diminished infiltration of megakaryocytes and granulocytes in the liver, and a profound reduction in the numbers of megakaryocytes within the spleen. Moreover, plasma levels of TGF-β a known myelofibrogenic cytokine, were decreased by more than 3-fold by the drug treatment. Both diMF and MLN8237 led to selective polyploidization of megakaryocytes in the spleen as well as marked reductions in the levels of p-AURKA. Of note, neither agent affected the extent of phosphorylation of STAT3 or STAT5. Therefore, we tested whether the combined use of a JAK inhibitor and a polyploidy inducer would show enhanced activity in vivo. Indeed, the combination of MLN8237 and ruxolitinib led to greater reductions in tumor burden in the MPLW515L mouse model than either agent alone. Similar results were obtained using the JAK2V617F knock-in model. To further validate our conclusion that AURKA is a target in PMF, we infected Aurkafl/fl floxed bone marrow progenitors with MPLW515L and transplanted the cells to irradiated recipients. Excision of both alleles of Aurka by Cre mediated recombination completely resolved the disease, while heterozygous deletion of Aurka significantly reduced the disease burden, in a manner similar to treatment with MLN8237. Given that heterozygous deletion of Aurka does not alter normal hematopoiesis in mice, the fact that a 50% reduction in kinase expression was associated with a significant decrease in disease burden suggests that there is an effective therapeutic window in which AURKA inhibitors will be effective against MPN while sparing normal hematopoiesis. Although JAK inhibitors provide symptomatic relief, it is becoming clear that they are not curative. Thus, there is an urgent need to develop new agents to use in combination with JAK inhibitors. Our data reveal that inducing polyploidization and differentiation of dysplastic megakaryocytes in PMF ameliorates features of the disease both in vitro and in vivo. These results support the initiation of clinical studies that combine a JAK inhibitor with an AURKA inhibitor. Disclosures: Crispino: Sanofi: Research Funding.

Description: Abstract 2839 Patients affected by low-risk essenthial thrombocythosis (ET) may develope thrombotic/haemorragic events at a lower rate compared to high-risk ET patients. So far, it has not be possible to identify useful markers to predict which of these patients are more likely to have an event. Previous authors [Carobbio A et al, Blood 2007] have shown that leukocytosis at diagnosis is associated with a high hazard risk (HR) of developing a thrombotic event, while high platelets count is not. Subsequently other authors [Gangant N et al, Cancer 2009] have contradicted this findings and instead shown that in low-risk ET, the increase in leukocyte count over time correlates with thrombotic events [Passamonti F et al ISTH 2009]. For these reasons we decided to evaluate risk parameters in a dynamic manner with the aim of identifying those patients who are more likely to have an event and might benefit from preventive treatment. We performed a large multicentre retrospective study that included several North Italian Haemathology centres and a large Austrian university hospital. Patient data was analysed using random effect linear regression model and a dedicated Cox model with dynamic proportional risk. We studied 136 patients with low risk ET. Out of those, 45 had a thrombotic/haemorragic event and 91 never had an event (events included: stroke, TIA, IMA, PE, PAD, epystaxis and gastrointestinal bleeding). Overall, the median age was 42 years (IQR 20; range 18–60), the median Hb was 14.0 g/dL (IQR 2.3; range 4.4–18), the median WBC was 8.1 ×103/Â μL (IQR 3.3; range 3.3–23.8), the median PLT was 701 ×103/ÂL (IQR 404; range 206–1806). Gender was M 33% (n=45), F 67% (n=91); smokers were 24% (n=18/N=74); hypercholesterolemia was 18% (n=17/N=92). The FBCs of both groups were recorded from the date of diagnosis (entry time) and up to 3 years of follow up or to the development of a thrombotic/haemorragic event (exit time). A total number of 1294 FBCs were provided by the group with event and compared to a total of 4487 FBCs from the group without event. The follow-up Hb values showed a decreasing linear pattern linear from baseline values. The PLT-count showed a trend similar to Hb over the period of follow-up in both the group without events and in the group with events. The WBC showed a decrease during follow-up in the group with events and an increase in the group without events. Surprisingly, the risk of developing an adverse event after 60 months of follow-up was reduced by 20% for each increase of 1 g/dL Hb (p =0.007), was increased by 8% for each WBC increase of 1 103/uL (p =0.026) and was decreased by 6% for each PLT increase of 100 × 103 /uL (p =0.434). No differences were seen between venous or arterious thrombotic events (Log rank test, p=0.842). In conclusion, this study confirms that baseline FBCs values are not predictive of events within the ET low risk group. The emerging new finding is that the risk of developing an event is higher when Hb is reduced. This strongly suggests a protective role of Hb in the low-risk ET group. Previous studies have shown that red cells might store and generate nitric oxide (NO), a key endothelial modulator [Kim-Shapiro DB et al 2006]. The presence of NO would keep PLT in resting state, would reduce endothelial cell adhesion and in turn reduce thrombosis rate. However this needs to be confirmed. Disclosures: Steurer: Amgen: Consultancy, Honoraria. Pizzolo:Hoffmann-La Roche: Consultancy, Honoraria.

Description: SRSF2 is a RNA-binding protein frequently mutated in CMML tasked with marking exon-intron boundaries during alternative splicing. SRSF2 contains a domain consisting of serine-arginine repeats that are dynamically phosphorylated and comprise a major regulatory mechanism in RNA capture. It has been previously demonstrated that EGFR signaling can elicit the phosphorylation of SRSF2 in an AKT dependent manner, resulting in functional alterations in exon usage of SRSF2 target genes. We previously reported that GM-CSF hypersensitivity is a reproducible feature of CMML. Because AKT is a known signaling intermediate of GM-CSF, we hypothesize that aberrant GM-CSF signaling could induce mutation-independent splicing abnormalities in CMML via phosphorylation of SRSF2. To test this hypothesis, we selected CMML samples that displayed GM-CSF hypersensitivity but lacked mutations by Sanger sequencing in 5 splicing-related genes commonly mutated in myeloid malignancies (SRSF2, SF3B1,U2AF1, ZRSF2,and PRPF40B) and labeled this group as CMML ‘splicing WT’. A second sample set included CMML specimens with isolated SRSF2 mutation (SRSF2 ‘splicing MT’). Bone marrow mononuclear cells from the SRSF2 ‘splicing WT’ group (n=4), CMML ‘splicing MT’ group (n=4), and normal controls (n=4) were lymphodepleted (CD3 and CD19) to enrich for the clonal myeloid population. RNA was extracted and whole transcriptome RNA sequencing and exon arrays were performed to compare the relative global exon usage of CMML ‘splicing WT’, CMML ‘splicing MT’, and normal controls. Briefly, the human exon 1.0 ST array was used for exon array analysis and splice index was calculated with the Exon/Gene Array Analyzer Web Tool (Gellert Bioinformatics 2009). RNA sequencing data was generated and aligned with TopHat2 (Kim Genome Bio 2013) while read counts and exon usage assignments were made with DexSeq (Anders Genome Res 2012). Splice indices determined by exon array demonstrated statistically significant exon usage differences between CMML ‘splicing MT’ and normal controls consistent with previously published results (Figure 1a). Interestingly, when CMML ‘splicing WT’ was compared to normal controls, a statistically significant difference in exon usage was also identified (Figure 1b). Further, when ‘splicing MT’ and ‘splicing WT’ were compared by splice index, differences in exon usage differences were dramatically reduced indicating similar splicing abnormalities in the CMML ’splicing WT’ group (1c). Euclidian hierarchical clustering at the gene- and exon-level separated normal controls from CMML groups but failed to separate ‘splicing MT’ from ‘splicing WT’, supporting the notion that mutation-independent splicing aberrancy may characterize CMML (1d). Global patterns in exon usage were also tested by whole transcriptome RNA-sequencing and were similar to those described above identified by exon array splice index.Figure 1Figure 1. We first attempted to determine if the transcript levels of core splicing components in CMML ‘splicing WT’ were altered but were unable to identify differences in expression when compared to CMML ’splicing MT’ and controls. Next we explored the possibility that GM-CSF signaling, known to be upregulated in CMML, could post-translationally modify SRSF2. The THP-1 monocytic leukemia cell line was stimulated with 10ng/ml of GM-CSF for 15 minutes. Cell lysates were immediately prepared and western blot analysis was used to assess SRSF2 phosphorylation after stimulation with GM-CSF, demonstrating induction of pSRSF2 at 15 minutes as accompanied by induction of the known GM-CSF signaling intermediates pJAK2, pAKT, and pERK. Pharmacologic inhibition of these intermediates abrogated GM-CSF-induced pSRSF2, whereas only the JAK 1/2 inhibitor ruxolitinib was able to inhibit pSTAT5, pAKT, and pERK, suggesting that JAK2 is a proximal kinase in the signaling cascade. Our results indicate that splicing abnormalities are present in CMML specimens lacking mutations in splicing-related genes. GM-CSF induces phosphorylation of SRSF2 for post-translational regulation of the RS domain. Low dose GM-CSF dependent pSRSF2 and functional splicing analyses are currently underway in primary CMML ‘SRSF2 WT’ samples to directly determine whether GM-CSF hypersensitivity is responsible for mutation-independent splicing aberrancies. Disclosures: List: Celgene: Membership on an entity’s Board of Directors or advisory committees.