Search

Heterozygous mutation targeting proline 95 in Serine/Arginine-rich Splicing Factor 2 (SRSF2) is associated with V617F mutation in Janus Activated Kinase 2 (JAK2) in some myeloproliferative neoplasms (MPNs), most commonly primary myelofibrosis. To explore the interaction of Srsf2P95Hwith Jak2V617F, we generated Cre-inducible knock-in mice expressing these mutants under control of the stem cell leukemia (Scl)gene promoter. In transplantation experiments, Srsf2P95Hunexpectedly delayed myelofibrosis induced by Jak2V617Fand decreased TGFβ1 serum level. Srsf2P95Hreduced the competitiveness of transplanted Jak2V617Fhematopoietic stem cells while preventing their exhaustion. RNA sequencing of sorted megakaryocytes identified an increased number of splicing events when the two mutations were combined. Focusing on JAK/STAT pathway, Jak2exon 14 skipping was promoted by Srsf2P95H, an event detected in patients with JAK2V617Fand SRSF2P95co-mutation. The skipping event generates a truncated inactive JAK2 protein. Accordingly, Srsf2P95Hdelays myelofibrosis induced by the thrombopoietin receptor agonist Romiplostim in Jak2wild-type animals. These results unveil JAK2exon 14 skipping promotion as a strategy to reduce JAK/STAT signaling in pathological conditions.

Islands of CD123highcells have been commonly described in the bone marrow of patients with chronic myelomonocytic leukemia (CMML). Using a multiparameter flow cytometry assay, we detected an excess of CD123+mononucleated cells that are lineage-negative, CD45+, CD11c−, CD33−, HLA-DR+, BDCA-2+, BDCA-4+in the bone marrow of 32/159 (20%) patients. Conventional and electron microscopy, flow cytometry detection of cell surface markers, gene expression analyses, and the ability to synthesize interferon alpha in response to Toll-like receptor agonists identified these cells as bona fide plasmacytoid dendritic cells (pDCs). Whole-exome sequencing of sorted monocytes and pDCs identified somatic mutations in genes of the oncogenic RAS pathway in the two cell types of every patient. CD34+cells could generate high amount of pDCs in the absence of FMS-like tyrosine kinase 3-ligand (FLT3L). Finally, an excess of pDCs correlates with regulatory T cell accumulation and an increased risk of acute leukemia transformation. These results demonstrate the FLT3L-independent accumulation of clonal pDCs in the bone marrow of CMML patients with mutations affecting the RAS pathway, which is associated with a higher risk of disease progression.

ABSTRACTThe SARS-CoV-2 pandemic still represents a threat for immunosuppressed and hematological malignancy (HM) bearing patients, causing increased morbidity and mortality. Given the low anti-SARSCoV-2 IgG titers post-vaccination, the COVID-19 threat prompted the prophylactic use of engineered anti-SARS-CoV-2 monoclonal antibodies. In addition, potential clinical significance of T cell responses has been overlooked during the first waves of the pandemic, calling for additional in-depth studies. We reported that the polarity and the repertoire of T cell immune responses govern the susceptibility to SARS-CoV-2 infection in health care workers and solid cancer patients. Here, we longitudinally analyzed humoral and cellular immune responses at each BNT162b2 mRNA vaccine injection in 47 HM patients under therapy. Only one-third of HM, mostly multiple myeloma (MM) bearing patients, could mount S1-RBD-specific IgG responses following BNT162b2 mRNA vaccines. This vaccine elicited a S1-RBD-specific Th1 immune response in about 20% patients, mostly in MM and Hodgkin lymphoma, while exacerbating Th2 responses in the 10% cases that presented this recognition pattern at baseline (mostly rituximab-treated patients). Performing a third booster barely improved the percentage of patients developing an S1-RBD-specific Th1 immunity and failed to seroconvert additional HM patients. Finally, 16 patients were infected with SARS-CoV-2, of whom 6 developed a severe infection. Only S1-RBD-specific Th1 responses were associated with protection against SARS-CoV2 infection, while Th2 responses or anti-S1-RBD IgG titers failed to correlate with protection. These findings herald the paramount relevance of vaccine-induced Th1 immune responses in hematological malignancies.

Background

INTRODUCTION:

Mutations in the gene encoding isocitrate dehydrogenase 2 (IDH2) occur in several types of cancer, including acute myeloid leukemia (AML). In model systems, mutant IDH2 causes hematopoietic differentiation arrest. Enasidenib, a selective small-molecule inhibitor of mutant IDH2, produces a clinical response in 40% of treated patients with relapsed/refractory AML by promoting leukemic cell differentiation. Here, we studied the clonal basis of response and acquired resistance to enasidenib treatment. Using sequential patient samples, we determined the clonal structure of hematopoietic cell populations at different stages of differentiation. Before therapy, IDH2-mutant clones showed variable differentiation arrest. Enasidenib treatment promoted hematopoietic differentiation from either terminal or ancestral mutant clones; less frequently, treatment promoted differentiation of nonmutant cells. Analysis of paired diagnosis/relapse samples did not identify second-site mutations in IDH2at relapse. Instead, relapse arose by clonal evolution or selection of terminal or ancestral clones, thus highlighting multiple bypass pathways that could potentially be targeted to restore differentiation arrest. These results show how mapping of clonal structure in cell populations at different stages of differentiation can reveal the response and evolution of clones during treatment response and relapse.

Recurrent mutations in isocitrate dehydrogenase 2 (IDH2) occur in ∼12% of patients with acute myeloid leukemia (AML). Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate resulting in DNA and histone hypermethylation, which leads to blocked cellular differentiation. Enasidenib (AG-221/CC-90007) is a first-in-class, oral, selective inhibitor of mutant-IDH2 enzymes. This first-in-human phase 1/2 study assessed the maximum tolerated dose (MTD), pharmacokinetic and pharmacodynamic profiles, safety, and clinical activity of enasidenib in patients with mutant-IDH2 advanced myeloid malignancies. We assessed safety outcomes for all patients and clinical efficacy in the largest patient subgroup, those with relapsed or refractory AML, from the phase 1 dose-escalation and expansion phases of the study. In the dose-escalation phase, an MTD was not reached at doses ranging from 50 to 650 mg per day. Enasidenib 100 mg once daily was selected for the expansion phase on the basis of pharmacokinetic and pharmacodynamic profiles and demonstrated efficacy. Grade 3 to 4 enasidenib-related adverse events included indirect hyperbilirubinemia (12%) and IDH-inhibitor–associated differentiation syndrome (7%). Among patients with relapsed or refractory AML, overall response rate was 40.3%, with a median response duration of 5.8 months. Responses were associated with cellular differentiation and maturation, typically without evidence of aplasia. Median overall survival among relapsed/refractory patients was 9.3 months, and for the 34 patients (19.3%) who attained complete remission, overall survival was 19.7 months. Continuous daily enasidenib treatment was generally well tolerated and induced hematologic responses in patients for whom prior AML therapy had failed. Inducing differentiation of myeloblasts, not cytotoxicity, seems to drive the clinical efficacy of enasidenib. This trial was registered at www.clinicaltrials.gov as #NCT01915498.

Recurrent mutations in isocitrate dehydrogenase 2 (IDH2) occur in ∼12% of patients with acute myeloid leukemia (AML). Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate resulting in DNA and histone hypermethylation, which leads to blocked cellular differentiation. Enasidenib (AG-221/CC-90007) is a first-in-class, oral, selective inhibitor of mutant-IDH2 enzymes. This first-in-human phase 1/2 study assessed the maximum tolerated dose (MTD), pharmacokinetic and pharmacodynamic profiles, safety, and clinical activity of enasidenib in patients with mutant-IDH2advanced myeloid malignancies. We assessed safety outcomes for all patients and clinical efficacy in the largest patient subgroup, those with relapsed or refractory AML, from the phase 1 dose-escalation and expansion phases of the study. In the dose-escalation phase, an MTD was not reached at doses ranging from 50 to 650 mg per day. Enasidenib 100 mg once daily was selected for the expansion phase on the basis of pharmacokinetic and pharmacodynamic profiles and demonstrated efficacy. Grade 3 to 4 enasidenib-related adverse events included indirect hyperbilirubinemia (12%) and IDH-inhibitor–associated differentiation syndrome (7%). Among patients with relapsed or refractory AML, overall response rate was 40.3%, with a median response duration of 5.8 months. Responses were associated with cellular differentiation and maturation, typically without evidence of aplasia. Median overall survival among relapsed/refractory patients was 9.3 months, and for the 34 patients (19.3%) who attained complete remission, overall survival was 19.7 months. Continuous daily enasidenib treatment was generally well tolerated and induced hematologic responses in patients for whom prior AML therapy had failed. Inducing differentiation of myeloblasts, not cytotoxicity, seems to drive the clinical efficacy of enasidenib. This trial was registered at www.clinicaltrials.govas #NCT01915498.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder that typically associates with mutations in epigenetic, splicing, and signaling genes. Genetically modified mouse models only partially recapitulate the disease phenotype, whereas xenotransplantation of CMML cells in immunocompromised mice has been rarely successful so far. Here, CMML CD34+cells sorted from patient bone marrow (BM) or peripheral blood (PB) were injected intravenously into NSG (NOD/LtSz-scid IL2rγnull) mice and NSG mice engineered to express human granulo-monocyte colony-stimulating factor, stem cell factor, and interleukin-3 (NSGS mice). Fifteen out of 16 patient samples (94%) successfully engrafted into NSG or NSGS or both mouse strains. The expansion of human cells, predominant in the BM, was also observed in the spleen and the PB and was greatly enhanced in mice producing the 3 human cytokines. Gene mutations identified in engrafted cells were mostly similar to those identified in patient cells before injection. Successful secondary engraftment was obtained in NSGS mice in 3 out of 10 attempts. Thus, primary CMML leukemic cells expand much better in NSGS compared with NSG mice with limited efficacy of secondary transplant.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder that typically associates with mutations in epigenetic, splicing, and signaling genes. Genetically modified mouse models only partially recapitulate the disease phenotype, whereas xenotransplantation of CMML cells in immunocompromised mice has been rarely successful so far. Here, CMML CD34+ cells sorted from patient bone marrow (BM) or peripheral blood (PB) were injected intravenously into NSG (NOD/LtSz-scid IL2r?null) mice and NSG mice engineered to express human granulo-monocyte colony-stimulating factor, stem cell factor, and interleukin-3 (NSGS mice). Fifteen out of 16 patient samples (94%) successfully engrafted into NSG or NSGS or both mouse strains. The expansion of human cells, predominant in the BM, was also observed in the spleen and the PB and was greatly enhanced in mice producing the 3 human cytokines. Gene mutations identified in engrafted cells were mostly similar to those identified in patient cells before injection. Successful secondary engraftment was obtained in NSGS mice in 3 out of 10 attempts. Thus, primary CMML leukemic cells expand much better in NSGS compared with NSG mice with limited efficacy of secondary transplant.

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome/ myeloproliferative neoplasm whose diagnosis is currently based on the elevation of peripheral blood monocytes to >1 × 109/L, measured for ≥3 months. Diagnosis can be ambiguous; for example, with prefibrotic myelofibrosis or reactive monocytosis. We set up a multiparameter flow cytometry assay to distinguish CD14+/CD16−classical from CD14+/CD16+intermediate and CD14low/CD16+nonclassical monocyte subsets in peripheral blood mononucleated cells and in total blood samples. Compared with healthy donors and patients with reactive monocytosis or another hematologic malignancy, CMML patients demonstrate a characteristic increase in the fraction of CD14+/CD16−cells (cutoff value, 94.0%). The associated specificity and sensitivity values were 95.1% and 90.6% in the learning cohort (175 samples) and 94.1% and 91.9% in the validation cohort (307 samples), respectively. The accumulation of classical monocytes, which demonstrate a distinct gene expression pattern, is independent of the mutational background. Importantly, this increase disappears in patients who respond to hypomethylating agents. We conclude that an increase in the fraction of classical monocytes to >94.0% of total monocytes is a highly sensitive and specific diagnostic marker that rapidly and accurately distinguishes CMML from confounding diagnoses.

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome/ myeloproliferative neoplasm whose diagnosis is currently based on the elevation of peripheral blood monocytes to >1 × 109/L, measured for ≥3 months. Diagnosis can be ambiguous; for example, with prefibrotic myelofibrosis or reactive monocytosis. We set up a multiparameter flow cytometry assay to distinguish CD14+/CD16− classical from CD14+/CD16+ intermediate and CD14low/CD16+ nonclassical monocyte subsets in peripheral blood mononucleated cells and in total blood samples. Compared with healthy donors and patients with reactive monocytosis or another hematologic malignancy, CMML patients demonstrate a characteristic increase in the fraction of CD14+/CD16− cells (cutoff value, 94.0%). The associated specificity and sensitivity values were 95.1% and 90.6% in the learning cohort (175 samples) and 94.1% and 91.9% in the validation cohort (307 samples), respectively. The accumulation of classical monocytes, which demonstrate a distinct gene expression pattern, is independent of the mutational background. Importantly, this increase disappears in patients who respond to hypomethylating agents. We conclude that an increase in the fraction of classical monocytes to >94.0% of total monocytes is a highly sensitive and specific diagnostic marker that rapidly and accurately distinguishes CMML from confounding diagnoses.

Megakaryopoiesis is a 2-step differentiation process, regulated by thrombopoietin (TPO), on binding to its cognate receptor myeloproliferative leukemia (MPL). This receptor associates with intracytoplasmic tyrosine kinases, essentially janus kinase 2 (JAK2), which regulates MPL stability and cell-surface expression, and mediates TPO-induced signal transduction. We demonstrate that JAK2 and MPL mediate TPO-induced proliferation arrest and megakaryocytic differentiation of the human megakaryoblastic leukemia cell line UT7-MPL. A decrease in JAK2 or MPL protein expression, and JAK2 chemical inhibition, suppress this antiproliferative action of TPO. The expression of JAK2 and MPL, which progressively increases along normal human megakaryopoiesis, is decreased in platelets of patients diagnosed with JAK2- or MPL-mutated essential thrombocytemia and primary myelofibrosis, 2 myeloproliferative neoplasms in which megakaryocytes (MKs) proliferate excessively. Finally, low doses of JAK2 chemical inhibitors are shown to induce a paradoxical increase in MK production, both in vitro and in vivo. We propose that JAK2 and MPL expression levels regulate megakaryocytic proliferation vs differentiation in both normal and pathological conditions, and that JAK2 chemical inhibitors could promote a paradoxical thrombocytosis when used at suboptimal doses.

Megakaryopoiesis is a 2-step differentiation process, regulated by thrombopoietin (TPO), on binding to its cognate receptor myeloproliferative leukemia (MPL). This receptor associates with intracytoplasmic tyrosine kinases, essentially janus kinase 2 (JAK2), which regulates MPL stability and cell-surface expression, and mediates TPO-induced signal transduction. We demonstrate that JAK2 and MPL mediate TPO-induced proliferation arrest and megakaryocytic differentiation of the human megakaryoblastic leukemia cell line UT7-MPL. A decrease in JAK2 or MPL protein expression, and JAK2 chemical inhibition, suppress this antiproliferative action of TPO. The expression of JAK2 and MPL, which progressively increases along normal human megakaryopoiesis, is decreased in platelets of patients diagnosed with JAK2- or MPL-mutated essential thrombocytemia and primary myelofibrosis, 2 myeloproliferative neoplasms in which megakaryocytes (MKs) proliferate excessively. Finally, low doses of JAK2 chemical inhibitors are shown to induce a paradoxical increase in MK production, both in vitro and in vivo. We propose that JAK2 and MPL expression levels regulate megakaryocytic proliferation vs differentiation in both normal and pathological conditions, and that JAK2 chemical inhibitors could promote a paradoxical thrombocytosis when used at suboptimal doses.

Despite advances in therapy, Waldenstrom's macroglobulinemia (WM) remains incurable. Guidelines on therapeutic alternatives in WM recommended the use of alkylating agents, rituximab, nucleoside analogues and anthracyclins either in first line or at relapse and in combination in fit patients. While the overall response rates of combination regimens reached up to 80 – 90% in some studies, the complete response rate is low, no greater than 10 – 20%; and the disease-related median survival for symptomatic patients is approximately 6 years. As such, new therapeutic agents are needed for the treatment of WM. In ongoing efforts, advances were made in the understanding of the biology of WM so as to better target therapeutics for this malignancy. Several preclinical studies have demonstrated that the NFκB pathway is a potential target for therapeutics in WM. Bortezomib (Velcade®) is the first approved proteasome inhibitor for treating relapse/refractory multiple myeloma and, among other mechanisms of action, significantly inhibits the NFkB pathway. This report provides an update on biological studies and clinical efforts to develop bortezomib as a new treatment of Waldenstrom's macroglobulinemia.

Background:The gain-of-function JAK2 V617Fmutant is the most common driver mutation identified in myeloproliferative neoplasms (MPNs). Additional somatic variants, also found in other malignant hemopathies, are detected in primary myelofibrosis (MF) and supposed to contribute to fibrosis or leukemia development. One of these mutations affects SRSF2, a gene encoding a component of the splicing machinery. SRSF2heterozygous mutation mainly affects the proline 95 residue of the protein. Its association with JAK2 V617Fcorrelates with a reduced leukemia free survival. Whether and how SRSF2 P95variants could favor fibrosis development in JAK2 V617Fcells remained unknown.

Abdel-Wahab: H3B Biomedicine: Consultancy, Research Funding; Foundation Medicine Inc: Consultancy; Merck: Consultancy; Prelude Therapeutics: Consultancy; LOXO Oncology: Consultancy, Research Funding; Lilly: Consultancy; AIChemy: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Envisagenics Inc.: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees.

ABSTRACTInduction chemotherapy (7 + 3 regimen) remains the gold standard for patients with acute myeloid leukemia (AML) but is responsible for gut damage leading to several complications such as bloodstream infection (BSI). We aimed to investigate the impact of induction chemotherapy on the intestinal barrier of patients with AML and in wild-type mice. Next, we assessed the potential benefit of strengthening the mucosal barrier in transgenic mice releasing a recombinant protein able to reinforce the mucus layer (Tg222). In patients, we observed a decrease of plasma citrulline, which is a marker of the functional enterocyte mass, of short-chain fatty acids and of fecal bacterial load, except for Escherichia coliand Enterococcusspp., which became dominant. Both the α and β-diversities of fecal microbiota decreased. In wild-type mice, citrulline levels decreased under chemotherapy along with an increase of E. coliand Enterococcusspp load associated with concomitant histologic impairment. By comparison with wild-type mice, Tg222 mice, 3 days after completing chemotherapy, had higher citrulline levels, a faster healing epithelium, and preserved α-diversity of their intestinal microbiota. This was associated with reduced bacterial translocations. Our results highlight the intestinal damage and the dysbiosis induced by the 7 + 3 regimen. As a proof of concept, our transgenic model suggests that strengthening the intestinal barrier is a promising approach to limit BSI and improve AML patients’ outcome.

Introduction:

de Botton: Forma: Consultancy, Research Funding; Bayer: Consultancy; Daiichi: Consultancy; Novartis: Consultancy; Astellas: Consultancy; Abbvie: Consultancy; Pierre Fabre: Consultancy; Syros: Consultancy; Agios: Consultancy, Research Funding; Janssen: Consultancy; Pfizer: Consultancy; Servier: Consultancy; Celgene: Consultancy, Speakers Bureau. Micol:AbbVie: Consultancy; Jazz Pharmaceuticals: Consultancy.

de Botton: Agios: Research Funding; Celgene: Honoraria, Research Funding. Benabelali:CERBA laboratory: Employment.

In 2015, a germline copy number variation of chromosome 14 (CNVdup14) including ATG2Band GSKIPgenes was described as a predisposition genetic factor responsible of familial myeloproliferative neoplasms from French West Indies (Saliba et al, Nat Gen 2015), frequently progressing to AML. In this study, we looked at the presence of this CNVdup14 in a cohort of Caribbean islands patients (pts) with non-secondary aggressive hematological malignancies (HM). We also studied the expression of ATG2Band GSKIPgenes in a cohort of acquired AML pts.

Quek: Celgene Corporation: Research Funding. Amatangelo: Celgene Corporation: Employment. Agresta: Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Yen: Agios: Employment, Equity Ownership. Stein: Pfizer: Consultancy, Other: Travel expenses; Agios Pharmaceuticals, Inc.: Consultancy, Research Funding; Constellation Pharma: Research Funding; Novartis: Consultancy, Research Funding; GSK: Other: Advisory Board, Research Funding; Celgene Corporation: Consultancy, Other: Travel expenses, Research Funding; Seattle Genetics: Research Funding. De Botton: Agios: Honoraria, Research Funding; Celgene: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Servier: Honoraria. Thakurta: Celgene Corporation: Employment, Equity Ownership. Levine: Qiagen: Equity Ownership; Qiagen: Equity Ownership; Celgene: Research Funding; Roche: Research Funding; Celgene: Research Funding; Roche: Research Funding. Vyas: Jazz Pharmaceuticals: Speakers Bureau; Celgene Corporation: Speakers Bureau.

Background.There is no current standard of care for the management of patients with relapsed or refractory B-cell non-Hodgkin Lymphoma (R/R B-NHL) ineligible for high-dose therapy. While cytarabine and etoposide are commonly used drugs in salvage regiments for patients eligible for high dose therapy (HDT) and auto-stem cell transplant, data are sparse in the context of ineligibility for high-dose therapy. We designed a dose-adjusted combination of rituximab plus mini-CYVE (CYtarabine bolus, VEpeside and dexamethasone) regimen (R-mini-CYVE), for R/R B-NHL patient's ineligible for HDT.

Background

Background.Isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) mutations are found in 10 and 15% of acute myeloid leukemia (AML) patients, respectively. IDH1/2 mutants' proteins produce high 2-hydroxyglutarate (2HG) levels that inhibit α-ketoglutarate-dependent dioxygenases including histone and DNA demethylases, as TET2 proteins. Furthermore, serum 2HG can act as a biomarker predictive of the presence of IDH1and IDH2mutations at diagnosis (cut-off value >2µM) but also correlate with response after intensive chemotherapy. 5-azacitidine (AZA) is a DNA methyltransferase inhibitor that demonstrated significant clinical benefit not only in high-risk MDS but also in AML. Hypomethylating agents yield higher response rate in the context of CpG island hypermethylation phenotype induced by TET2mutations in myelodysplastic syndrome (MDS). Thus, we evaluate AZA response in the context of IDH1/2mutations and the effect of AZA on serum 2HG production.

Context: Allogeneic hematopoietic stem cell transplant (HCT) represents a curative option in acute myeloid leukemia (AML) in patients older then 60 years. The use of reduced intensity conditioning regimens (RIC) has decreased treatment related toxicity and minimized the role of age as a limiting factor. Other variables such as disease status, cytogenetics, donor type and comorbidities gained importance in the pre-transplant risk assessment. In 2014, Sorror et al., proposed a risk-adapted strategy, integrating AML-, HCT- and patient-specific risk factors to guide decisions about HCT versus no HCT in elderly patients.

Palacino: H3 Biomedicine Inc.: Employment. Seiler:H3 Biomedicine: Employment. Buonamici:H3 Biomedicine: Employment. Smith:H3 Biomedicine Inc.: Employment.

No relevant conflicts of interest to declare.

Michot: Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Ribrag:ArgenX: Research Funding; Esai: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; NanoString: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees.

Somervaille: Novartis: Consultancy, Honoraria; Imago Biosciences: Consultancy. Pigneux:Agios: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria. Recher:Celgene, Sunesis, Amgen, Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene, Sunesis, Amgen, Novartis, Chugai: Research Funding. Molinero:Oryzon Genomics: Employment, Equity Ownership. Mascaro:Oryzon Genomics: Employment. Maes:Oryzon Genomics: Employment, Equity Ownership.

Introduction:Low-dose radiation therapy (LD-RT) is a therapeutic option in indolent non Hodgkin B-cell lymphomas (iNHL), usually in the palliative setting. If most iNHL are highly sensitive to radiation therapy, with good local control obtained with a dose of 4 Gy in 2 fractions, little is known about the efficacy and outcome of repetitive courses of LD-RT. We report here the results of a study cohort of repetitive LD-RT in iNHL.

Mutations in genes encoding RNA splicing factors constitute the most common class of alterations in patients with myelodysplasticsyndromes (MDS). These occur predominantly as heterozygous point mutations at restricted residues in SF3B1, SRSF2, and U2AF1in a mutually exclusive manner, suggesting that spliceosomal gene mutations confer gain-of-function with converging biological effects. However, recent studies suggest that mutations in each splicing factor result in distinct alterations in pre-mRNA splicing. It is therefore unclear if such mutual exclusivity is due to overlapping biological effects and/or synthetic lethal interactions. Furthermore, although cells bearing mutant splicing factors have been shown to require the wildtype allele for survival, whether these mutations can exist in a homozygous state is unknown. Here we addressed these questions by analyzing the effects of expressing SF3B1and SRSF2mutations simultaneously or in a homozygous state in vivo.

In preclinical studies, LSD1 inhibitors derived from tranylcypromine were active in acute myeloid leukemia models, particularly in the MLL-translocated subtype. We now report the safety, PK and PD properties of ORY-1001 (a potent and selective inhibitor of LSD1) in a multicenter phase I study (EUDRACT nº 2013-002447-29).

Therapy-related acute myeloid leukemia/myelodysplastic syndrome (t-AML/MDS) arise after cytotoxic chemotherapy and/or radiotherapy administered for a prior neoplasm and have a dismal outcome (median survival of 8 months in the largest series published including 306 patients (pts), Smith, Blood 2003). Recent registry data suggested a continued increase in survival in AML (Derolf, Blood 2009) and we wondered whether this was also observed in the setting of t-AML/ MDS.

No relevant conflicts of interest to declare.

Ribrag: Celgene: Research Funding; Esai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmamar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. De Botton:Agios pharmaceuticals: Research Funding.

Ribrag: Celgene: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Esai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmamar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. De Botton:Agios pharmaceuticals: Research Funding.

Background:Cancer patients (pts) who receive chemotherapy and/or radiation therapy for their primary tumor are at risk for developing therapy-related myeloid neoplasms (t-MN). Estimates of t-MN prevalence are mainly derived from retrospective series from hematology departments: they account for 10 to 20% of all AML cases. However this condition is frequently diagnosed in daily practice in comprehensive cancer centers (CCC). This suspected higher frequency might be due to optimized follow-up protocols and improved survival outcomes after tumor remission. The aim of this study was to assess clinical factors associated with t-MN in 2 French CCC focusing on delay of onset, survival, cytogenetically defined prognosis, treatment received for primary tumor and myeloid disease presentation.

Myeloid sarcoma (MS) is defined as a tumor mass consisting of myeloid blasts with or without maturation occurring at an anatomical site other than bone marrow (BM). MS may occur before, concurrently or after a characterized acute myeloid leukemia (AML). Cytogenetic abnormalities are found in 50% of the cases but molecular alterations are less well described and involved FLT3and/or NPM1mutations. Mutations in IDH1and IDH2genes are found in 15% to 20% of patients with AML but have never been described in MS. Mutated IDH enzymes produce in vast excess D-2-hydroxyglutarate (2-HG) in leukemic cells, which can act as a biomarker predictive of the presence of IDH1and IDH2mutations. As availability of DNA sequencing techniques on paraffin samples are limited, molecular characterization of MS remained difficult. We asked whether in MS, serum 2-HG would predict the presence of IDH1/2mutations at diagnosis, and could provide a biomarker for follow up.

Introduction:

Quivoron: Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la recherche contre le Cancer (ARC): Grant, Grant Other; AGIOS: Grant Other. David:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la Recherche contre le Cancer (ARC): Grant, Grant Other; Association Laurette Fugain: Grant, Grant Other; AGIOS: Grant Other. Straley:Agios Pharmaceuticals: Employment, Stockholder Other. Travins:Agios Pharmaceuticals: Employment, Stockholder Other. Kim:Agios Pharmaceuticals: Employment, Stockholder Other. Chen:Agios Pharmaceuticals: Employment, Stockholder Other. Zhu:Agios Pharmaceuticals: Employment, Stockholder Other. Bawa:AGIOS: Grant Other. Bernard:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Ligue Nationale contre le cancer (LNCC): Grant, Grant Other; AGIOS: Grant Other. Yang:Agios Pharmaceuticals: Employment, Stockholder Other. Agresta:Agios Pharmaceuticals: Employment, Stockholder Other. de Botton:AGIOS: Grant Other. Yen:Agios: Employment. Penard-Lacronique:Institut National de la Santé Et de la Recherche Médicale (INSERM): Grant Other; Association Laurette Fugain: Grant, Grant Other; Institut National du Cancer (INCa): Grant, Grant Other; Association pour la recherche contre le Cancer (ARC): Grant, Grant Other; AGIOS: Grant Other.

No relevant conflicts of interest to declare.