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Acute myeloid leukemia (AML) is a hematological malignancy with an undefined heritable risk. Here we perform a meta-analysis of three genome-wide association studies, with replication in a fourth study, incorporating a total of 4018 AML cases and 10488 controls. We identify a genome-wide significant risk locus for AML at 11q13.2 (rs4930561; P = 2.15 × 10−8; KMT5B). We also identify a genome-wide significant risk locus for the cytogenetically normal AML sub-group (N = 1287) at 6p21.32 (rs3916765; P = 1.51 × 10−10; HLA). Our results inform on AML etiology and identify putative functional genes operating in histone methylation (KMT5B) and immune function (HLA)., Genome wide association studies in cancer are used to understand the heritable genetic contribution to disease risk. Here, the authors perform a genome wide association study in European patients with acute myeloid leukemia and identify loci associated with risk of developing the disease.

Blinatumomab is a bispecific T-cell engager approved for B-cell precursor acute lymphoblastic leukemia (B-ALL) with persistent minimal residual disease (MRD) or in relapse. The prognostic impact of tumor load has been suggested before other immunotherapies but remains poorly explored before blinatumomab. We retrospectively analyzed the outcome of 73 patients who received blinatumomab either in first complete remission (CR) with MRD (n=35) or at relapse (n=38). Among MRD patients, 91% had MRD >0.01% before blinatumomab, and 89% achieved complete MRD response after blinatumomab. High pre-blinatumomab MRD levels were associated with shorter relapse-free survival (P=0.049) and overall survival (OS) (P=0.011). At 3 years, OS was 33%, 58% and 86% for pre-blinatumomab MRD >1%, between MRD 0.1- 1% and

Targeting TP53 mutated myelodysplastic syndromes and acute myeloid leukemia remains a significant unmet need. Recently, new drugs have attempted to improve the outcomes of this poor molecular subgroup. The aim of this article is to review all the current knowledge using active agents including hypomethylating agents with venetoclax, eprenetapopt or magrolimab. We include comprehensive analysis of clinical trials to date evaluating these drugs in TP53 myeloid neoplasms as well as discuss future novel combinations for consideration. Additionally, further understanding of the unique clinicopathologic components of TP53 mutant myeloid neoplasms versus wild-type is critical to guide future study. Importantly, the clinical trajectory of patients is uniquely tied with the clonal burden of TP53, which enables serial TP53 variant allele frequency analysis to be a critical early biomarker in investigational studies. Together, significant optimism is now possible for improving outcomes in this patient population.

TP53-mutated acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are among the myeloid malignancies with the poorest prognosis. In this review, we analyze the prognosis of these two diseases, focussing particularly on the extent of the mono or biallelic mutation status of TP53 mutation, which is largely correlated with cytogenetic complexity. We discuss the possible/potential improvement in outcome based on recent results obtained with new drugs (especially eprenetapopt and magrolimab). We also focus on the impact of allogeneic hematopoietic stem cell transplantation (aHSCT) including post aHSCT treatment.

Background Core-binding factor acute myeloid leukemia (CBF AML) with recurrent genetic abnormalities inv(16)(p13.1q22) or t(16;16)(p13.1;q22)/ CBFB-MYH11 are usually prognostically favorable but heterogeneous group and additional abnormalities change their prognosis. Materials and Methods To evaluate the impact of a complex karyotype on CBF AML prognosis, we included 24 patients with a median age of 56.4 years (23.2-83.3) and a median number of abnormalities of 5 (4-13). Results Median follow-up was 110.4 months. Among patients with a primary clone, complete remission (CR) was reached in 66.7% of patients. 31.3% of patients experienced AML relapse with a median of 8.5 months. Median OS for transplanted patients was 80.7 versus 40.5 months for non-transplanted patients, excluding the 4 patients with early death. Among patients harboring AML with clonal evolution, CR was reached in 62.5% of patients. 50% of patients underwent allogeneic stem cell transplantation (ASCT). In these, median RFS was 19.3 versus 0 months in non-transplanted patients. Median OS seemed also longer in transplanted patients with 23.5 versus 2.95 months in non-transplanted. Conclusion Use of new treatment and tailored strategy based on measurable residual disease monitoring may now improve these results. However, these data allow us to reconsider the good prognosis historically associated with CBF patients despite of karyotype and the place of ASCT in the strategy.

Acute myeloid leukemia (AML) is a hematological malignancy with an undefined heritable risk. Here we performed a meta-analysis of three genome-wide association studies, with replication in a fourth study, incorporating a total of 4018 AML cases and 10488 controls. We identified a genome-wide significant risk locus for AML at 11q13.2 (rs4930561; P = 2.15 × 10-8; KMT5B). We also identified a genome-wide significant risk locus for the cytogenetically normal AML sub-group (N=1287) at 6p21.32 (rs3916765; P = 1.51 × 10-10; HLA). Our results inform on AML etiology by identifying putative functional genes operating in histone methylation (KMT5B) and immune function (HLA).

The use of antihuman T-lymphocyte immunoglobulin in the setting of transplantation from an HLA-matched related donor is still much debated. Acute and chronic graft-versus-host disease are the main causes of morbidity and mortality after allogeneic hematopoietic stem cell transplantation in patients with myelofibrosis. The aim of this study was to evaluate the effect of antihuman T-lymphocyte immunoglobulin in a large cohort of patients with myelofibrosis (n=287). The cumulative incidences of grade II-IV acute graft-versus-host disease among patients who were or were not given antihuman T-lymphocyte immunoglobulin were 26% and 41%, respectively. The corresponding incidences of chronic graft-versus-host disease were 52% and 55%, respectively. Non-adjusted overall survival, disease-free survival and non-relapse mortality rates were 55% versus 53%, 49% versus 45%, and 32% versus 31%, respectively, among the patients who were or were not given antihuman T-lymphocyte immunoglobulin. An adjusted model confirmed that the risk of acute graft-versus-host disease was lower following antihuman T-lymphocyte immunoglobulin (hazard ratio, 0.54; P=0.010) while it did not decrease the risk of chronic graft-versus-host disease. The hazard ratios for overall survival and non-relapse mortality were 0.66 and 0.64, with P-values of 0.05 and 0.09, respectively. Antihuman T-lymphocyte immunoglobulin did not influence disease-free survival, graft-versus-host disease, relapse-free survival or relapse risk. In conclusion, in the setting of matched related transplantation in myelofibrosis patients, this study demonstrates that antihuman T-lymphocyte immunoglobulin decreases the risk of acute graft-versus-host disease without increasing the risk of relapse. ispartof: HAEMATOLOGICA vol:104 issue:6 pages:1230-1236 ispartof: location:Italy status: published

Quizartinib improved outcome compared to chemotherapy in the QuANTUM-R study (median overall survival (OS): 6.2 months for quizartinib vs. 4.7 in the chemotherapy group; hazard ratio 0.76, p = 0.02...

This phase II study assessed the safety and efficacy of eprenetapopt in combination with AZA in untreated high or very high International Prognostic Scoring System-RFifty-twoIn this very high-risk population of

Approximately 20% of patients withThis was a phase Ib/II study to determine the safety, recommended phase II dose, and efficacy of eprenetapopt administered in combination with azacitidine in patients withFifty-five patients (40 MDS, 11 AML, and four MDS/myeloproliferative neoplasms) with at least oneCombination treatment with eprenetapopt and azacitidine is well-tolerated yielding high rates of clinical response and molecular remissions in patients with

CPX-351 is a liposomal formulation of cytarabine and daunorubicin approved for the treatment of adults with newly diagnosed, therapy-related acute myeloid leukemia (t-AML) or AML with myelodysplasia-related changes (MRC-AML). We retrospectively analyzed the efficacy and safety of CPX-351 in a real-world setting in 103 patients from 12 French centers, including the evaluation of molecular abnormalities at baseline and minimal residual disease (MRD) in responding patients, compared with a historical data set from Bordeaux-Toulouse DATAML registry. A favorable safety profile was observed, with a low frequency of alopecia (11%) and gastrointestinal toxicity (50%). The overall response rate after induction was 59%, and MRD

The value of pretransplant splenectomy in patients with myelofibrosis (MF) is subject to debate, since the procedure may preclude subsequent allogeneic hematopoietic cell transplantation (allo-HCT). To determine the impact of pretransplant splenectomy on the incidence of allo-HCT, we conducted a comprehensive retrospective study of all patients with MF for whom an unrelated donor search had been initiated via the French bone marrow transplantation registry (RFGM) between 1 January 2008 and 1 January 2017. Additional data were collected from the patients' medical files and a database held by the French-Language Society for Bone Marrow Transplantation and Cell Therapy (SFGM-TC). We used a multistate model with four states ("RFGM registration"; "splenectomy"; "death before allo-HCT", and "allo-HCT") to evaluate the association between splenectomy and the incidence of allo-HCT. The study included 530 patients from 57 centers. With a median follow-up time of 6 years, we observed 81 splenectomies, 99 deaths before allo-HCT (90 without splenectomy and nine after), and 333 allo-HCTs (268 without splenectomy and 65 after). In a bivariable analysis, the hazard ratio [95% confidence interval (CI)] for the association of splenectomy with allo-HCT was 7.2 [5.1-10.3] in the first 4 months and 1.18 [0.69-2.03] thereafter. The hazard ratio [95% CI] for death associated with splenectomy was 1.58 [0.79-3.14]. These reassuring results suggest that splenectomy does not preclude allo-HCT in patients with MF.

We develop a new algorithm for computing rational solutions of partial pseudo-linear systems. The algorithm uses a recursive process based on the computation of rational solutions for a sole pseudo-linear system. Using the general setting of pseudo-linear algebra, we revisit the computation of rational solutions for a pseudo-linear system. In particular, we provide a unified and efficient approach for computing a universal denominator. All the algorithms are implemented in Maple.

In order to identify cytomegalovirus (CMV)-seropositive patients who are at risk of developing CMV infection following first allogeneic hematopoietic cell transplantation (allo-HCT), we built up a scoring system based on patient/donor characteristics and transplantation modalities. To this end, 3690 consecutive patients were chronologically divided into a derivation cohort (2010-2012, n = 2180) and a validation cohort (2013-2014, n = 1490). Haploidentical donors were excluded. The incidence of first clinically significant CMV infection (CMV disease or CMV viremia leading to preemptive treatment) at 1, 3, and 6 months in the derivation cohort was 13.8%, 38.5%, and 39.6%, respectively. CMV-seropositive donor, unrelated donor (HLA matched 10/10 or HLA mismatched 9/10), myeloablative conditioning, total body irradiation, antithymocyte globulin, and mycophenolate mofetil significantly and independently affected the incidence of 3-month infection. These six factors were selected to build up the prognostic model. Four risk groups were defined: low, intermediate-low, intermediate-high, and high-risk categories, with a 3-month predicted incidence of first clinically significant CMV infection in the derivation cohort of 22.2%, 31.1%, 45.4%, and 56.9%, respectively. This score represents a framework for the evaluation of patients who are at risk of developing clinically significant CMV infection following allo-HCT. Prospective studies using this score may be of benefit in assessing the value of anti-CMV prophylaxis in well-defined patient cohorts.

Overcoming acquired drug resistance is a primary challenge in cancer treatment. Notably, more than 50% of patients with BRAFV600E cutaneous metastatic melanoma (CMM) eventually develop resistance to BRAF inhibitors. Resistant cells undergo metabolic reprogramming that profoundly influences therapeutic response and promotes tumor progression. Uncovering metabolic vulnerabilities could help suppress CMM tumor growth and overcome drug resistance. Here we identified a drug, HA344, that concomitantly targets two distinct metabolic hubs in cancer cells. HA344 inhibited the final and rate-limiting step of glycolysis through its covalent binding to the pyruvate kinase M2 (PKM2) enzyme, and it concurrently blocked the activity of inosine monophosphate dehydrogenase, the rate-limiting enzyme of de novo guanylate synthesis. As a consequence, HA344 efficiently targeted vemurafenib-sensitive and vemurafenib-resistant CMM cells and impaired CMM xenograft tumor growth in mice. In addition, HA344 acted synergistically with BRAF inhibitors on CMM cell lines in vitro. Thus, the mechanism of action of HA344 provides potential therapeutic avenues for patients with CMM and a broad range of different cancers. Significance: Glycolytic and purine synthesis pathways are often deregulated in therapy-resistant tumors and can be targeted by the covalent inhibitor described in this study, suggesting its broad application for overcoming resistance in cancer.

13 pages; International audience; Generalizing the main result of (Aparicio, Compoint, Weil 2013), we prove that a system is in reduced form in the sense of Kochin and Kovacic if and only if any differential module in an algebraic construction admits a constant basis. Then we derive an explicit version of this statement, which was implicit in (Aparicio, Compoint, Weil 2013) and is a crucial ingredient of (Barkatou, Cluzeau, Di Vizio, Weil 2016). We finally deduce some properties of the Lie algebra of Katz's intrinsic Galois group, which is actually another fundamental ingredient of the algorithm in (Barkatou, Cluzeau, Di Vizio, Weil 2016).

Background: Patients with anemia and lower-risk myelodysplastic syndromes in whom erythropoiesis-stimulating agent therapy is not effective generally become dependent on red-cell transfusions. Luspatercept, a recombinant fusion protein that binds transforming growth factor β superfamily ligands to reduce SMAD2 and SMAD3 signaling, showed promising results in a phase 2 study. Methods: In a double-blind, placebo-controlled, phase 3 trial, we randomly assigned patients with very-low-risk, low-risk, or intermediate-risk myelodysplastic syndromes (defined according to the Revised International Prognostic Scoring System) with ring sideroblasts who had been receiving regular red-cell transfusions to receive either luspatercept (at a dose of 1.0 up to 1.75 mg per kilogram of body weight) or placebo, administered subcutaneously every 3 weeks. The primary end point was transfusion independence for 8 weeks or longer during weeks 1 through 24, and the key secondary end point was transfusion independence for 12 weeks or longer, assessed during both weeks 1 through 24 and weeks 1 through 48. Results: Of the 229 patients enrolled, 153 were randomly assigned to receive luspatercept and 76 to receive placebo; the baseline characteristics of the patients were balanced. Transfusion independence for 8 weeks or longer was observed in 38% of the patients in the luspatercept group, as compared with 13% of those in the placebo group (P Conclusions: Luspatercept reduced the severity of anemia in patients with lower-risk myelodysplastic syndromes with ring sideroblasts who had been receiving regular red-cell transfusions and who had disease that was refractory to or unlikely to respond to erythropoiesis-stimulating agents or who had discontinued such agents owing to an adverse event. (Funded by Celgene and Acceleron Pharma; MEDALIST ClinicalTrials.gov number, NCT02631070. opens in new tab; EudraCT number, 2015-003454-41. opens in new tab.)

Acute myeloid leukemia (AML) is frequently associated with hyperleukocytosis [white blood cell count (WBC) of >50 or >100 × 109/L at presentation] [1]. Hyperleukocytosis also predicts a higher risk...

International audience; The purpose of this chapter is to present a survey on the effective algebraic analysis approach to linear systems theory with applications to control theory and mathematical physics. In particular, we show how the combination of effective methods of computer algebra -- based on Gröbner basis techniques over a class of noncommutative polynomial rings of functional operators called Ore algebras -- and constructive aspects of module theory and homological algebra enables the characterization of structural properties of linear functional systems. Algorithms are given and a dedicated implementation, called OreAlgebraicAnalysis, based on the Mathematica package HolonomicFunctions, is demonstrated.

International audience; In this paper, we show how stabilizing controllers for 2D systems can effectively be computed based on computer algebra methods dedicated to polynomial systems, module theory and homological algebra. The complete chain of algorithms for the computation of stabilizing controllers, implemented in Maple, is illustrated with an explicit example.

International audience; Within the algebraic analysis approach to linear systems theory, we investigate the equivalence problem of linear functional systems, i.e., the problem of characterizing when all the solutions of two linear functional systems are in a one-to- one correspondence. To do that, we first provide a new characterization of isomorphic finitely presented modules in terms of inflation of their presentation matrices. We then prove several isomorphisms which are consequences of the unimodular completion problem. We then use these isomorphisms to complete and refine existing results concerning Serre’s reduction problem. Finally, different consequences of these results are given. All the results obtained here are algorithmic for rings for which Gröbner basis techniques exist and the computations can be performed by the Maple packages OreModules and OreMorphisms or the Mathematica package OreAlgebraicAnalysis.

In this study, we aimed to refine prognostication of older with acute myeloid leukemia (AML) after intensive chemotherapy. Five hundred and nine patients aged 60 years or older (median age, 68 years) were prospectively enrolled in the intensive Acute Leukemia French Association (ALFA)-1200 trial between 2012 and 2016, and 471 patient samples were submitted to multigene analysis. Mutations in any of 8 genes frequently altered in myelodysplastic syndromes (MDS), including ASXL1, SRSF2, STAG2, BCOR, U2AF1, EZH2, SF3B1, and ZRSR2, defined a secondary AML (sAML)-like disease, as reported. Of the samples analyzed, 48% included sAML-like gene mutations. These mutations were associated with a shorter event-free survival, both overall (hazard ratio, 1.46; 95% confidence interval, 1.19-1.79; P < .001) and within the European LeukemiaNet (ELN)-2017 intermediate-risk subgroup (hazard ratio, 1.52; 95% confidence interval, 1.01-2.28; P = .044), which excludes ASXL1-mutated cases by definition. We therefore included patients with intermediate-risk AML carrying sAML-like mutations in a single high-risk patients group together with adverse-risk patients with AML, whereas other intermediate-risk patients were included in a standard-risk group together with favorable-risk patients (high-risk/standard-risk patient ratio, 1.00). Using this 2-class risk assessment, we observed that transplantation prolonged overall survival from remission in patients with high-risk AML only, not in patients with standard-risk AML. Routine analysis of sAML-like gene mutations may thus improve the definition of high-risk older patients with AML, and better identify the half of older patients who clearly derive survival benefit from allogeneic transplantation in first remission. This trial was registered at www.clinicaltrials.gov as #NCT01966497.

Hypomethylating agent (HMA) failure in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) carries a poor prognosis with limited treatment options. Although intensive, remission induction chemotherapy is often used subsequently, in particular to bridge to allogeneic transplantation, it is not clear whether an advantage exists for any particular regimen. Based on an international collaboration, we retrospectively analyzed induction response rate and survival in 366 patients after HMA failure. Patients received 7+3, intermediate- to high-dose cytarabine (IDAC), or purine nucleoside analog-based regimens. For the MDS cohort (n = 307), the overall response rate (ORR) was 41%; median overall survival (OS) was 10.8 months, and 40% of responding patients bridged to allogeneic stem cell transplant (allo-SCT). For the AML cohort (n = 59), the ORR was 32%, OS 6 months, and 42% of responding patients bridged to allo-SCT. Prognostic factors for response in MDS included adverse cytogenetics (odds ratio [OR], 0.46, P = .01), age ≥65 years (OR, 0.47; P < .01), and use of IDAC (OR, 2.91, P = .01). Shorter survival was associated with adverse cytogenetics (hazard ratio [HR], 1.43; P = .06). In the AML cohort, OS was decreased by disease progression at time of HMA failure (HR, 2.66; P = .02) and prolonged with use of an anthracycline-containing regimen (HR, 0.37; P = .01). In conclusion, intensive chemotherapy after HMA failure may be a reasonable treatment option for selected patients as a bridge to allogeneic transplantation and should be considered a potential platform for future investigations.

Isolated trisomy 8 (+8) is a frequent cytogenetic abnormality in the myelodysplastic syndromes (MDS), but its characteristics are poorly reported. We performed a retrospective study of 138 MDS patients with isolated +8, classified or reclassified as MDS (excluding MDS/myeloproliferative neoplasm). Myeloproliferative (MP) features were defined by the repeated presence of one of the following: white blood cell count >10 × 109 /l, myelemia (presence of circulating immature granulocytes with a predominance of more mature forms) >2%, palpable splenomegaly. Fifty-four patients (39·1%) had MP features: 28 at diagnosis, 26 were acquired during evolution. MP forms had more EZH2 (33·3% vs. 12·0% in non-MP, P = 0·047), ASXL1 (66·7% vs. 42·3%, P = 0·048) and STAG2 mutations (77·8% vs. 21·7%, P = 0·006). Median event-free survival (EFS) and overall survival (OS) were 25 and 27 months for patients with MP features at diagnosis, versus 28 (P = 0·15) and 39 months (P = 0·085) for those without MP features, respectively. Among the 57 patients who received hypomethylating agent (HMA), OS was lower in MP cases (13 months vs. 23 months in non-MP cases, P = 0.02). In conclusion, MP features are frequent in MDS with isolated +8. MP forms had more EZH2, ASXL1 and STAG2 mutations, responded poorly to HMA, and tended to have poorer survival than non-MP forms.

Patients with primary refractory or relapsed-acute myeloid leukemia (RR-AML), particularly older adults, have dismal outcomes and limited therapy options [1]. Given the tolerability of hypomethylat...

This article deals with stability and stabilization issues for linear two-dimensional (2D) discrete models. More precisely, we focus on repetitive processes and Roesser models. Within the algebraic analysis approach to linear systems theory, we first show how a given linear repetitive process can be transformed into an equivalent linear Roesser model. We then prove that the structural stability is preserved by this equivalence transformation. This enables us to design new approaches for stabilizing linear repetitive processes by means of existing methods for computing a state feedback control law stabilizing a linear 2D discrete Roesser model. We also show that we can interpret the stability along the pass of a linear repetitive process as its structural stability. This implies that one of our new approaches can be applied to stabilize along the pass a linear repetitive process which is only stable from pass to pass.

Karyotype according to the revised IPSS is a strong independent prognostic factor for overall survival (OS) in myelodysplastic syndromes (MDS), however established in untreated patients. The prognostic impact of cytogenetics and cytogenetic response (CyR) in MDS patients receiving azacitidine (AZA) remains uncertain. We examined the prognostic value of baseline cytogenetics and CyR for overall response rate (ORR) and OS in 702 AZA-treated higher risk MDS and low blast count acute myeloid leukemia (AML), including 493 (70%) with abnormal karyotype. None of the cytogenetic abnormalities had significant impact on ORR (43.9%) or complete response (15.35%), except 3q abnormalities and complex karyotypes, which were associated with a lower ORR. OS differed significantly across all R-IPSS cytogenetic subgroups (p

Background: Allo HSCT is a potentially curative treatment in MDS which, in higher risk (IPSS high and int 2) MDS demonstrated an overall survival (OS) advantage over conventional treatment (especially HMAs) in retrospective (Koreth et al., JCO 2013) and prospective (Robin et al. leukemia 2015) studies. Retrospective studies, on the other hand, suggested no OS advantage for allo HSCT in lower risk MDS (IPSS low and int 1), except possibly in the "poorest" lower risk MDS subsets, as classified by the WPSS (Alessandrino et al. AMJH 2013) However, about 25% of lower risk MDS patients are reclassified as higher risk by the R-IPSS and a proportion of other lower risk MDS can also harbor some higher risk features that compromise their outcome. MDS-ALLO-RISK trial (clinicaltrial.gov NCT02757989), was designed to assess outcome of lower risk MDS patients with some high-risk features after HLA-matched donor HSCT. Method: The primary objective of this study was to demonstrate an OS improvement in lower risk MDS patients with some high risk features with a donor compared with those without a donor (with a 3 year OS of 70% versus 40%, respectively) . Inclusion criteria were: IPSS low or int1 MDS with at least one of the following characteristics: 1) R-IPSS intermediate or higher 2) RBC transfusion dependent anemia and failure to two or more treatments (including EPO, Lenalidomide or HMA ); 3) platelets < 20 G/L requiring transfusions 4) ANC < 0.5 G/L with severe infection 5) no contra indication to allo HSCT 6) age Results: 79 patients were included, 64 in group A and 15 in group B. Median age was 62.4 (IQR: 58-65) years in group A and 66 (IQR: 60.5-68) years in group B. Patients in group A were more frequently males (73 vs 40%, p=0.029), WHO was CMML in 8 (10%), MDS-SLD in 5 (8%), MDS-MLD in 9 (11%), MDS-EB1 in 41 (52%), MDS-RS in 12 (15%), unclassified in 4 (6%) without significant differences between the two groups. IPSS /IPSS-R was similar in both groups: IPSS low in 10% (11% in group A and 7% in group B) and Int-1 in 90%. IPSS-R: very low risk (6% vs 0%); low risk (25% vs 27%); intermediate (50% vs 47%); high (19% vs 27%); no very high risk. Among the 64 patients with a donor, 58 (92%) received HSCT, 2 died before HSCT; 2 had progressive disease and 2 are planned for HSCT. Transplanted patients received reduced intensity conditioning regimen with busulfan 6.4mg/kg, fludarabine 150mg/m2 and ATG (rabbit antithymocyte globulin therapy, grafalon®) 30mg/kg and cyclosporine-mycophenolate mofetil as GVHD prophylaxis. In group A, 21/64 had died, including 13 died from a non-relapse cause. In group B, 4/15 patients had died, 3 from MDS progression and one from CNS bleeding. Three-year OS was 60% (95%CI: 46.9-76.8) in group A and 64.2% (41.3-99.6) in group B (p=NS). At the time of analysis, 20 and 5 patients had progressed/relapsed in group A and B respectively. with a cumulative incidence of relapse/progression (from inclusion) of 27.4% (IC95%: 15;39.8) in group A and 41.7% (IC95%:9.2;74.2) in group B (p=0.71). Among the 58 transplanted patients, 11 (19%) died without disease progression, including one death from a solid tumor. 3 years non-relapse mortality in transplanted patients was 23.4% (IC95%:9.7;37). 3 years Incidence of grade 2 to 4 acute GVHD was 40.8% and 3 years chronic GVHD was 24.9%. Conclusion: In this, to our knowledge, first prospective study in IPSS lower risk patients with some unfavorable clinical or biological features, HLA identical donor (sibling or 10/10 unrelated) HSCT yielded a 3-year OS of 60%. Non relapse mortality was however 23%, and OS somewhat lower than expected (70% at 3 years) and similar to that observed in patients without a donor. Long-term follow-up is needed to better define subgroups of IPSS lower risk MDS that may benefit from allo HSCT. Disclosures Sebert: Abbvie: Consultancy; BMS: Consultancy. Cluzeau: Pfizer: Other: travel, accommodations, expenses; Astellas: Speakers Bureau; Amgen: Speakers Bureau; Agios: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Speakers Bureau; Roche: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Speakers Bureau; Takeda: Other: travel, accommodations, expenses; Jazz Pharma: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau. Loschi: AbbVie: Ended employment in the past 24 months, Honoraria; CELGENE/BMS: Honoraria; Gilead: Ended employment in the past 24 months, Honoraria; Novartis: Ended employment in the past 24 months, Honoraria; Servier: Ended employment in the past 24 months, Honoraria; MSD: Honoraria. Huynh: Jazz Pharmaceuticals: Honoraria. Ades: ABBVIE: Honoraria; NOVARTIS: Honoraria; CELGENE/BMS: Honoraria; CELGENE: Research Funding; JAZZ: Honoraria, Research Funding; TAKEDA: Honoraria. Fenaux: JAZZ: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria. Robin: NEOVII MEDAC NOVARTIS: Research Funding.

Background and aims: intensive chemotherapy (IC) has been used since the early 90's in the treatment of higher risk MDS, yielding 40 to 50% complete response (CR) but prolonged myelosuppression and 10 to 30% early deaths. IC is also recommended before allogeneic (allo) SCT when marrow blasts are increased (De Witte et al, Blood, 2017). CPX-351, a liposomal combination of cytarabine and daunorubicin, proved greater efficacy than classical IC with 3+7 in secondary-AML, including in patients with 20-30% marrow blasts and those who subsequently received allo SCT (Lancet et al, Lancet Haematol, 2021). We evaluated response to CPX-351 in a group of untreated higher risk MDS patients, most of whom were candidates for allo SCT. Methods: This prospective study, involving 12 GFM centers, included int-2 or high IPSS MDS, previously untreated with HMA or chemotherapy, and aged Results: 31 patients were included between July 2020 and January 2021. Median age was 62 years (range 31-69); WHO classification: 26 MDS-EB2, 5 CMML-2; IPSS: int-2: 84%, high: 16%; R-IPSS: intermediate: 29%, high: 55%, very high: 16%; karyotype: 2 very good, 22 good, 3 intermediate, 2 poor, 2 very poor. 27 patients received one induction cycle and 4 (in stable disease (SD) after the first cycle), a second induction cycle. Response rates, eventually evaluated a median of 53 days (range 28-112) from onset of induction, were with ELN 2017 criteria: CR: 52%, CRi: 13%, MLFS: 23%, SD: 13% and with IWG 2006 criteria : CR: 23%, mCR: 45%, mCR + HI-P: 6%, mCR + HI-P + HI-N: 6%, mCR + HI-N: 3%, PR: 3%, SD: 13%. Minimal residual disease assessment by NGS and flow cytometry will be presented at the meeting. 24/27 patients with baseline marrow blasts >10%, reached 20G/L and >50G/L were: 16 (range 0-55) days and 28 (range 8-51), respectively and to ANC >1G/L: 26 (range 2-60) days. Only one patient had grade ≥ 3 mucositis and 4 had grade ≥ 2 alopecia during induction treatment. No patient died during induction treatment or required management in the intensive care unit. With a median follow-up of 201 days (range 102-350), 22 of the 30 patients initially considered for allo SCT received transplant after no (10 pts), 1 (9 pts), 2 or 3 (3 pts) consolidation cycles and 5 are planned for allo SCT. Reasons for not being transplanted were, investigators' choice (n=1), relapse (1), no donor (1) and invasive fungal infection (n=1). None of the 4 non transplanted patients received consolidation cycles. Reasons for not receiving consolidation cycles were persistent cytopenia (n=5), cardiac toxicity (n=2), failure to achieve CR or PR (n=2). At the time of analysis (June 2021), 4 patients had relapsed, after 3 to 6 months of response. Conclusions : CPX-351 is effective in higher risk MDS/CMML, especially to achieve blast clearance, and as a bridge to allo SCT. Figure 1: waterfall plot according to IWG 2006 and ELN 2017 criteria Figure 1 Figure 1. Disclosures Fenaux: Novartis: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria; Takeda: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. OffLabel Disclosure: CPX-351 use off-label for myelodysplastic syndroms in a prospective trial

Background : ENA is a selective inhibitor of IDH2 approved in the US for the treatment of patients with relapsed/refractory IDH2 mutated AML. Little is known on its efficacy in patients with IDH2m myelodysplastic syndromes. Here we report the preliminary results of a Phase 2 study evaluating the safety and efficacy of ENA in three different cohorts of MDS : Higher risk MDS having failed HMA (cohort A, n=29), untreated higher risk MDS without life threatening cytopenias (ie ANC < 500/mm3 or any recent severe infections and/or platelets below 30,000/mm3 and any bleeding symptom, cohort B, with the addition of AZA in non-Responders after 3 cycles, n=29) and lower risk MDS having failed ESA (cohort C, n=10). (ClinicalTrials.gov NCT03744390). Methods : Subjects enrolled in cohort A, B or C received continuous 28-day cycles of ENA - 100 mg PO QD. In cohort B, Azacitidine (75 mg/m2/d x 7 days, SC) was added to Enasidenib after 3 cycles, only in the absence of IWG 2006 response (absence of CR, PR or HI). The primary endpoint was Overall hematological response (including CR, PR,stable disease with HI according to IWG 2006). All patients who achieved CR, PR or HI were considered as responders and could continue treatment until loss of response. Secondary endpoints of the trial included safety,duration of response, EFS, Overall survival and translational project evaluating the role of biomarkers on response.We report interim results in the first 26 pts enrolled. Resul t s : At data cut off (6/15/2021), 45 pts were enrolled, including 26 who were evaluable for the primary endpoint. 11, 9 and 6 were enrolled in cohort A, B and C respectively. Median age was 75.5 years and 34.6% were female. WHO was MDS-MLD, MDS-RS-SLD, MDS-RS-MLD, MDS-EB1, MDS-EB2, CMML and AML (with 20-30% blast) in 1, 2, 3,4, 10, 2 and 4 pts, respectively. IPSS was low, intermediate 1, int 2 and high in 1, 7, 13, 5 resp. IPSS-R was low,intermediate, high and very high in 4, 8, 11, 3 resp. At data cut off, 10 pts were still on treatment. Most common reasons for discontinuing ENA were Treatment failure (7.7%), disease progression (23.1%), adverse events (7.7%) and death (3.8%). Three patients experienced a differentiation syndrome (1 in cohort A and 2 in cohort B) that resolved without sequelae. Other most common grade 3-4 AEs were nausea/diarrhea (n=4) and thrombocytopenia (n=5). Overall best response rate (ORR including CR, PR, and HI) was achieved in 11 pts (42 %), including 6 CR (55%), 2 PR (18%), 2 mCR with HI (18%), 1 Stable disease with HI (9%). ORR was achieved in 3 (27 %), 5 (56 %) and 3 (50%)in cohort A, B and C respectively. In cohort B, AZA wad added to ENA in 3 patients who were primarily resistant to ENA. Among them, 2/3 patients subsequently achieved a response. Moreover, CR was seen in 2, 1 and 3 in cohort A, B and C respectively. The 6 months response rate was 29.5 % [6 ;59], 53.1 % [11.7 ;83] and 50 % [7.7 ;82.9] in cohort A, B and C respectively. At the time of analysis, all responses but 2 were sustained. Responses were lower (p=0.27) among the 23 pts with IDH2 R140 (30.4%) as compared to the 3 with IDH2 R172 mutation (66.7%). With a median follow up of 8.6 months, the median OS was 17.3 months (figure 1). Six patients died during follow-up, including 4/11 in cohort A, 1/9 in cohort B and 1/6 in cohort C. The 6 months death rate observed was 8.2 % [0 ;18.4] and the 1-year OS was 55.4%, 100% and 80% in cohorts A, B and C, respectively. Four patients evolved to AML (2 and 2 in cohort A and B) with a 1y risk of AML of 19.3%. Conclusion : Results from the first 26 patients included in this study show that ENA has no limiting toxicity in patients with MDS and that it can provide responses in 42% of patients. These responses appear to be encouraging, especially in first-line (low and high risk) patients. An update of this study will be presented. Figure 1 Figure 1. Disclosures Ades: JAZZ: Honoraria; Novartis: Honoraria; Abbvie: Honoraria; Takeda: Honoraria; Celgene: Honoraria, Research Funding. Sebert: BMS: Consultancy; Abbvie: Consultancy. Stamatoulas Bastard: Pfizer: Other: Travel Support; Celgene: Membership on an entity's Board of Directors or advisory committees. Laribi: Novartis: Other: Personal Fees, Research Funding; AstraZeneca: Other: Personal Fees; BeiGene: Other: Personal Fees; Takeda: Other: Personal Fees, Research Funding; Jansen: Research Funding; Le Mans Hospital: Research Funding; IQONE: Other: Personal Fees; AbbVie: Other: Personal Fees, Research Funding; Astellas Phama, Inc.: Other: Personal Fees. Vey: Amgen: Honoraria; BMS: Honoraria; BIOKINESIS: Consultancy, Research Funding; NOVARTIS: Consultancy, Honoraria, Research Funding; SERVIER: Consultancy; JAZZ PHARMACEUTICALS: Honoraria; JANSSEN: Consultancy. Platzbecker: AbbVie: Honoraria; Takeda: Honoraria; Celgene/BMS: Honoraria; Janssen: Honoraria; Geron: Honoraria; Novartis: Honoraria. Fenaux: Janssen: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria. OffLabel Disclosure: enasidenib is not approved for MDS

Background: Pts with HR-MDS unfit for hematopoietic stem cell transplant (HSCT) have poor outcomes and limited survival with single-agent hypomethylating agent (HMA) therapy. Novel treatments that provide durable responses and clinically meaningful survival benefit for pts with HR-MDS are needed. TIM-3 is a promising target in myeloid malignancies as it regulates innate and adaptive immune cells and is expressed on leukemic stem cells (LSCs) and blasts but not normal hematopoietic stem cells. Sabatolimab (MBG453) is a novel immuno-myeloid therapy that binds to TIM-3 on immune cells, facilitating antileukemic immune activation and phagocytic killing of leukemic cells. Sabatolimab also binds to TIM-3 on leukemic cells, potentially impeding self-renewal of LSCs via inhibition of TIM3-galectin-9. In an early phase (ph) trial (NCT03066648) sabatolimab + HMA therapy showed a durable clinical benefit and was well tolerated in pts with HR-MDS (Wei, EHA 2021). Study Design and Methods: The STIMULUS immuno-myeloid clinical trial program is investigating the safety, efficacy, and durability of multiple sabatolimab-based combination therapies in pts with myeloid malignancies. Additional exploration of the mechanism of action of sabatolimab and identification of potential biomarkers predictive of response is planned. This abstract summarizes the design of the 4 ongoing STIMULUS trials in previously untreated adult pts with HR-MDS who are not eligible for intensive chemotherapy (IC) or HSCT. STIMULUS-MDS1 (NCT03946670) is an international, randomized, double-blind, placebo-controlled Ph II trial evaluating sabatolimab + HMA therapy in pts with very-high, high-, or intermediate-risk (vH/H/IR)-MDS which has completed enrollment (N=127). The primary endpoints of STIMULUS-MDS1 are complete response (CR) and progression-free survival (PFS). STIMULUS-MDS2 (NCT04266301) is an ongoing, international, randomized, double-blind, placebo-controlled, Ph III trial of sabatolimab + azacitidine (AZA) in pts with vH/H/IR-MDS or chronic myelomonocytic leukemia-2. Target enrollment is ~500 pts. The primary endpoint in this trial is overall survival (OS). Key secondary endpoints are time to definitive deterioration of fatigue; duration of RBC transfusion-free interval; and improvement of fatigue, physical functioning, and emotional functioning. Other endpoints include CR, marrow CR (mCR), partial remission (PR), PFS, and leukemia-free survival (LFS). STIMULUS-MDS2 is a trial that aims to determine if sabatolimab + HMA has a statistically significant and clinically meaningful benefit in OS and quality of life vs HMA alone. STIMULUS MDS-US (NCT04878432) is a US-based, open-label, single-arm, Ph II trial investigating sabatolimab + HMAs of investigators' choice (AZA intravenous [IV] or subcutaneous, decitabine IV or oral decitabine) in pts with vH/H/IR-MDS. Target enrollment is 90 pts. Primary endpoint is safety, which will be evaluated via incidence and severity of adverse events (AEs) and serious AEs. Secondary endpoints include CR, PFS, LFS, and OS. This trial will provide further understanding of sabatolimab + HMA therapy with additional insight into the safety and efficacy of sabatolimab + oral HMA. STIMULUS-MDS3 (NCT04812548) is an international, open-label, single-arm, Ph II trial that explores triplet therapy of sabatolimab combined with AZA and the BCL-2 inhibitor venetoclax (VEN) in pts with vH/HR-MDS. Part 1 of this trial is a safety run-in comprising 2 safety cohorts with ~6 pts receiving sabatolimab 400 mg + AZA + VEN and ~12 pts receiving sabatolimab 800 mg + AZA + VEN. Primary endpoint of part 1 is safety (dose-limiting toxicities between cycle 1 day 8 and end of cycle 2). If (both 400 and 800 mg) sabatolimab + AZA and VEN are safe, the trial will progress to an expansion cohort (~58 pts) of sabatolimab 800 mg Q4W + AZA + VEN. The primary endpoint is CR. Secondary endpoints include CR + mCR rate, overall response rate (CR + mCR + PR + hematologic improvement), OS, PFS, LFS, and event-free survival. The STIMULUS immuno-myeloid clinical trial program is investigating the efficacy, safety, and improved quality of life of multiple sabatolimab-based combination therapies in pts with myeloid malignancies. The goal of ongoing STIMULUS-MDS trials is to gain insight into the promising durable benefit of sabatolimab combination therapies in pts with HR-MDS. Figure 1 Figure 1. Disclosures Zeidan: Jazz: Consultancy; Jasper: Consultancy; Pfizer: Other: Travel support, Research Funding; AstraZeneca: Consultancy; Janssen: Consultancy; Novartis: Consultancy, Other: Clinical Trial Committees, Travel support, Research Funding; Loxo Oncology: Consultancy, Other: Clinical Trial Committees; Ionis: Consultancy; Kura: Consultancy, Other: Clinical Trial Committees; Incyte: Consultancy, Research Funding; Gilead: Consultancy, Other: Clinical Trial Committees; Genentech: Consultancy; Epizyme: Consultancy; Daiichi Sankyo: Consultancy; Geron: Other: Clinical Trial Committees; BMS: Consultancy, Other: Clinical Trial Committees, Research Funding; Cardiff Oncology: Consultancy, Other: Travel support, Research Funding; Boehringer Ingelheim: Consultancy, Research Funding; BioCryst: Other: Clinical Trial Committees; BeyondSpring: Consultancy; Astex: Research Funding; Astellas: Consultancy; Aprea: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Agios: Consultancy; ADC Therapeutics: Research Funding; Acceleron: Consultancy, Research Funding; AbbVie: Consultancy, Other: Clinical Trial Committees, Research Funding. Al-Kali: Astex: Other: Research support to institution; Novartis: Research Funding. Borate: Takeda: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharma: Research Funding; Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: 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; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rampal: Membership on an entity's Board of Directors or advisory committees; Galecto, Inc.: Consultancy; Promedior: Consultancy. Cluzeau: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Speakers Bureau; Abbvie: Consultancy, Honoraria, Speakers Bureau; Agios: Honoraria; Amgen: Speakers Bureau; Jazz Pharma: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Astellas: Speakers Bureau; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau; Pfizer: Other: travel, accommodations, expenses; Takeda: Other: travel, accommodations, expenses. DeZern: Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees. Esteve: Jazz: Consultancy; Novartis: Consultancy, Research Funding; Astellas: Consultancy; Abbvie: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Pfizer: Consultancy; Novartis: Research Funding. Giagounidis: Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Platzbecker: Celgene/BMS: Honoraria; Novartis: Honoraria; Janssen: Honoraria; Geron: Honoraria; AbbVie: Honoraria; Takeda: Honoraria. Sallman: Kite: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Syndax: Membership on an entity's Board of Directors or advisory committees; Intellia: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Magenta: Consultancy. Santini: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Menarini: Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Geron: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Astex: Membership on an entity's Board of Directors or advisory committees. Sanz: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Speakers Bureau; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Helsinn Healthcare: Consultancy, Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Other: Travel, accommodations, and expenses. Sekeres: Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Wei: Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; Pfizer: 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; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Van Hoef: Novartis Pharma: Current Employment. Nourry-Boulot: Novartis: Current Employment. Sadek: Novartis: Current Employment. Bengoudifa: Novartis Pharma AG: Current Employment. Sachs: Novartis Pharma AG: Current Employment. Sabo: Novartis: Current Employment, Current holder of stock options in a privately-held company. OffLabel Disclosure: Sabatolimab is a novel immuno-myeloid therapy targeting TIM-3 and is under investigation for the treatment of patients with myeloid malignancies

Introduction: TP53 gene mutations (m TP53), found in up to 20% of MDS or AML pts and 30-40% of therapy-related (TR) MDS/AML cases, represent a distinct molecular cohort with poor outcomes. Hypomethylating agents (HMA) are the frontline standard of care, with CR rates of ~20% and median OS of < 12 months. APR-246 is a novel, first-in-class small molecule that reactivates the mutant p53 protein and targets cellular redox balance, ultimately inducing apoptosis and ferroptosis in m TP53 cancer cells. We previously reported the Phase 2 results of 2 parallel trials of APR-246+AZA (Sallman et al and Cluzeau et al., JCO 2021). We now report analyses of the combined Phase 2 cohorts and long-term follow-up. Methods: This is a multicenter, international collaboration of the US MDS clinical research consortium and the GFM of HMA-naïve m TP53 higher-risk MDS, MDS/MPN and oligoblastic AML (≤ 30% blasts) pts (NCT03072043/NCT03588078). Pts received APR-246 4500mg IV (days 1-4) + AZA 75 mg/m 2 SC/IV x 7 days (days 4-10 or 4-5 and 8-12) in 28-day cycles. Primary objective was CR rate by International Working Group (IWG) 2006 criteria. Secondary objectives included ORR, OS, outcome following allogeneic hematopoietic stem cell transplant (allo-HSCT), with serial high depth next generation sequencing (NGS, 0.1% cutoff) for evaluation of measurable residual disease (MRD). Results: As of July 15, 2021, 100 pts had been enrolled with a median age of 68 years (range, 34-87; 47% male). By WHO, 74 pts had MDS, 22 AML-MRC and 4 CMML/MDS-MPN; 83% complex karyotype (CK) and 88% were CK and/or biallelic for TP53 mutations; 92% had a TP53 missense mutation in the DNA binding domain. In 63 pts, TP53 was the only mutation detected (i.e. isolated m TP53). Median time on treatment was 6 cycles (1-25+) with 5 pts ongoing and 23 pts who proceeded to allo-HSCT. Non-hematologic treatment (Tx)-related adverse events (AEs) in ≥20% of pts included nausea/vomiting (58%), ataxia (26%), and dizziness (23%). Neurologic AEs were reversible in 100% of cases. Febrile neutropenia occurred in 37% of pts. Thirty and 60-day mortality was 1% (n=1) and 7% (n=7), respectively. Dose reductions of APR-246 and AZA occurred in 16% and 1% of pts, respectively, with only 1 treatment discontinuation due to a treatment-related AE. By intention-to-treat (ITT) analysis, ORR by IWG was 69% with 43 CR, 1 PR, 10 marrow CR (mCR)+HI, 9 HI alone, and 6 with mCR. Of non-responders, 6 had stable disease and 7 pts had progressive disease. The median duration of CR/PR was 10.6 months (95% CI 8.8-12.3, 23+ months ongoing). CR/PR rate for MDS was 49% (36/74), 36% for AML (8/22) and 0% for MDS/MPN (0/4) with an ORR rate of 70%/64%/75%, respectively. Isolated m TP53 was predictive for a higher CR rate (52% vs 30%; P=.04). Patients who had biallelic TP53 or CK had a significantly higher CR rate vs pts without (49% vs 8%; P=0.01). On serial TP53 NGS using a VAF cutoff of 5%, 40 pts achieved NGS negativity with 6 pts MRD negative (VAF < 0.1%). Of NGS negative pts (TP53 VAF At data-cutoff by ITT analysis with a median follow up of 27.8 months, median OS was 11.8 months (95% CI 9.4-14.3). Pts undergoing allo-HSCT had a median OS of 16.1 months (95% CI 14-18.1). Impact of response and NGS clearance was evaluated by landmark analysis at 6 months. Pts achieving CR/PR or NGS negativity had improved OS (15.8 vs 10.1 months; P=0.002; Fig 1A). Additionally, pts who became MRD negative had a 2-year OS of 50% vs 23% (P=0.21). Although allo-HSCT was not predictive of OS in the overall cohort by landmark analysis (14.7 vs 14.4 months; P=0.15; Fig 1B), significant OS improvement was noted in allo-HSCT pts based on CR/PR or NGS negativity (P=0.002; Fig 1C). Notably, pts who achieved CR/PR/NGS negativity and were bridged to allo-HSCT had a median OS that was not reached (95% CI 10.4-NR) vs 9.1 months (95% CI 7.4-NR) in allo-HSCT pts who did not achieve this response (P=0.01). Conclusions: In this international, combined analysis of P2 APR-246+AZA pts, the combination was well-tolerated with high response rates in m TP53 MDS/AML. Quality of response and NGS negativity strongly predicted OS, particularly in the setting of allo-HSCT, validating NGS clearance as a critical biomarker of allo-HSCT outcomes in m TP53 pts. Figure 1 Figure 1. Disclosures Sallman: Intellia: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Membership on an entity's Board of Directors or advisory committees; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees; Magenta: Consultancy; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees. Komrokji: BMS: Honoraria, Speakers Bureau; JAZZ: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau; Novartis: Honoraria; Geron: Honoraria; Acceleron: Honoraria; Agios: Honoraria, Speakers Bureau. DeZern: Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Sebert: BMS: Consultancy; Abbvie: Consultancy. Steensma: Novartis: Current Employment. Roboz: Astellas: Consultancy; Otsuka: Consultancy; Blueprint Medicines: Consultancy; AbbVie: Consultancy; Bayer: Consultancy; Glaxo SmithKline: Consultancy; Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Helsinn: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Jasper Therapeutics: Consultancy; MEI Pharma - IDMC Chair: Consultancy; Janssen: Research Funding; AstraZeneca: Consultancy; Jazz: Consultancy; Amgen: Consultancy; Daiichi Sankyo: Consultancy; Mesoblast: Consultancy; Agios: Consultancy; Pfizer: Consultancy; Astex: Consultancy; Actinium: Consultancy; Roche/Genentech: Consultancy. Sekeres: BMS: Membership on an entity's Board of Directors or advisory committees; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Sweet: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kuykendall: Incyte: Consultancy; Novartis: Honoraria, Speakers Bureau; Prelude: Research Funding; PharmaEssentia: Honoraria; CTI Biopharma: Honoraria; Celgene/BMS: Honoraria, Speakers Bureau; BluePrint Medicines: Honoraria, Speakers Bureau; Abbvie: Honoraria; Protagonist: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Recher: Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; Janssen: Honoraria; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MaatPharma: Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Raffoux: ASTELLAS: Consultancy; ABBVIE: Consultancy; PFIZER: Consultancy; CELGENE/BMS: Consultancy. Padron: Incyte: Research Funding; BMS: Research Funding; Blueprint: Honoraria; Kura: Research Funding; Taiho: Honoraria; Stemline: Honoraria. Attar: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kantarjian: Amgen: Honoraria, Research Funding; KAHR Medical Ltd: Honoraria; BMS: Research Funding; AbbVie: Honoraria, Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Astellas Health: Honoraria; Jazz: Research Funding; Aptitude Health: Honoraria; Astra Zeneca: Honoraria; Ipsen Pharmaceuticals: Honoraria; NOVA Research: Honoraria; Precision Biosciences: Honoraria; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Taiho Pharmaceutical Canada: Honoraria. List: Precision BioSciences: Current Employment, Current equity holder in publicly-traded company; Aileron Therapeutics: Consultancy; CTI Biosciences: Consultancy; Halia Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company. Ades: Celgene: Honoraria, Research Funding; Abbvie: Honoraria; Takeda: Honoraria; Novartis: Honoraria; JAZZ: Honoraria. Lancet: BerGenBio: Consultancy; Celgene/BMS: Consultancy; Millenium Pharma/Takeda: Consultancy; Jazz: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy; ElevateBio Management: Consultancy; Agios: Consultancy; AbbVie: Consultancy. Fenaux: Janssen: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria.

On behalf of the GRAALL group, the Czech Republic ALL group, the Finland ALL group and the EWALL group. Introduction. Treatment of older patients (pts) with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) remains an unmet medical need. Inotuzumab ozogamicin (INO), an anti-CD22 antibody conjugated to calicheamicin, is approved for the treatment of relapsed/refractory BCP-ALL in adults, sinusoidal obstruction syndrome (SOS) being the major adverse event associated with INO. A previous first line study conducted by the MDACC in pts 60 years or older successfully used INO in combination with a lower intensity version of the hyper-CVAD (mini-hyper-CVD). Due to the occurrence of SOS, the total doses were fixed at 1.3 mg/m² for cycle 1 followed by 3 cycles at 1 mg/m² (Kantarjian H et al. Lancet Oncol, 2018). Here, we aimed to assess the activity and safety of fractionated INO at a reduced dosage in combination with low-intensity chemotherapy as frontline therapy for older pts with CD22+ Philadelphia chromosome-negative (Ph-neg) BCP-ALL. Methods. EWALL-INO is a single arm prospective phase 2 multicentric study conducted in European centers belonging to the EWALL group. Eligibility criteria were pts aged 55y or older, performance status ≤2, and newly diagnosed CD22+ (20% or more of positive blast cells) Ph-neg BCP-ALL without central nervous system involvement. After a prephase including 5 days (D) of dexamethasone (DEX) 10mg per D and a single intrathecal injection (IT), the induction regimen was begun and split in 2 parts. Induction part I (Induc1) consisted of one triple IT, vincristine (VCR) 2 mg (1 mg over 70y) D1 D8 D15 D22 and DEX 20 mg D1D2 D8D9 D15D16 D22D23 combined with 3 injections of INO (0.8 mg/m² D1, 0.5 mg/m² D8 and D15). Induction part II (Induc2) was offered to pts in CR or CRp (CR with platelets < 100 G/l) after Induc1 or as salvage therapy. Induc2 consisted of DEX 20mg D1D8, cyclophosphamide (CY) 300 mg/m² D1 to D3, one triple IT D2 and 2 injections of INO (0.5 mg/m² D1 and D8). Pts in CR/CRp were programmed to receive 6 blocks of consolidation (Ara-C 1.5g/m²/12h adapted to renal clearance D1D2 and DEX 10mg/12h D1D2, cycles 1 and 4; Methotrexate (MTX) 1.5 g/m² over 24h D1, VCR 1 or 2 mg D1, one triple IT D2 and 6-mercaptopurin (6-MP) D1 to D7, cycles 2 and 5; CY 500 mg/m² D1D2, VP16 75 mg/m² D1D2, one triple IT D2 and MTX 25 mg/m² D1, cycles 3 and 6) followed by a POMP maintenance (VCR, 6-MP, MTX, DEX) during 18 months. Allograft was allowed after at least 3 blocks of consolidation at the discretion of the investigators. The evaluable population was pts who received at least 1 dose of INO. Analyses were by modified intention to treat and performed JUN 28, 2021. All pts gave informed consent. The study is registered at ClinicalTrials.gov under the NCT number: NCT03249870. Results. Between DEC 29, 2017 and JUN 22, 2021, 115 pts (out of 130 planned pts) were enrolled including 6 pts with screen failure. The first 90 eligible pts (up to MAR 1, 2021) were considered for this analysis to obtain a minimum of 4 months follow-up. Median age was 69y (range 55-84) and median follow-up for alive pts was 1.18 years (range 0.3-3.5). At time of analysis, 90 and 88 pts had started induc1 and induc2, respectively. Treatment related mortality was 2.2% (2/90) and CR/CRp rate was 85.5% (77/90, 6 CRp) after induc1. Three cases relapsed between induc1 and induc2 and 5 pts were salvaged by induc2 allowing to a CR/CRp rate of 87.7% (79/90, 8 CRp) after induc2. One pts died from refractory disease during induc2. One, 2, 3 4 and 5 injections of INO were administered to 2 (2.2%), 2(2.2%), 11 (12.2%), 2 (2.2%) and 73 pts (81.1%) respectively. Only 6 pts were allografted. One-year OS was estimated to be 78.5% (95%CI 68-85.9) and median OS was not reached. One-year relapse free survival was 74.5% (95CI 63.5-82.6) (Figure 1). Grade 3-4 liver toxicity was observed in 8 pts (8.8%) during the study including 3 pts (3.3%) developing SOS, 2 related to INO during induc1 and one occurred after transplant. Twenty-nine pts died during the follow-up, 16 from relapses (overall incidence 18%) and 13 from adverse events (overall incidence 14.4%), including one COVID19 fatal infection during consolidation. Conclusion. Fractionated inotuzumab ozogamicin at reduced doses (0.8/0.5/0.5/0.5 mg/m²) combined with low-intensity chemotherapy is a very active and well tolerated frontline therapy for older patients with CD22+ Ph-neg BCP-ALL. Figure 1 Figure 1. Disclosures Doubek: Janssen-Cilag, AbbVie, AstraZeneca, Amgen, Gilead, Novartis: Honoraria, Research Funding. Huguet: Novartis: Other: Advisor; Jazz Pharmaceuticals: Other: Advisor; Celgene: Other: Advisor; BMS: Other: Advisor; Amgen: Other: Advisor; Pfizer: Other: Advisor. Raffoux: ABBVIE: Consultancy; PFIZER: Consultancy; CELGENE/BMS: Consultancy; ASTELLAS: Consultancy. Boissel: CELGENE: Honoraria; Servier: Consultancy, Honoraria; Incyte: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; PFIZER: Consultancy, Honoraria; JAZZ Pharma: Honoraria, Research Funding; SANOFI: Honoraria. Dombret: Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Servier: Research Funding; Abbvie: Honoraria; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. Rousselot: Incyte, Pfizer: Consultancy, Research Funding. OffLabel Disclosure: Inotuzumab ozogamicin as first line therapy in newly diagnosed CD22+ Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia

Background: Ivosidenib (IVO) is an oral, targeted, small-molecule inhibitor of mutant IDH1 approved in the US for adult patients with unfit or relapse/refractory AML with IDH1 mutation. Little is known on its efficacy in patients with IDH1 mutated MDS. Here we report interim results of a Phase 2 study evaluating safety and efficacy of IVO in three different cohorts of MDS patients: Higher risk MDS having failed azacytidine (AZA) (cohort A, n=29), untreated higher risk MDS without life threatening cytopenias (ie ANC < 500/mm3 or any recent severe infections and/or platelets below 30,000/mm3 and any bleeding symptom,) as a first line treatment (cohort B, with the addition of AZA in non-Responders after 3 cycles, n=29) and lower risk MDS having failed EPO (cohort C, n=10). (ClinicalTrials.gov NCT03503409). Methods: Subjects enrolled in cohort A, B or C received continuous 28-day cycles of IVO - 500 mg orally QD. In cohort B, AZA (75 mg/m2/d x 7 days, SC) was added to IVO after 3 cycles, only in the absence of IWG 2006 response (absence of CR, PR or HI). The primary endpoint was overall hematological response rate (ORR) at 3 and 6 months (including CR, PR, stable disease with HI according to IWG 2006). All responders allowed to continue treatment until loss of response. Secondary endpoints included safety, duration of response, EFS, overall survival and translational project evaluating the role of biomarkers on response. We report the preliminary results on the first 26 pts enrolled. Results: At data cut off (6/15/2021), 32 patients had been enrolled, including 26 who were evaluable for the primary endpoint. 13, 11 and 2 were enrolled in cohort A, B and C respectively. Median age was 76 years and 50% were female. WHO was MDS-MLD, MDS-EB1, MDS-EB2, CMML and low blast count AML in 2, 2, 12, 1 and 9 patients respectively. IPSS-R was low, intermediate, high and very high in 2, 6, 5 and 13 resp. IDH1 mutation was p.R132C in 15 patients, p.R132H in 7, p.R132G/S in 3 and not specified in 1. The ORR was 69% (18 patients) including 12 CR (46%), 1 PR and 5 HI. Most patients achieved response after 3 cycles (17/18). Response was achieved in 7 (54%), 10 (91%) and 1 (50%) in cohort A, B and C respectively. Moreover, CR was achieved in 3, 8 and 1 in cohort A, B and C respectively. In cohort B, AZA was added to IVO in one patient after 3 cycles, without additional response. With a median follow up of 9.1 months, the median duration of response of the 18 responders was 7.4 months, 9 of them lost their response, and two had died without loss of response (from bleeding and after HSCT, respectively). IPSS-R was the only prognostic factor of response after 6 cycles. At data cut off, 12 patients had progressed (9 in cohort A, 2 in cohort B and 1 in cohort C) and 11 (42%, 10 in cohort A and 1 in cohort C) patients had died, mostly of relapse/progression (n=5/11), infection in 1, suicide in 1, hemorrhage in 1 and other unrelated causes in 3. Median overall survival was 14 months in the whole cohort, 7.7 and not reached in cohort A and B resp. The most common treatment-related serious adverse event (SAE) was differentiation syndrome (4/5), one died and three resolved without sequelae. One patient had febrile neutropenia related to IVO, resolved without sequelae. Conclusion: IVO was well tolerated in MDS patients with significant responses in all the cohorts. With a response rate of 91%, IVO was particularly effective in treatment naïve higher risk MDS patients with IDH1 mutations (cohort B). These encouraging preliminary results have to be confirm in more patients. The IDIOME study is still ongoing, and molecular monitoring results of IDH1 mutations will be presented. Disclosures Sebert: BMS: Consultancy; Abbvie: Consultancy. Cluzeau: Abbvie: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Speakers Bureau; Agios: Honoraria; Amgen: Speakers Bureau; Takeda: Other: travel, accommodations, expenses; Astellas: Speakers Bureau; Jazz Pharma: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau; Pfizer: Other: travel, accommodations, expenses. Stamatoulas Bastard: Pfizer: Other: Travel Support; Celgene: Membership on an entity's Board of Directors or advisory committees. Fenaux: Abbvie: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria. Ades: Abbvie: Honoraria; Takeda: Honoraria; Novartis: Honoraria; JAZZ: Honoraria; Celgene: Honoraria, Research Funding.

Methods : This multicentric retrospective study aimed to evaluate the efficacy and the safety of the combination of BBV in patients with non-cutaneous R/R PTCL among 21 LYSA centers in France and Belgium. The primary objective was to evaluate the best overall response rate (ORR) (complete response (CR) and partial response (PR)). Secondary objectives were progression free survival (PFS), overall survival (OS), duration of response (DoR), impact of transplantation on outcome, and safety. Patients treated between January 2013 and October 2020 were reviewed and all the data were collected through an electronic questionnaire sent to all the physicians. Results : Eighty two patients with R/R PTCL (40 angioimmunoblastic lymphoma (AITL), 2 T-cell lymphoma with TFH phenotype ,13 PTCL not otherwise specified (PTCL NOS), 5 Alk+ anaplastic large cell lymphoma (ALCL), 17 Alk- ALCL, , 1 Extranodal NK-/T-cell lymphoma, 3 Enteropathy-associated T-cell lymphoma (EATL), 1 subcutaneous panniculitis) were included. Median age at beginning of BBV was 60 years, most of patients were male (61%), had advanced stage (88%) and an IPI ≥ 2 (79%). Half of patients were refractory to their last treatment. Median number of prior regimens was 1 (range 1 to 6). The best ORR was 71%, with 51% of patients in CR. In multivariable analysis, only the relapse status after the last regimen (relapse vs refractory) was associated with ORR, relapsed patients having a better ORR (83% vs 57% in refractory patients, p=.014, OR=3.70 (95%CI:1.3-10.5)). Median DoR was 15.4 months in patients with CR but differed significantly whether patients were transplanted or not (Not reached vs 8.4 months, p=.0055). Twenty-two patients (30% of patients ≤ 70 years of age) were transplanted (6 autologous and 16 allogenic). With a median follow-up of 9 months, the median PFS and OS were 8.3 and 26.3 months respectively. In multivariable analysis, only 2 factors had a significant impact on PFS and OS: best response (CR/PR vs SD/PD with a median PFS of 17.4 vs 1.9 months, p Fifty-nine percent of patients experienced a grade 3 to 4 adverse event which was mainly hematologic toxicity. Treatment had to be stopped in 11% of patients. Conclusion: To the best of our knowledge, this is the first study reporting on the combination of BBV in the treatment of R/R PTCL in such a large cohort. The results are very encouraging with a high response rate, long DoR in responding patients and a very good outcome. Furthermore, patients in CR who are eligible for transplant have the best outcome, making this combination a good candidate as salvage therapy before transplant consolidation in these high-risk lymphomas with limited treatment options. Figure 1 Figure 1. Disclosures Bouabdallah: Kite/Gilead: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Herbaux: Takeda: Honoraria, Research Funding; Janssen: Honoraria; Roche: Honoraria; Abbvie: Honoraria, Research Funding. Brice: MSD: Research Funding; Amgen: Other: Travel/accommodations/expenses; Roche: Other: Travel/accommodations/expenses; Takeda: Research Funding. Sibon: Abbvie: Consultancy; Janssen: Consultancy; Roche: Consultancy; iQone: Consultancy; Takeda: Consultancy. Laribi: AstraZeneca: Other: Personal Fees; AbbVie: Other: Personal Fees, Research Funding; IQONE: Other: Personal Fees; Astellas Phama, Inc.: Other: Personal Fees; BeiGene: Other: Personal Fees; Takeda: Other: Personal Fees, Research Funding; Novartis: Other: Personal Fees, Research Funding; Le Mans Hospital: Research Funding; Jansen: Research Funding. Damaj: roche: Consultancy, Honoraria; takeda: Consultancy, Honoraria. OffLabel Disclosure: Brentuximab Vedotin and Bendamustine

Introduction Failure to respond to steroid therapy for intestinal acute graft-versus-host disease (aGvHD) is associated with limited further therapeutic options. Fecal microbiotherapy is defined as the perfusion of treated stool from one or several healthy donors via the upper or lower gastrointestinal (GI) route aiming at improving microbial diversity and functionality. Here we report clinical outcomes from a 76-patient cohort with steroid refractory (SR) GI-aGvHD treated with the pooled allogenic fecal microbiotherapeutic MaaT013. Twenty-four patients were treated in the prospective, single-arm, phase IIa, HERACLES study (NCT03359980) while 52 patients were treated in an expanded access program (EAP). Patients and methods For HERACLES, 24 patients with grade III-IV SR-GI-aGvHD were treated with MaaT013 in 26 European sites, as a 2 nd line therapy after SR diagnosis and evaluable for treatment response. In EAP, 52 patients with steroid-dependent or SR-GI-aGvHD (classical n=41, late onset n=3, overlap syndrome n=8) were treated. These patients had previously received and failed 1 to 6 lines (median 3; 40/52 received ruxolitinib) of GvHD systemic treatments. GI-GvHD response was evaluated weekly and 28 days after day (D) 0 (inclusion for HERACLES or 1st dose for EAP). For all patients, GI-overall response rate (ORR) at D28 was defined as the proportion of patients achieving complete response (CR), very good partial response (VGPR) or partial response (PR), compared to D0, without the use of additional systemic therapy. Other endpoints included the best overall response (BOR) achieved at any time, and overall survival (OS). Prepared under GMP, MaaT013 is characterized by a highly consistent richness of 455 ±3% OTUs and an Inverse Simpson index > 20. Treatment comprised 3 MaaT013 doses, each composed of 30 g of feces in 150 mL volume of inoculum (total 90 g of feces from 4 to 8 healthy donors) administered by enema (except for 2 EAP patients by nasogastric tube). All patients received at least 1 MaaT013 dose, 92% (HERACLES) and 87% (EAP) at least 2 doses, and 50% (HERACLES) and 71% (EAP) the full treatment course. In HERACLES, the reasons for not applying the 3 rd dose were death (n=5), physician decision to introduce salvage therapy (n=5), and ICU hospitalization (n=2)). Results In HERACLES, the GI-ORR was 38% including 5 CR, 2 VGPR and 2 PR. In EAP, positive GI-response was achieved in 31/52 patients (60% with 16 CR, 11 VGPR and 4 PR). Considering the GI-BOR, 13/24 (54%) and 35/52 (67%) achieved at least a PR in HERACLES and EAP respectively. In HERACLES, OS was 29% at month (M) 6 and 25% at M12. OS was significantly higher in responding (R) patients (achieving at least PR at D28) compared to non-responding (NR) (44% vs 20% at M6 and 44% vs 13% at M12, logrank p=0.047). In EAP, OS was 48% at M6 and 37% at M12, and significantly higher in R patients compared to NR (71% vs 17% at M6 and 62% vs 6% at M12, logrank p In HERACLES, treatment with MaaT013 was characterized by excellent tolerance: 252 Treatment-Emergent Adverse Events (TEAE) were reported for the 24 patients, the majority being infections (79%) and GI disorders (62%), as expected in GvHD patients. Of these 252 TEAE, only 2% (5 serious events in 2 patients) could not reasonably be excluded from being related to MaaT013 by the investigators. Shotgun sequencing in these 5 TEAE revealed that the causative infectious agents could not be detected in the administered MaaT013. In EAP, the safety profile of MaaT013 was considered satisfactory for all patients. 16S microbiome analyses were performed in the HERACLES population and showed that MaaT013 produced an early increase in α-diversity at genus level with a significant increase in Richness index at all evaluated timepoints (p Conclusion We herein report the treatment of 76 SR-GI-aGvHD patients using a full ecosystem, pooled-donor, high-richness biotherapeutic. The D28 GI-ORR was 38% and 60% in HERACLES and EAP respectively and this clinical benefit positively and significantly impacted OS (44% and 62% M12 in HERACLES and EAP R patients respectively). MaaT013 was shown to be safe and effective in these heavily immunocompromised patients, warranting further exploration of this approach. Figure 1 Figure 1. Disclosures Malard: JAZZ pharmaceuticals: Honoraria; Sanofi: Honoraria; Astellas: Honoraria; Biocodex: Honoraria; Therakos/Mallinckrodt: Honoraria; Janssen: Honoraria. Loschi: CELGENE/BMS: Honoraria; AbbVie: Ended employment in the past 24 months, Honoraria; Gilead: Ended employment in the past 24 months, Honoraria; Novartis: Ended employment in the past 24 months, Honoraria; Servier: Ended employment in the past 24 months, Honoraria; MSD: Honoraria. Cluzeau: Agios: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses, Speakers Bureau; Roche: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria, Speakers Bureau; Jazz Pharma: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Speakers Bureau; Amgen: Speakers Bureau; Pfizer: Other: travel, accommodations, expenses; Astellas: Speakers Bureau; Takeda: Other: travel, accommodations, expenses. Huynh: Jazz Pharmaceuticals: Honoraria. Holler: MaaT Pharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Vehreschild: SocraTec R&D GmbH: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Ferring: Consultancy, Speakers Bureau; Farmak International Holding GmbH: Consultancy, Honoraria, Speakers Bureau; Bio-Mérieux: Consultancy, Speakers Bureau; Basilea: Consultancy, Speakers Bureau; Arderypharm: Consultancy, Speakers Bureau; Alb Fils Kliniken GmbH: Consultancy, Speakers Bureau; Takeda Pharmaceutical: Research Funding; Seres Therapeutics: Research Funding; Roche: Consultancy, Research Funding, Speakers Bureau; Organobalance: Consultancy, Research Funding, Speakers Bureau; Merck/MSD: Consultancy, Research Funding, Speakers Bureau; MaaT Pharma: Consultancy, Research Funding; Immunic AG: Consultancy, Research Funding, Speakers Bureau; Glycom: Research Funding; Gilead Sciences: Consultancy, Research Funding, Speakers Bureau; Evonik: Research Funding; Da Volterra: Consultancy, Research Funding, Speakers Bureau; Biontech: Research Funding; Astellas Pharma: Consultancy, Research Funding, Speakers Bureau; 3M: Research Funding. Gasc: MaaT Pharma: Current Employment. Plantamura: MaaT Pharma: Current Employment. Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria.

Accumulating evidence implicates innate immune activation in the pathobiology of myelodysplastic syndromes. A key myeloid-related inflammatory protein, S100A9, serves as a Toll-like receptor ligand regulating tumor necrosis factor-α and interleukin-1β production. The role of myelodysplastic syndrome-related inflammatory proteins in endogenous erythropoietin regulation and response to erythroid-stimulating agents or lenalidomide has not been investigated. The HepG2 hepatoma cell line was used to investigate in vitro erythropoietin elaboration. Serum samples collected from 311 patients with myelodysplastic syndrome were investigated (125 prior to treatment with erythroid-stimulating agents and 186 prior to lenalidomide therapy). Serum concentrations of S100A9, S100A8, tumor necrosis factor-α, interleukin-1β and erythropoietin were analyzed by enzyme-linked immunosorbent assay. Using erythropoietin-producing HepG2 cells, we show that S100A9, tumor necrosis factor-α and interleukin-1β suppress transcription and cellular elaboration of erythropoietin. Pre-incubation with lenalidomide significantly diminished suppression of erythropoietin production by S100A9 or tumor necrosis factor-α. Moreover, in peripheral blood mononuclear cells from patients with myelodysplastic syndromes, lenalidomide significantly reduced steady-state S100A9 generation (P=0.01) and lipopolysaccharide-induced tumor necrosis factor-α elaboration (P=0.002). Enzyme-linked immunosorbent assays of serum from 316 patients with non-del(5q) myelodysplastic syndromes demonstrated a significant inverse correlation between tumor necrosis factor-α and erythropoietin concentrations (P=0.006), and between S100A9 and erythropoietin (P=0.01). Moreover, baseline serum tumor necrosis factor-α concentration was significantly higher in responders to erythroid-stimulating agents (P=0.03), whereas lenalidomide responders had significantly lower tumor necrosis factor-α and higher S100A9 serum concentrations (P=0.03). These findings suggest that S100A9 and its nuclear factor-κB transcriptional target, tumor necrosis factor-α, directly suppress erythropoietin elaboration in myelodysplastic syndromes. These cytokines may serve as rational biomarkers of response to lenalidomide and erythroid-stimulating agent treatments. Therapeutic strategies that either neutralize or suppress S100A9 may improve erythropoiesis in patients with myelodysplastic syndromes.

In this paper, we study the internal stabilizability and internal stabilization problems for multidimensional (nD) systems. Within the fractional representation approach, a multidimen-sional system can be studied by means of matrices with entries in the integral domain of structurally stable rational fractions, namely the ring of rational functions which have no poles in the closed unit polydisc U n = {z = (z 1 ,. .. , z n) $\in$ C n | |z 1 | 1,. .. , |z n | 1}. It is known that the internal stabilizability of a multidimensional system can be investigated by studying a certain polynomial ideal I = p 1 ,. .. , p r that can be explicitly described in terms of the transfer matrix of the plant. More precisely the system is stabilizable if and only if V (I) = {z $\in$ C n | p 1 (z) = $\times$ $\times$ $\times$ = p r (z) = 0} $\cap$ U n = $\emptyset$. In the present article, we consider the specific class of linear nD systems (which includes the class of 2D systems) for which the ideal I is zero-dimensional, i.e., the p i 's have only a finite number of common complex zeros. We propose effective symbolic-numeric algorithms for testing if V (I) $\cap$ U n = $\emptyset$, as well as for computing, if it exists, a stable polynomial p $\in$ I which allows the effective computation of a stabilizing controller. We illustrate our algorithms through an example and finally provide running times of prototype implementations for 2D and 3D systems.

In this paper, we revisit the notions of structural stability and asymptotic stability that are often considered as equivalent in the field of multidimensional systems. We illustrate that the equivalence between asymptotic and structural stability depends on where we define the boundary conditions. More precisely, we show that structural stability implies asymptotic stability when the boundary conditions are imposed on the positive axes. But a carefully designed counterexample shows that the opposite does not hold in this case. This illustrates once again the importance of the boundary conditions when dealing with multidimensional systems.

// Thomas Prebet 1 , Thomas Cluzeau 2,* , Sophie Park 3,4,* , Mikkael A. Sekeres 5 , Ulrich Germing 6 , Lionel Ades 4,7 , Uwe Platzbecker 8 , Katharina Gotze 9 , Norbert Vey 4,10 , Esther Oliva 11 , Mary M. Sugrue 12 , Cecile Bally 4 , Charikleia Kelaidi 4 , Najla Al Ali 2 , Pierre Fenaux 4,7 , Steven D. Gore 1,* and Rami Komrokji 2,* 1 Moffit Cancer Center, Tampa, Florida, USA 2 Cote d’Azur University, Nice Sophia Antipolis University, Centre Hospitalier Universitaire de Nice, Nice, France 3 U1065, Mediterranean Center of Molecular Medecine, Nice, France 4 Groupe Francophone des Myelodysplasies, Hopital Saint Louis, Paris, France 5 Leukemia Program, Cleveland Clinic, Cleveland, OH, USA 6 Department Hematology, Oncology and Clinical Immunology, Heinrich Heine University, Dusseldorf, Germany 7 Service Hematologie Senior, Hopital Saint Louis, Paris, France 8 Universitats Klinikum Carl Gustav Carus, Dresden, Germany 9 Klinikum Rechts der Isar, Technische Universitat Munchen, Munchen, Germany 10 Departement d’Hematologie, Institut Paoli-Calmettes, Marseille, France 11 Hematology Unit, Azienda Ospedaliera Bianchi Melacrino Morelli, Reggio Calabria, Italy 12 Celgene Corporation, Summit, NJ, USA * These authors have contributed equally to this work Correspondence to: Thomas Prebet , email: // Keywords : myelodysplasia, outcome, lenalidomide Received : April 18, 2017 Accepted : April 24, 2017 Published : June 14, 2017 Abstract While lenalidomide (LEN) is the standard of care for the lower-risk myelodysplastic syndromes (MDS) patients with deletion 5q, 35% will not respond to or do not tolerate the drug. Moreover, most of the patients will lose their response after a few years. Defining the outcome of patients with LEN failure and determining the impact of subsequent therapies is therefore important to develop alternative strategies. Based on an international collaboration, we were able to compile a total of 392 patient cases of lower-risk MDS patients with 5q deletion and to analyze their outcome after failure of lenalidomide. The median survival following LEN failure was 23 months. We observed a negative impact on survival of advanced age, higher bone marrow blast count at LEN initiation, progression after LEN failure, and unfavorable cytogenetics. Among the treatment strategies, we observed a relatively prolonged survival of patients treated subsequently with hypomethylating agents and only a limited impact on survival of allogeneic transplantation. In conclusion, our work stresses the relatively short survival of this group of patient and defines the expected baseline for the needed future investigations in this group of patients.

Anemia is a key survival prognostic factor in lower-risk myelodysplastic syndromes (MDS). Lenalidomide (LEN) can correct anemia in 25% of MDS patients without deletion 5q (del5q). As this therapy will inevitably fail, understanding the outcome of these patients will facilitate development of subsequent treatment strategies. To answer this question, an international retrospective study focused on LEN-treated lower-risk, non-del5q, MDS patients was performed. We analyzed the overall survival after LEN failure, its prognostic factors and the impact of post LEN treatment options. We included a total of 384 patients. The median overall survival after failure of LEN was 43 months. In multivariate analysis, adverse cytogenetics, excess of blasts at the initiation of LEN, and the type of failure (classified as stable disease, relapse, intolerance, or progression) were the main determinants of outcome. Subsequent therapy with hypomethylating agents was associated with a prolonged survival compared to BSC (median OS= 51m vs. 36m, p=0.01). In conclusion, the survival for non-del5q MDS patients after failure of LEN remains relatively prolonged, though with a wide range. Clinical trial participation remains the recommendation for these patients even if options such as hypomethylating agents may be considered.

*AK, PP shared first-, UP, HM, LA shared senior authors Introduction: Hypomethylating agents (HMAs) are the standard of care for patients with higher-risk myelodysplastic syndrome (HR-MDS) or acute myeloid leukemia (AML), not eligible for intensive chemotherapy or allogeneic stem cell transplantation. However, the majority of patients do not respond to these agents. Patients failing HMA therapy still have a dismal outcome with very limited treatment options available. Bemcentinib (BEM) is a selective small molecule inhibitor of AXL, a surface membrane protein kinase receptor mediating resistance to chemotherapeutic agents and decreased antitumor immune response. AXL is overexpressed on leukemic cells, especially in the stem cell compartment, and represents a potential novel target in patients with MDS and AML. Methods: The multicenter phase 2 BERGAMO trial evaluated the safety and efficacy of BEM in patients with HR-MDS or AML, refractory to or relapsing after at least six or four cycles of either azacitidine (AZA) or decitabine (DAC), respectively. Patients received an initial loading dose of 400mg BEM orally administered on d1-3 of cycle 1 and a maintenance dose of 200mg BEM on d4-28 of cycle 1 as well as on d1-28 in subsequent 28-day cycles. The primary endpoint was overall response rate (CR, CRi, PR or SD) assessed after 4 treatment cycles. All patients who achieved CR, CRi, PR or SD after 4 cycles of BEM were considered as responders and allowed to continue treatment for a total of up to 9 cycles. Non-responding patients stopped treatment after 4 cycles. Secondary endpoints of the trial included a translational project evaluating the role of biomarkers and response. Results: Between 2018 and 2020, 58 patients in 10 European centers were screened (MDS=27/AML=31) with a median age of 78 years (range, 62-86 years). 45 patients (MDS=21, AML=24) received at least one cycle of BEM and were eligible for safety and efficacy analysis after the first 4 months of treatment. Thirty six (80%) out of 45 patients were considered relapsed after a response to HMA, 8 (18%) had primary resistance and 1 patient (2%) had HMA intolerance. The median number of prior AZA or DAC cycles was 13. In addition, 18 patients (40%) (MDS=9/AML=9) were red blood cell transfusion-dependent. Treatment with BEM was generally well tolerated with only low rates of grade 3-4 hematologic toxicities (n=7). Forty-seven serious adverse events (SAE) occurred in 22 patients (MDS=9/AML=13), mostly due to infectious complications (n=12), hematological toxicity (n=4) or gastrointestinal disturbance (n=6). Until the first 4 months of BEM treatment, the median number of BEM treatment cycles received was 1.5 (range, 0.5-4). During study, 9 patients (20%) died due to infection (MDS=1/AML=3), deterioration of general condition (MDS=1/AML=2) and progressive disease (MDS=0/AML=2). BEM treatment is currently ongoing in four patients (MDS=3/AML=1). The primary endpoint was met in 9 of 45 patients (20.0%). Within the MDS cohort 33.3% achieved a response (n=7/21; CR=1, CRi= 3, SD=3), while 8.3% of patients (n=2/24) with AML achieved stable disease(SD). The 4 MDS patients achieving CR/CRi had a normal karyotype and a median baseline IPSS-R score of 4 (range 3-5). Among the MDS non-responders 4 patients had a complex karyotype, median IPSS-R score was 5 (range 3-5). Median baseline bone marrow blast count was 15% vs. 13% and median pretreatment hemoglobin-, platelet- and WBC levels were 9.2 g/dl (range 7.9-11.8 g/dl), 51 G/L(range 26-120 G/L) and 1.9x109/l (range 1.18-8.9 x109/l) vs. 9.6 g/dl (range 7.9-11.3 g/dl), 35 G/L (range 0-167 G/L) and 1.45x109/l (range 0.82-6.97 x109/l) comparing MDS responders (CR/CRi) vs MDS non-responders, respectively. Preliminary data evaluating soluble AXL (sAXL) in blood plasma at baseline showed that 66.6 % (n=2/3) of MDS patients achieving CR/CRi displayed sAXL levels below a defined threshold, while this was only seen in 20% (n=2/10) of MDS non-responders. Conclusion: These results of the prospective phase II BERGAMO trial confirm, that single agent BEM is generally safe and well tolerated in this patient population with an unmet medical need. Importantly, BEM showed clinical efficacy in a subgroup of MDS patients. These encouraging clinical results are being further explored by an in depth translational research program aiming to identify additional molecular and biological prognostic factors associated with response. Disclosures Kubasch: Celgene: Research Funding; Shire: Research Funding; Novartis: Research Funding. Cluzeau:Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Menarini: Consultancy; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees. Götze:Celgene: Research Funding. Teipel:janssen: Honoraria. Jentzsch:Novartis: Honoraria; JAZZ Pharmaceuticals: Honoraria. Giagounidis:Novartis: Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees. McPherson:BerGenBio ASA: Current Employment. van de Loosdrecht:novartis: Honoraria; celgene: Honoraria. Fenaux:Jazz: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Platzbecker:BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Geron: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Honoraria, Research Funding. Medyouf:Bergenbio: Consultancy, Research Funding. Ades:Celgene/BMS: Research Funding; novartis: Research Funding; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. OffLabel Disclosure: Bemcentinib is currently undergoing Phase II clinical trials for non-small-cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), acute myeloid leukemia /myelodysplastic syndrome (AML/MDS), melanoma and metastatic pancreatic cancer. In 2019, FDA have granted fast track designation to bemcentinib for the treatment of elderly patients with acute myeloid leukemia (AML) whose disease has relapsed.

Introduction: A novel genomically defined subset of non-APL AML patients (pts) with an actionable target characterized by overexpression of RARA has been identified (McKeown, Cancer Discovery 2017). RARA-positive (RARA+) pts can be detected by a novel blood-based biomarker test that predicts sensitivity to SY-1425, an oral potent and selective RARα agonist (Vigil, ESH 2017). Approximately 30% of newly diagnosed (ND) unfit AML pts are RARA+ (de Botton, ESH 2019), and recent data demonstrates RARA+ AML is correlated with venetoclax resistance, which may suggest a new poor prognostic risk (Fiore, ASH 2020). Preclinical synergy of SY-1425 with azacitidine (aza) supported clinical development of the combination (McKeown, Haematologica 2018), which is currently being evaluated in RARA+ ND unfit AML (NCT02807558). Early data of SY-1425 + aza demonstrated high response rates and a rapid onset of responses in the RARA+ ND unfit AML cohort (Cook, ASH 2018; de Botton, ESH 2019). Updated data for the fully enrolled cohort are presented here. Methods: Both RARA+ and RARA-negative (RARA-) ND unfit AML pts were enrolled, and all pts received aza at 75 mg/m2 IV/SC daily on days 1-7 followed by SY-1425 at 6 mg/m2/day PO in divided doses twice daily on days 8-28 of each 28-day cycle. The primary objective was characterization of activity by the overall response rate (ORR) per IWG. Analyses of the composite complete response rate, time to response, comparison of responses across RARA+ and RARA- cohorts, transfusion independence, and safety were also included. Results: A total of 51 pts were treated, 22 RARA+ and 29 RARA-, with data available through 27 May 2020 reported. Baseline characteristics included 32 (63%) male; median age 76 (60-91); 17 (33%) poor and 33 (65%) intermediate cytogenetic risk; 29 (57%) de novo and 22 (43%) secondary AML; and 33 (65%) with marrow blasts > 30%. Time on treatment was up to 18.2 months, with discontinuation of treatment primarily due to AE (33%), the majority being not treatment-related, and disease progression (22%). Among 18 response-evaluable RARA+ pts, analysis for best response showed an ORR of 67% (12/18), with complete responses in 61% (11/18; 9 CR, 2 CRi, 0 CRh) and MLFS in 6% (1 pt). CRs showed a high rate (89%, 8/9) of complete molecular or cytogenetic remissions (3 molecular, 5 cytogenetic). Median time to initial complete response was rapid at 1.2 months. Transfusion independence (TI) was achieved in 13 (72%) of 18 TI evaluable pts, including conversion to TI in all 6 (100%) who were transfusion dependent at baseline. Of the 28 response-evaluable RARA- pts, the ORR and complete response rate were lower and time to initial response was longer relative to RARA+ pts. ORR was 39%, with complete responses in 29% (8/28; 6 CR, 2 CRi, 0 CRh). Median time to initial complete response was 2.9 months. The AE profile of the combination is consistent with that previously reported for single-agent SY-1425 or aza in AML. Most common AEs (all grades/causality) included decreased appetite (41%; 21/51 pts), hypertriglyceridemia (41%), nausea (39%), constipation (39%), fatigue (35%), peripheral edema (35%), pyrexia (33%) and febrile neutropenia (33%). Hematologic AEs ≥ grade 3 included febrile neutropenia (33%), thrombocytopenia (24%), anemia (20%) and neutropenia (16%). The majority of non-hematologic AEs were low grade. The most frequent SAEs included febrile neutropenia (27%), pyrexia (12%), pneumonia (12%), and sepsis (10%). Conclusion: SY-1425 + aza was generally well-tolerated without evidence of increased toxicity of the combination relative to either as a single agent. Importantly, rates of myelosuppression were comparable to single-agent aza in this population. There was evidence of clinical activity with a high CR rate and rapid time to initial response, with evidence of clinical benefit associated with TI in a majority of RARA+ ND unfit AML pts. Use of the novel blood-based biomarker test to predict sensitivity to SY-1425 in AML pts was supported by clinical outcomes, with higher response rates and a more rapid onset in RARA+ vs RARA- pts, whose responses were consistent with single-agent aza. SY-1425 + aza shows potential as a novel targeted regimen for the treatment of RARA+ ND unfit AML and warrants further development in this genomically defined subset of AML pts, as well as other related RARA+ pt populations. Updated data, including mature duration of response and survival, will be presented. Disclosures Cluzeau: Celgene: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Menarini: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Vigil:BerGenBio ASA: Research Funding. Rousselot:Pfizer: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Incyte: Consultancy, Research Funding. Rizzieri:Acrobiotech: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Mustang: Membership on an entity's Board of Directors or advisory committees; Celltrion: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; abbvie: Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Liesveld:Abbvie: Honoraria; Onconova: Other: data safety monitoring board. Fenaux:Abbvie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Jazz: Honoraria, Research Funding. Braun:Servier: Research Funding; Daiichi Sankyo: Honoraria. Savona:Ryvu: Consultancy; Karyopharm: Consultancy, Current equity holder in publicly-traded company; Gilead: Consultancy; AbbVie: Consultancy; Boehringer Ingelheim: Patents & Royalties; BMS: Consultancy; TG Therapeutics: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Astex: Consultancy, Research Funding. Kelly:Syros Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Volkert:Syros Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Zhou:Syros Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company; Incyte: Current equity holder in publicly-traded company, Ended employment in the past 24 months. Kang-Fortner:Syros Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Roth:Syros Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Stein:Amgen: Consultancy; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Research Funding; Seattle Genetics: Consultancy; Bayer: Research Funding; Syros: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Biotheryx: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.