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Myelodysplastic syndromes (MDS) are hematological malignancies classically defined by the presence of cytopenia(s) and dysmorphic myeloid cells. It is now known that MDS can be preceded by a pre-malignant condition called clonal cytopenia of unknown significance (CCUS), which associates a clonality marker with cytopenia in the absence of criteria of dysplasia. However, to date, it is not clear whether chromosomal abnormalities should be considered in the definition of CCUS or if they carry a prognostic impact in CCUS patients. In this study, we analyzed the clinico-biological features and outcomes of 34 patients who presented with one or more cytopenias, an absence of significant dysplasia, and a presence of a chromosomal abnormality (CA). We named this entity chromosomal abnormality with cytopenia of undetermined significance (CACtUS). We show that these patients are slightly older than MDS patients and that they more frequently presented with normocytic anemia. Most CACtUS patients exhibited only one unbalanced CA. The number and type of mutations were comparable between CACtUS patients and MDS patients. Regardless of the cytogenetic abnormality, the clinicobiological characteristics, overall survival, and risk of progression to high-risk (HR) MDS were similar between CACtUS patients and low-risk MDS patients. Thus, we suggest that CACtUS patients can be considered as HR-CCUS and should receive the follow-up regimen recommended for MDS patients.

MDS-RS patients are characterized by chronic anemia and a low risk of Acute Myeloid Leukemia (AML) progression and they generally become Red Blood Cell (RBC) transfusion dependent (TD).We performed a retrospective "real-life" observational study of 6 months in 100 MDS-RS TD patients, recruited in 12 French centers, to describe transfusion characteristics, and evaluate the frequency and causes of hospitalizations, health costs, and morbidity, associated with transfusion dependency, in a French population of RBC transfusion-dependent MDS-RS patients.79% of the patients had high transfusion burden (HTB) and 21% low transfusion burden (LTB). HTB patients had a longer disease duration (6 vs. 3.7 years, p = 0.0078), more frequent iron chelation (82% vs. 50%, p = 0.0052) and higher serum ferritin (p = 0.03). During the 6-month study period, 22% of the patients required inpatient hospitalization, 36% of them for symptomatic anemia requiring emergency RBC transfusion. The 6-month median transfusion costs, including the cost of the day care facility, transportation to and from the hospital, iron chelation, and lab tests, was 16,188€/patient.MDS-RS represents the archetypal type of chronically transfused lower-risk MDS. Most of those patients have a high transfusion burden and thus frequently need visits to the hospital's day care facility, and frequent hospitalizations, with an overall high median treatment cost. Those costs should be compared with costs of new treatments potentially able to avoid RBC transfusion dependence and to reduce the complications of chronic anemia in MDS-RS patients.

We analyzed 526 consecutive acute myeloid leukemia patients refractory to or relapsing after chemotherapy. 270 patients received intensive salvage chemotherapy (IC), 97 azacitidine (AZA) and 159 best supportive care (BSC). Complete response was obtained in 37/19/0% (

The EUROPE phase 2 trial investigated the predictive value of biomarkers on the clinical efficacy of single agent romiplostim (ROM) treatment in patients with lower-risk myelodysplastic neoplasms (LR-MDS) and thrombocytopenia within the ‘European Myelodysplastic Neoplasms Cooperative Group‘ (EMSCO) network. A total of 77 patients with LR-MDS and a median platelet count of 25/nl were included, all patients received ROM at a starting dose of 750 μg by SC injection weekly. Thirty-two patients (42%) achieved a hematologic improvement of platelets (HI-P) with a median duration of 340 days. Neutrophil (HI-N) and erythroid (HI-E) responses were observed in three (4%) and seven (9%) patients, respectively. We could not confirm previous reports that HI-P correlated with baseline endogenous thrombopoietin levels and platelet transfusion history, but SRSF2 mutation status and hemoglobin levels at baseline were significantly linked to HI-P. Sequential analysis of variant allelic frequency of mutations like SRSF2 did not reveal an impact of ROM on clonal evolution in both responders and non-responders. In summary, our study confirms the safety and efficacy of ROM in LR-MDS patients and may allow to better define subgroups of patients with a high likelihood of response.

Systemic inflammatory and autoimmune diseases (SIADs) occur in 10-20% of patients with myelodysplastic syndrome (MDS). Recently identified VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome, associated with somatic mutations in UBA1 (Ubiquitin-like modifier-activating enzyme 1), encompasses a range of severe inflammatory conditions along with hematological abnormalities, including MDS. The pathophysiological mechanisms underlying the association between MDS and SIADs remain largely unknown, especially the roles of different myeloid immune cell subsets. The aim of this study was to quantitatively evaluate peripheral blood myeloid immune cells (dendritic cells (DC) and monocytes) by flow cytometry in MDS patients with associated SIAD (n = 14, most often including relapsing polychondritis or neutrophilic dermatoses) and to compare their distribution in MDS patients without SIAD (n = 23) and healthy controls (n = 7). Most MDS and MDS/SIAD patients had low-risk MDS. Eight of 14 (57%) MDS/SIAD patients carried UBA1 somatic mutations, defining VEXAS syndrome.Compared with MDS patients, most DC and monocyte subsets were significantly decreased in MDS/SIAD patients, especially in MDS patients with VEXAS syndrome. Our study provides the first overview of the peripheral blood immune myeloid cell distribution in MDS patients with associated SIADs and raises several hypotheses: possible redistribution to inflammation sites, increased apoptosis, or impaired development in the bone marrow.

Aims Azacitidine (AZA), a pyrimidine analogue, is validated for high-risk myelodysplastic syndrome or low-blast acute myeloid leukaemia in unfit patients for more intensive treatment. This study assessed the putative link between cardiac failure (CF) and AZA exposure. Methods Cases of CF in patients treated with AZA were retrospectively collected and described from several centres of the Groupe Francophone des Myelodysplasies. A description analysis and a disproportionality analysis using Vigibase, the WHO Global Individual Case Safety Reports (ICSRs) database, were conducted on ICSRs by the Standardized MedDRA Queries (SMQ broad) cardiac failure and by preferred terms cardiac failure and cardiac failure acute. The reported odds ratio (ROR) and its 95% 2-sided confidence interval was computed by comparing the proportion of CF reports with the suspected drug (AZA) and the proportion of reports of the same adverse drug reaction with all other suspected drugs in the database during the same period. Results In the 4 case reports, all patients presented a cardiovascular history. In 1 patient, CF recurred after AZA re-challenge. The pharmacovigilance analysis in Vigibase retrieved 307 ICSRs of CF (SMQ) with AZA. Significant disproportionality signals associated with AZA were identified by using the SMQ cardiac failure (ROR 1.3) and the preferred terms cardiac failure (ROR 5.1) and cardiac failure acute (ROR 23.2). Conclusion This study points to the potential role of AZA in the occurrence of CF. Cardiac evaluation before AZA initiation and regular monitoring of cardiac function during AZA treatment should be performed in patients with a history of cardiovascular disease.

International audience; In order to improve the outcome observed with azacitidine (AZA) in higher-risk Myelodysplastic syndrome (MDS), its combination with other drugs in MDS must be evaluated. So far, no combination has not been shown to be more effective than AZA alone. AZA-PLUS was a phase II trial that, in a "pick a winner" approach, randomly assigned patients with higher-risk MDS, CMML and low blast count AML to: AZA; AZA plus lenalidomide; AZA plus Valproic Acid or AZA plus Idarubicin. 322 patients were included. After six\,cycles, 69 (21.4%) CR\,+\,PR were observed with no benefit from any combination. Median EFS and OS were 17.2 and 19.7\,months in the whole cohort, respectively, with no difference across randomised arms. Infection and rates of hospitalisation during the first six\,cycles were higher in the AZA-LEN And AZA-IDA arm, related to increased myelosuppression. Factors associated with better response were IPSS, favourable or intermediate karyotype, haemoglobin, lower circulating blast count, fibrinogen level and lower LDH, while poorer survival was seen in therapy-related MDS and, in the case of TP53, PTPN11 or CSF3R mutation. The combinations used did not improve the outcome obtained with AZA alone. However, our "pick a winner" randomised strategy may remain useful with potentially more active drugs to be tested in combination with AZA.

International audience; Objectives: Myelodysplastic syndromes (MDS) and chronic myelomonocytic leukaemia (CMML) are associated with systemic inflammatory and autoimmune diseases (SIADs) in 10-30% of cases. The aims of this study were (i) to evaluate the prevalence of venous thromboembolism VTE in patients presenting with both MDS/CMML and SIADs, (ii) to describe risk factors associated with thrombosis, and (iii) to analyse the impact of VTE on overall survival and transformation to acute myeloid leukaemia in comparison to patients with MDS/CMML-associated SIADs without VTE.Methods: This retrospective multicentre case-control study was conducted among patients with MDS/CMML and dysimmune disorders and featured in the French retrospective database of the French Network of Dysimmune Disorders Associated with Hemopathies (MINHEMON), diagnosed with MDS/CMML and dysimmune disorders.Results: During a median follow-up of 16 months (5-48) VTE occurred in 35 patients (21.6 %) whereas 127 patients did not. Among those with VTE, 8 patients (22.9%) experienced two or more VTE. Common prothrombotic risk factors were not significantly different in patients with or without VTE. CMML was more frequent in patients without VTE (37 % vs. 14.3%, p=0.01), whereas myelodysplasic/myeloproliferative neoplasm (MDS/MPN) was higher in VTE patients (20 % vs. 5.5 %, p=0.01). In a multivariate analysis, only MDS/CMML progression at the time of VTE (odds ratio 28.82, 95 % CI (5.52-530.70) was significantly associated with VTE. When treated with an anticoagulation therapy, bleeding occurred in 19.4% of cases (6/31). Overall survival was not significantly different between patients with and without VTE (p=0.68). Leukaemia-free survival between groups was not significantly different (p=0.83).Conclusions: VTE is a common complication in MDS/CMML-associated SIADSs with an increased risk of bleeding when treated by anticoagulants. In the MDS/CMML subgroup, SIADS flares and MDS/CMML progression seem to be prothrombotic risk factors.

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.

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: Systemic autoimmune and inflammatory diseases (SAIDs) occur in 10-15% of MDS or CMML patients. They are often severe, difficult to treat and steroid resistant/dependent disorders. In a retrospective report of 22 patients with steroid-dependent MDS/CMML associated SAID, we observed promising results with azacytidine (AZA) on the SAID component (Fraison et al, Leuk Res, 2016). In this prospective French nationwide trial, we aimed at confirming this effect prospectively. Patients and Methods: This open-label, single-arm multicenter, phase II study included MDS/CMML patients with IPSS/CPSS int 2 or high, or lower IPSS/CPSS but with significant cytopenias, especially ESA resistant anemia (or, for CMML, proliferative features) and SAID with steroid dependence and/or resistance. The primary endpoint was response rate (RR, including CR and PR) of SAID after 6 cycles of AZA. Secondary endpoints included RRof SAID after 3 cycles of AZA, response of MDS, time to MDS progression (including to AML), overall survival (OS) and safety. AZA was used at 75 mg/m²/d x 7 days, every 4 weeks for a minimum of 6 cycles (unless overt disease progression occurred before). At the onset of AZA, prednisone (PRED) was administered at 1 mg/kg during 1 month and then decreased progressively over 6 months. Results: 30 patients were included between July 2017 and June 2020 , 29 of whom received AZA and were considered evaluable: median age 72 [range 68-78], 69% males; WHO: MDS ML (n=11; 41%), CMML (n=11, 41%), MDS-RS (n=2, 7%), EB-1 (n=1) and EB-2 (n=1), unclassified (n=3); IPSS-R : good (n=15, 54%), very good (n=3; 11%, each), intermediate (n=7; 25%) and very poor profile (n=3; 11%) (all CMML had WBC 19 patients (65.5%, IC95% [45.7.82.1]) obtained a SAID response after 6 cycles (including 8 CR and 11 PR), while 17 (58.6% (IC95% [38.9; 76.5]) patients achieved an IWG 2006 hematological response (7 CR, 9 SD with HI and 1 marrow CR). All the 13 patients who received 12 cycles of AZA achieved SAID CR or PR at 12 months, and 10 of them had a hematological response (6 CR, 1PR, 2 HI, 1 marrow CR). The SAID response rate at 12 month was at 72.4% (IC95% : [51.3;85.6]). SAIDs complete/partial response occurred in 3/9 (33%) UBAI-positive versus 8/19 (42%) non-mutated cases. No significant prognostic factor of SAID response after 6 cycles, including sex, age, WHO classification, IPSS-R, UBA1 and TET-2 mutation status was found. With a median follow-up of 18.5 months [11.8; 24.3], 9 (31%) patients had died, with a 1-year OS of 82.3% (IC95% [69.4; 97.7]. At least one SAE occurred in 23 patients, with a median of 2 events/patient [1.5; 5.5]. Death was due to infection (n=5, two of them in patients with good IPSS-R, but severe steroid dependent SAID), MDS progression (n=2), or unrelated causes (n=2). Conclusion We confirmed prospectively an effect of AZA on the autoimmune/inflammatory component in two thirds of MDS/CMML patients with steroid dependent / refractory concomitant systemic autoimmune/inflammatory disease. No significant difference in AZA response was noted between UBA1 mutated and unmutated MDS patients. The adverse events and mortality rates, often from infectious origin, appear to be those expected in such an MDS population, potentially worsened by the associated SAID and background of immunosuppressive treatment (especially steroids) Disclosures Terriou: Alexion, AstraZeneca Rare Disease: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vey: Amgen: Honoraria; BMS: Honoraria; BIOKINESIS: Consultancy, Research Funding; NOVARTIS: Consultancy, Honoraria, Research Funding; SERVIER: Consultancy; JAZZ PHARMACEUTICALS: Honoraria; JANSSEN: Consultancy. Ades: ABBVIE: Honoraria; TAKEDA: Honoraria; CELGENE/BMS: Honoraria; NOVARTIS: Honoraria; JAZZ: Honoraria, Research Funding; CELGENE: Research Funding. Fenaux: Abbvie: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Syros Pharmaceuticals: Honoraria.

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.

*UP, LA contributed equally Introduction A significant proportion of lower risk (LR)-MDS patients present with thrombocytopenia, being associated with shortened survival and higher risk of progression to acute myeloid leukemia (AML). Treatment options for patients with LR-MDS and severe thrombocytopenia remain limited apart from transfusion support. Romiplostim (ROM), a thrombopoietin receptor agonist (TPO-RA) has shown safety and efficacy dependent on endogenous TPO levels as well as platelet transfusion history in a poorly defined subset of LR-MDS patients (Giagounidis et al. Cancer 2014, Sekeres et al. BJH 2014). Methods The multicenter phase 2 EUROPE trial investigated potential biomarkers of response (e.g. TPO levels, molecular markers) to single agent ROM in LR-MDS patients with severe thrombocytopenia. Patients were eligible if platelet counts were ≤30 G/L or ≤50 G/L in case of bleeding history. The primary efficacy endpoint was the rate of hematologic improvement of platelets (HI-P, according to IWG 2006 criteria) lasting for at least 8 weeks after 16 weeks of ROM (750µg SC qw) treatment. At the time of screening, patients were assigned into 3 different cohorts based on their previous platelet transfusion events (PTE) as well as centrally assessed TPO serum levels (A: TPO Results From 2015 to 2019, a total of 79 patients were included at 29 trial sites in Germany, France and the Czech Republic. Patients' median age was 74 years (range 42-93), median baseline platelet count was 25.5 G/L (range 3-50 G/L) and they were stratified into cohort A (n=51) or B+C (n=28), respectively. The primary endpoint was met with 34 out of 79 (43%) patients responding (HI-P), with response being markedly higher in cohort A (49%, n=25) vs. cohort B and C (32%, n=9) (p=0.145). Ten (13%) and eight (10%) patients had additional neutrophil (HI-N) and erythroid (HI-E) responses, respectively. During treatment, six patients had transient increases in peripheral blasts to more than 10% and one patient progressed to AML after one month of ROM. Although a higher number of responders was observed in group A, neither TPO level at screening (p=0.21), nor number of pretreatment PTE (p=0.12) were significantly associated with response to ROM treatment. Thus, our findings do not confirm that baseline TPO levels and number of pretreatment PTE alone allow reliable prediction of response to ROM. With the aim to identify new molecular patterns correlating with response, we performed a targeted NGS analysis for somatic variants in 54 candidate genes in 75 patients at baseline and in 44 patients after 16 weeks of ROM. Responders (R) more frequently exhibited mutations like SRSF2 (R=39%, NR=17%), RUNX1 (R=24%, NR=14%) and TET2 (R=30%, NR=29%), whereas non-responders (NR) exhibited mutations like DNMT3A (R=12%, NR=21%), U2AF1(R=9%, NR=14%) or ASXL1 (R=6%, NR 17%) more frequent. The percentages of patients with a response to ROM were similar regardless of total number of baseline somatic mutations. Comparing responders vs. non-responders, we found no significant changes of variant allelic burden of variants detected pre- and post-ROM (Fig. 1). We identified the presence of a SRSF2 mutation as a significant predictor of response to ROM treatment (p=0.031, logistic regression). Mutated SRSF2 was significantly more frequent in responders (39%) compared to non-responders (17%) (p=0.036, Fisher's exact test) (Fig. 2A,B). We used logistic regression with stepwise backward selection to assess the influence of the presence of ASXL1, DNMT3A, RUNX1, TET2 and SRSF2 mutations on response. Our final regression model excludes the non-significant ASXL1, DNMT3A, RUNX1 and TET2 mutations and includes the significant SRSF2 mutation, resulting in an overall accuracy of 64.0% for a correct ROM response prediction in this patient cohort. Conclusion: This prospective study did not confirm a significant association between response to ROM, pretreatment PTE burden and endogenous TPO levels. Instead, patients with a mutated SRSF2 displayed a significantly higher response to ROM treatment. This may allow personalized treatment approaches in patients with LR-MDS and severe thrombocytopenia. In this study, extended treatment with ROM did not lead to a significant increase in AML cases. Disclosures Kubasch: Shire: Research Funding; Celgene: Research Funding; Novartis: Research Funding. Giagounidis:AMGEN: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Götze:Celgene: Research Funding. Cony-Makhoul:Novartis: Consultancy; Pfizer: Consultancy; Incyte Biosciences: Speakers Bureau; BMS: Consultancy; BMS: Speakers Bureau. Laribi:takeda: Research Funding; novartis: Honoraria, Research Funding; amgen: Research Funding; abbvie: Honoraria, Research Funding. Park:Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Other: Travel expenses. Metzeler:Astellas: Honoraria; Otsuka Pharma: Consultancy; Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy; Novartis: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria. Thiede:AgenDix GmbH: Other: Co-owner and CEO. Schlenk:PharmaMar: Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses, Research Funding, Speakers Bureau; Novartis: Speakers Bureau; Roche: Research Funding; AstraZeneca: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Fenaux:Novartis: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Platzbecker:Novartis: Consultancy, Honoraria, Research Funding; Amgen: Honoraria, Research Funding; BMS: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Geron: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding. Ades:Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; novartis: Research Funding; Celgene/BMS: Research Funding; jazz: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Romiplostim is a thrombopoietin receptor agonist indicated for the treatment of thrombocytopenia in patients with chronic immune thrombocytopenia (ITP). Limitations of Use: Romiplostim is not indicated for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS) or any cause of thrombocytopenia other than chronic ITP.

Background: MDS-RS are associated with a low risk of Acute Myeloid Leukemia (AML) progression and prolonged survival in most cases, but recurring anemia whose treatments, including Erythropoiesis Stimulating Agent (ESA), Lenalidomide, hypomethylating agents (HMAs), Luspatercept, and experimental drugs generally have transient effect and/or are not widely available. MDS-RS patients thus eventually have regular Red Blood Cells (RBC) transfusion dependency (TD) associated with mean low hemoglobin levels, and chronic anemia responsible for reduced quality of life, cardiovascular complications, and iron overload with organ dysfunction. We performed a retrospective observational study to describe transfusion characteristics and costs, along with clinical events, in a French population of RBC TD MDS-RS patients. Methods: Adult RBC-TD patients with MDS-RS from 12 hematology departments of the GFM were included. The number of RBC concentrates transfused was assessed over the last 6 months (during which no other treatment than transfusions was received), and patients categorized in low transfusion burden (LTB: 3 to 7 RBC/16 weeks) and high transfusion burden (HTB: ≥8 RBC concentrates /16 weeks). Data about iron chelation, full time hospitalization (differing from day care facility stays for programmed transfusions), causes of hospitalization, treatment of anemia before inclusion and transfusion costs was collected. Results: 100 patients MDS-RS were included, with a median time from diagnosis of 5 years (1 to 21 years). Median age was 78 years (57 to 99). Patients had received a median of 2 lines of treatment (including an ESA in 97% of them). 21% had LTB and 79% HTB. HTB patients had a longer disease duration, more frequent iron chelation (82% versus 50% in LTB patients, p=0.0052) and higher serum ferritin at inclusion (median 1958 µg/l versus 1176 µg/l, p=0.03). During the 6-month study period, 22% of the patients required full time hospitalization (in addition to day care facility for transfusions), including 25% of patients with HTB and 15% with LTB, and 43% during overall disease follow-up. Causes of full time hospitalization (figure) were symptomatic anemia (41%), general condition degradation (5%) or cardiac disease (8%), to both of which anemia potentially contributed, infection (23%), bleeding (8%), pulmonary (2%), 13% for other reasons. 15 HTB patients versus 1 LTB patient were hospitalized for symptomatic anemia. The 6-months average transfusion costs, including cost of the day care facility for RBC transfusion, transportation to and from the hospital, lab tests and iron chelation were $21459/patient, excluding costs of full-time hospitalization for complications. The average cost in HTB and LTB patients was $22829 and $7586/patient, respectively. Conclusion: Most MDS-RS patients currently become RBC-TD, often during several years, and most have high transfusion burden. The average cost of RBC transfusions and iron chelation was $21459/ 6 months. During this short observation time, 22% of the patients required full time hospitalization, due to complications of anemia in at least 50% of the cases, which also increased costs (comparison with rates of hospitalization in an age and sex matched general population will be presented). Poor quality of life associated with chronic anemia should also be taken into account in those RBC-TD patients. Widely available treatments, capable of avoiding RBC transfusion dependence and improving mean hemoglobin levels, are required in those MDS-RS patients. Disclosures Cony-Makhoul: BMS: Speakers Bureau; Incyte Biosciences: Speakers Bureau; BMS: Consultancy; Novartis: Consultancy; Pfizer: Consultancy. Thepot:astellas: Honoraria; novartis: Honoraria; sanofi: Honoraria; celgene: Honoraria. Cluzeau:Celgene: 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; Abbvie: 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; Roche: Membership on an entity's Board of Directors or advisory committees. Stamatoulas Bastard:Takeda: Consultancy; Pfizer: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Celgene: Honoraria. Fenaux:Jazz: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Park:Pfizer: Other: Travel expenses; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees.

We performed a retrospective study to identify pretransplantation risk factors for steroid-refractory (SR) acute graft-versus host disease (aGVHD) after allogeneic stem cell transplantation from matched donors in 630 adult patients who underwent transplantation at our center between 2000 and 2012. The cumulative incidence (CI) of SR aGVHD was 11.3% ± 2.3%. The identified independent risk factors were matched unrelated donor (hazard ratio [HR], 2.52; P = .001), female donor for male recipient (HR, 1.84; P = .023) and absence of antithymocyte globulin (HR, 2.02; P = .005). Three risk groups were defined according to the presence of these risk factors. In the whole cohort, the CI of SR aGVHD was 3.5% ± 1.7% in the low-risk group (0 risk factor, n = 115), 9.3% ± 1.6% in the intermediate-risk group (1 risk factor, n = 323), and 19.3% ± 2.9% in the high-risk group (2 or 3 risk factors, n = 192). Our study suggests that pretransplantation characteristics might help identify patients at high risk for SR aGVHD. A risk adapted first-line treatment of aGVHD could be evaluated in those patients.

Introduction: Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis and peripheral cytopenia. In about half of patients with lower-risk (LR) MDS, thrombocytopenia is present at the time of diagnosis and associated with shortened survival and an increased risk of progression to acute myeloid leukemia (AML). The thrombopoietin receptor agonist (TPO-RA) romiplostim has shown safety and marked efficacy in a still poorly-defined subset of LR-MDS patients with thrombocytopenia. Methods: The EUROPE multicenter phase 2 trial within the EMSCO network investigated the impact of biomarkers like endogenous thrombopoietin (TPO) level and platelet transfusion events (PTE) on the efficacy of romiplostim (750µg SC qw) treatment in patients with LR-MDS (IPSS low/int-1). Patients were eligible if baseline bone marrow blast count was Results: From 2015 to 2018, a total of 68 patients were included in 20 trial sites in Germany, France and Czech Republic. Patients displayed a median age of 74 years and a median platelet count of 25 G/L (range 1-50 G/L) and were stratified into cohort A (n=47), B (n=17) or C (n=4), respectively. All patients received at least one cycle of romiplostim with a median weekly dose of 750μg and a median of 15 cycles of romiplostim until week 16. Reasons for premature study discontinuation before week 16 were investigator/patient decision (n=8), adverse events (n=5), disease progression (n=4) or death (n=1). There were 9 reported severe treatment-related adverse events in seven patients including pulmonary embolism (n=1), subacute stroke (n=1), mucocutaneous hemorrhage (n=1), asthenia (n=1), suspicion of anti-romiplostim antibodies (n=1), progression to AML (n=1) and varicella zoster infection (n=1). Two patients had transient increases in peripheral blasts to more than 10% and 1 patient progressed to AML after 1 month of treatment. HI-P was observed in 26 of 68 (38%) patients, while response was ongoing in 24 of them beyond week 16. Moreover, rate of HI-P lasting for at least 8 weeks was notably higher in cohort A (45%, n=21/47) compared to patients in cohort B and C (24%, n=5/21) (p=0.11). Median peak increase of PLT count in responding patients was 199 G/L in cohort A and 83 G/L in cohort B (p=0.25) and was observed in median after 7 weeks (range 3-16). In addition, responses occurred also in 2 patients in the neutrophil (HI-N) and in 7 patients in the erythroid (HI-E) lineage according to IWG 2006 criteria (Table 1). Explorative analysis showed a correlation between pretreatment platelet transfusion requirement and endogenous TPO-levels (spearman-test, p=0.034). Median pretreatment endogenous TPO-level was lower in responders compared to non-responders (82 vs. 103 pg/ml, p=0.15). Higher response rates occurred in patients with lower TPO-levels ( Conclusion: This prospective study confirms that romiplostim treatment is highly effective in a subgroup of LR-MDS patients, but neither baseline platelet transfusion requirements nor baseline TPO levels were significantly associated with clinical response to romiplostim. Further translational analyses are ongoing to elucidate potential biomarkers of response. Disclosures Platzbecker: Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Götze:AbbVie: Membership on an entity's Board of Directors or advisory committees. Cony-Makhoul:Pfizer: Consultancy; Novartis: Consultancy; Incyte Biosciences: Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau. Park:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Thiede:Daiichi Sankyo: Honoraria; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; AgenDix GmbH: Employment, Equity Ownership; Diaceutics: Membership on an entity's Board of Directors or advisory committees. Ades:Helsinn Healthcare: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Silence Therapeutics: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. OffLabel Disclosure: Romiplostim is formally not licensed for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS).

Background information. The identification of a source of stem cells able to regenerate skeletal muscle was the goal of numerous studies with the aim to develop new therapeutic approaches for genetic muscle diseases or muscle injuries. A series of studies have demonstrated that stem cells derived from various tissues may have a role in the regeneration of damaged muscles, but this contribution is always very weak. Thus we established a project aiming to reprogramme non-muscle cells into the skeletal striated differentiation pathway. Results. We transduced several human primary adult stem or progenitor cells using a recombinant lentivirus containing the coding sequence of the Myf5 gene considered as a master gene for the determination of skeletal striated muscle. These original results are the first demonstration of a myogenic conversion of human mesenchymal and endothelial cells by Myf5. Conclusions. The procedure described in the present paper could be used to develop new research protocols with the prospect of using these cells as therapeutic agents.

e19564 Background: The aim of this single centre study was to assess the outcome of pts with MM following the relapse after ASCT, according to whether or not a RICALLO was performed. Methods: Recor...

The standard risk factors for acute graft-versus-host disease (aGVHD) after allogeneic stem cell transplantation (allo-SCT) from related or unrelated donors are well defined and include HLA mismatch or unrelated donor, older recipient age, and female donor for male recipient (FM). The steroid-refractory (SR) forms of aGVHD are important to consider because they often have a major deleterious impact on transplant outcome. Unfortunately, the specific risk factors for SR aGVHD are less clearly defined. To characterize these risk factors after allo-SCT from matched related or unrelated donors, we undertook a retrospective analysis of adult patients transplanted at our center between 01/01/2000 and 12/31/2012. Steroid-refractory aGVHD was defined as aGVHD progressing after 3 days of treatment, or unchanged after 7 days, or in incomplete response after 14 days. GVHD occurring after donor lymphocytes infusion were excluded. Overall survival (OS) was calculated using the Kaplan-Meier estimate. Cumulative incidences (CI) were used for SR aGVHD in a competing risk setting with death as a competing event. The Gray test was used to compare CI curves. For multivariate analysis, the variables with p value < 0.1 were entered into a Fine-Gray model and the least significant variables were excluded in sequential fashion until all remaining factors were significant at the p=0.05 level. The variables considered were recipient age (≥ vs < 50 years, median age), female vs male donor, FM vs other combinations, matched related (MRD) vs matched unrelated donor (MUD), peripheral blood (PB) vs bone marrow (BM) graft, GVHD prophylaxis with cyclosporine (CsA)+metho vs others, myeloablative (MAC) vs reduced-intensity conditioning (RIC) regimen, antithymocyte globulin (ATG) vs no ATG, number of CD34+ cells in the graft ≥ vs < 5.6 x 106/kg (median number), early (CR1, PR1, chronic phase, or untreated) vs advanced disease, CMV-seropositive vs seronegative recipient. Unrelated donors were matched at the allele level for HLA-A, B, C, DRB1, DQB1. Six hundred and thirty four patients were identified and included in the present study. The median age was 50 years (18-67). Diseases were AML (n=230), ALL (n=104), myeloma (n=80), NHL (n=74), Hodgkin's disease (n=18), MDS (n=47), CLL (n=29), CML (n=18), aplastic anemia (n=19), and MPS (n=15). Status at transplant were CR1 or PR1 or chronic phase (n=260), > CR1 or PR1 (n=237), refractory (n=101), or untreated (n=36). Conditioning regimens were RIC (n=405) or MAC (n=229). Rabbit ATG was administered to 327 patients, of whom 298 received a RIC regimen. Donors were MRD (n=360) or MUD (n=274). Sources of stem cells were PB (n=452), BM (n=177), missing data (n=5). The prophylaxis of GVHD was CsA+metho for 339 patients. In the whole population, 71 patients presented a SR aGVHD at a median time of 29 days (8-137) after transplant, representing a CI of 11.2% ± 1.2%. Their OS at 1 year post-transplant was 27% ± 5%. In univariate analysis, the risk factors for SR aGVHD were MAC (p=0.02), MUD (p=0.02), no ATG (p=0.01), and a trend for FM (p=0.07). Other variables considered in univariate analysis were recipient age (p=0.6), female vs male donor (p=0.6), recipient CMV status (p=0.7), status at transplant (p=0.2), PB vs BM graft (p=0.9), number of CD34+ cells (p=0.4), and GVHD prophylaxis (p=0.6). In multivariate analysis, the risk factors for SR aGVHD were MUD (HR=2.5, 95%CI: 1.5-4.1, p=0.0003), FM (HR=2, 95%CI: 1.2-3.4, p=0.008), and no ATG (HR=2.1, 95%CI: 1.3-3.4, p=0.002). Patients were then divided into 3 groups. The CI of SR aGVHD was 2.7% ± 1.6% in the low-risk group (no MUD + no FM + ATG; n=112), 21.8% ± 3.4% in the high-risk group (MUD + FM +/- ATG, or MUD + no FM + no ATG; n=147), and 9.6% ± 1.5% in the intermediate-risk group (n=375); p=10-6. We conclude that MUD, FM, and no ATG were independent risk factors for SR aGVHD in adult patients after allo-SCT from MRD or MUD. These data support the prevalent roles of HLA and donor T cell alloreactivity in the pathogenesis of SR aGVHD and may help identify patients at high risk of SR aGVHD, candidates for experimental first-line therapies of aGVHD. Disclosures: No relevant conflicts of interest to declare.

The female donor/male recipient combination (FM) increases the risks of graft-versus-host disease (GVHD) and non-relapse mortality (NRM) after allogeneic stem cell transplantation (allo-SCT), with a possible deleterious impact on overall survival (OS) [Gahrton G. Best Pract Res Clin Haematol. 2007 Jun;20(2):219-29]. Most patients in these studies received T-cell replete transplants. As a consequence, and because antithymocyte globulin (ATG) reduces the risk of GVHD, the impact of FM in the specific setting of allo-SCT with ATG remains poorly defined. To explore the impact of FM in the ATG setting, we undertook a retrospective analysis of male adult patients transplanted with rabbit ATG at our center between 01/01/2000 and 12/31/2012. Overall survival and disease-free survival (DFS) were calculated using the Kaplan-Meier estimate, with comparisons by the log-rank test. Cumulative incidences (CI) were used for NRM, relapse (REL), and GVHD in a competing risks setting, NRM being a competing event for REL, and death for GVHD. The Gray test was used to compare CI curves. For multivariate analysis, the variables with p value < 0.1 were entered into a Fine-Gray model where the least significant variables were excluded in sequential fashion until all remaining factors were significant at the p=0.05 level. The following variables were considered: recipient age (≥ vs < 56 years, median age), female donor (FD) vs male donor (MD), matched related (MRD) vs matched unrelated (MUD) donor, peripheral blood (PB) vs bone marrow (BM) graft, GVHD prophylaxis with cyclosporine (CsA)+metho vs others, myeloablative (MAC) vs reduced-intensity conditioning (RIC) regimen, CMV-seropositive vs seronegative recipient, early (CR1 or PR1 or chronic phase or untreated) vs advanced disease. Steroid-refractory (SR) acute (a) GVHD was defined as aGVHD progressing after 3 days of treatment, or unchanged after 7 days, or in incomplete response after 14 days. MUD were matched at the allele level for HLA-A, B, C, DRB1, DQB1. Two hundred and twelve male patients were identified and included in the present study. The median age was 56 years (18-67). Diseases were AML (n=61), ALL (n=16), NHL (n=36), Hodgkin's disease (n=10), myeloma (n=37), MDS (n=26), aplastic anemia (n=7), CLL (n=11), CML (n=1), and MPS (n=7). Status at transplant were CR1 or PR1 or chronic phase (n=74), > CR1 or PR1 (n=83), refractory (n=34), or untreated (n=21). Conditioning regimens were RIC (n=195) or MAC (n=17). Donors were MRD (n=110) or MUD (n=102). Eighty-eight patients were transplanted with a FD. Source of stem cells were PB (n=193), BM (n=18), missing data (n=1). Prophylaxis of GVHD consisted of CsA+metho for 84 patients. The median follow-up was 42 months (5-149). In univariate analysis, the 3-year OS and DFS in FD vs MD groups were 48% ± 6% vs 56% ± 5% (p=0.3) and 42% ± 5% vs 50% ± 5% (p=0.4), respectively. The 3-year NRM and REL in the same groups were 25% ± 5% vs 19.6% ± 4% (p=0.4) and 30% ± 5% vs 31% ± 4% (p=0.9), respectively. The CI of aGVHD II-IV, aGVHD III-IV, SR aGVHD, and extensive chronic GVHD in FD vs MD groups were 37.5% ± 5% vs 33% ± 4% (p=0.5), 22.7% ± 4% vs 17% ± 3% (p=0.3), 17.2% ± 4% vs 8.3% ± 3% (p=0.049), and 20% ± 4% vs 22.5% ± 4% (p=0.9), respectively. Other variables considered in univariate analysis for SR aGVHD were recipient age (p=0.9), recipient CMV status (p=0.7), disease status (p=0.9), RIC vs MAC (p=0.16), MRD vs MUD (p=0.09), PB vs BM graft (p=0.4), and GVHD prophylaxis (p=0.2). In multivariate analysis, the risk factors for SR aGVHD were FD (HR=3.1, 95%CI: 1.2-7.9, p=0.01) and MUD (HR=2.9, 95%CI: 1.1-7.1, p=0.02). The CI of SR aGVHD were 32.3% ± 9.7% in the FD + MUD group (n=29), 9.7% ± 3.8% in the MD + MUD group (n=73), 10.7% ± 4.1% in the FD + MRD group (n=59), and 6.5% ± 3.7% in the MD + MRD group (n=51); p=0.004. We conclude that FD was an independent risk factor for SR aGVHD after allo-SCT with rabbit ATG in male adult patients mostly transplanted with PB after RIC. There was no impact of FD on aGVHD II-IV or III-IV, chronic GVHD, NRM, REL or survival. Finally, the absence of impact of FD on NRM and survival should be interpreted with caution given the retrospective design of the study and because we cannot exclude a possible limiting effect of an insufficient number of patients. Disclosures: No relevant conflicts of interest to declare.

Introduction Isolated trisomy 8 is a frequent cytogenetic abnormality in MDS, but hematological characteristics of MDS with isolated trisomy 8 have not been reported in detail. Patients and Methods This was a retrospective analysis of cases of MDS with isolated trisomy 8 diagnosed in 6 French centers of the Groupe Francophone des Myélodysplasies (GFM) between 2003 and 2013. Only patients with isolated trisomy 8 diagnosed as MDS or MPN/MDS (other than CMML) according to WHO were eligible, excluding AML, well characterized MPN (PV, ET) and CMML. Myeloproliferative (MP) features were defined by repeated presence (in the absence of infection) of one of the following: WBC > 10G/L, circulating immature granulocytes (myelemia ) > 2%, or palpable splenomegaly. Results 103 patients with isolated trisomy 8 were identified, with a median age of 75 years, and M/F 1.7. At diagnosis, median WBC count was 4.1 G/L, with WBC ≥ 10 G/L in 13 patients (12.6 %), myelemia ≥ 2% in 27 patients (26.2 %), palpable splenomegaly in 9 patients (8.7 %). WHO diagnosis included 20 RA, 2 RARS, 22 RCMD, 1 RCMD-RS, 1 RCUD, 21 RAEB-1, 18 RAEB-2, 7 MDS-U, 10 MDS/MPN, 1 hypoplastic MDS. IPSS was intermediate 1 (72.2 %), intermediate 2 (19.6 %), high (8.2 %) ; IPSS-R was low (37.1 %), intermediate (29.9 %), high (22.7 %), very high (10.6 %). MP features were found in 50 patients (48.5 %): 31 at diagnosis, 19 during evolution (in patients without MP features at diagnosis). Bone marrow morphological features could be reviewed in 15 MP cases, showing hypercellular marrow in 60 % cases, granulocytic hyperplasia (E/G Mutations were seen, for MP cases, in ASXL1 (64%), EZH2 (50%), TET2 (40%), RUNX1 (33%), SRSF2 (27%), DNMT3A (15%), JAK2 (14%), IDH2 (14%), NRAS (8%), SF3B1 (9%), U2AF1 (8%); for non MP cases in ASXL1 (33%), SRSF2 (27%), SF3B1 (27%), TET2 (20%), DNMT3A (13%), JAK2 (13%), RUNX1 (13%), EZH2 (7%), IDH2 (7%), ZRSR2 (7%), NRAS (0%). In spite of a trend for more mutations of ASXL1 (p=0.128), and EZH2 (p=0.053) in MP forms, the difference with non MP forms was not significant, possibly due to small patient numbers. 40 patients received an HMA (AZA in 36, DAC in 4) and 27.3% responded (4 CR, 1 PR, 1 marrow CR, 3 HI), including 11.7% of MP cases and 43.8% of non MP cases (p=0.057). 5 patients received intensive chemotherapy (with 2 CR). 42 (40.8%) received an ESA, with 60% responses, including 50% in MP and 73% in non MP patients (p= NS).10 (9.7%) received hydroxyurea. With a median follow up of 30 months, progression to AML was seen in 26% and 18.9% in MP and non MP patients, respectively (p= NS). Median survival was 35 months in the whole cohort, without difference between patients who, at diagnosis had MP features and no MP features (35 months for both). Conclusion Myeloproliferative (MP) features were found at diagnosis or during evolution in our experience in about 50% of MDS with isolated trisomy 8, a finding not previously reported, to our knowledge, and suggesting that some of those patients may have to be reclassified among MDS/MPN. The subset of patients with MP features tended to have a higher frequency of ASXL1 and EZH2 mutations (findings that will have to be confirmed on larger patient numbers), and seemed to respond poorly to HMA, although its survival was not lower than that of non MP forms in our experience. Disclosures Park: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hospira: Research Funding; Celgene: Research Funding. Fenaux:AMGEN: Honoraria, Research Funding; CELGENE: Honoraria, Research Funding; JANSSEN: Honoraria, Research Funding; NOVARTIS: Honoraria, Research Funding.