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Introduction. The boundaries between MDS and AML are still a matter of debate. In the 2001 WHO Classification, the myeloblast count distinguishing AML and MDS was lowered from 30% to 20% of the bone marrow (BM) cells or peripheral blood (PB) leukocytes. It was justified on the basis that treating patients with 20-29% BM blasts with intensive chemotherapy showed a similar outcome to those with > 30% BM blasts. However, the better knowledge of the biology of both diseases is showing that in several cases AML and high risk MDS share identical genetic profiles, as it is well known in AML with myelodysplasia- related changes (AML-MRC). Currently there are new therapeutic options, less toxic, and suitable for elderly people.The threshold of 20% BM blast is artificial, but it is still the main criterion used in clinical trials and also in real life to discriminate patients that probably belong to the spectrum of the same biological entity. Treatment of patients with MDS or AML is widely based in this relatively arbitrary condition. Objective: To study if the threshold of 20% bone marrow blasts, distinguishing MDS with excess of blasts type 2 (MDS EB 2) and AML, is reproducible among different observers. Methods. 120 bone marrow samples from patients previously diagnosed with MDS-EB-2, AML or therapy-related myeloid neoplasms (t-MN) according to 2016 WHO classification were included. The diagnosis of MDS required cytogenetics and/or FISH, and the cases with AML should have been classified following the 2017 ELN recommendations, regarding immunophenotyping, cytogenetics and molecular biology. The design of the study was established to include cases with Results. Finally 116/120 samples were considered suitable for the study. Regarding 2016 WHO categories, 55 cases showed MDS EB-2, 44 AML-MRC, 8 t-MN, 4 AML- NOS, 2 NPM1-mutated AML, 2 RUNX1-RUNX1T1 AML, 1 BCR-ABL1+ AML. Next generation sequencing was performed in 79 cases. Discordance was observed in 34/116 cases (29.3%). 14 cases with MDS-EB2 (1 NPM1+) were classified as AML-MRC by the second observer, 16 AML cases as MDS EB-2, 3 MDS EB-2 as MDS- EB1 and 1 AML as MDS- EB1. The genetic and /or molecular profile of the discordant cases was heterogeneous. Regarding the threshold of 20% BM blasts, discrepancies were 31/116 (26.7%, I Kappa test = 0.46, moderate agreement). The agreement between MDS-EB-2 and AML-MRC, with discordance in 28/98 cases (28.6%), was moderate-fair (Kappa test= 0.42). Conclusion. The threshold of 20% BM blasts did not accurately separate AML from MDS EB-2. Particularly less concordance was seen for AML-MRC. Incorporation of genetic and molecular characteristics to the morphologic diagnosis is needed to optimize the definition of both entities. Acknowledgment: Angel Cedillo, Secretaría Técnica AMHH. Disclosures Font Lopez: GILEAD: Membership on an entity's Board of Directors or advisory committees; CELGENE-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Loscertales: Janssen, Abbvie, Astra-Zeneca, Beigene, Roche, Gilead: Consultancy; Janssen, Abbvie, Roche, Gilead: Speakers Bureau. Cedena: Janssen, Celgene and Abbvie: Honoraria.

Introduction: High-dose post transplant cyclophosphamide (PTCY) effectively prevents graft-versus-host disease (GVHD) after unmanipulated HLA-haploidentical hematopoietic stem cell transplant (HSCT) and offer low rates of GVHD in the setting of HLA identical transplant. The objective of our study was to compare the outcomes of haplo vs HLA identical HSCT in patients undergoing HSCT for acute myeloid leukemia (AML) using PTCY. Patients and methods: We conducted a retrospective study of 229 patients undergoing a first HSCT for AML using PTCY, 130 from an haploidentical donor between 2013 and 2018 (median follow up 62.5 months) and 99 from a matched sibling (MSD) (n=38) or unrelated donor (MUD) (n=61) (median follow up 27 months) between 2013 and 2019, in 20 centers in Spain. Last update of the cohort was performed in March 2021. Results: Baseline characteristics are summarized in Table 1. There were more patients with active disease at transplant (5% MSD/MUD vs. 20% haplo, p=0.001), high/very high DRI (32% vs. 67%, p=0.000) and prior autologous HSCT (2% vs. 11%, p=0.010) in the haplo group. Mobilized peripheral blood stem cells was the most frequent stem cell source in both groups. Most patients received myeloablative conditioning (55% vs. 64%, p=0.170). All Patients in the haplo group received PTCY days +3+4 followed by a calcineurin inhibitor (CNI) and MMF from +5. In the MSD/MUD group, 37% received both CNI+MMF, 33% only CNI and 30% PTCY with sirolimus+MMF (this group included only MUD donors). None of the patients received ATG. Cumulative incidence of neutrophil recovery at day 28 was 97% in both groups, with a median of 16 and 17 days respectively (p=0.948). Both 2-year overall survival (OS) (72% vs. 62%, p=0.07) and event-free survival (EFS) (70% vs. 54%, p=0.055) were higher in the MSD/MUD group, but the difference was not statistically significant (Figure 1). Multivariate analysis only identified age and pre-transplant status as independent risk factors for OS, and pre-transplant status for EFS. No differences were found in the cumulative incidence of relapse at 2 years (19% vs. 25%, p=0.13) and non-relapse mortality (14% vs. 19%, p=0.145). Cumulative incidence of grade II-IV acute GVHD was lower in MSD/MUD (14% vs. 47%, p=0.000, Figure 2), while III-IV aGVHD was similar (4% vs. 9%, p=0.14). Cumulative incidence of chronic GVHD and moderate-severe cGVHD at 2 years was similar for both groups (42% vs. 33% (p=0.051); 22% vs. 19% (p=0.28)). No differences were found in GRFS (48% vs. 46% (p=0.506)). Most frequent cause of death in the early post-transplant period was non-GVHD related infection in both groups. Conclusions: in our experience, PTCY as GVHD prophylaxis in both MSD/MUD and Haplo transplant in AML using mostly PBSC effectively prevents GVHD and offers similar NRM, relapse and survival rates. Poor control of the disease before transplant was the only factor affecting OS and EFS in this setting. Prospective studies are needed to confirm our results. Figure 1 Figure 1. Disclosures Bailen: Pfizer, Kite-Gilead, Gilead: Honoraria. Guerreiro: Novartis, Gilead: Consultancy, Honoraria. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Background. Donor specific antibodies (DSAs) are preformed IgG antibodies with specificity against HLA molecules not shared with the donor that can lead to graft failure (GF) in the setting of mismatched HSCT. The aim of this study is to report the experience of the Spanish Group of Hematopoietic Transplant (GETH-TC) in patients with DSAs undergoing haplo-HSCT. Methods. Patients undergoing haplo-HSCT in centers from the GETH-TC from 2013 to 2021 were included in the study. DSAs were analyzed with a solid-phase single-antigen immunoassay (Luminex®); monitoring was performed prior to desensitization, prior to infusion and after infusion. Desensitization strategies used depended on center experience, immunofluorescence intensity, complement fixation and type of antibodies. Results. 59 haplo-HSCT with DSAs were performed in 57 patients in 13 centers. Characteristics of the population are shown in Table 1. 53 (93%) patients were female (91% with prior pregnancies). All patients lacked a suitable alternative donor. 51 (89%) received peripheral blood as stem cell source. Conditioning was myeloablative in 58% and all patients received post-transplant cyclophosphamide based GVHD prophylaxis; 3 (5%) patients received also ATG. 28 (49%) patients presented anti-HLA class I DSAs 22 of them with >5000MFI), 14 (25%) presented anti-HLA class II (6 with >5000MFI) and 15 (26%) presented both anti-HLA class I and II DSAs (13 with >5000MFI). Five patients did not receive desensitization treatment, 4 of them with After a median follow-up of 24 months, 2-year OS and EFS were 52% and 42%, respectively. 2-year cumulative incidence of relapse at was 14% and NRM was 41%. Cumulative incidence of grade II-IV aGVHD at day 180 was 13% and chronic GVHD was 25%. Conclusions. The use of desensitization treatment guided by DSAs intensity kinetics constitute an effective approach with high rates of engraftment for patients with DSAs in need for an haplo-HSCT lacking an alternative suitable donor, including non-malignant disorders. Figure 1 Figure 1. Disclosures Bailen: Pfizer, Kite-Gilead, Gilead: Honoraria. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Introduction: Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are the two autologous anti-CD19 chimeric antigen receptors T cells commercially approved in Europe for relapsed/refractory (R/R) DLBCL. We performed a retrospective study to evaluate patients characteristics, efficacy and safety for axi-cel and tisa-cel in a large cohort of patients within the GETH-TC (Spanish Group of Stem Transplantation and Cell Therapy)-GELTAMO (Spanish Group of Lymphoma and Autologous Stem Cell Transplantation). Methods: Ten Spanish centers contributed data. Data were collected retrospectively from consecutive patients with DLBCL in whom apheresis was performed for axi-cel or tisa-cel treatment. CRS and ICANS were graded with the ASTCT consensus criteria. Response was assessed according to the Lugano criteria. Patients included had at least 30 days of follow-up. Results: A total of 268 patients with R/R DLBCL underwent apheresis for axi-cel (n=123) and tisacel (n=145) from Nov-2018 to May-2021, of which 232 (86%) received CART-cell infusion (n=110, 89% and n=122, 84%, respectively). Reasons for not undergoing infusion were progression in 10 cases, tumor lysis syndrome in 1, infection in 1, and CR after bridging therapy in 1 for the axi-cel cohort, and progression in 21 (4 after manufacture failure), psychiatric disorder in 1, and post-apheresis cerebral hemorrhage in 1 case for the tisa-cel cohort. Time between apheresis and infusion was 41 days (IQR 40-56) and 49 days (IQR 46-62) (p=0.006), respectively. Characteristics at baseline, apheresis and at lymphodepletion are summarized in Tables 1 and 2. Median age was 60 (range 19-79), 61% of patients were male, most of them treated for DLBCL NOS (66%). There were no significant differences between patients intended to be treated with axi-cel and tisa-cel. 82% of the infused patients received bridging therapy. At apheresis and at lymphodepletion ECOG performance status score was 0-1 in 93% and 91%, and 7 and 32 patients were in response, respectively. The overall response rates (ORRs) at 1 month and 3 months were 65% and 56%, respectively, with 34% and 45% achieving a complete response (CR), respectively. In the intention-to-treat analysis, with a median follow-up of 9 months (IQR 5-15), EFS and OS at 9 months was 44% (95%CI 38-51)(Figure 1) and 59% (95%CI 53-66) with a median EFS and OS of 6 months and 11 months, respectively. At lymphodepletion, characteristics of infused patients and disease were not significantly different between axi-cel and tisa-cel cohorts. Rates of CRS, CRS grade 3-4, ICANS, ICANS grade 3-4 were 89% and 71% (p=0.001), 10% and 7% (p=0.34), 42% and 16% (p=0.001), 20% and 4% (p=0.001) for the axi-cel and tisa-cel cohorts, respectively. ICU admission was needed in 25% and 15% of patients (p=0.06), respectively. Non-relapse mortality at days 100 were 2.5% and 1.4%, and at day 180, 5.4% and 2.2% (p=0.08) for the axi-cel and tisa-cel groups, respectively. With a median follow-up of 8 months for patients who received infusion with axi-cel and 12 months for patients infused with tisa-cel, EFS and OS at 12 months were 48% and 33% (p=0.33), and 53% and 50% (p=0.27), respectively, with a median EFS of 11 and 6 months and a median OS of 13 and 12 months, respectively. In the multivariate analysis, the only factor associated with poor PFS was having ECOG-PS ≥2 at lymphodepletion (HR13, p=0.03). No factors were identified as associated independently to OS. Factors associated to CRS grade 3-4 were IPI score 4-5 at lymphodepletion (OR 1.4, p=0.03) and ECOG-PS ≥2 at apheresis (OR 1.5, p=0.03). For ICANS grade 3-4, factors associated were the use of axi-cel (OR 8, p=0.04) and diagnosis of HG double/triple hit lymphoma (OR 9, p=0.022). Conclusions:This multicentric analysis describes one of the largest real-life cohorts of patients treated with axi-cel and tisa-cel for R/R aggressive B cell lymphoma in Europe. Results are comparable to those from the pivotal studies and other large real-life experiences. Up to now, patients included for one or other product in Spain do not differ significantly in terms of baseline characteristics, and within this setting, results are comparable between both products in terms of efficacy. The use of axi-cel was associated to higher rates of CRS and especially, severe forms of ICANS. However, mortality associated to toxicity were low and not significantly different between both cohorts. Figure 1 Figure 1. Disclosures Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria. Iacoboni: BMS/Celgene, Gilead, Novartis, Janssen, Roche: Honoraria. Reguera: Janssen, Kite/Gilead, Novartis: Speakers Bureau; BMS-Celgene, Novartis: Membership on an entity's Board of Directors or advisory committees. Lopez Corral: Gilead, Novartis: Consultancy, Honoraria. Guerreiro: Novartis, Gilead: Consultancy, Honoraria. Caballero: Novartis, Gilead: Honoraria. Ortiz-Maldonado: Kite, Novartis, BMS, Janssen: Honoraria. Sanchez: Janssen, Jazz Pharmaceuticals, Gilead, Novartis, Amgen: Consultancy. Sancho: Roche, Janssen, Celgene-BMS, Gilead, Novartis, Takeda: Honoraria, Speakers Bureau; Roche, Janssen, Celgene-BMS, Gilead, Novartis, Incyte, Beigene: Speakers Bureau. Bastos-Oreiro: Janssen: Honoraria, Speakers Bureau; F. Hoffmann-La Roche: Honoraria, Research Funding, Speakers Bureau; Takeda: Speakers Bureau; Novartis: Honoraria, Speakers Bureau; BMS-Celgene: Honoraria, Speakers Bureau; Gilead: Honoraria; Kite: Speakers Bureau. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Mussetti: Gilead: Other: Unspecified, Research Funding; Novartis: Honoraria, Other: Unspecified; Takeda: Honoraria. Bailen: Gilead, Pfizer: Speakers Bureau. Martin Garcia-Sancho: Takeda: Honoraria; Novartis: Consultancy; Incyte: Consultancy; Celgene/BMS: Consultancy; Celgene: Honoraria, Other: travel; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Janssen: Honoraria, Research Funding; Servier: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Gilead: Consultancy, Honoraria; Morphosys: Consultancy; Kyowa Kirin: Consultancy; Clinigen: Consultancy; Eusa Pharma: Consultancy; Kern Pharma: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Barba: Amgen, Celgene, Gilead, Incyte, Jazz Pharmaceuticals, MSD, Novartis, Pfizer and Roche, Jazz Phar,aceuticals: Honoraria; Cqrlos III heqlth Institute, aSOCIACION espanola contra el cancer, PERIS: Research Funding.

Introduction: The severity of acute clinical outcomes and mortality in hematologic malignancy (HM) patients infected by SARS-CoV-2 was exhaustively documented in the first weeks of the pandemic. A consistent increased mortality compared to non-cancer patients was observed across studies. In this study we aimed to estimate survival in COVID-19 HM patients by type of malignancy, to describe acute and post-acute clinical outcomes, and to compare outcomes in early and later pandemic periods. Methods: In this population-based registry study sponsored by the Madrid Society of Hematology (Asociación Madrileña de Hematología y Hemoterapia), we collected de-identified data on clinical characteristics, treatment and acute and post-acute outcomes in adult patients with hematologic malignancies and confirmed SARS-CoV-2 infection within the Madrid region of Spain. Our case series included all eligible patients admitted to 26 regional health service hospitals and 5 private healthcare centers between February 28, 2020 and February 18, 2021 with a coverage of 98% on a population of 6.6 million inhabitants. The study outcomes were all-cause mortality, severity of disease (WHO), oxygen support, ICU admission, and follow-up symptoms and signs and complications. Survival probabilities were estimated with the actuarial method and reported overall and stratified by type of malignancy and for two study periods (early cohort,-COVID-19 diagnosis from February 28 to 31 May, 2020, and later cohort, up to February 18, 2021). Results: Of the 1408 patients reported to the HEMATO-MADRID COVID-19 registry, 1166 were included in the present analyses; 839 (72%) had a lymphoid malignancy, including 325 (28%) with non-Hodgkin lymphoma, 50 (4%) with Hodgkin lymphoma and 263 (23%) with multiple myeloma; and 327 (28%) had a myeloid malignancy, including 115 (10%) with myelodysplastic syndrome, 92 (8%) with acute myeloid leukemia (AML) and 87 (7%) with Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms. Overall COVID-19 clinical severity was classified as critical in 19% of patients, severe in 36%, moderate in 22%, and mild in 22%; 10% were admitted to an ICU; 8% were on mechanical ventilation and 19% on noninvasive ventilation. Mild disease increased between early and later period from 15% to 38% of patients; severe disease decreased from 42% to 24%, p At follow-up, 22% reported persistent symptoms related to COVID-19 at 2 months, 16% at 4 months and 14% at 6 months. 381 of 1166 (33%) patients died. Overall 30-day survival was 68%; 2 and 3-month overall survival probabilities were 56% and 53%, respectively. Survival was more favorable for patients with myeloproliferative neoplasms (82%, 69% and 65% at 30-days, 2 and 3 months, respectively) than for those with lymphoid malignancies (68%, 56% and 54%) or myelodysplastic syndrome/acute myeloid leukemia (61%, 51%, 46%), p=001. 285 (37%) patients died in the early period vs 96 (24%) in the later, p Conclusions. A population-based registry in Spain provided strong evidence that although COVID-19 severity decreased over year 1 of the pandemic, mortality remained high, and survival was stable over time in the group of patients with hematological malignancy infected by SARS-Coc-2. A relevant proportion of the infected patients (1 in 6) referred persistent symptoms attributable to COVID-19. The improved clinical management of severe COVID-19 in non-cancer patients that followed the dissemination of evidence-based recommendations did not translate in more favorable survival in patients with hematological malignancies. Research is needed to address the specific characteristics and improve the clinical management of this vulnerable population. Disclosures Martinez-Lopez: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Incyte: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Astellas: Research Funding, Speakers Bureau. Jiménez-Yuste: Pfizer: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria, Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Honoraria, Research Funding; BioMarin: Consultancy; Sobi: Consultancy, Honoraria, Research Funding; Octapharma: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding. Kwon: Gilead: Honoraria.

Introduction: Chimeric antigen receptor (CAR) T-Cell therapy is approved for relapse/refractory diffuse large B cell lymphoma (DLBCL) patients after two lines of therapy. Although it is an effective treatment, approximately 20-30% of patients have an early relapse. In this context, biomarkers that helps to identify those patients who will be refractory to this therapy are relevant. Cell-free DNA (cfDNA) has emerged as a new tool for non-invasive monitoring of patients with lymphoma, therefore the aim of this study was to evaluate dynamic cfDNA concentration in addition to other biomarkers (LDH, CRP, ferritin) before CAR T-cell infusion to detect early progressors. Methods: We selected 44 r/r DLBCL patients treated with CAR T-cell in our centre. Plasma samples were collected pre-apheresis (PA) and pre-infusion (PI)(∆cfDNA). Other biomarkers (LDH, CRP, Ferritin) were studied PA, pre-lymphodepletion (PL) and PI, tumour volume metabolic (TMV) are also studied. CfDNA were obtained from plasma using QIAamp® Circulating Nucleic Acid (Qiagen) and quantified by QuantiFluor dsDNA System (Promega). The Mann-Whitney test was used to compare differences between two independent quantitative variables . ROC analysis was conducted to determine the cut-off value of biomarkers. Cumulative incidence of progression (1 and 3 months) was calculated from the date of CAR T-cell infusion. Data analysis was performed using Stata. Results: Cumulative incidence of relapse at 1 month and 3 months was 20% and 30% respectively. The correlation between the progression (1 month, 3 months) and the different biomarkers is shown in Table 1. The CRP PL, CRP PI, LDH PI and ∆cfDNA (PI-PA, median time 41.5 days [range:31-107]) was correlated with early progression (1 month). No differences were found with progression at 3 months. The different cut-off for the biomarkers selected was 9 ng/mL for ∆cfDNA, 225 U/L for LDH and 1.35 mg/dL for CRP. Cumulative incidence of progression at 1 month was calculated for these biomarkers (figure 1): ∆cfDNA, HR: 4.3 (1.05-17), p=0.042; CRP PL: HR: 6.9 (1.5-31.1), p=0.012; CRP PI, HR: 11.2 (1.5-83), p=0.019 and LDH PI, HR: 3.4 (1-17) p=0.11. It should be noted that 83.3% (10/12) of the patients who progressed during the first month had at least one of the above variables. Conclusions: Our results highlight that increase in cfDNA higher than 9 ng/mL, CRP PL and PI >1.35 mg/dL and LDH PI > 225 U/L before CAR T-cell therapy may detect early progressors within the first month after treatment. Therefore, ∆cfDNA, CRP and LDH could be useful to identify patients who highly probable will not benefit from the CAR T infusion, in which another prior strategy could be considered in an attempt to control the disease. These results need to be confirmed with a larger cohort. Figure 1 Figure 1. Disclosures Bailén: Pfizer: Honoraria; Kite-Gilead: Honoraria; Gilead: Honoraria. Kwon: Gilead: Honoraria.

Introduction: Idarucizumab is a humanized monoclonal antibody fragment that binds to dabigatran and reverses its anticoagulant activity. It has been available in Spain since June 2016 and is indicated for imminent surgery or invasive procedures and life-threatening bleeding. The aim of the study was to describe the actual experience with idarucizumab in different centers in Madrid. Methods: Patients with electronic prescription of idarucizumab between June 2016 and July 2021 were included. Demographic information, comorbidities, laboratory parameters, dabigatran indication, anticoagulation resumption, adverse events related to idarucizumab and death within 30 days were collected from medical records. Qualitative data are presented as frequencies and percentages. Quantitative data are presented as mean ± standard deviation (SD) or median (interquartile range -IQR-). Cumulative survival was calculated by dividing the number of patients alive by the number of patients in each indication category for idarucizumab in a 30-day post-infusion period. Results: A total of 69 patients from 8 hospitals in Madrid were included. Ninety-six percent received dabigatran for prevention of stroke and embolism in nonvalvular atrial fibrillation and 4% received it for the treatment of thromboembolic disease. The mean age was 73.5 ± 13.9 years, and 55.6% were men. Median aPTT was 45.6 seconds and was prolonged in 72.1% (49). Patient characteristics, concomitant conditions and laboratory parameters are reviewed in Table 1. The main indication for idarucizumab was reversal of anticoagulation for persistent bleeding (46.4%), followed by surgery (44.9%). Fibrinolysis due to ischemic stroke was performed in 3 patients (4.3%), dabigatran intoxication occurred in 3 patients due to acute renal failure (4.3%). Gastrointestinal bleeding was the most common type of bleeding. Two of the patients intoxicated with dabigatran also had gastrointestinal bleeding. Cardiac surgery was the most common type of intervention, with heart transplant being a common indication (9/13). Minor surgical procedures included 2 lumbar punctures and 1 central venous catheterization. In one case, the type of surgery was not available. Figure 1 A and B summarize the bleeding location and type of surgery. The median time between infusion of idarucizumab and cessation of bleeding or onset of surgery was 3 hours, however this information was only available in 43 patients. No reports of excessive bleeding during surgery or after fibrinolysis were noted. One patient with dabigatran intoxication was reported to have an episode of persistent melena in which the trough plasma level was 1178.1 ng/mL. This patient died of an aggressive lymphoproliferative disorder that couldn´t be biopsied due to altered coagulation. A case of auricular thrombosis occurred in a patient with a heart transplant due to hyperthophic cardiomiopathy and end-stage heart failure requiring thrombectomy. The patient required a biventricular assistance and died of myocardial infarction. Full 30-day follow-up was available for 68 patients, during this period 11 died. Five patients in the bleeding group died, 3 from hypovolemic shock, 1 from intraparenchymal hemorrhage and data were missing for 1. Two patients who received a heart transplant died, one as described previously 10 days after the transplant and the other 2 days after the transplant from hemorrhagic shock. Three patients who underwent abdominal surgery died of septic shock. One patient with dabigatran intoxication died. Cumulative survival after a follow-up period of 30 days was 86% (Figure 2). Seventy-seven percent (53) resumed anticoagulation after a median of 3 days (0-180), and 62.3% (33) were bridged with low molecular weight heparin (LMWH) at prophylactic doses. Finally, 75% (40) maintained LMWH (7) or restarted dabigatran or another direct oral anticoagulant (33). A total of 13 patients didn´t resume any anticoagulation. Conclusions: Idarucizumab is an effective drug for reversal of dabigatran anticoagulation in bleeding or imminent surgery/invasive procedures. In this cohort it was used safely in patients awaiting a heart transplant. No cases of bleeding after infusion or during surgery were reported, except for a single case of auricular thrombosis. Most patients resumed anticoagulation at discharge. The experience described confirms the safety of idarucizumab in daily clinical practice. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

BACKGROUND The revised genetic risk classification established by the European Leukemia Net (ELN) in 2017 stratifies patients diagnosed with acute myeloid leukemia (AML) into 3 prognostic categories (favourable, intermediate, and adverse) based on cytogenetic and molecular characteristics.The ELN classification is widely accepted in AML patients despite the fact that validation studies were performed in participants who received exclusively first-line treatment with intensive chemotherapy. For this reason, it is not well established whether the ELN risk groups are applicable to patients on non-intensive first-line treatment. OBJECTIVES - To describe and compare baseline characteristics at diagnosis between patients with AML treated with intensive and non-intensive therapy. - To assess whether the ELN prognostic classification is applicable in these subgroups of patients. METHODS We retrospectively analysed patients with newly diagnosed AML admitted to our center between 2007 and 2020. Patients with acute promyelocytic leukemia (M3), patients younger than 18 years old and/or patients who received exclusively supportive treatment were excluded. Demographic and clinical data, disease characteristics at diagnosis and first-line treatment were collected. Cytogenetic and molecular characteristics were used to classify patients in ELN risk groups. RESULTS Of the total of patients (n=218), one hundred and fifty-six (71.6%) received intensive chemotherapy treatment, while 62 (28.4%) were treated with non-intensive strategies. Idarubicin and cytarabine based schemes regimens (IA) were administered in most patients (98.6%) who received intensive treatment while the rest received fludarabine based regimens. One patient (0.6%) was treated with danurubicin and cytarabine liposome (CPX-351). Fifty-four (87%) patients treated with non-intensive regimens received hypomethylating agents, mostly azacitidine. Five patients (8%) were treated with venetoclax in combination with a hypomethylating agent. Table 1 shows the characteristics at diagnosis in both groups of patients. Patients who received intensive chemotherapy were younger and had higher leukocyte count, LDH values and a higher percentage of blasts in peripheral blood and bone marrow with a median of 40% and 62% blasts respectively. On the other hand, patients under non-intensive treatment more frequently presented a past history of hemopathy and a higher percentage of bone marrow dysplasia. Regarding ELN stratification significant differences were found between both groups. Patients who received aggressive chemotherapy vs patients who did not, were classified in low (28% vs. 7%), intermediate (36% vs. 58%) and high risk (36% vs. 35%) respectively (Figure 1). At the end of the follow-up, 41% of the patients who had received intensive therapy were alive while only 6.5% of the patients who had received non-intensive treatment were alive. Significant differences in survival were observed between both groups (p In the intensive chemotherapy group, significant differences in survival were observed according to ELN risk stratification (p However, in patients receiving non-intensive therapies, there were no significant differences in survival among different prognostic categories (p=0.06). In this group, 1-year OS was 25%, 57.6% and 40.7% and median OS was 2.1, 14.8 and 10.1 months for low, intermediate and high-risk groups respectively. See Figure 2. CONCLUSIONS: As validated in previous trials, ELN classification constitutes an adequate prognostic marker for patients with newly diagnosed AML treated with intensive chemotherapy. In our series, this classification does not appear to be a good predictor of survival for patients diagnosed with AML who initiated non-intensive treatments. Further validation in prospective studies are needed to better classify this growing subgroup of patients in clinical practice. Figure 1 Figure 1. Disclosures Martín-Rojas: Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Font Lopez: Pfizer: Membership on an entity's Board of Directors or advisory committees; GILEAD: Membership on an entity's Board of Directors or advisory committees; CELGENE-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

INTRODUCTION Several studies have shown that morphological remission at day 14 is a predictor of post-induction response in patients with acute myeloid leukemia (AML) undergoing an intensive treatment. However, the role of measurable residual disease (MRD) by multiparameter flow cytometry (MFC) at day 14 remains unknown. The aim of our study is to explore the role of MRD at day 14 and its association with outcomes of patients with AML undergoing an intensive treatment. METHODS We conducted a retrospective study in adult patients with newly a diagnosed AML in our center between 2007 and 2020. Adult patients who received intensive chemotherapy, excluding those with an acute promyelocytic leukemia, were included. Bone marrow aspiration was performed at day 14 after induction to assess morphological response and MRD by MFC. Early blast clearance (EBC) was defined as RESULTS A total of 131 patients were analyzed. Median age was 55.6 years (IQR 42.3-64.2). The most frequent AML subtype was AML with myelodysplasia-related changes (34.4%), followed by NPM1-mutated AML (32.1%). The most commonly used induction regimen was "7+3" (96.2%) (Table 1). On day 14 bone marrow aspiration, median cellularity was 0.5/5 (IQR 0.5-1). 107 patients (81.7%) showed a blast reduction >50% compared to diagnosis and 87 patients (66.4%) had less than 5% of blasts. In this latter group, 28.6% of patients had a positive MRD and 71.4% had a negative MRD. NPM1-mutated AML showed the highest EBC rates while AML with myelodysplasia-related changes had the lowest rates (83.3% versus 55.5%; p=0.04). Furthermore, there were statistically significant differences in EBC rates based on the 2017 European Leukemia Net risk stratification, with 80% of EBC in low risk, 66.6% in intermediate risk and 53.4% in high risk AML (p=0.038). No differences were observed in MRD at day 14 based on AML subtypes or risk stratification. We subsequently analyzed the negative (NPV) and positive predictive values (PPV) of day 14 bone marrow aspiration results by morphology and MFC to predict post-induction results. As a predictor of post-induction CR, day 14 EBC had a NPV of 82% and a PPV of 69%, while day 14 MRD had a NPV of 86% and a PPV of 49%. However, for predicting post-induction MRD, day 14 EBC had a NPV of 49% and a PPV of 15%, while day 14 MRD had a NPV of 71% and PPV of 74%. The correlation between day 14 and post-induction bone marrow aspiration is shown in Table 2. Bivariate analysis showed that achieving CR with negative MRD in post-induction bone marrow aspiration was associated with EBC (p CONCLUSION Patients showing EBC with negative MRD on day 14 bone marrow aspiration are more likely to achieve post-induction CR with negative MRD, with day 14 MRD by MFC being the only independent factor able to predict post-induction CR with negative MRD in our cohort. However, further prospective studies are needed to confirm our findings. Figure 1 Figure 1. Disclosures Martín-Rojas: Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Background: Prediction of patient outcomes following allogeneic hematopoietic stem cell transplantation (HSCT) remains a tenacious problem. An important limitation of current prediction models is the heterogeneity in outcome even among similar cases. We introduce a novel approach to individualizing estimates of leukemia-free survival (LFS) in acute leukemia patients undergoing haploidentical (haplo) HSCT. Methods: Data were obtained from the registry of the European Society for Blood and Marrow Transplantation for all cases of haplo HSCT for acute leukemia performed between 2011 and 2017. Patients receiving ex-vivo T-cell depleted grafts were excluded. Acute myeloid leukemia patients were classified by clinical disease ontogeny (de novo vs. secondary), cytogenetics, and FLT3-ITD/NPM1mut status; acute lymphoblastic leukemia patients by disease status and the presence of the Philadelphia chromosome. Common patient and transplantation parameters including recipient age, Karnofsky performance status (KPS), time from diagnosis to transplantation, conditioning and graft-versus-host disease (GvHD) prophylaxis were included. Data were split into training and geographic validation sets. Results: A total of 2,001 patients was included in the training set and another 270 in the validation cohort. In the training set, the median age was 50 years; 68% of patients were in complete remission, and 69% had a KPS ≥ 90; 87% received post-transplant cyclophosphamide and 13% antithymocyte globulin for GvHD prophylaxis. To provide the clinician insight on outcomes of similar patients, we developed a descriptive tool to visually explore outcomes of cases with comparable features. We next generated 50 random survival forest models for the prediction of 1-year LFS. In contrast to single point-estimates, the ensemble of 50 models generates a prediction interval accounting for predictive uncertainty. There was heterogeneity of variable importance between models, with either disease status or KPS leading in all models (Figure A). The model was well calibrated (Figure B); the median c-statistic was 0.64 on the validation set. An online interface presents the individual outcomes of the fifteen patients most similar to the index case, the prediction interval, and a visualization of all 50 survival forest predictions. Predictions for a sample patient are shown in Figure (C). Conclusions: We present the first system for individualized prediction of leukemia-free survival following T-cell replete haplo transplantation. A key, novel component of the model, distinguishing it from standard risk scores, is that it provides a measure of predictive certainty. This is essential for judging the robustness of prediction. Our approach is applicable to other clinical settings and can be used for designing risk-guided interventions and for informing patients and clinicians. Figure Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Blaise:Jazz Pharmaceuticals: Honoraria. Sica:F. Hoffmann-La Roche Ltd: Other: All authors received support for third-party writing assistance, furnished by Scott Battle, PhD, provided by F. Hoffmann-La Roche, Basel, Switzerland., Research Funding. Mohty:Stemline: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Introduction. In the absence of an HLA-identical sibling or a matched unrelated donor, whether to prefer a Haploidentical (Haplo) or a one antigen mismatched unrelated donor (MMUD) for allogeneic hematopoietic cell transplantation (HCT) remains an unanswered question. Implementation of graft-versus-host disease (GVHD) prophylaxis with post-transplant cyclophosphamide (PTCY) was initially pioneered in the Haplo and then also extended to MMUD setting, resulting in low rates of GVHD. Methods. This was a retrospective study from the EBMT registry. Included were adults undergoing either Haplo- or MMUD-HCT for acute myeloid leukemia during the period 2010-2018 and who were in first or second complete remission at allo-HCT. Only patients receiving unmanipulated grafts with PTCY as GVHD prophylaxis were included. Ex vivo and in vivo T-cell depletion were exclusion criteria. Comparisons were made among three groups: MMUD-HCT with peripheral blood as stem cell source (PBSC; n=124); Haplo-HCT with bone marrow (Haplo-BM; n=560); Haplo-HCT with PBSC (Haplo-PB; n=769). Results. Patients in Haplo-PB were older (median age of 55 years versus (vs) 52 and 51 years in MMUD-HCT and Haplo-BM, respectively; p Conclusion. According to our results, use of MMUD is associated to significantly higher LFS. However, our results highlight that both MMUD- and Haplo-HCT are valid options for transplant candidates, with no differences in GRFS. On the other hand, when choosing Haplo over MMUD, one should consider BM as stem cell source in order to better prevent GVHD. Further strategies to better prevent NRM are needed, particularly in Haplo-HCT. Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Blaise:Jazz Pharmaceuticals: Honoraria. Sica:F. Hoffmann-La Roche Ltd: Other: All authors received support for third-party writing assistance, furnished by Scott Battle, PhD, provided by F. Hoffmann-La Roche, Basel, Switzerland., Research Funding. Pane:Amgen: Consultancy, Other: Travel Expenses, Speakers Bureau; AbbVie: Consultancy, Other: Travel Expenses, Speakers Bureau; Daiichi Sankyo: Consultancy, Other: Travel Expenses; Jazz Pharmaceuticals: Consultancy, Other: travel expenses, Speakers Bureau; Novartis pharma SAS: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Other: Travel Expenses; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mohty:BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Stemline: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau.

INTRODUCTION Allogeneic hematopoietic stem cell transplantation (alloHSCT) has been established as a powerful treatment modality for patients with hematological malignancies. The graft-versus-leukemia effect, however, is strongly associated with the occurrence of graft-versus-host disease (GVHD) and subsequent transplant-related mortality (TRM). Several strategies are applied in order to prevent GVHD, the post-transplant cyclophosphamide (PT-Cy) is one of the most used in Haploidentical HSCT (Haplo-HSCT). Cyclophosphamide (CY) is an alkylating agent with antineoplastic and immunosuppressive activities. CY is metabolized by highly polymorphic enzymes to produce phosphoramide mustard which is a bifunctional DNA alkylating agent, is the therapeutically active metabolite. Thus, the aim of our study is to identity polymorphisms in the genes of the CY metabolism and correlated with complications post-HSCT (GVHD, TRM, veno-occlusive disease (VOD) or hemorrhagic cystitis (HC)). METHODS We selected 182 consecutive patients who received an Haplo-HSCT from 2007 to 2019. Eleven genes related to CY metabolism were analyzed (Table 1). The genotyping was performed in peripheral blood samples for recipient using an enrichment-capture custom gene panels (IDT probes) in a MiSeq platform (Illumina, USA). The bioinformatic analysis was carried out with BaseSpace software (Illumina, USA). Variants located in coding region and splicing sites were analyzed. We selected polymorphisms corresponding to read depth ≥30X in the canonical isoform with an allele frequency ≥0.4 and represented in at least 5% in our cohort. The collected clinical variables were age/gender recipient and donor, pathology, pretransplant status, conditioning regimen, total body irradiation, basal ferritin and CMV reactivation. Fisher test was used to compare the differences among groups. Statistical Package for the Social Sciences (SPSS, Chicago, USA) was used for statistical test. RESULTS The cumulative incidence rates for aGVHD of II-IV and III-IV grades at 100 days was 39% and 12% respectively. The cumulative incidence rates for cGVHD, moderate or severe cGVHD and TRM at 1000 days were 37%, 19% and 29%, respectively. Among the cases analyzed, 9% developed VOD and 25% HC. Patients who received ablative conditioning regimen presented a higher incidence of TRM (p=0.005). No other clinical data was associated with complications post HSCT. Forty polymorphisms were detected in 9 genes by bioinformatic analysis. The variants that presents some correlation (p Overall, polymorphisms related with decrease activity of enzymes that active cyclophosphamide (level lor active metabolite) were correlated with higher aGVHD, cGVHD, TRM and VOD (Table 1). On the other hand, polymorphisms associated with low activity in detoxification enzymes were correlated with higher toxicity (TRM). As described in bibliography, GSTM1 null allele were correlated with higher probability of developing VOD. CONCLUSIONS Genetic analysis of CY metabolism genes correlated with several post HSCT complications. The analyses of this variants before transplant could facilitate personalized risk and clinical management of patients undergoing Haplo HSCT. Results must validated in others cohorts of patients. Disclosures Kwon: Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Jazz: Consultancy, Honoraria.

Peter Paschka and Hartmut Döhner contributed equally. Background. SARS-CoV-2 infection (COVID-19) has had a great impact worldwide and its mortality has been reported to be higher in patients with haematological malignancies. However, description of its effects and outcomes among recipient of hematopoietic stem cell transplantation (HSCT) is scarce. Objectives. To describe the characteristics, treatment and outcome of COVID-19 in recipients of HSCT reported to the Madrid registry of COVID-19 ("HEMATO-MADRID COVID-19 registry"). Results. Data of 842 patients from 23 hospitals with haematological malignancies and COVID-19 infection were reported in the Madrid registry between March and June 2020. Among those, 87 (10.3%) patients were HSCT recipients: 58 auto-HSCT and 29 allo-HSCT (7 of them from matched related donor (MRD), 12 matched unrelated donor (MUD) and 10 haplo-HSCT). Characteristics of the population are described in Table 1. Median age at COVID-19 infection was 61 years (IQR, 53-67) and 35 patients (40%) were female. Recipients of auto-HSCT with COVID-19 were older and showed a trend towards a higher incidence of arterial hypertension (28% vs 10%, p=0.067) without statistical differences in other comorbidities; active disease requiring treatment at COVID-19 diagnosis was more frequent in auto-HSCT recipients (65% vs. 21%, p Conclusion. In our multicentric experience in a high COVID-19 impacted area, the median time of COVID-19 infection presentation was relatively late in transplanted patients, however shorter in allo-transplanted patients. COVID-19 related mortality was high in HSCT recipients, significantly higher in allo-transplanted patients. Factors associated to this higher mortality should be further investigated to promptly identify high-risk patients since the pandemic is still highly active worldwide. Disclosures Kwon: Gilead: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Jazz: Consultancy, Honoraria. Duarte:Incyte Corporation: Other: Has received speaker and advisor fees. Hernandez-Rivas:Rovi: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees. Jimenez Yuste:NovoNordisk: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Grifols: Honoraria, Research Funding; Bayer: Honoraria; Sobi: Consultancy, Honoraria, Research Funding; CSL: Honoraria; Octapharma: Honoraria.

¶ Martin-Rojas RM and Oarbeascoa G contributed equally to this work. INTRODUCTION Relapse is the main cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). The evaluation of minimal residual disease (MRD) could provide a more accurate assessment of the depth of response, and therefore identify patients with higher risk of relapse. AIMS The aim of our study was to analyze the impact of pre-HSCT flow cytometry (FCM) and molecular MRD together with chimerism and MRD in the early post-HSCT period in patients with AML. METHODS We conducted a retrospective study in patients with complete remission AML who underwent a HSCT between 2008 and 2019 in our center. MRD was analyzed by flow cytometry in bone marrow aspirates and by quantitative RT-PCR (NMP1, RUNX1-RUNX1T1, CBFB-MYH11, KMT2A-MLLT3, WT1) in bone marrow aspirates and/or peripheral blood. MRD was determined within the 30 days preceding the HSCT and at day +30 and +90 post-HSCT. Bone marrow and selected CD34+ lineage chimerism was analyzed by STR (AmpFISTR SGM Plus, Thermo Fisher) at days +30 and +90 post-HSCT. This study was approved by our Institutional Ethics Committee. Data were analyzed using IBM SPSS Statistics version 24 and R version 3.5.1. RESULTS A total of 115 patients were analyzed. Pre-HSCT MRD was negative in 58 patients (50.4%) and positive in 57 patients (49.6%). We found no statistically significant differences in the characteristics between the two groups (Table 1). Median follow up was 39 months (IQR 10.4-55.8). 3-year overall survival (OS) for patients with pre-HSCT negative MRD was 72.5% versus 70.3% in patients with positive MRD (p=0.41), with an event free survival (EFS) of 66.9% versus 66.1 (p=0.48) respectively (Figure 1). Median time to the beginning of immunosuppression withdrawal was 82.5 days (IQR 59-93) for patients with negative MRD and 68 days (IQR 55.3-85.3) for patients with positive MRD (p Patients with negative MRD at day +30 showed a 2-year OS of 83.5% versus 58.1% in patients with positive MRD (p=0.03) and a EFS of 79.9% versus 48.6% (Figure 2). The cumulative incidence of relapse was more elevated in patients with positive MRD (29.8% versus 13.6%) at day +30. Patients with mixed chimerism (MC) at day +30 showed a significantly lower 3-year OS and EFS than patients with complete chimerism (CC). Likewise, the cumulative incidence of relapse was significantly higher in patients with MC, both if detected in bone marrow aspirate and in CD34+ cells. The multivariate analysis revealed that MRD status at day +30 post-HSCT was an independent prognostic factor for EFS (HR 3.74; 95% CI 1.38-10.1; p=0.009). CONCLUSIONS Patients with AML presenting a positive MRD in the early post-HSCT period and those who show a MC at day +30 post-HSCT have lower EFS, with positive MRD at day +30 being an independent prognostic factor for EFS. The evaluation of MRD and chimerism in the early post-HSCT period is useful to identify patients with higher risk of relapse, who may take advantage of preemptive measures. Disclosures Kwon: Gilead, Novartis, Pfizer, Jazz: Consultancy, Honoraria.

INTRODUCTION COVID-19 is associated with coagulopathy that correlates with poor prognosis. Although the underlying mechanism of COVID-19 coagulopathy remains unknown, early reports suggested that it may be a form of disseminated intravascular coagulation (DIC). However, recent studies have highlighted the potential role of endothelial cell injury in its pathogenesis. AIMS The aims of our study were to analyze the coagulation parameters of critically and non-critically ill patients with COVID-19 pneumonia admitted to our hospital, determine if coagulation factors consumption occurs, identify potential prognostic biomarkers of this new disease and explore possible underlying mechanisms of COVID-19 coagulopathy. METHODS We conducted a retrospective cohort study performed at Gregorio Marañon Hospital in Madrid, Spain. Adult patients with a diagnosis of COVID-19 hospitalized in our center were recruited, including those admitted to the ICU and to general wards. Patients were randomly selected from blood samples that arrived at our Hemostasis laboratory during April 2020. For each patient, we conducted a complete analysis of coagulation parameters, including basic coagulation tests, quantification of coagulation factors and physiological inhibitor proteins, evaluation of the fibrinolytic system and determination of von Willebrand Factor (vWF) and ADAMTS13. Laboratory data were compared with clinical data and outcomes. Data were analyzed using IBM SPSS Statistics for Mac, version 24. This study was approved by our institutional Ethics Committee and it was executed along with the international ethics recommendations for conducting research in humans following the latest revision of Declaration of Helsinki. RESULTS A total of 62 patients (31 ICU, 31 non-ICU) were analyzed. Mean age of the sample was 61.8 (SD 15.2) years and 69.4% of the patients were male. The coagulation parameters assessment demonstrated normal median PT, INR and APTT in our cohort and all coagulation factors were within normal range. Factor VIII showed an increasing trend (194.5±71.9) which could be interpreted as an acute phase reactant, and it was significantly higher in non-survivors (p=0.003). Similarly, we did not observe consumption of physiological inhibitor proteins and platelet counts were also within the normal limits, despite being slightly lower in non-survivor patients (p=0.006) (Table 1). Von Willebrand Factor (vWF) was above the normal range (median 216%, IQR 196-439, normal range 62-175%) in our cohort and higher levels of vWF-antigen (p=0.001) and vWF-activity (p=0.02) were associated with poor prognosis. Likewise, a lower ADAMTS13 activity was observed in non-survivors (p=0.008). Regarding the fibrinolytic pathway, PAI levels were above the normal range (median 52.6ng/ml, IQR 37.2-85.7, normal range 4-40ng/ml), but we found no statistically significant differences based on survival. The remaining parameters of the fibrinolytic pathway (plasminogen and alpha-2 antiplasmin) were within normal range (Table 1). ICU-patients had a poorer prognosis, with a higher rate of mortality (p=0.003). Likewise, they showed more elevated acute phase reactants (p CONCLUSIONS COVID-19 infection is associated with coagulopathy that correlates with poor prognosis. However, coagulation factors, physiological inhibitory proteins and alpha-2-antplasmin levels were preserved in our study. Similarly, we did not observe platelets or fibrinogen consumption, which leads us to assume that COVID-19 coagulopathy is not a form of DIC. Increased vWF and decreased ADAMTS13 activity in our cohort could indicate that the underlying mechanism of this coagulopathy may reside in the endothelial cells and share a similar pathogenesis with thrombotic microangiopathy (TMA), as it has been recently suggested in some scientific reports. Disclosures No relevant conflicts of interest to declare.

Introduction: Non-Hodgkin B lymphomas (NHL-B) are a large group of heterogeneous diseases, with well-defined, histological and clinical features. Currently, the lymph node biopsy is essential for diagnosis, often obtained from hard to reach areas. Our aims with this study was to analyze genetics variants at diagnosis trying to discriminate between different NHL-B histologic subtypes using formalin fixed paraffin embedded (FFPE) tissue sections and circulating tumor free DNA (ctDNA) samples. Material and Methods: This is a retrospective, cross-sectional, single-center study. Sixty patients were selected with a diagnosis of different NHL-B subtypes: Diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), marginal lymphoma (ML), mantle cell lymphoma (MCL) and plasmablastic lymphoma (PL). Sixty FFPE tissue samples and 23 ctDNA specimens obtained at diagnosis were selected. We performed an enrichment panel of 54 genes recurrently mutated in lymphomas (Lymphoma Solution; Sophia Genetics) by next generation sequencing (NGS; NextSeq; Illumina). The depth of 90% of the readings was greater than 2600x. Quantitative variables were expressed as median and range. Categorical variables were expressed as frequency and percentage. The Fisher exact test was used to compare the distribution of categorical variables. The Mann-Whitney test was used to compare differences between quantitative variables. Statistical significance was set at p < 0.05. Results: Our study shows that 97% (58/60) of patients presented any variant. The most frequently mutated genes were KMT2D, EP300 and SOCS1. Exclusive variants were detected in FL in the genes CCND1, PAX5, CREBBP, BCL2 and REL genes. In the same way, in DLCBL the variants detected in the BRAF, TCF3, XPO1, PIM1, CHD2, ID3 and BCL6 genes were exclusive of this subtype. Furthermore, the genes BCL2 (p=0.0021), CREBBP (p=0.0004), NOTCH2 (p=0.03), PAX5 (p=0.01) and TNFRSF14 (p=0.04) are more frequently altered in patients with FL, ATM (p=0.02) gene in MCL; NFKBIE (p=0.03), CIITA (p=0.02), MYC (p=0.009) and PIM1 (p=0.04) in DLCBL, among which it was found that high-grade lymphomas are more frequently associated with mutations in CHD2 (p=0.02), MYC (p=0.03) and MYD88 (p=0.02; data not shown). In the subgroup of 23 patients with paired samples (FFPE/ctDNA), 95% (22/23) of patients had mutations in any of the genes on the panel in FFPE tissue samples and 82% (19/23) in ctDNA specimens. The number of variants detected was different depending on the type of sample analysed, 52% of the variants were detected in both specimens, 39 only in FFPE tissue and 9% in ctDNA; Figure 1). In variants detected in both samples, the average value of the VAF was higher that when is detected only in one of the samples (FFPE: 28.1 vs 5.8 (p We did not find significant differences in the number of variants depending on the stage, classification, tumour burden or bulky mass (Table 1). Conclusion: In our study, we were able to identify genetic variables that could characterize different histological groups of NHL-B in FFPE tissue and ctDNA samples, by using a commercial gene panel of NGS. The mutational profile obtained from ctDNA and FFPE tissue is comparable in all histological subtypes, regardless tumour burden, aggressiveness or stage, throwing each one of them complemental information. These results support the hypothesis that could be possible to distinguish different histologies through non-invasive strategies, specially oriented to lesions where obtaining a tissue sample is difficult. We are working on the development of clinical-genetic algorithms that allow us to achieve our goal. Disclosures No relevant conflicts of interest to declare.

Introduction: The use of post-transplant cyclophosphamide (PTCy) is highly effective in preventing graft-versus-host disease (GVHD) in the haploidentical (Haplo) transplant setting and is being increasingly used in matched sibling (MSD) and matched unrelated (MUD) transplants. Although PTCy-Haplo has been compared with different transplant platforms, there is no information on the impact of donor types using homogeneous prophylaxis with PTCy. Methods:We retrospectively analysed outcomes of adult patients with acute myeloid leukemia (AML) in first complete remission (CR1) that received a first allogeneic stem cell transplantation (SCT) with PTCy as GVHD prophylaxis from MSD (n=215), MUD (n=235) and Haplo (n=789) donors registered in the EBMT database between 2010 and 2017. The median follow up period of the entire cohort was 2 years. Results: Median age of patients was 52 years (range, 18-76), 693 (56%) were male and 928 (78%) were CMV seropositive. AML was de novo in 1,046 (84%) patients, while 47 (6%),543 (66%) and 239 (29%) had standard, intermediate and high risk cytogenetics, respectively. Peripheral blood (PB) was used as the stem cell source in 814 (66%) patients. Regarding conditioning, 962 (78%) were chemotherapy based regimens and 500 (41%) patients received reduced intensity conditioning (RIC). Preferred conditioning regimens were thiotepa, busulfan, fludarabine for Haplo (n= 371; 47%) and busulfan, fludarabine for MSD (n= 83; 39%) and MUD (n= 102; 43%). Patients received a variety of PTCy containing immune suppressive regimens, the most frequently used being PTCy, calcineurin inhibitor and mycophenolate mofetil in Haplo (n= 684; 87%) and PTCy and calcineurin inhibitor alone in MSD (n= 52; 24%) and MUD (n= 74; 31%). In-vivo T-cell depletion (TCD) was used in 164 (13%) patients. Compared to MSD and MUD, Haplo patients were older and less frequently received RIC, TCD and PB but the distribution of cytogenetic risk group was similar between the donor types. Cumulative incidence of neutrophil recovery at 60 days was 95% (95% CI 94-96). The cumulative incidence of 100 day acute GVHD grade II-IV and III-IV, and 2-year chronic and chronic extensive GVHD were 25% (95% CI 23-28), 9% (95% CI 7-10), 31% (95% CI 28-34) and 12% (95% CI 10-14), respectively. At 2 years, the cumulative incidence of relapse and non-relapse mortality (NRM) and the probability of leukemia-free survival (LFS) and overall survival (OS) were 25% (95% CI 22-28), 19% (95% CI 17-21), 56% (95% CI 53-59) and 63% (95% CI 60-66), respectively. On multivariable analysis, outcomes were not significantly different for MSD and MUD. Haplo-SCT carried a significantly increased risk of acute grade II-IV GVHD (HR 1.6; 95% CI 1.1-2.4) but the risk was not significant for chronic GVHD (HR 1.2; 95% CI 0.8-1.8). Haplo-SCT carried a higher risk of NRM (HR 2.6; 95% CI 1.5-4.5) but a lower risk of relapse (HR 0.7; 95% CI 0.5-0.9) that translated to no change in LFS (HR 1.1; 95% CI 0.8-1.4) or GVHD/relapse-free survival (HR 1; 95% CI 0.8-1.3). The most frequent cause of death was relapse for MSD (n= 36, 53%) and MUD (n= 41, 48%) and infection for Haplo (n = 107, 39%). Interestingly, the use of PB was associated with an increased risk of acute (HR 1.9; 95% CI 1.4-2.6) and chronic GVHD (HR 1.7; 95% CI 1.2-2.4) but a lower risk of relapse (HR 0.7; 95% CI 0.5-0.9). Other variables that had an impact on LFS were: poor risk cytogenetics (HR 1.4; 95% CI 1.1-1.7), use of MAC-Chemo (HR 0.7; 95% CI 0.6-0.9), Karnofski performance status Conclusions:The use of PTCy in patients with AML in CR1 receiving SCT from MSD, MUD and Haplo is safe and effective and rates of GVHD are low, especially chronic. HLA mismatch in Haplo has a negative impact on acute GVHD and NRM in this setting but also offers increased anti-leukemic efficacy. As seen in other transplant scenarios, PB is associated with more GVHD and less relapse. Figure Disclosures Angelucci: Novartis: Honoraria, Other: Chair Steering Committee TELESTO protocol; Celgene: Honoraria, Other: Participation in DMC; BlueBirdBio: Other: Local advisory board; Jazz Pharmaceuticals: Other: Local advisory board; Roche: Other: Local advisory board; Vertex Pharmaceuticals Incorp., and CRISPR Therapeutics: Other: Participation in DMC. Blaise:Jazz Pharmaceuticals: Honoraria; Sanofi: Honoraria; Pierre Fabre medicaments: Honoraria; Molmed: Consultancy, Honoraria. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding.

INTRODUCTION Allogeneic haematopoietic stem cell transplant (allo-HSCT) could be the only curative therapy for patients with hematological malignancies due to graft effect against tumor. However, approximately 40% of patients develop post-transplantation complications such as acute graft-versus-host disease (aGVHD). Cytokines and their receptors are involved in regulatory and inflammatory processes that occur during GVHD. Therefore, the analysis of polymorphisms (SNPs) that affect the expression or activity of these genes could be used as biomarkers to predict the development of these complication. The aim of this study was to select new polymorphisms in cytokine genes (interleukins, chemokines and their receptors) to build models to predict the development of aGVHD after allo-HSCT from an HLA-identical sibling donor. METHODS We retrospectively selected 88 patients with hematological malignancies who received an allo-HSCT from an HLA-identical sibling donor from 2000 to 2015. A total of 176 pre-transplant recipient (R) and donor (D) peripheral blood samples were collected. The genotyping was performed using an enrichment-capture gene panels (include 132 genes (73 interleukins, 59 chemokines) in a HiSeq platform (Illumina, USA). The bioinformatic analysis was carried out with the GeneSystemssoftware (Sistemas Genómicos, Spain). Variants located in coding region, splicing sites, and UTR, 5'upstream and 3'downstream zones (+ 200pb) were analyzed. We selected polymorphisms corresponding to non-synonymous variants, represented in at least 5% of our cohort, with readings ≥30X in the canonical isoformwith an allele frequency ≥ 0.4. Fisher test was used to compare the differences among groups. Multiple logistic regression models were performed using combination of interleukins and chemokines polymorphisms selected previously that could be applied to clinical practice to predict aGVHD. The models with the highest AUC value, sensitivity and specificity value and the lowest number of genetic variants used were selected.Statistical Package for the Social Sciences (SPSS, Chicago, USA) was used for statistical test. RESULTS The cumulative incidence rates for aGVHD of grades II-IV and III-IV at 100 days after transplantation were 48.93% and 18.08%, respectively. The clinical variables (age, gender, pathology, stem cell source and previous transplantation) were not correlated with II-IV or III-IV aGVHD. However, patients who received ablative conditioning regimen presented a lower incidence of III-IV aGVHD (p= 0.041). Using filters defined previously, we detected 481 polymorphisms (350 coincident, 68 specific R and 63 for D) in the interleukins group. On the other hand, we detected 339 polymorphisms (267 coincident, 29 specific R and 43 for D) in the group of chemokines. Finally, 17 polymorphisms were selected in the interleukin group and 10 in the chemokine group for its correlation with the aGVHD (p We developed multiple logistic regression models for II-IV and III-IV aGVHD in interleukins and chemokines genes (Table 3). The identification of these 15 polymorphisms could help us to prevent the developing II-IV and III-IV aGVHD. CONCLUSIONS We have identified new genetic polymorphisms correlate with the risk of developing aGVHD after allo-HSCT from an HLA-identical sibling donor. Based on these data, we have developed a genetic score that encompasses polymorphisms of greater relevance. In this way, patients at greatest risk for developing this type of post-transplantation complication who could benefit from personalized management through immunosuppression and other drugs. Disclosures No relevant conflicts of interest to declare.

Background: The number of non T depleted haploidentical stem cell transplantations (haplo SCT) with post transplantation cyclophosphamide (PTCy) in adult patients (pts) with acute lymphoblastic leukemia (ALL) is increasing (Shemtov N et al, Leukemia 2019). Although the original haplo SCT with PTCy were performed with bone marrow (BM) grafts, the use of peripheral blood stem cells (PBSC) as the stem cell source may provide some advantages in engraftment and anti-leukemic effect which may be of special importance in ALL. Aim: The goal of this study was to compare BM to PBSC as stem cell source for non-T-cell-depleted haplo SCT with PTCy in adult pts with ALL in first or second complete remission (CR). Methods: The study was based on the haplo SCT with PTCy in adult pts with ALL that met the study inclusion criteria and that were reported to the European Society for Blood and Marrow Transplantation (EBMT) registry from 2010 to 2018. Multivariate analyses (MVA) were performed using the Cox proportional hazard model. Results: A total of 314 pts were reported, 157 of whom received BM and 157 received PBSC as the stem cell source. The median age at transplantation was 37 years (range, 18-68 years) and 36 years (range, 18-73 years), 66% and 62% were males, respectively. Diagnosis was Ph negative B-ALL in 39% and 41% of the pts, Ph positive in 32% and 34 % and T ALL in 29% and 25%, respectively.61% and 65% were in CR1, while 39% and 35% were in CR2. Pts and donor characteristics did not differ between the groups. More pts in the BM group received myeloablative conditioning (MAC), 87% vs 71% in the PBSC group, p Conclusion: In pts with ALL in remission receiving haplo SCT with PTCy, the use of BM versus PBSC grafts resulted in better LFS, OS and GRFS. Disclosures Angelucci: Jazz Pharmaceuticals: Other: Local advisory board; Roche: Other: Local advisory board; Vertex Pharmaceuticals Incorporated, and CRISPR Therapeutics: Other: Partecipation in DMC; BlueBirdBio: Other: Local advisory board; Novartis: Honoraria, Other: Chair Steering Committee TELESTO protocol; Celgene: Honoraria, Other: Partecipation in DMC. Socie:Alexion: Consultancy. Blaise:Molmed: Consultancy, Honoraria; Sanofi: Honoraria; Pierre Fabre medicaments: Honoraria; Jazz Pharmaceuticals: Honoraria. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding.

Background The intensity of a conditioning regimen has significant impact on outcomes of allogeneic hematopoietic cell transplantation in acute leukemia. In acute lymphoblastic leukemia (ALL) patients undergoing matched donor transplant, total body irradiation (TBI)- based myeloablative conditioning (MAC) regimen was associated with improved leukemia free survival (LFS) compared to chemotherapy (CT)-based MAC (Eder S. et al. 2017). Haploidentical hematopoietic cell transplantation(haplo-HCT) with post-transplant cyclophosphamide (PTCy) has emerged as a safe alternative in absence of a matched donor. The optimal MAC in haplo-HCT setting is yet to be defined. We studied the outcomes of TBI- vs. CT-based MAC in ALL patients undergoing haplo-HCT and reported to the Acute Leukemia Working Party of the EBMT. Methods The study included 427 ALL (B-ALL-75%) patients, that underwent haplo-HCT with PTCy during the years 2010-2018, following TBI- (n=188, 44%) or CT- (n=239, 56%) based MAC. Regimen intensity was defined by EBMT criteria and cases with busulfan dose Results In univariate analysis, day 100 incidences of acute GVHD II-IV and III-VI were 38% vs. 30% (p-0.07) and 19% vs. 13% (p-0.14) for TBI and CT cohort, respectively. Two-year overall and severe chronic GVHD incidences were 34% vs. 30% (p-0.51) and 17% vs. 12% (p-0.18) for TBI and CT cohort, respectively. Graft failure was reported in 6 (3%) and 19 (8%)(p-0.09) patients who received TBI and CT-based MAC, respectively. Death from veno-occlusive disease was reported in 4 (5%) TBI patients and 8 (7%) CT patients. There was no difference in reported deaths due to infection (28%) or interstitial pneumonitis (4%) among study cohorts. In multivariate analysis, TBI was associated with significant improvement in nonrelapse mortality (NRM) [HR=0.51, 95% CI:0.32-0.83, p In a subgroup univariate analysis of patients Conclusions TBI based MAC resulted in significant reduction of NRM, translating into a better LFS without impacting aGVHD III-IV, chronic GVHD, RI or OS when compared to CT based MAC. Non-significant difference in OS between TBI and CT cohorts might be related to lower number of events, short follow-up and/or salvage therapies after relapse. These novel findings based on a large cohort of ALL patients, support the use of TBI based MAC and bone marrow graft in haplo-HCT with PTCy. Disclosures Dholaria: Celgene: Honoraria. Labopin:Jazz Pharmaceuticals: Honoraria. Angelucci:Novatis: Honoraria, Other: Chair Steering Committee TELESTO protocol; Celgene: Honoraria, Other: Participation in DMC; BlueBirdBio: Other: Local advisory board; Jazz Pharmaceuticals: Other: Local advisory board; Roche: Other: Local advisory board; Vertex Pharmaceuticals Incorp., and CRISPR Therapeutics: Other: Participation in DMC. Apperley:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Socie:Alexion: Consultancy. Mohty:Jazz Pharmaceuticals: Honoraria, Research Funding.

Background: The use of unmanipulated Haploidentical HSCT (Haplo-HSCT) with post-transplant Cyclophosphamide (PT-Cy) as GVHD prophylaxis has widely extended. Veno-occlusive disease (VOD) is a threatening complication after both autologous and allogeneic HSCT, with high mortality rates despite early medical treatment, including the use of defibrotide. The objective of this study was to describe characteristics and outcomes of patients with refractory very severe VOD after Haplo-HSCT with PT-Cy, treated with TIPS as salvage procedure. Methods: We retrospectively analysed 176 Haplo-HSCT with Cy-post consecutively performed between 2011 and May 2019 in a single centre. VOD was defined according to modified Seattle, Baltimore or revised EBMT criteria. Severity was retrospectively graded according to revised EBMT severity criteria into four categories: mild, moderate, severe and very severe. Complete response (CR) was defined as a normal total bilirubin level ( Results: Sixteen patients (9.1%) met the modified Seattle, Baltimore or revised EBMT diagnostic criteria for VOD. Ultrasound with Doppler ultrasonography was performed in all patients, and at least indirect signs of VOD were found in all cases. Based on revised EBMT severity criteria, there were 2 mild (12.5%), 2 moderate (12.5%), 2 severe (12.5%) and 10 very severe (62.5%) grade VOD. Twelve patients (75%) were treated with defibrotide, including all patients with very severe VOD, except one with CNS hemorrhage (Patient 1). Six patients with very severe VOD, were treated with TIPS due to rapid clinical or analytical deterioration or refractory hepatorenal syndrome, despite medical treatment including defibrotide (Table 1). All were male patients, with a median age of 31 years (range 22-36), all transplanted with myeloablative conditioning regimen. TIPS insertion was performed on a median time since VOD diagnosis of 5 days (range 1-28) without technical complications in any case. Median total bilirubin, ALT, creatinine and INR the day of procedure were 3 mg/dL (range 2.2-11.2), 1120 UI/L (range 10-2595), 2.45 mg/dL (range 2.06-3.58) and 1.96 (range 1.1-4) respectively. Median hepatic venous pressure gradient (HVPG) prior to and after TIPS was 22.5 (range 14-29) and 6.5 (range 2-10) mmHg respectively, with a median drop of 16.5 mmHg (range 9-19). Following TIPS, all patients showed clinical improvement with hepatomegaly, ascites and renal failure resolution, and all showed analytical improvement with bilirubin, creatinine and ALT values reduction, except for patient 2, whose TIPS indication was refractory hepatorenal syndrome with normal ALT levels (Figure 1). The 5 patients who had iniciated defibrotide before TIPS, completed 21 days of treatment. All patients met criteria for CR in a median of 8 days after TIPS insertion (range 2-82). The 100-day overall survival (OS) was 100%. Five patients were alive with normal liver and renal function at last follow up, and one patient died due to infection 7 months after Haplo-HSCT, with VOD in complete resolution. Conclusions: Incidence of VOD after Haplo-HSCT with PT-Cy is comparable to those reported after HLA-identical HSCT series. Most of the patients developed very severe VOD according to revised EBMT severity criteria. For patients with rapid progressive VOD, early TIPS insertion allowed completion of defibrotide therapy. The use of TIPS together with defibrotide resulted in complete response and no associated complications with a 0% of VOD associated mortality in spite of high severity. ALT values may be the best predictor of CR after TIPS procedure. In our experience, timely and individualized use of TIPS significantly improves outcome of very severe VOD after Haplo-HSCT. Therefore, TIPS should be promptly considered in rapid progressive cases. Disclosures No relevant conflicts of interest to declare.

Introduction: Invasive Fungal Infection (IFI) is a serious complication after allogeneic stem cell transplantation (alloSCT). Its incidence and outcome are not well characterized in the setting of peripheral blood, non-manipulated haploidentical stem cell transplantation with postransplant cyclophosphamide (HaploSCT). The aim of the study is to analyze our experience among patients who underwent HaploSCT at our institution and developed an IFI, in order to identify the incidence, risk factors and its impact in survival. Materials and methods: One hundred and thirty-three patients underwent peripheral blood HaploSCT with postransplant cyclophosphamide at our institution between 2011 and 2017. IFI was classified according to the EORTC definitions. Proven and probable IFI were included. Results: Patients´ characteristics are shown in Table 1. Patients received primary antifungal prophylaxis with micafungin from the day before stem cell infusion, during admission and until neutrophil engraftment was stablished. Patients on steroid treatment due to GVHD received prophylaxis with micafungin or posaconazole. Twenty-three episodes of IFI were observed in 20 patients, 10 proven and 13 probable, with a cumulative incidence of IFI of 15% at 500 days. Most commonly isolated organism was Aspergillus spp (5 cases), followed by Candida spp (4 cases: 1 C. kruseii and 3 C. parapsilosis) and Fusarium spp (2 cases). Additionally we observed some isolated cases of Inonotus spp,Mucor spp and Trichosporon Ashii. Pulmonary involvement was the most frequent presentation (11 cases), followed by fungemia (5 cases, 4 Candida and 1 Trichosporon Ashii) and skin-pulmonary involvement (2 cases). Thirteen cases were diagnosed early, in the pre-engraftment period, 5 just after the engraftment and 5 cases developed later. Among patients with late occurrence of IFI, median time of IFI was 220 days, and all of them were associated with GVHD (3 grade III-IV acute GVHD and 2 moderate/severe chronic GVHD). IFI outcome was favorable in 14 out of the 23 documented IFI, with antifungal therapy. Treatment chosen was liposomal amphotericin B in 7 cases, voriconazole in 5 and combined treatment (with amphotericin B and azole) in 6. Death related to IFI was documented in 7 out of the 20 patients, with an IFI mortality cumulative incidence of 6.4%. Prior transplant (OR 4.5, p Conclusions: In our experience, cumulative incidence of IFI in the setting of HaploSCT was similar than the one observed in other studies with alloSCT. Mortality associated to IFI in the whole cohort was low (6.4 %). The most significant factor related to IFI development was having received a previous transplant, especially alloSCT. Therefore, this high risk population should be closely monitored and could benefit from prophylaxis with azoles. Disclosures No relevant conflicts of interest to declare.

Background: Post-transplant high dose cyclophosphamide (PT-CY) effectively prevents graft-versus-host disease (GVHD) after HLA-haploidentical hematopoietic stem cell transplantation (HSCT). However, the use of PT-CY in HLA-identical HSCT is less explored. In this study, we analyzed the results of PT-CY as GVHD prophylaxis in HLA-identical sibling HSCT and compared them with those obtained after prophylaxis with methotrexate (MTX) plus cyclosporine (CsA). Methods: 107 HLA-identical sibling (10/10) HSCT from 2 Spanish centers have been analyzed: 50 performed consecutively between 2010 and 2015 using MTX-CsA as GVHD prophylaxis, and 57 performed consecutively between 2014 and 2018 using PT-CY. Results: Baseline characteristics and post-transplant complications are shown in Table 1. GVHD prophylaxis consisted in MTX days +1, +3, +6 and +11, and CsA from day -1 in the MTX-CsA group. The PT-CY group received cyclophosphamide 50 mg/kg/d on days +3 and +5 in 38 patients (65%), combined with CsA from day +5, and cyclophosphamide on days +3 and +4 in 19 patients (35%), followed by CsA and mycophenolate mofetil from day +5. Graft source was PBSC in 96% in the MTX-CsA group and 86% in the PT-CY group. Conditioning regimen was myeloablative in 64% and 40%, respectively. Neutrophil and platelet engraftment was significantly delayed in the PT-CY group (14.5 (11-27) vs 15.5 (13-37), p=0.02; 11.5 (8-180) vs 20.5 (10-43), p=0.02). After a median follow-up of 60 months for the MTX-CsA group and 15 months for the PT-CY group, 2-year overall survival (OS) was 56% (42-70) and 78% (67-90) (p=0.088), and event-free survival (EFS) was 48% (34-62) and 62.5% (42.5-82.5) (p=0.054), respectively. Cumulative incidence at 100 days of grade II-IV (52.2% vs. 22.6%, p=0.0015), and III-IV (24.4% vs. 8.8%, p=0.016) acute GVHD were significantly higher in the MTX-CsA group (Figure 1A). No differences were observed in the 2-year cumulative incidence of chronic moderate to severe GVHD (26% vs. 16.7% (p=0.306)). No differences were observed in the 2-years cumulative incidence of relapse (27% vs. 28% (p=0.47)). Non-relapse mortality (NRM) at 2-years showed a higher trend in the MTX-CsA cohort (24% vs. 8.8%, p=0.054). Finally, the composite endpoint of GVHD and relapse-free survival (GRFS) at 2-years was significantly better in the PT-CY group (48% vs. 24%, p=0.011) (Figure 1B). Conclusions: In our experience, GVHD prophylaxis using PT-CY combined with additional immunosuppression after HLA-identical sibling HSCT, using mostly peripheral blood as graft source, reduced the cumulative incidence of acute GVHD compared to standard prophylaxis with MTX-CsA, leading to an impact on GRFS. To our knowledge, this is the largest comparative retrospective cohort reported. Further prospective studies with longer follow-up are needed to confirm these observations. Disclosures No relevant conflicts of interest to declare.

Introduction Donor cell derived myeloid neoplasm (DCMN), defined as the development of de novohematological malignancies from cells of donor origin,is a late complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We report on seven cases of DCMN in which whole-exome sequencing (WES) at different time-points after allo-HSCT, as well as in a sample from each donor, was performed. The ultimate objective was to accurately described the clonal architecture, spatial heterogeneity and identify somatic mutations that are induced in the process of leukemogenesis and clonal evolution of myeloid neoplasm. Donors were also analyzed to detect underlying condition predisposing to the development of DCMN. Patient and Methods Seven patients with a confirmed diagnosis of DCMN and their donors were recruited from different Spanish institutions. This cohort included a total of 32 BM samples at different time points after allo-HSCTand one PB sample from each donor (one case received dual allo-HSCT, CB and PB from both donors were obtained), which provided a total of 40 samples. Genomic DNA samples were prepared according to Agilent SureSelect-XT Human exon 50Mb enrichment kit (Agilent Technlogies, Santa Clara, CA) preparation guide and libraries were sequenced on Illumina HiSeq platform (Illumina, San Diego, CA). DNA sequencing data from recipient post-transplant BM samples, were matched against their donor PB sample and previous post-transplant BM samples to identify the acquisition of mutations along the post allo-HSCT period.Germline variants in donors were studied in order to detect mutations that predisposed to the development of a myeloid neoplasm.The research protocol was approved by the Ethic Committee of Gregorio Marañón General University Hospital. Patients´ and donors´ information was collected from their medical records. Results Clinical and biological characteristics of the 7 patients with DCMN and their donors are shown in Table 1. Mutational profiles obtained from the follow-up samples at different time-points post-HSCT demonstrated high intra-tumor genetic heterogeneity and clonal dynamic for all cases. The number of variants are increased over time and at the moment of DCMN diagnosis, the median number of variants was 28, ranging from 18 to 92 variants (Figure 1). WES identified in DCMN patients gene mutations commonly seen in adult AML or MDS, such as in SETBP1, DNMT3A, TET2, RUNX1, CSF3R, EP300and IDH2.In addition, others non-silent variants were acquired in all cases. Among the additional novel alterated genes, we found 23 strong candidateswith oncogenic potential. LUC7L2, NOP14, LAMA5, SKOR2, EML1, SNX13, RHPN2, IRS1, MTG2, TENM2, MEFV, GSE1, NOTCH4, DTX1, CNOT4, PNKP, GRB7,SENP7,TAF1L, ZKSCAN2, ZBTB20, ZNF461 and MEGF10. Analysis of CNVs revealed numerical alterations across the post allo-HSCT samples in patients 1, 2, 3, 4, 5 and 7. The most common chromosomal alterations in DCMN were monosomy 7 and other chromosome 7 abnormalities, which detected in the 86% (6/7) of the patients. Although none of the donors developed a myeloid neoplasm at the moment of diagnosis of DCMN in recipient, donor 1 revealed an abnormal karyotype (45,XY,-7) at the moment of the allo-HSCT. All other donors harbored at least one pathogenic or probably-pathogenic variants, most probably of germline origin, in genes involved in hematological or solid tumor predisposition. Conclusions The development of DCMN involves dynamic genomic processes that begin months before the clinical onset. In this study, our integrated multi-step analysis revealed the intra-tumor heterogeneity and evolutionary history of seven DCMN. The present study reveals a process of sequential clonal expansions promoted by the acquisition of somatic mutations in donor hematopoietic cells. Detection of heritable or acquired gene mutations in donors associated with predisposition to haematological malignancies could have clinical implications for the patients undergoing to allo-HSCT. Leukemic transformation ofdonor hematopoietic stem cells provides a useful in vivomodel to study the mechanisms involved in leukemogenesis. Novel approaches based on high-depth next generation sequencing to study consecutive samples from post-transplant period in these patients, appear promising to discover new genes involved in myeloid neoplasm and to decipher the mechanisms of leukemogenesis. Disclosures No relevant conflicts of interest to declare.

Introduction: Multidrug-resistant organisms (MDRO) are a challenge in patients undergoing stem cell transplant (SCT) which often result in an increase in mortality. To our knowledge, current literature defines only screening at the time of work-up for SCT-patients. The aims of the study were to assess the rate of MDRO colonization with weekly screening, rate of infection and the associated mortality in patients undergoing SCT. Patients and methods: Consecutive patients admitted at the SCT unit between January-18 to July-18 were reviewed in our institution. Screening consisted of rectal and perineal swab on admission and weekly until the date of discharge. In case of detection of MDRO , patients were isolated and infection control strategies were applied. Results: 41 patients were analysed, with 47 admissions, 6 patients had 2 admissions. The median duration of hospitalization was 27 days/patient (range 8-100). 168 rectal-and perineal swab were performed with a median of 3 swabs/patient (range 1-7). Patient characteristics are shown in Table 1. 36 patients (87%) spiked fever in a median of 8,5 days after admission (1-38days). 24,4% (n=10) had a positive screening: 2/10 patients at baseline and 8/10 patients (80%) were detected for the first time beyond baseline screen. Rate of MDRO colonization was 3% per week (95%CI 1.4-5.4). MDRO identified were : 4 patients with Extended-spectrum beta-lactamases producing E. Coli (ESBL-EC), Multidrug-resistant (MR) Pseudomonas aeruginosa (n=3), Vancomycin-resistant Enterococci (n=2) and 1 patient with carbapenem-resistant Citrobacter freundii. 6/10 patients developed MDRO infection (60%), all with previous MDRO positive detection: MR-Pseudomonas aeruginosa in urine culture (n=3) 2 treated with ceftolozane/tazobactam, 1 with meropenem+amikacin; ESBL-EC in urine culture (n=2) both treated with meropenem and 1 with Klebsiella pneumoniae carbapenemase in urine culture treated with ceftazidime/avibactam. The infection rate was 4,6% (95% CI 3.9-5.2). In 80% patients (n=8) antibiotic treatment was guided by positive screening, 3 patients were admitted to intensive care unit for sepsis. No mortality was associated to MDRO. In 76%of patients (n=28) screening was negative for MDRO. 24/28 (85%) spiked fever with a median of 10 days after admission (1-38days). None MDRO-infections in negative-screened patients were detected. Conclusions : Weekly screening for MDRO identified a high number of MDRO colonizations allowing to apply early strategies of infection control in high risk patients . Besides, MDRO infection occurred only in patients previously colonized, therefore, 80% of our cohort could benefit from guided treatment by the time of the febrile episode. Early identification of MDRO colonization might have helped to reduce MDRO related mortality. However, these findings should be confirmed with further studies, comparing baseline with weekly MDRO screening strategies. Disclosures No relevant conflicts of interest to declare.

Introduction: Cytokine Release Syndrome (CRS) is a systemic inflammatory response síndrome related to aberrant immune activation or immune hyperstimulation, leading to elevated cytokine levels (including IL-6, interferon-γ, IL-2) and inflammation. CRS has been described after infusion of T-repleted haploidentical progenitors in post-transplant cyclophosphamide (PTCy) based conditioning regimens. We analyzed the outcomes of 144 T cell-repleted transplants with PTCy (days +3, +4), MMF and CsA as GVHD prophylaxis in our institution. Patients and methods: A total of 105 haplo-HSCT and 39 HLA-identical HSCT (19 and 20 from sibling and unrelated donor, respectively) with PTCy were analyzed retrospectively in 141 consecutive patients from 2010 to 2017. Two patients with haplo-HSCT were excluded, one due to early death on day +1 and other for lack of information. CRS was defined and graduated according to Lee et al. criteria published in 2014.1 Chi-squared test was used to study the association of different qualitative clinical variables and CRS and Mann-Whitney U test for the association between CRS and total nucleated cells (TNC) infused. The determination of the best cut-off of TNC to stratify patients with CRS was performed with ROC curves. The stadistical program used was R v2.15.0. Results: The characteristics of the 142 transplants analyzed are shown in Table 1. CRS occurred in 77% of haplo-HSCT (79/103) and in 18% of identical HSCT (7/39). Most patients with CRS presented sings and symptoms in the first 24 hours after the infusión.The majority was grade 1. Only 5 patients who underwent haplo-HCT showed grade 2 CRS. They needed vasoactive drug, oxygen therapy (without mechanical ventilation) and low doses of corticosteroids. Of those 5 patients, 4 were lymphomas with a previous autologous transplant. The stem cell source of the 5 patients was peripheral blood (PB). We did not have cases of grades 3-4 CRS. No patient required Tocilizumab. The clinical and analytical characteristics of CRS are shown in Table 2. In the univariate analysis, the use of PB was significantly associated with the development of CRS (p = 0.001). No statistical association was found with other variables (underlying disease, disease status, cryopreserved product, previous autologous or allogeneic transplant, conditioning, age, sex, CD34 infused, etc.). In the haplo-HSCT cohort, patients who presented CRS showed higher content of TNC infused (median (range): 9.1 (1.17-18.77) vs. 6.9 (0.63-26) x108 / kg, p = 0.023). The best cut-off of TNC calculated was 6.02 x108 / kg (S 82%, E 47%, p = 0.02).CI of CRS in patients with TNC greater than 6.02x108 / kg was 84% compared to 53% in lower (HR 6.6, p = 0.0099, Figure1). Patients with CRS developed grade II-IV acute GVHD more frequently than those who did not present CRS (60% vs. 28.6%, p = 0.012). No association was observed between CRS and chronic GVHD, relapse, non relapse mortality, overal survival or event free survival. Conclusion: CRS appears more frequently in patients with haplo-HSCT compared to HLA-identical donors using PTCy and PB as stem cell source. In our experience, cases with grades 3-4 CRS are infrequent. The majority of CRS cases remit after PTCy and progress well with symptomatic treatment. In the haplo-HSCT cohort, the number of cells infused is associated with higher incidence of CRS and with the presentation of EICRa grade II-IV.Lee DW, Gardner R, Porter DL, et al. Current concepts in the diagnosis and management of cytokine release syndrome How I Treat Current concepts in the diagnosis and management of cytokine release syndrome. Blood. 2014; 124(2):188-195. DOI: 10.1182/blood-2014-05-552729 Disclosures No relevant conflicts of interest to declare.

Background: Haploidentical (Haplo) stem cell transplantation (SCT) provide a curative option for nearly all Acute Myeloid Leukemia (AML) patients lacking an HLA matched donor. However, outcomes following Haplo-SCT vary and are dependent on a number of individual features. Integrative prognostic models for decision support towards a Haplo-SCT are lacking. We sought to develop a prediction model of Leukemia-Free Survival (LFS) for AML patients undergoing a Haplo-SCT. Methods: A total of 1,804 de-novo (80%) and secondary (20%) AML patients who received a non-T-cell depleted Haplo-SCT between the years 2005-2017 were included. All patients were reported to the registry of the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT). To account for non-linear associations, violation of the proportional hazard assumption, and to reduce bias associated with feature selection, a non-parsimonious non-parametric machine learning algorithm, Random Survival Forest (RSF), was used. RSF provides a continuous probabilistic estimation of LFS by fitting an ensemble of decision trees. Variables included in the model were reflective of patient, disease, and transplantation characteristics. Since RSF models are not readily interpretable (i.e., "black box" models) variable importance (VIMP) of covariates included in the model (Xv), were assessed by calculating the difference in prediction error before and after permuting Xv. The model's generalizability and accuracy were tested through repetitive bootstrapping (5000 iterations) and calculation of the C-index. Results: The median age of the patients was 53 years. The majority had an early disease status (complete remission [CR] 1[44%]) with intermediate cytogenetic risk (43%) and were undergoing allogeneic transplantation for the first time (93%). Reduced-intensity conditioning (RIC) was used in 57% of cases, and grafts were from peripheral blood in 54% of transplants. For graft-versus-host disease (GvHD) prophylaxis, 82% of the patients received post-transplant cyclophosphamide (PTCy) and 18% anti-thymocyte globulin (ATG). The median follow-up duration was 2.0 years. In the RSF prediction model, the top-ranking variables (Figure A) were disease status, GvHD prophylaxis, time from diagnosis to transplantation, and age. Bootstrapped C-index of the prediction model was 0.66. Prognostic discrimination was assessed by dividing the predicted LFS probabilities into quartiles that were then used to plot Kaplan-Meier curves, demonstrating LFS ranging from 24.8%-60.1% at 2-years (Figure B). Differing features of the four prognostic groups are listed in the Table. Conclusions: Our group has developed the first prediction model for LFS in AML patients treated with a Haplo-SCT. The model is based on a machine learning technique and provides an individualized estimation of LFS probability. It is conceivable that once this model is verified, it could serve as an important clinical tool when considering a patient to Haplo-SCT. Figure. Figure. Disclosures Angelucci: Vertex Pharmaceuticals Incorporated (MA) and CRISPR CAS9 Therapeutics AG (CH): Other: Chair DMC; Jazz Pharmaceuticals Italy: Other: Local ( national) advisory board; Celgene: Honoraria, Other: Chair DMC; Novartis: Honoraria, Other: Chair Steering Comiittee TELESTO Protocol; Roche Italy: Other: Local (national) advisory board. Tischer:Jazz Pharmaceuticals: Other: Jazz Advisory Board. Mohty:MaaT Pharma: Consultancy, Honoraria.

Introduction . Allogeneic stem-cell transplantation (SCT) is a curative approach in acute myeloid leukemia (AML) by providing dose-intensive chemo-radiotherapy and enhancing a graft-versus-leukemia (GVL) effect. The GVL effect is provided by alloimmune T- cells and is usually closely associated with graft-versus-host disease (GVHD). Patients with GVHD have a lower incidence of relapse, but at high grades a higher incidence of non-relapse mortality (NRM). However, GVL can also occur independently of GVHD. The use of haplo-identical SCT is rapidly increasing over the last decade due to the introduction of non-T depleted methods, in particular with post-transplant cyclophosphamide (PTCy), with expected outcomes that are similar to other donor sources. The GVL effect after T- depleted haplo-identical SCT is mostly related to natural-killer cell alloreactivity and is not necessarily associated with GVHD. However, there is no definite data whether GVL after SCT in the non-T depleted setting is similarly associated with GVHD as in the matched donor setting. Methods . We assessed the impact of acute and chronic GVHD on SCT outcomes in patients with AML following non-T depleted haplo-identical SCT with PTCy, by using a series of landmark analyses. Results . The study included 605 patients with AML in CR1 (73%) or CR2 (27%) after non-T depleted haplo-identical SCT with PTCy, given during the years 2009-2016. The median age was 53 years (range, 18-76). 71% had myeloablative conditioning and 29% had reduced-intensity conditioning . The overall rate of acute GVHD grade II-IV and III-IV was 28.4% and 8.0%, respectively. The rates of chronic GVHD all grades and extensive were 32.7% and 12.3%, respectively. The rate of relapse and NRM were 21.8% and 18.2% and the rates of leukemia-free survival (LFS) and overall survival, 2 years after SCT were 59.9% and 64.1%, respectively. 509 patients were alive and leukemia-free 100 days after transplant. 366 had no prior acute GVHD at this landmark, 107 had acute GVHD grade II and 36 had grade III-IV. The overall rate of subsequent relapse was 20.3%, 18.3% and 11.9%, respectively (P=0.60). The overall rates of subsequent NRM were 10.3%, 19.0% and 35.7%, respectively (P Conclusions. By a series of landmark analyses at 100 days, 6 months and 1 year after SCT, we did not find any association of acute GVHD grade II or III-IV or chronic GVHD (limited or extensive) with subsequent relapse. Acute GVHD grade III-IV was associated with a higher NRM and lower LFS rates after day100. All grades of acute GVHD were associated with a higher incidence of chronic GVHD. Previous extensive chronic GVHD was also associated with a higher NRM and a lower LFS. GVL is thus not associated with GVHD after non T-deleted haplo-identical SCT with PTCy. Future novel strategies for prevention of significant GVHD are warranted. Disclosures Angelucci: Vertex Pharmaceuticals Incorporated (MA) and CRISPR CAS9 Therapeutics AG (CH): Other: Chair DMC; Roche Italy: Other: Local (national) advisory board; Novartis: Honoraria, Other: Chair Steering Comiittee TELESTO Protocol; Celgene: Honoraria, Other: Chair DMC; Jazz Pharmaceuticals Italy: Other: Local ( national) advisory board. Mohty:MaaT Pharma: Consultancy, Honoraria.

Background: Graft failure (GF) is an unusual but threatening complication after allogeneic HSCT (allo-HSCT). Early diagnosis is crucial for therapeutic interventions to be effective. The monitoring of chimerism in peripheral blood (PB) and T lymphocytes (TL) has shown to contribute in the early detection of this complication. The objective of this study was to describe chimerism dynamics in patients who developed GF after allo-HSCT. Methods: Nineteen patients out of 416 procedures were diagnosed with GF after allo-HSCT since 2003 in our center. Chimerism studies were performed by STR-PCR (AmpFLSTR™ SGM Plus™, Thermo Fisher) in PB and TL weekly since day +14. Patients were classified into three groups: primary GF (absence of neutrophil engraftment by day +28), secondary GF (development of severe cytopenias and progressive mixed chimerism (MC) after initial achievement of neutrophil engraftment), and incipient GF (development of increasing MC with non severe cytopenias) [1]. Relapse/progression was ruled out in all cases. [1] Díez-Martín et al. Bone Marrow Transplant. (2004) 33, 1037-1041. Results: Seven patients were diagnosed with primary GF, 7 with secondary GF and 5 with incipient GF (Table 1). No evident causes of GF were detected in all primary GF cases. Chimerism analysis on day +14, +21 y +28 revealed persistent high percentages of recipient cells before GF were diagnosed, in PB and mainly and earlier in TL (Fig. 1A). Median time to salvage allo-HSCT was 45 days (range 35-77). Two patients were treated with donor lymphocytes infusion (DLI) and five with second allo-HSCT. Five patients achieved engraftment, and six achieved complete chimerism (CC). Six-months OS after salvage was 43%. The 7 patients diagnosed with secondary GF had achieved initial neutrophil engraftment in a median of 17 days (range 13-28). Median time to GF after allo-HSCT was 75 days (range 39-108). Six of them developed CMV reactivation before GF. Chimerism analysis before and at diagnosis of secondary GF, showed persistent high percentages of recipient cells, with a trend towards increasing dynamics in PB and mainly in TL (Fig. 1B). Median time to salvage therapy was 35 days (range 8-817) after GF confirmation. One patient was treated with DLI and six with second allo-HSCT. Five patients achieved engraftment and CC. Six-months OS was 57%. The 5 patients diagnosed with incipient GF showed persistent high percentages of recipient cells, with a trend towards increasing dynamics particularly in TL before and at diagnosis of GF (Fig. 1C). As salvage treatment, patients were treated with immunosuppression withdrawal followed by at least one DLI as salvage theraphy, in a median of 83 days (range 61-126) after allo-HSCT. All patients achieved CC in both PB and TL. Four patients developed grade II-IV GVHD. Six-months OS was 57%. Conclusions: Patients with primary GF presented MC in serial chimerism analysis after allo-HSCT, with persistent high percentages of recipient cells particularly in TC. Patients with secondary and incipient GF showed increasing MC mainly in TC, before GF was established. Early T-cell chimerism dynamics may be the best predictor of GF, allowing early therapeutic interventions. In our experience, timely and individualized second allo-HSCT after GF may improve outcome after primary or secondary GF. On the other hand, early DLI could benefit patients with incipient GF. Disclosures No relevant conflicts of interest to declare.

The outcome of patients with severe aplastic anemia (SAA) has greatly improved in recent years but is still poor for patients who failed or relapsed after immunosuppressive therapy (IST) and don't have a matched donor. Recent use of eltrombopag shows blood count improvements in 40% of cases, but most patients refractory to immunosuppressive therapy, are also unresponsive to eltrombopag. In this situation, hematopoietic stem cell transplantation (HSCT) using alternative donor sources (mismatched unrelated donors, cord blood, and haploidentical family donors) may be curative but are also associated with a high risk of morbidity and mortality. Moreover, ethnic minorities have limited access to an alternative donor, especially in the adult population. Haploidentical transplantation using post-transplant cyclophosphamide (Haplo-PTCy) has been shown to facilitate engraftment and shows GvHD rates comparable to those of matched sibling HSCT in hematologic malignancies. However, few papers have been published on Haplo-PTCy in the context of aplastic anemia. We conducted a retrospective analysis of 36 patients (72% male), who received an haplo-PTCy for aplastic anemia in 22 EBMT centers from June 2010 to March 2017. Haplo-PTCy was the first transplantation for 81% patients (second, 11%; third, 8%). The non-myeloablative preparatory regimen included anti-thymocyte globulin in 33% of patients and low dose TBI in 58% of patients. Donors were father (n=12, 35%), mother (n=12, 35%), brother (n=5, 15%), sister (n=3, 9%), cousin (n=1, 3%) and daughter (n=1, 3%). The stem cell source was mainly bone marrow (55%). All patients received cyclophosphamide 50mg/kg/day IV on days +3, and +4 post-transplant and 75% received tacrolimus or cyclosporine plus mycophenolic acid. The primary endpoint was the probability of OS. Secondary study endpoints included probability of neutrophil recovery (ANC 500/ μL for at least 3 consecutive days), platelet recovery (platelets 20 000/ μL for at least 3 consecutive days, and 7 days after the last transfusion), cumulative incidences of acute and chronic GVHD and relapse-free survival without Grade III-IV acute GvHD and without extensive chronic (GRFS). Thirty-two patients were diagnosed with moderate (7%), severe (52%) or very severe idiopathic aplastic anemia (41%), while 4 patients were transplanted for congenital aplastic anemia (3 Fanconi Anemia and 1 Diamond Blackfan). The median age was 19.4 years (range 2.5-45.4 years; 58% adults). Median disease duration before haplo-PTCy was 11.3 months (1.9-201.2). Thirty patients (83%) received pretreatment (77% anti-thymocyte globulin plus cyclosporine, 12% eltrombopag, and 1 patient (3%) received androgens). Cumulative incidence (CI) of neutrophil recovery at day 60 was 78% (64-91) with a median time of 21 days (18-26). Cumulative incidence (CI) of platelet recovery at day 60 was 60% (44-76) with a median time of 31 days (22-185). The CI of grade II-IV acute GvHD was 26% (12-41%) (grade II 19% (7-32%), grade III 6% (0-13%) and no grade IV). CI of chronic GvHD was 17% (5-30) at 1 year (6% (0-13%) extensive) and a CI of 22% (7-37) at 2 years (only limited, there was no new case of extensive cGvHD after one year). With a median follow-up of 24.6 months (15.9 - 38.2), the estimated probability of overall survival (OS) was 78% (64-91) at 1 year and 74% (60-89) at 2 years. Of note, among the 4 patients with inherited disorders, 2 died [1 infection (Diamond Blackfan) and 1 aGvHD (Fanconi Anemia)] and 2 are alive at month 12 and month 15 of follow-up, respectively. Nine patients died during the study. The main cause of death was infection (n=6, 67%). Finally, the GRFS (alive, full donor chimerism, without previous grade III-IV GvHD and without extensive cGvHD) was 58% (41-75) at 2 years. In conclusion, with a median follow-up of 2 years, Haplo-PTCy leads to 74% overall survival in 36 patients with aplastic anemia, with almost 60% of the patients being free from GvHD complication. In a population with no other therapeutic options, our data suggests haplo-PTCY is a feasible option. However, prospective well-designed trials are urgently needed before the inclusion of Haplo-PTCy in the treatment strategy of aplastic anemia. Disclosures Bloor: Janssen: Research Funding; AbbVie: Research Funding. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Tilly:Celgene: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Russell:Pfizer: Consultancy, Honoraria, Speakers Bureau; Jazz Pharma: Speakers Bureau; Daiichi Sankyo: Consultancy. Kerre:Celyad: Consultancy; BMS: Consultancy; Celgene: Consultancy, Research Funding. Peffault De Latour:Novartis: Consultancy, Honoraria, Research Funding; Pfizer Inc.: Consultancy, Honoraria, Research Funding; Amgen Inc.: Research Funding; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding.

BACKGROUND Graft-versus-host disease (GvHD) remains an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation, despite the improvements in GvHD prophylaxis. First line treatment of GvHD (acute or chronic) consists of high dose corticosteroids, with a response rate of around 50%. Extracorporeal photopheresis (ECP) is an effective and safe treatment strategy in corticosteroid refractory GvHD, although most of the studies are limited to retrospective series. The main objectives of this study were to analyze the clinical response and impact of ECP therapy in corticosteroid dose reduction. METHODS 114 patients from 7 Spanish transplantation centers were analyzed retrospectively. The characteristics of the patients are shown on Table 1. A total of 1940 ECP procedures were performed from January-2011 to June-2017 in 65 patients (57%) with acute GvHD (aGvHD) and 49 (43%) with chronic GvHD (cGvHD). Glucksberg and the NIH criteria were used for the diagnosis and grading of acute and chronic GvHD, respectively. All ECP procedures were performed with the off-line system: after the lymphoapheresis, 8-MOP was added to the apheresis product and finally photoinactivated in the Macogenic G1 (Macopharma®) irradiator. During the first 4 weeks, patients underwent 1-2 weekly procedures, followed by 1-2 procedures every 2 weeks and tailored by clinical response. The response was classified as complete response (CR), partial response (PR) or no response (NR). % of the initial corticosteroid dose reduction was registered at the end of treatment. RESULTS Patients with aGvHD underwent a median of 13 processes (interquartile range 9-19), and those with cGvHD a median of 19 processes (IQR 13-24). The median number of processes until response was 3 in patients with aGvHD and 4 for patients with cGvHD. ECP was the second line therapy in the 47% of aGvHD cases and 49% in cGvHD. 71% of the cases of aGvHD were grade 3-4, and 69% of the cases of cGvHD corresponded to severe forms. The overall response rate in aGvHD was 66% (CR 55%), whereas in cGvHD the rate was 67% (CR 22%). The most involved organ was the skin, with a response rate of 80% (CR 68%) in aGvHD and 69% (CR 22%) in cGvHD. In acute digestive GvHD, the response rate was 61% (CR 50%), and 75% (CR 50%) in the chronic form. For liver involvement, response rates were 67% (CR 57%) in acute and 70% (CR 30%) in cGvHD. 80% of the patients with chronic lung involvement showed an overall response (20%CR). At the end of ECP treatment, 71% of the patients treated for aGvHD and 61% of patients with cGvHD were able to reduce the corticosteroid dose, with a median dose reduction of 90% and 100% in all patients, respectively. With a median follow-up of 31 months in aGvHD and 68 months in cGvHD, the 2-year overall survival (OS) was 47% and 83%, respectively. Significant OS differences were noted between responding (CR+PR, 2-year OS 62%) and no responding (NR, 2 year OS 18%, HR=2.5, p CONCLUSIONS ECP is a valid therapeutic alternative in patients with corticosteroid refractory acute and cGvHD, with higher CR rates in patients with aGvHD. ECP allowed for significant corticosteroid dose reductions in more than 2/3 of the patients in both GvHD settings, and granted longer OS in responding patients. The results obtained are similar to those published by other groups. Disclosures No relevant conflicts of interest to declare.

BACKGROUND: Anemia is the most common manifestation of low-risk myelodysplastic syndromes (MDS). Iron-overload in MDS can occur before transfusion dependence in the context of ineffective erythropoiesis. Significantly lower hepcidin levels have been described in patients with sideroblastic refractory anemia compared to higher risk MDS, promoting inadequate iron absorption that leads to higher iron overload. Erythroferrone (ERFE) is a hormone that stimulates erythropoiesis and regulates iron homeostasis; in physiological conditions, is stimulated by erythropoietin and increases iron absorption inhibiting hepcidin. There are no studies describing the activity of ERFE in MDS. The objective of this study was to describe the relationship among hepcidin, ERFE and iron overload in 31 patients with low-risk MDS. METHODS: 50 samples were analized, 31 from patients (16 males, 17 females) with low-risk MDS: 10 low IPSS-R and 21 very-low IPSS-R; and 19 from healthy controls. 13 patients showed severe anemia with transfusion dependence, 4 patients received only erythropoiesis stimulating agents (ESA) and 14 patients did not receive any treatment for the anemia. Patient characteristics are summarized in table 1. Hepcidin levels were measured using the DRG Hepcidin 25 (bioactive) HS ELISA Kit (DRG Diagnostics GmbH), and ERFE was measured with the FAM132B (Human) OKEH02395 ELISA kit (Aviva Systems). For the analysis, two groups of patients were considered: 13 with severe and transfusion dependent anemia and 18 with mild/moderate anemia. RESULTS: Patients with severe anemia showed higher serum ferritin levels (median 2143ng/mL vs 204ng/mL, p CONCLUSIONS: To the best of our knowledge, this is the first simultaneous analysis of hepcidine and ERFE in MDS. Patients with severe anemia showed significantly higher ERFE levels compared to those with moderate anemia, suggesting a higher erythropoietic stimulus. Patients with severe anemia showed significantly superior hepcidin levels, hindering iron absorption in situations of massive iron overload. Accordingly, ERFE did not show negative correlation with hepcidin in either cohort, supporting the abnormal iron metabolism in MDS. Larger studies are required to define the relationship between hepcidin and ERFE in low-risk MDS. Disclosures No relevant conflicts of interest to declare.

Introduction: Immune reconstitution (IR) has a significant impact in HSCT outcome with a role against opportunistic infections and in disease control. In the setting of unmanipulated haploidentical transplantation (Haplo-HSCT), some groups have identified the absolute leukocyte count on day +30 (ALC30) as an independent prognostic factor in terms of overall survival (OS), disease free survival (DFS) and infection related mortality (IM). The aim of this study was to evaluate the impact of early IR on different HSCT outcomes in patients who underwent Haplo-HSCT with postransplant cyclophosphamide (PTCy) at our institution. Patients and methods: Eighty-eight patients received a Haplo-HSCT from 2011 to 2016. Thirty-six percent of the patients received myeloablative conditioning regimen and 64% received reduced intensity regimen. Graft-versus-host disease (GVHD) prophylaxis was based on PTCy, cyclosporine and mycophenolate mofetil. Early IR was assessed through the analysis of different lymphocyte subpopulations at days +30 and +90 after transplantation, including ALC30 (cellular analyzer DXH, Beckman Coulter®); CD3+ lymphocyte count and their different subpopulations (CD4+ and CD8+ lymphocytes, naive and memory T cells) and NK cells count. Lymphocytes subpopulations were determined by multiparametric flow cytometry (FC500 and Navios, Beckman Coulter®). ROC curves were used to determine the optimal cut-off values for each of the studied variables. Results: Eighty-one patients were studied, excluding 7 who died before day +30. Median follow-up was 26 months (10-43). Patient´s characteristics are shown in Table 1. CMV reactivation was documented in 76% (62) of the patients, 4% (3) developed a proven invasive fungal infection, and 31% (25) presented hemorrhagic cystitis. Median OS and DFS were 26 months (10-43) and 24 months (9-39), respectively. IM rate and NRM rate were 10% and 24%, respectively, at the end of follow up. Median lymphocyte populations counts at day +30 are shown in Table2. ALC30 below 100 cells/uL (p= 0.027) and CD4+ naïve lymphocytes below 12 cells/uL (p=0.033) (both corresponding to the 25 percentile) were associated with lower OS compared to patients with higher counts at day +30 (Figure 1). Patients with ALC30 lower than 300 cells/uL (p=0.026) showed significantly higher NRM; CD8+ count lower than 20 cells/uL (p=0.022) also showed higher NRM. NK cells counts at day +30 lower than 14 cells/uL (p=0.014), near to percentile 25, predicted higher IM (62.5% vs 37.5%). We did not identify any lymphocyte subpopulation that could predict DFS. Patients with acute GVHD grades II-IV showed values of ALC30 lower than 200 cells/uL (p=0.051), although non-statistically significant. No relationship was found between lymphocytes subpopulations at day +90 and HaploSCT outcomes. Conclusions: Our study supports the prognostic significance of early IR after unmanipulated haploidentical transplantation with PTCy, as previously described by other groups. ALC30, CD4+ naïve lymphocytes, and CD8+ lymphocyte count at day +30 may be good early predictors for OS and NRM in this setting. On the other hand, low NK cells counts (lower than percentile 25) predicted higher IM. Patients with very low lymphocyte counts should be monitored closely as they are at high risk for infectious complications, NRM and OS. Disclosures No relevant conflicts of interest to declare.

Allogeneic stem cell transplantation (SCT) is potentially curative for patients with lymphoma who progress after autologous SCT. For patients with no HLA identical donor, haploidentical transplant is becoming the major source of alternative donors, particularly with the use of post transplant cyclophosphamide (ptCy). However, there are little data on whether outcomes are affected by the characteristics of the haploidentical donor, the stem cell source or the conditioning. To address this important subject, we identified 474 adult patients (35% females; median age 41 years; range 18-72) with Hodgkin lymphoma (HL-240; 51%), peripheral T cell lymphoma (PTCL-88; 19%), diffuse large B cell lymphoma (DLBCL-77; 16%), mantle cell lymphoma (MCL-40; 8%) or follicular lymphoma (FL-29; 6%), who received a haploidentical SCT (haploSCT) with ptCy between 2010 and 2016 at EBMT participating centers. Patients, donors and transplant characteristics are summarized in Table 1. Median follow-up of alive patients was 32 months (range 3-93). Engraftment by day 100 was successful in 95% of patients. In multivariate Cox analysis (MVA), the use of peripheral blood stem cells (PBSC) positively affected engraftment (HR=1.53; p In conclusion, this is the largest study on the influence of donor characteristics, stem cell source and conditioning in haploSCT with ptCy for lymphoma. These results provide critical information to help selecting the best donor in the setting of haploSCT for lymphoma. Our results indicate that the use of PBSC significantly improves engraftment but increases the risk of acute GVHD. Conditioning only influenced NRM but had no effect on PFS or OS. The use of female donors increases the risk of chronic GVHD. Of note, PFS and OS are mostly influenced by disease characteristics (i.e disease status and lymphoma subtype), whereas, with the exception of CMV compatibility, no other donor characteristics (donor age and gender, relationship of the donor to the recipient, degree of HLA mismatch or ABO incompatibility, prior donor pregnancy) impact on PFS or OS, supporting the use of any haplo-identical family member as a donor. Table. Table. Disclosures Tischer: Jazz Pharmaceuticals: Other: Jazz Advisory Board. Mohty:MaaT Pharma: Consultancy, Honoraria. Chalandon:Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel costs. Sureda:BMS: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Sanofi: Honoraria; Merck: Consultancy, Honoraria; Roche: Honoraria.

Introduction: Lymphomas continue to be a leading cause of death in HIV-positive patients (HIV+ pts) in the cART era. The aim of this study was to review our 15-year single institution experience in performing Autologous Stem Cell Transplantation (ASCT) for HIV-infected and non-HIV patients with high-risk or relapsed lymphomas, focusing on infectious complications. Patients and Methods: We retrospectively evaluated our cohort of 28 HIV+ pts who underwent an ASCT between 2000-2015, and compared it with a well-matched control group of 39 HIV-negative pts. Patient and ASCT characteristics are described in Table 1. All HIV+ pts were on cART. Chemomobilization was used in 60% of the HIV cohort and 84% of the controls. BEAM conditioning regimen was the most common. All transplants were performed in the same tertiary hospital JACIE-accredited SCT unit. The primary end points were first-year cumulative incidence (CI) of infection, total infectious episodes and infection-related mortality. For the analysis, we defined 3 different time frames: 1st Pre-engraftment; 2nd from engraftment to day +100 and 3rd from day +100 until 1 year after SCT. Events occurring during the first 2 periods were considered early infections as compared to late. Results: All patients received antiviral and anti-PJP prophylaxis, but a significantly higher proportion of HIV+ pts were given antibacterial and antifungal prophylaxis (2/3 vs 1/3 approximately, Table 1). G-CSF support was initiated in all HIV recipients and 66% of controls, and the median days of use was longer for the HIV group (7 vs 4 days, p= 0.04). Median time to neutrophil engraftment was similar in both groups (13 vs 11 days, p=0.55); 93% of HIV pts and all control pts reached ANC > 500c/uL by day +30. Infectious episodes (IE) are described in Table 2, divided by pathogen subtype and time frame. Globally, all infection subtypes were more common in the HIV-infected cohort at some point. The most significant findings from the analysis are as follows. CI of early global infections: HIV 75% vs non-HIV 25% (p= 0.04), Figure 1. Median number of global infectious events: HIV 65 vs non-HIV 39 (p= 0.002; OR 1.8 [1.2-2.8]). Bacteria: CI of pre-engraftment and early bacterial infections were not different among groups (42% vs 28%, p= 0.47), but the median number of bacterial episodes was clearly different: HIV 17 vs non-HIV 12 (p= 0.08; OR 2.16 [0.96-4.8]). Fungi: CI of early fungal infections: HIV 10.7% vs non-HIV 0% (p= 0.03); minor infections were not considered. Viruses: CI of early viral infections: HIV 46% vs non-HIV 15% (p= 0.004). Median nº of early viral IE: HIV 19 vs non-HIV 6 (p= 0.007; OR 4.16 [1.43-12]). CI of late viral infections: HIV 30% vs non-HIV 11.7% (p= 0.04). CMV reactivations were by far more common in the HIV cohort (p=0,01). HIV viral load bleeps were documented in 35% of the HIV patients (most commonly in the day +30 control) and one post-transplant virological failure was diagnosed, forcing HAART substitution. Of note, 1st year CI of infection-related mortality was 14% in the HIV group vs 0% in the non-HIV group (p= 0.01), Figure 2. Three HIV+ pts suffered early fulminant septic episodes (1 E. coli + Enterococcus, 1 Rothiamucilaginosa, 1 non-clarified - possible Stenotrophomonasmaltophilia) and a 29-year old woman in CR after a 1st line for a stage IVsB Burkitt-like lymphoma died due to a severe influenza A pneumonia. Length of admission was also significantly longer for the HIV+ pts (median days 34 vs 28, p=0.041). Regarding long-term outcome, median follow up as of July 2016 is 82 months for the HIV+ group and 70 months for the control group: 57% and 61% of the pts in each cohort are still alive, respectively. One HIV-infected pt and 3 controls have been lost to follow-up. EFS: 1 year 71.4% vs 81.9% (ns); 5 years: 63.9% vs 66.5% (ns). Overall Survival: 1 year 75% vs 84% (ns); 5 years 66.3% vs 74.6% (ns). Conclusion: Autologous stem cell transplantation has been proven to be feasible and effective in HIV-related lymphomas, but in our experience and despite great advances in cART and virological control, HIV+ patients are at high risk of infection and this might influence post-ASCT short-term survival. It is mandatory to focus on prophylactic and supportive measures and to choose carefully the optimal timing for transplantation. Table 2 Table 2. Disclosures No relevant conflicts of interest to declare.

INTRODUCTION Post-transplant high-dose cyclophosphamide (PTCy) has shown to prevent graft versus host disease (GvHD) after haploidentical allogeneic hematopoietic cell transplantation (HSCT). Although less extended, its use after matched unrelated donor (MUD) HSCT in combination with additional immunosuppression has been encouraging. The aim of this study was to analyze and compare outcomes of antithymocyte globulin based (ATG) versus PTCy-based GvHD prophylaxis in matched unrelated donor HSCT. MATERIAL AND METHODS We retrospectively analyzed 51 MUD (8/8 HLA-matched) transplants performed in two Spanish centers: 25 received ATG-based prophylaxis and were performed from 2010 to 2013, and 26 received PTCy-based prophylaxis and were performed from 2013 to 2016. RESULTS Characteristics of patients and post-HSCT complications are detailed in Table 1. There were no significant differences in age, gender, diagnosis and Disease risk index. For the ATG group, conditioning regimen consisted of fludarabine combined with busulfan (80%) or melphalan (12%), and TBI plus cyclophosphamide (8%). All patients received ATG 2 mg/kg from day -4 to day -2 followed by methotrexate and cyclosporine (CsA). Conditioning regimen for patients from the PTCy group consisted of fludarabine and busulfan (85%) and thiotepa combined with busulfan and fludarabine (15%). GvHD prophylaxis consisted of PTCy 50 mg/kg on days +3 and +4, combined with: CsA plus MMF in 57%, CsA alone in 31%, or tacrolimus plus MMF or sirolimus in 8%, and tacrolimus alone in 4%. With a median follow-up of 58 months for the ATG group and 12 months for the PTCy group, there were no statistically significant differences in overall survival at 18 months (56% vs 85%, p=0.08), in event free survival (56% vs 68%, p=0.5), and in cumulative incidence of relapse (12% vs 18%, p=0.3). Non-relapse mortality at 12 months was significantly higher in the ATG group (32% vs 10%, p = 0.04). The ATG group presented more cases of hepatic toxicity grades I-IV and hemorrhagic cystitis than PTCy group (Table 1). Cumulative incidence of acute GvHD grades II-IV was higher in the ATG group as well as acute GvHD grades III-IV, with no differences in moderate/severe chronic GvHD incidence (Figure A). CONCLUSION In our experience, albeit differences in follow-up and limited number of patients, we conclude that PTCy combined with additional immunosuppression after MUD allogeneic HSCT offers lower rates of acute GvHD together with less toxicity and non-relapse mortality compared to ATG-based prophylaxis. Further analysis including larger series and follow-up are needed to confirm these observations. Disclosures No relevant conflicts of interest to declare.

Introduction: Patients infected with HIV have an increased risk of developing aggressive B-cell non-Hodgkin lymphoma and Hodgkin lymphoma (HL). The continuous development of cART during the last decade has improved the prognosis of HIV-associated lymphoma considerably. However, a significant proportion of these patients will experience lymphoma relapse and may be candidates for autoSCT. The purpose of the present study was to investigate if recent advances in anti-lymphoma therapy and anti-infectious strategies have influenced the outcome of autoSCT for HIV-related lymphoma. Patients and methods: For this retrospective study, all EBMT-registered patients aged 18 years or older with HIV-positive serostatus who were treated with a first autoSCT between 2007 and 2013 were eligible. Baseline patient, disease, and transplant data were collected from MED-A forms. Centers were requested to provide additional HIV and lymphoma treatment and follow-up information. Statistical analysis used log rank test to assess the impact of baseline characteristics on survival endpoints. In multivariate analysis, the relevance of prognostic factors was estimated using Cox regression models. Curves of cumulative incidence of relapse (IR) and non-relapse mortality (NRM) were compared by Gray's test. Results: 138 patients from 25 European centers met the eligibility criteria and had the full data set required for this analysis available. 86% were male, median age was 44 years (range 24-69). Underlying diagnoses were diffuse large B cell lymphoma (DLBCL) in 46%, HL in 21%, Burkitt lymphoma in 14%, plasmablastic lymphoma (PBL) in 10%, and other lymphoma in 9% of the patients. Disease status at autoSCT was complete remission (CR) in 51%, partial remission (PR) in 33%, and less than PR in 16% of the patients, achieved after 1 (28%), 2 (58%), or more than 2 lines of chemotherapy (14%). With HIV load below the threshold of detection in 74% of the patients, the median CD4+ cell count was 187/µl (range 0-800) at transplant. 95% of the patients continued with cART during salvage and high-dose chemotherapy. BEAM was used as high-dose regimen in 77% of the patients. With a median follow-up of 4 years, 2-year NRM, IR, progression-free survival (PFS) and overall survival for the whole series were 9%, 23%, 68% and 70%, respectively. By multivariate analysis, diagnosis DLBCL or PBL (vs HL), increasing number of chemotherapy pretreatment lines, and less than PR at autoSCT were significant predictors of an unfavorable PFS; whilst age, high-dose regimen, performance status, and viral load had no significant impact. 2-year PFS in patients with 1st-line CR, later CR, PR, or less than PR at autoSCT was 91%, 80%, 64%, and 23%, respectively. Conclusions: This series, which is the largest ever on lymphoma transplants in HIV+ patients, suggests that in the cART / chemoimmunotherapy era, the outcome of autoSCT for HIV-related lymphoma is driven by lymphoma-dependent risk factors rather than by characteristics of HIV infection. AutoSCT under ongoing cART therapy remains the treatment of choice for HIV+ patients with PBL or recurrent DLBCL or HL. Disclosures Kröger: Sanofi: Honoraria, Research Funding; Neovii: Honoraria, Research Funding; Riemser: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Montoto:Roche: Honoraria; Gilead: Research Funding. Dreger:Novartis: Consultancy; Gilead: Speakers Bureau; Novartis: Speakers Bureau; Gilead: Consultancy; Janssen: Consultancy; Roche: Consultancy.

Introduction: Allogeneic transplantation is the only curative option for patients with high risk leukemias or MDS. Only one third of them have an HLA identical sibling donor and around 60-70% will find an unrelated donor, that´s why haploidentical stem cell transplantation (HAPLO-HSCT) offers a therapeutic option to most of these patients. Myeloablative conditioning (MAC) produce better disease control than reduced intensity conditioning regimens (RIC), but with higher toxicity, rendering long term similar results. Patients and methods: We retrospectively evaluated the results of our MAC-HAPLO regimens in patients diagnosed with high risk leukemias or MDS (Fludarabine 30 mg/m2 x5 days, Cyclophosphamide14,5 mg/kg x2 days, IV Busulfan 3,2 mg/kg x 3 days (BUX3), or Fludarabine 40 mg/m2 x4 days and IV Busulfan 3,2 mg/kg x 4 days (BUX4)) with GVHD prophylaxis based on PT-CY (50 mg/kg on days +3 and +4) and a calcineurin inhibitor plus mycophenolate from day +5, performed in GETH centers (Spanish Group for Hematopoietic Transplantation). Results: From Feb-2012, 65 MAC-HAPLO HSCT have been reported by 14 centers. Median age was 41 years (15-67), 66% were males and all were in advanced disease phase or presented high risk features (AML 47/ALL 8/MDS 5/ Others 5). Previous HSCT had been employed in 12% (autologous in 5, allogeneic in 3), and in 88% the HAPLO-HSCT was their first transplant. Disease status at HAPLO-HSCT was morphologic CR in 80%, but disease persisted in 52% (MRD+ by flow or molecular markers 32%, morphologic disease 20%). Their disease risk index (DRI) was high or very high in 65%, and the comorbidity index (HCT-CI) was higher than 2 in 18%. PBSC was the graft source in 56 (86%), non T-cell depleted in all cases. The haploidentical donor was the patient´s mother (21.5%), father (12%), siblings (43%) or offspring (23%). MAC regimen was BUX3 in 25 (38.5%) and BUX4 in 40 patients (61.5%). Median infused CD34+ cells were 5.31 x10e6/kg (2.75-11.42). There were no graft failures. Median neutrophils engraftment was reached at day +17 (12-29) and platelets >20K at day +26 (11-150). Complete chimerism was obtained at a median of 28 days (13-135) in 60 evaluated patients. Cumulative incidence (CI) of non-relapse mortality (NRM) was 12.5% at day +100 and 19% at 1 year. CI of grade II-IV acute GVHD was 28.5% at day +100, and grade III-IV was 6.5%. CI of chronic GVHD at 2 years was 28%, being extensive in 8% . No differences in acute or chronic GvHD CI were seen when comparing BUX3 against BUX4. After a median follow-up of 17 months (5-50), estimated 24-months event-free survival (EFS) and overall survival (OS) were 58,5% and 60% respectively. CI of relapse or progression was 21%. No significant differences in NRM, EFS, OS and relapse incidence were detected between BUX3 and BUX4. The impact of CR prior to MAC-HAPLO, the DRI or chronic GvHD in the disease control have not been apropiately demostrated probably due to the limited number of events in our series. Conclusions: IV Busulfan based MAC-HAPLO with PT-CY in the treatment of high risk leukemias and MDS offers good disease control with manageable toxicity, with either BUX3 or BUX4. These efective MAC regimens combined with peripheral blood HAPLO donors could control high risk hematologic diseases in the long term. Severe acute or chronic GvHD are low frecuency events, but relapses persist as the main problem in this patients population. Disclosures No relevant conflicts of interest to declare.

Introduction Donor cell leukemia (DCL) is a rare complication of allogeneic stem cell transplantation (allo-SCT). The leukemic transformation of otherwise healthy donor stem cells provides a useful in vivo model to study the mechanisms involved in leukemogenesis. The objective of the present study is to study the dynamics of emergence of mutations that precede the development of DCL. Material and methods We report the case of a female patient diagnosed of acute lymphoblastic leukemia with t(1;19), who developed normal karyotype acute myeloid leukemia (AML) of donor origin 16 months after unrelated cord blood transplantation (UCBT). Whole exome sequencing(SureSelect-XT Human exon capture 50Mb Agilent Technologies) was performed by next generation sequencing (Hiseq 2000 Illumina) on bone marrow samples post allo-SCT, obtained in the days +98, +189, +350, +486 (DCL diagnosis) and + 569 (DCL relapse) as well as on the UCB unit used in SCT. The exome of bone marrow samples post allo-SCT were aligned to the human reference genome (NCBI build 37/hg19), non-synonymous variants in the coding regions of genes related to leukemia were selected and matched to the UCB exome to identify the acquired variants. Variants meeting such criteria were evaluated with three softwares (SIFT, Polyphen and Mutation Taster) to predict their functional effects. The UCB exome was aligned to the human reference genome (NCBI build 37/hg19). Results In silico variants analysis revealed progressive emergence of multiple mutations related to the development of leukemia in bone marrow samples post allo-SCT (Figure 1). Interestingly three of the mutated genes (PTPN11, NRAS, MAP2K1) are part of the same cellular pathway (RAS-MAPK). In addition, mutations in leukemic subclones that disappear after chemotherapy were indentified, as well as the acquisition of new mutations in resistant subclones (Figure 2). Finally a mutation in SH2B3 gene, a gene that encodes for a regulatory protein of the JAK-STAT pathway, which links strongly to JAK2 inhibiting the activation of the pathway, was detected in the CBU. Conclusions The present study reveals the acquisition of additional somatic mutations in donor cells during leukemogenesis, including mutations not previously described in AML initiation (POU2F2, CA9, POU4F1, FMN2, TLR9, ELF5). Although the cause of DCL onset seems to be multifactorial, the infusion of a CBU with pre-leukemic potential due to mutation in SH2B3 in a context of residual toxicity in recipient as a result of pre-transplant chemotherapy, a post-transplant environment characterized by a decreased immune surveillance may well have played role in the case here reported. The study of a greater number of DCL cases by next generation sequencing could help to understand the process of leukemogenesis. Figure 1 Mutations related to the onset of donor cell leukemia after hematopoietic transplantation. Figure 1. Mutations related to the onset of donor cell leukemia after hematopoietic transplantation. Figure 2 Dynamic of mutation acquisitions in leukemic clones.(DCL: Donor cell leukemia, CBU: Cord blood unit, CBT: Cord blood transplantation, Quim: Quimerism, CQ: Complete quimerism) Figure 2. Dynamic of mutation acquisitions in leukemic clones.(DCL: Donor cell leukemia, CBU: Cord blood unit, CBT: Cord blood transplantation, Quim: Quimerism, CQ: Complete quimerism) Disclosures No relevant conflicts of interest to declare.

Hemophagocytic lymphohistiocytosis (HLH; hemophagocytic syndrome) is a rare syndrome of potentially fatal, uncontrolled hyperinflammation. Allogeneic stem cell transplantation (alloSCT) is indicated in familial, recurrent or progressive HLH. Additional recommendations include central nervous system involvement and unknown triggering factor. While data for alloSCT outcome are available for the pediatric setting, information for adults is very limited. The aim of this study was to retrospectively analyze the information from the EBMT databases about adult HLH patients who underwent allogeneic stem cell transplantation. We obtained data of 67 adult (≥18 years of age) patients transplanted due to HLH. The first reported transplantation was in 1995. Due to the rise of HLH awareness, the number was steadily growing. Until 2006 only 12 transplants were performed, while in the next 10 years it was 55. Median age at transplantation was 28 (range: 18-65). There was a slight male predominance 43/67 (64%). The majority of patients were reported with secondary HLH 33/67 (49%), the familial disease was reported in 29/67 (43%) patients. In two patients triggering factor was attributed to malignancy. The majority of patients received stem cells obtained from the peripheral blood (52/67; 78%) while for the remaining ones it was bone marrow. Reduced intensity conditioning was used since 2004 in 23/63 (37%)of patients. Thirteen (19%) patients received TBI. Donor choice was: matched unrelated 33 (50%), mismatched unrelated 7 (11%), identical sibling 26 (39%). Engraftment was observed in 55/61 (77%); 7/61 (12%) patients suffered from primary and 2/61 (3%) from secondary graft failure. The cumulative incidence of acute graft versus host disease (GvHD) at 100 days was 26% (95% CI 15-37%). The cumulative incidence of chronic GvHD at 1 year after alloSCT was 13% (95% CI 2-23%) and increased to 31% at 3 years (95% CI 16-47%). The overall survival until three years is shown in Fig.1. The median survival time was 8 months. The three year OS was 41% (95% CI 28-55%). For patients who survived until 3 months, this proportion was more favorable with an OS of 62% (95% CI 45-78%) at 3 years after transplantation. Among 19 patients with observation times longer than 15 months, only one patient died (in the 48th month after alloSCT due to relapse which occurred in the 12th month). Main causes of death in the described group were: relapse or progression 10/36 (28%), infection 9/36 (25%) and GvHD 6/36 (17%). After 12 months no more relapses of HLH were recorded - the cumulative incidence reached 19%. The non-relapse mortality reached 42% after 15 months. The familial disease was associated with a better prognosis than secondary HLH (p=0.04). Unlike the pediatric population, where reduced intensity conditioning (RIC) was associated with higher survival, in adult patients there was no difference between the conditioning types. The choice of donor: matched related versus matched unrelated did not alter the survival. To our knowledge, this is the largest group of adult patients with HLH who underwent allogeneic stem cell transplantation. Relatively low relapse incidence shows that alloSCT can effectively cure HLH. Patients who survive the first period after this procedure can expect a long disease-free survival. Figure Overall survival after allogeneic stem cell transplantation for adult HLH patients until 36 months (95% Confidence Intervals are shown in grey). The number of patients at risk is indicated below the time axis at the corresponding time points. Figure. Overall survival after allogeneic stem cell transplantation for adult HLH patients until 36 months (95% Confidence Intervals are shown in grey). The number of patients at risk is indicated below the time axis at the corresponding time points. Disclosures Jedrzejczak: Celgene: Consultancy; Roche: Consultancy, Research Funding; Jansen-Cilag: Consultancy; Novartis: Consultancy, Research Funding; Amgen: Research Funding; BMS: Research Funding; Angelini: Consultancy; Sandoz: Consultancy. Kobbe:Jansen: Honoraria, Other: travel support; Celgene: Honoraria, Other: travel support, Research Funding. Kroeger:Sanofi: Honoraria, Research Funding.

Introduction: Early immune reconstitution (EIR) is clinically relevant for the outcome of allogeneic hematopoietic stem cell transplantation. In the setting of unmanipulated haploidentical transplantation (Haplo-HSCT), some groups have identified the absolute leukocyte count on day +30 (ALC30) as an independent prognostic factor in terms of overall survival (OS), disease free survival (DFS) and infectious mortality (IM). The aim of this study was to evaluate the impact of EIR on OS, DFS and IM among patients who underwent Haplo-HSCT with postransplant cyclophosphamide (PTCy) at our institution. Patients and methods: Sixty-six patients received a Haplo-HSCT at our institution from July 2011 to February 2016. Conditioning regimen consisted of fludarabine, cyclophosphamide and busulfan. Forty-five percent of the patients received a myeloablative regimen, including busulfan for 3 or 4 days, while 55% were conditioned using a reduced intensity regimen with 1 or 2 days of busulfan. Graft-versus-host disease (GVHD) prophylaxis was based on PTCy, cyclosporine and mycophenolate mofetil. EIR was assessed by means of ALC30 (cellular analyzer DXH, Beckman Coulter®), CD3+ lymphocyte count on day +30 (CD3-30) and NK-lymphocyte count on day +30 (NK30), both determined by multiparametric flow cytometry (FC500 and Navios, Beckman Coulter®). The Kaplan-Meier method was used to evaluate OS rate and DFS rate. Differences in survival rate were assessed using the log-rank test. P values Results: We analyzed 66 patients, with a median follow-up of 17 months (8-31). The median age of the patients was 43 years (range 30-57), 77% were men. The diagnosis were: acute myeloid leukemia 33%, acute lymphoid leukemia 8%, chronic myeloid leukemia 6%, Hodgkin lymphoma 21%, non-Hodgkin lymphoma 17%, myelodysplastic syndrome 8%, myelofibrosis (MF) 4%, others 3%. Most patients were in complete remission at the time of the transplant (56%), while 21% were in partial remission and 23% with overt disease. CMV reactivation was documented in 74% of the patients, 8% developed a proven invasive fungal infection and 36% suffered from hemorrhagic cystitis. Median OS and DFS were 17 (8-31) and 13 months (7-26), respectively. IM rate was 27% at the end of follow up. ROC curves were used to determine the optimal cut-off values for each of the studied variables: 300 cells/µL for ALC30, 120 cells/µL for CD3-30 and 40 cells/µL for NK30 were chosen. Those patients with an ALC30 ≥ 300/µL had longer OS (p=0.001) and DFS (p=0.005). Median OS and DFS were 25 months vs. not reached (NR) and 13 months vs. NR respectively. Patients with CD3-30 ≥120/µL had better OS (p=0.07, non-significant) and similar DFS than those with CD3-30 120/µL had a lower incidence of relapse than patients with CD3-30 Conclusions: Our study supports the independent prognostic significance of early immune reconstitution after unmanipulated haploidentical transplantation with postransplant cyclophosphamide, previously described by other groups. Patients with an ALC30 count over 300 cells/µL have a statistically significant better overall survival, disease free survival and a lower cumulative incidence of infectious mortality. However, ALC30 seems to have no correlation with relapse rate. CD3+ and NK-cell total counts on day 30 seem to have less prognostic impact, according to our study. Disclosures No relevant conflicts of interest to declare.

Introduction: CD34+ and CD3+ cell dose in peripheral blood stem cell (PBSC) graft have been related with increased incidence of graft versus host disease (GVHD) in some transplant settings. Our aim in this study was to evaluate the impact of CD34+ and CD3+ cells graft composition on GVHD incidence in the setting of haploidentical transplant (haplo-HSCT) with post-transplant cyclophosphamide (PT-Cy), in a multicenter analysis. Materials (or patients) and methods: We retrospectively evaluated 175 patients with hematologic malignancies who were treated with a haplo-HSCT from 2011 to 2014 with PBSC in GETH centers. All patients received Busulfan-Fludarabine as conditioning regimen and GVHD prophylaxis was performed with PT-Cy (50 mg/kg on days +3 and +4) and a calcineurin inhibitor plus mycophenolate from day +5. We analyzed the impact of CD34+ and CD3+ cell doses (low vs. high with cut-off at the median value, and the 25-75 percentiles) on the development of acute and chronic graft versus receptor disease. Death before GVHD development was considered as a competitive event. The analysis was adjusted for conditioning intensity. STATA software was used for data analysis Results: We analyzed 175 patients. Patient characteristics are resumed in table 1. Median CD34+ and CD3+ cell dose was 5.31x10e6/kg (p 25-75: 4.31-6.1) and 2.07x10e8/kg (p25-75: 1.19-2.94), respectively. Cumulative incidences of grade II-IV acute GVHD and all grades chronic GVHD was 32.6% and 30% respectively. The median follow-up was 12.3 months (r:6-46). No difference in terms of GVHD (acute and chronic), was found between low and high CD34+ cell doses. However, if we focus on T cells, high doses of CD3+, for values above the median, have been has been associated with increased incidence of acute GVHD II-IV (day 150: 47% vs 26% p=0.01, figure 2), as well as cGVHD (30 month: 39% vs 16%, p= 0.01 figure 1). If we focus the analyses regarding the intensity of conditioning regimen, the influence of CD3+ doses remains for the group of reduced-intensity conditioning (RIC) (aGVHD, day 150: 54% vs 24%, p=0.003; cGVHD, 30 month: 47% vs 16%, p=0.006 figure 2), but lost for patients who receive myeloablative intensity (aGVHD, day 150: 33% vs 33% p=0-8; cGVHD, 30 month: 21% vs 16%, p=0.81) Conclusion: In our series, in the setting of haplo-HSCT with Pt-Cy, the highest dose of lymphocytes was associated with a higher incidence of aGHVD II-IV and cGV HD, especially for the RIC procedures. Disclosures No relevant conflicts of interest to declare.

Introduction Post-hematopoietic stem cell transplantation (SCT) chimerism monitoring is important to assess engraftment, anticipate relapse and provide information on the development of graft versus host disease, facilitating therapeutic intervention. The aim of this study was to test the technical efficacy and clinical utility of a novel quantitative PCR approach targeting insertion/deletion polymorphisms (indel-PCR). Materials (or patients) and methods This study included 157 samples (81 bone marrow, 60 peripheral blood (PB), 11 T-cells, 2 myeloid cells, 2 CD34-cells, 1 NK-cells purified using immunomagnetic technology) of 24 patients who underwent SCT for haematological malignancies. Additionally, 2 sets of 11 artificial mixtures were created using PB leukocytes of two healthy subjects (a male and a female) with known percentages of male leukocytes (putative recipient): 100, 75, 50, 25, 10, 5, 3, 1, 0.1, 0.01, 0. Chimerism analysis was performed by the gold-standard STR-PCR (AmpFlSTR SGM Plus®, Life Technologies, USA) and by indel-PCR (Mentype® DIPscreen, Mentype® DIPquant, Biotype, Germany). Concordance between both methods was calculated with SPSS using intraclass correlation coefficient. Results The number of informative loci identified with indel-PCR (>3/patient) was higher than with STR-PCR for all patients. Concordance between both methods for the 157 patient samples and 11 artificial mixtures was "very good" (intraclass correlation coefficient=0.96). Of note, analysis of artificial mixtures provides evidence of significantly (≥2 logs) higher sensitivity by indel-PCR (0.01%) than by STR-PCR (1%, Table 1). Moreover, indel-PCR shows unprecedented quantification capacity (Table 1). Out of the 168 samples analyzed, 32 were positive and 15 negative by both methods, while 121 were positive only by indel-PCR (95% with Clinical outcome and chimerism dynamics of 24 patients are described in figure 1, data of 4 of them were censored (engraftment failure, disease progression, insufficient number of samples). All the samples presented complete donor chimerism by STR-PCR. Of the 9 patients who showed stable or decreasing percentage of recipient cells, only one (11%) presented extramedulary relapse. Of the 11 patients who presented increasing percentage of recipient cells in one determination, relapse occurred in 5 patients (45%, 3/6 patients who did not have further determinations, 2/4 who showed stable or decreasing recipient cell percentage, and 0/1 patient who presented increasing recipient cells in subsequent determinations). Conclusion This novel indel-PCR is a simple and accurate technique that, in comparison with the current gold standard STR-PCR, shows very good concordance and provides higher rates of informative loci per patient, as well as unprecedented combined sensitivity and quantification capacity. Such features allow minutely monitoring chimerism dynamics and might improve clinical management of transplanted patients, specially predicting relapse in those patients who do not have a molecular marker available for disease follow up. Disclosures No relevant conflicts of interest to declare.

Autologous stem cell transplantation (ASCT) has been successfully used in HIV-related lymphoma (HIV-Ly) patients on highly active antiretroviral therapy. We report the first comparative analysis between HIV-Ly and a matched cohort of HIV− lymphoma patients. This retrospective European Group for Blood and Marrow Transplantation study included 53 patients (66% non-Hodgkin and 34% Hodgkin lymphoma) within each cohort. Both groups were comparable except for the higher proportion of males, mixed-cellularity Hodgkin lymphoma and patients receiving granulocyte colony-stimulating factor before engraftment and a smaller proportion receiving total body irradiation-based conditioning within the HIV-Ly cohort. Incidence of relapse, overall survival, and progression-free survival were similar in both cohorts. A higher nonrelapse mortality within the first year after ASCT was observed in the HIV-Ly group (8% vs 2%), predominantly because of early bacterial infections, although this was not statistically significant and did not influence survival. Thus, within the highly active antiretroviral therapy era, HIV patients should be considered for ASCT according to the same criteria adopted for HIV− lymphoma patients.

Introduction: It´s well known that NK cells exert an important role in postransplant immune reconstitution. Their maturation process through the contact with recipient´s bone marrow stromal cells is crucial for the development of their functional capacities. Previous studies showed the relevance of NK alloreactivity in relapse prevention and the influence of NK subpopulations and expression of activating receptors on CMV infection control, antitumor effects, and graft versus host disease (GVHD). Unmanipulated Haploidentical (Haplo) transplantation with postrasplant cyclophosphamide (Cy) is an emerging alternative for patients (pts) with no identical sibling donor with encouraging results. We previously reported preliminary data of NK cell reconstitution in 7 pts in Haplo setting. Our aim is to contrast our previous data in 22 pts comparing with conventional HLA-identical (HLAid) Stem Cell Transplantation (SCT) and to analyse the relationship between NK reconstitution and CMV reactivation and GVHD. Methods: 22 pts received an Haplo SCT and 7 pts an HLAid SCT in Gregorio Marañon Hospital between January 2013 and April 2014. Peripheral blood was used in all cases. Conditioning regimen comprised fludarabine (Flu), Cy and busulfan (Bux) for Haplo and Flu/Bux or Flu/Melphalan for HLAid SCT. Prophylaxis for GVHD consisted of high dose Cy on +3, +4, cyclosporine (CsA) A and mycophenolatemofetil for Haplo and CsA/Methotrexate for HLAid. Table1 show patients characteristics. For analysis of NK reconstitution and receptor expression multi-colour flow cytometry on FC500 and Navios Beckman Coulter® was used. Total NK cells, CD56 intensity and expression of NKG2A, NKp30, Nkp46 and NKG2D was studied at +15, +30, +60, and +90. For comparison between the two groups Mann–Whitney U-test was used. Results: Median NK cells/mm3 on +15 and +30 were significantly lower on Haplo than HLAid group ( 0 (0-5.5) and 28.5 (12.2-96.5) vs 69.5 (55-134) and 276 (151-422); p Conclusions: After Haplo SCT with postransplant Cy NK cell reconstitution seem to be delayed comparing with HLAid sibling SCT, reaching normal levels at +60. As previously reported, we confirm in our series that NK maturation also show a different pattern. In Haplo setting NK cells remains in an immature phenotype with high proportion of NK CD56b and expression of NKG2A much longer than in HLAid pts. Interestingly activating receptors expression, normally linked to maturation is only lower in Haplo pts in +15, but it is similar in both SCT types by day +30 and later, what should translate in appropriate cytotoxic capacity. In Haplo group, those patients with and without CMV reactivation had similar NK cell reconstitution. Patients with GVHD seem to have an impaired early NK reconstitution, but this fact needs to be contrasted. Acknowledgments: Fundación Mutua Madrileña. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Introduction: Extracorporeal photopheresis (ECP) is a treatment modality that entails leukapheresis followed by mixing the buffy coat with 8-methoxypsoralen (8-MOP) and exposing it to UVA light. The buffy coat is then returned to the patient. ECP may be performed employing two different techniques: an on-line and off-line procedure. The off-line system includes two steps: a processing of buffy coat before reinfused to the patient. The treatment is thought to have an immunomodulatory effect and is most commonly used to treat cutaneous T cell lymphoma, acute and chronic graft-versus-host disease (GVHD), and heart and lung allograft rejection. The exact mechanism and optimal cells dose to be treated is unknown. At the present time, a standard protocol is used generally without considering peripheral blood (PB) leukocytes counts or lymphocyte subpopulations (LP) of the patient. With the off-line system, PB leukocytes counts and LP analysis may be useful to choose the amount and distribution of cells to be infused. The first objective of this study is to examine the quantitative correlation between PB LP and the buffy-coat in order to set individualized guidelines of treatment. Once this relationship is understood, the PB LP may serve as a surrogate marker for cell dose treated and help predicting the efficiency of ECP. The second objetive of this study is to examine the mean performance of the buffy coat LP categorized according to PB leukocytes counts (1.5x 109/L). Patients and methods: Twenty two consecutive patients with refractory GVHD were prospectively studied, from november 2009 to may 2014. Apheresis procedures were perfomed with COBE Spectra system (Terumo BCT®, Lakewood, CO, USA; version 7.0) by processing 1.5-2 times the patient blood volume. The product was transferred to a UVA-permeable bag (UVA, Macopharma, France), added 5 mL (0.1 mg) of 8-methoxypsoralen (8-MOP) aqueous solution (S.A.L.F.®, Cenate Sotto, Italy), exposed to UVA irradiation (Macogenic G2, Macopharma®), and then reinfused. Peripheral blood sample was drawn before ECP. Just before reinfused, buffy coat sample was drawn. Spearman correlation analysis was performed between the LP CD3+CD4+, CD3+CD8+, CD19+, NK of the preapheresis peripheral blood patient and the buffy coat infused analyzed by multiparameter flow cytometry 5 colors (FC500-Beckman Coulter®) in the total sample and in three groups according to preapheresis leukocytes counts (7.5x 109/L). The mean performance was calculated: CD3+CD4+, CD3+CD8+, CD19+, NK+ LP count in buffy coat/ CD3+CD4+, CD3+CD8+, CD19+, NK+ PB /ml x treatment volume (ml) x 100. The mean performance of the buffy coat LP categorized according to preapheresis leukocytes counts (1.5 109/L) were compared by Mann-Whitney test. Results: A total of 22 patients and 136 procedures were included in the final analysis. CD3+CD4+, CD3+CD8+, CD19+, NK LP in peripheral blood significantly correlated with those in buffy coat collected by COBE Spectra system, r= 0,74, 0.78, 0,92, 0,39 respectively (table 1). The LP mean doses and mean performance in buffy coat infused are specified in Table 1. The correlations was stronger in all LP with PB leukocytes counts 1.5x109/L). Conclusions: The buffy coat contains great variability in lymphocyte subpopulations with predominant levels of CD3+CD8+. There is a robust linear relationship between all PB and buffy coat LP. The mean performance LP was around 40% and it was not related to very low PB leukocyte count ( Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Introduction The human recombinant filgrastim G-CSF has been widely used for mobilisation of CD34+ cells of healthy donors (HD) since 90´s. In 2008, G-CSF biosimilars were approved by the European Medicines Agency for the same indications as those authorized for original filgrastim (Neupogen®). These new drugs were authorized on the basis of extensive physicochemical and biological protein characterization and pharmacodynamics data as well as clinical comparative studies in the particular field of chemotherapy–induced neutropenia in patients with solid tumors. Since then, the reported experience on the use of G-CSF biosimilars for PBSC mobilisation has been very limited particularly, in the setting of HD mobilization for allogeneic transplant. We report our single center experience on the use of filgrastim biosimilar Zarzio® (Sandoz Biopharmaceuticals®) for mobilization of HD, compared with a cohort of donors mobilized with the original filgrastim. Methods Retrospective comparative analysis of all consecutive HD undergoing a 1st attempt of PBSC mobilisation using 10 mcg/Kg/24h x4 days G-CSF (Filgrastim biosimilar Zarzio® [case cohort] or Filgrastim, Neupogen® [control cohort]) and collected with the same cellular separator (Cobe Spectra, Terumo®). Apheresis was initiated on day 5 and was daily repeated, if needed, in order to achive at least 3.5 x106/Kg patient body weight (PBW). SAEs were also analysed in both cohorts. For the porpoise of the post-transplant engraftment analysis both cohorts were independently compared according to the grade of HLA compatibility (HLA identical vs Haploidentical). Volunteer HD were excluded from the engraftment analysis. Non-parametric test was used for 2 cohorts comparison. Results Forty five HD cases and 41 controls undergoing G-CSF mobilization between June-09 and April-14 were eligible for the analysis. Donor features were comparable for both cohorts (table 1). Doses of G-CSF required, pre-apheresis analytical parameters, leukapheresis procedures, processed volume and collected graft parameters were found similar in both groups (table 1). All donors collected more than 2 x106/Kg CD34+ cells. Cummulative incidence of engraftment at day 30 was 100% for both cohorts, the HLA identical setting (p=0.53) and the haplo sub-group (p=0.25). AES were not observed for both cohorts. Conclusions In our experience, efficacy of G-CSF biosimilar Zarzio® was similar to reference filgrastim (Neupogen®) in terms of dose administered, CD34+ cells collected, stem cell functionality and engraftment. No SAEs were found for both cohorts. These preliminary results should be confirmed with a longer follow up within a prospective randomized trial. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Introduction. Graft versus host disease (GvHD) is the main cause of morbimortality after allogeneic stem cell transplantation (allo-SCT). Several single-nucleotide polymorphisms (SNPs) in cytokine genes have shown to influence gene expression and are therefore associated with donor-recipient alloreactivity and, ultimately, with SCT outcome. Interleukin 1 (IL1) is a proinflammatory cytokine that induces the production of cytokines and chemokines and plays an important role in the inflammatory processes. IL1 is involved in various cellular functions, including cell proliferation, differentiation, and apoptosis. The IL1 family consists of two biologically actives forms (IL1A and IL1B). Several polymorphisms of these genes have been implicated in the pathogenesis of autoimmune diseases, however, their importance in SCT is not well-known. Objective To investigate the relationship between 4 SNPs in IL1A and IL1B genes and the susceptibility to the development of GvHD and other complications after HLA-identical allo-SCT. Patients and methods Genomic DNA obtained from peripheral blood samples belonging to 509 patients and their HLA-identical sibling donors (Table 1) included in the DNA Bank of the Spanish Group for Hematopoietic Stem Cell Transplantation (GETH). One SNP, rs1800587 (-889 C>T), in the promoter region of the IL1A gene and three SNPs in the IL1B gene (two in the promoter region rs16944 (-511C>T), rs1143627 (-31 T>C) and one in exon 5 rs1143634 (+3954 C>T) were genotyped by multiplex primer extension followed by mass spectrometry (MALDI-TOF; Sequenom MassArray). Univariate and multivariate regression analysis were performed using Cox regression in the presence of competing risks except for chronic GvHD for which we used logistic regression model. All variables with p≤0.10 according to univariate analysis were included in the multivariate analysis. For multivariate analyses, p values were two sided and the outcomes were considered to be significant for p Results Genotypic frequencies observed for the 4 SNPs analyzed were in accordance with the Hardy-Weinberg equilibrium and were similar to those previously reported. Results of the multivariate analysisof the association between IL1A and IL1B genotypes and complications after allo-SCT are shown in Table 2. No association between the SNPs analyzed and complications other than acute GVHD were found. Patients with the alloreactive TT genotype for the SNP rs1143627 show increased risk of grade II-IV and III-IV acute GvHD (HR=6.87 and HR=19.19 respectively). In addition the presence of the rs16944 alloreactive A allele in the recipient was also associated with a significantly higher incidence of grade II-IV and mainly III-IV acute GvHD (HR=11.85 for grade II-IV and HR=53.48 for grade III-IV) Finally a higher risk of grades III-IV acute GvHD was observed in patients harboring alloreactive TT genotype for SNP rs1800587 (HR=3.12). Conclusions These results further support the idea of a genetic predisposition to certain complications after allo-SCT especially GvHD. IL1A and IL1B SNP genotyping might be useful to anticipate complications after sibling HLA-identical allo-SCT and, therefore to tailor the use of immunomodulatory approaches and, ultimately, to improve the clinical management of transplanted patients. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.