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Introduction: Cytogenetics remains one of the most important prognostic factors in acute myeloid leukemia (AML) patients, even for outcomes after allogeneic hematopoietic cell transplantation (allo-HCT). Complex karyotype (CK) constitutes a cytogenetic category with a very adverse prognosis in this setting. However, CK is a heterogenous and loosely defined category which comprises a high diversity of cytogenetic subtypes, which is highly enriched with specific cytogenetic subtypes characterized by losses of chromosomal material at critical regions known to confer a poor prognosis per se, such as monosomal karyotype, del(7q)/-7, del(5q)/-5 or abnormalities leading to 17p region loss. On the contrary, rare AML cases characterized with only multiple numerical abnormalities known as pure hyperdiploid karyotype (HDK), have a controversial prognosis. We hypothesized that pure complex HDK AML has a distinct and much better prognosis after allo-HCT compared to non-HDK, CK AML. Methods: We selected from the EBMT registry adult patients with AML and a full cytogenetic report. HDK was defined by the presence of 49 chromosomes or more. Patients were then stratified by pure HDK (pHDK) and HDK with other cytogenetic abnormalities (HDK+), characterized by HDK and the presence of a prognostic-defining cytogenetic abnormality such as del(5q)/-5, del(7q)/-7, del(17p)/-17/i(17q), inv(3q21-26)/t(3;3)(q21;q26) or t(9;22). We included only first allo-HCT from a sibling or unrelated donor (UD) performed between 2000 and 2018. Results: A total of 236 patients were identified as having HDK. There were 95 pHDK and 141 HDK+. Median age at transplantation was 53 years (range, 18-74) and median follow-up was 43 months (range, 35-56). A diagnosis of secondary AML was reported in 48 patients (20%). At the time of allo-HCT, 180 patients (76%) were in first remission (CR1), and 56 were beyond CR1 (24%). Eighty-five (39%) patients received an allo-HCT from a sibling donor, with more matched unrelated donors (MUD) in HDK+ patients (p=0.02). Most patients (70%) had a Karnofsky performance status (KPS) score of more than 90% at the time of transplantation. A myeloablative conditioning regimen was administered in 46% of the patients. In vivo T-cell depletion was part of the regimen in 66% of the patients. The most frequent trisomies were trisomy 8, 21, 13, and 22. The 2-year probability of non-relapse mortality (NRM) was 26% for the entire cohort. The 2-year probability of LFS was 50% for pHDK and 31% for HDK+ (p=0.003). The 2-year probability of overall survival (OS) was 57% for pHDK and 36% for HDK+ (p=0.007). The 2-year cumulative incidence of relapse (RI) was 22% for pHDK and 44% for HDK+ (p=0.001) (Figure 1). The cumulative incidence of grade II-IV acute graft-versus-host disease (GvHD) and chronic GvHD was 34% and 33%, respectively, for the entire cohort. Finally, the 2-year probability of GvHD and relapse-free survival (GRFS) was 36% for pHDK and 21% for HDK+ (p=0.01). On multivariate analysis, pHDK remained associated with significantly better LFS, OS and GRFS and higher RI (all p-values Conclusions: AML with pHDK has a better outcome after allo-HCT in terms of RI, LFS, OS and GRFS. pHDK AML constitutes probably a distinct cytogenetic entity from HDK+ or other non-hyperdiploid CK AML. CK remains a strong indication for allo-HCT, but the type of abnormalities included in CK significantly influences the outcome and should guide how to manage patients after allo-HCT in terms of immunosuppression withdrawal or prophylactic/preemptive post-transplant interventions such as use of hypomethylating agents or donor lymphocyte infusions. Figure 1 Figure 1. Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Ganser: Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria; Celgene: Honoraria. Socie: Alexion: Research Funding. Forcade: Novartis: Other: travel grant. Chalandon: Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Gilead, Amgen, Jazz, Astra Zenec: Other: Travel EXpenses, Accomodation; Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Amgen: Other: Advisory Board; Incyte: Speakers Bureau. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Kröger: Novartis: Research Funding; Riemser: Honoraria, Research Funding; Sanofi: Honoraria; Neovii: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Gilead/Kite: Honoraria; Celgene: Honoraria, Research Funding; AOP Pharma: Honoraria. Esteve: Jazz: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Abbvie: Consultancy; Novartis: Consultancy, Research Funding; Astellas: Consultancy; Pfizer: Consultancy; Novartis: Research Funding. Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria.

Background: Haploidentical stem cell transplantation (Haplo HSCT) has emerged in the past three decades as an alternative curative option when an HLA match donor is not available. Over time, the use of Haplo has increased dramatically, reaching superimposable results when compared to unrelated and related HSCT strategies, confirming its validity. The widespread use of Haplo mainly relies upon technical advances, control of alloreactivity through graft-versus-host disease (GvHD) prophylaxis combined with a rapid and almost universal probability to find an Haplo donor for any candidate patient. The aim of our study was to provide a picture of acute (aGvHD) and chronic GvHD (cGvHD) incidence in Haplo HSCT across different platform in the past 15 years, where Haplo moved from ex-vivo T-cell depleted (TCD) platform to in-vivo TCD platform to the post-transplantation cyclophosphamide (PTCy). Methods: We compared the outcomes of adult patients receiving a 1st Haplo HSCT for any hematological malignancy according to GvHD prophylaxis - ex-vivo + in-vivo TCD (n=160), in-vivo only TCD (n=507) or PTCy (n=2593) - and reported to the EBMT registry in 2004-2016. Patients with missing data on disease status at last follow-up and GvHD information were excluded. Primary endpoint was GvHD-free & Relapse-free survival (GRFS) with events defined by death or relapse or grade ≥3 aGvHD or extensive (ext) cGvHD. Secondary endpoints were progression-free survival (PFS), overall survival (OS), aGvHD and cGvHD, incidence of relapse (IR) and non-relapse-mortality (NRM). Due to sample size in the first cohort of ex-vivo TCD, multivariate analysis compared only in-vivo TCD vs PTCy cohorts. Table 1 illustrates patients' characteristics. Results: Univariate analysis for 3-year outcomes are reported on table 2. PTCy provides better GRFS, OS, PFS, NRM versus ex-vivo or in-vivo. IR was not significantly different. Likewise, the 3-year CI of cGvHD and ext cGvHD were similar between PTCy, in vivo TCD and ex-vivo TCD (cGvHD 27% [25-29%], 25% [21-29%], 18% [12-25%], p 0.03; ext cGvHD 11% [10-12%], 10% [8-13%], 8% [4-13%], p 0.45). On the contrary the 100-day CI of grade ≥2 aGvHD were lower in the ex-vivo TCD vs PTCy and in-vivo TCD (19% [14-26%], 28% [26-30%], 32% [28-36%], p 0.002) while grade ≥3 aGvHD were lower in the PTCy group vs ex-vivo and in-vivo TCD (9% [8-10%], 11% [7-17%], 14% [11-18%], p After adjustment for diagnosis, patient age, disease status, Karnofsky PS, donor/patient gender and CMV, cell source, conditioning intensity, previous auto and year of transplant, the multivariable model comparing in-vivo TCD and PTCy showed better outcome for PTCy. Compared to in-vivo TCD, the hazards for GRFS was 0.76 for PTCy (p 0.004), the HR for PFS was 0.71 (p 0.001) and the HR for OS was 0.7 (p 0.0008), the HR for NRM was 0.63 (p 0.001). Moreover, compared to in-vivo TCD, PTCy yielded similar hazards for grade≥2 aGvHD (HR: 1.02, p 0.89), grade≥3 aGvHD (HR 0.79, p 0.27), cGvHD (HR 1.17, p 0.37), ext cGvHD (HR 1.18, p 0.52) and relapse (HR 0.8, p 0.1). Variables associated with GRFS were active disease, Karnofsky PS ≥90%, diagnosis, donor/patient gender and CMV. An ancillary analysis evaluating the stem cell source effect in the PTCy cohort only, demonstrates comparable outcome endpoints (OS, PFS, NRM, IR) at 2-year between bone marrow (BM) and peripheral blood (PB) PTCy. In univariate analysis GRFS and the 2-year CI of cGvHD were not different between BM and PB (GRFS 47% [45-50%], 46% [44-49%], p 0.085; 2-year CI of cGvHD 25% [23-28%], 27% [25-30%], p 0.2) while ext cGvHD, 100-day CI of grade ≥2 aGvHD and grade ≥3 aGvHD were lower in BM PTCy vs PB PTCy (ext cGvHD 8% [7-10%], 12% [10-14%], p Compared to BM PTCy, the HR for cGvHD was 1.55 for PB PTCy (p 0.001), the HR for ext cGvHD was 2.04 (p 0.0003), the HR for grade ≥2 aGvHD was 1,94 (p Conclusions: In the present EBMT registry study on more than 3000 patients transplanted from an Haplo donor, we report improved outcome (better GRFS - in spite of comparable chronic GvHD - OS and PFS, lower NRM) and widespread use in different diagnosis setting other than acute leukemia in PTCy platform. PTCy strategy provides a concrete progress into the field: even if cGvHD still represent a major issue, exploitation of BM PTCy seems to protect against most severe GvHD manifestation. Disclosures Mohty: Jazz Pharmaceuticals: Honoraria, Research Funding. Kröger:Sanofi-Aventis: Honoraria; Riemser: Research Funding; Novartis: Honoraria, Research Funding; Neovii: Honoraria, Research Funding; Medac: Honoraria; JAZZ: Honoraria; DKMS: Research Funding; Celgene: Honoraria, Research Funding. Basak:Celgene: Honoraria; Teva: Honoraria.

We analyzed the prognostic impact of donor and recipient cytomegalovirus (CMV) serostatus in 16,628 de novo acute leukemia patients after allogeneic stem cell transplantation (allo-SCT). Compared with CMV-seronegative recipients who underwent allograft from a CMV-seronegative donor, cases of CMV seropositivity of the donor and/or the recipient showed a significantly decreased 2-year leukemia-free survival (44% vs 49%, P < .001) and overall survival (50% vs 56%, P < .001), and increased nonrelapse mortality (23% vs 20%, P < .001). Both groups showed a comparable relapse incidence and 2-year probability of graft-versus-host disease. The negative prognostic effects of CMV seropositivity of the donor and/or the recipient (vs CMV seronegativity of both) were significantly stronger for acute lymphoblastic leukemia (ALL) than for acute myeloid leukemia (AML), resulting in a markedly reduced 2-year overall survival (46% vs 55% for ALL compared with 52% vs 56% for AML). The important prognostic impact of donor/recipient CMV serostatus remained in a multivariate Cox regression analysis including the other prognostic variables. We conclude that donor and/or recipient CMV seropositivity is still associated with an adverse prognosis in de novo acute leukemia patients after allo-SCT despite the implementation of sophisticated strategies for prophylaxis, monitoring, and (preemptive) treatment of CMV.

Patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) have a poor prognosis with conventional chemotherapy. In the present study, we retrospectively analyzed the outcome of patients with BPDCN who underwent allogeneic stem cell transplantation (allo-SCT) or autologous stem cell transplantation (auto-SCT). A total of 39 patients (allo-SCT, n = 34; auto-SCT, n = 5) were identified in the European Group for Blood and Marrow Transplantation registry. The 34 allo-SCT patients had a median age of 41 years (range, 10-70) and received transplantations from sibling (n = 11) or unrelated donors (n = 23) between 2003 and 2009. MAC was used in 74% of patients. Nineteen allo-SCT patients (56%) received transplantations in first complete remission. The 3-year cumulative incidence of relapse, disease-free survival, and overall survival was 32%, 33%, and 41%, respectively. By univariate comparison, being in first remission at allo-SCT favorably influenced survival, whereas age, donor source, and chronic GVHD had no significant impact. We conclude that high-dose therapy followed by allo-SCT from related or unrelated donors can provide durable remission even in elderly patients with BPDCN. However, it remains to be shown if graft-versus-malignancy effects can contribute significantly to BPDCN control after allo-SCT.

Background: Allogeneic stem cell transplantation is a potentially curative procedure to a long list of hematological malignancies, but involves substantial risk of morbidity and mortality. Means for accurately predicting outcome and assessing risk are thus greatly needed. The Disease Risk Index (DRI) is a prognostic tool developed and validated by Armand et al. across a wide range of hematological malignancies (Blood 2012, Blood 2014) on cohorts of American patients. The Index stratifies patients into 4 distinct risk groups (low, intermediate, high, very high) and has yet to be validated in an international cohort. We sought to evaluate the validity of the DRI in a large cohort of European patients. Methods: This was a retrospective validation study on an independent cohort of patients undergoing allogeneic HSCT and reported the European Society for Blood and Marrow Transplantation (EBMT). Patients included had a hematological malignancy and underwent allogeneic transplantation between the years of 2000 and 2015. Risk groups were coded in accordance with the refined DRI (Blood, 2014). Outcomes were evaluated 4 years after the allogeneic HSCT. Overall survival (OS) was calculated with the Kaplan-Meier method. The log-rank test was used for comparisons of Kaplan-Meier curves. Cumulative incidence curves for nonrelapse mortality (NRM) and relapse with or without death were constructed reflecting time to relapse and time to NRM, respectively, as competing risks. The difference between cumulative incidence curves in the presence of a competing risk was tested with the Gray method. The prognostic effect of the DRI strata was estimated using a Cox proportional hazard model for OS and a Fine and Gray model for NRM and relapse. Results: A total of 89,061 patients from 423 transplantation centers were included in the analysis. Median age was 48.3 (IQR 36.2-57.5). The most frequent indication for transplantation was AML (39,530 patients) followed by ALL (16,206) and MDS (9,750); other indications spanned the spectrum of hematological malignancies. The majority of patients were in 1st or 2nd complete remission (54%). The median follow-up period was 3.6 years. Approximately 63% of patients were classified as intermediate risk by DRI, suggesting that this group could be further partitioned. The 4 year overall survival (95% CI) of the low, intermediate, high, and very high risk groups was 60.8% (59.9-61.8), 51.3% (50.8‐51.8), 27.0% (26.1‐27.8), 18.4% (17.1-19.8) (Figure 1). The same groups corresponded with increasing cumulative incidence of relapse; 8.9% (8.3-9.4), 19.3% (18.9-19.7), 39.0% (37.8-39.6), 45.1% (43.4-46.7), respectively. The DRI groups also showed increasing hazard between strata in the overall survival setting; intermediate risk was associated with a hazard ratio of 1.32, high risk 2.67 and very high risk 3.71 relative to low risk. Relapse showed a similar pattern. NRM was less strongly stratified by DRI (Table 1). The DRI groups maintained a similar risk, regardless of whether the transplantation was performed prior or after 2008. DRI was the strongest determinant of overall survival and relapse when introduced to a multivariable model with additional covariates. AUC for the index at 4 years was 62.5 for OS, 58.5 for NRM and 68.2 for relapse. Conclusions: We have validated the Disease Risk Index in a massive European data set. The groupings suggested by the DRI corresponded with distinct risk groups for overall mortality and relapse. Overall, our results indicate the international applicability of this robust prognostic tool. Figure 1. Kaplan-Meyer survival curves for overall survival, stratified by DRI Figure 1. Kaplan-Meyer survival curves for overall survival, stratified by DRI Table 1 Table 1. Disclosures Bader: Medac: Consultancy, Research Funding; Riemser: Research Funding; Neovii Biotech: Research Funding; Servier: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Bonini:Molmed SpA: Consultancy; TxCell: Membership on an entity's Board of Directors or advisory committees. Dreger:Gilead: Consultancy; Janssen: Consultancy; Novartis: Speakers Bureau; Gilead: Speakers Bureau; Novartis: Consultancy; Roche: Consultancy. Kuball:Gadeta B.V,: Membership on an entity's Board of Directors or advisory committees. Montoto:Roche: Honoraria; Gilead: Research Funding.

Introduction CK AML patients have high relapse rate and poor outcomes when treated with conventional chemotherapy. Allogeneic hematopoietic stem cell transplantation (AHSCT) may cure this disease; however, relapse rate remains a major limitation and survival is one of the worst amongst AML patients. Here we aimed to identify prognostic factors associated with survival in patients with AML and CK using combined data from the EBMT and MDACC. Methods A total 1,342 consecutively transplanted patients with CK (>3 cytogenetic abnormalities) AML reported to EBMT (N=1,118) and at MDACC (N=224) between 01/2000-12/2015 were included.The median age was 52 years (range 18-76 years), 335 patients (25%) were older than 60 years. Seven hundred and twenty-nine patients (54.3%) were male, 239 patients (17.8%) had secondary AML. Disease status before transplant was CR1, CR2 and activediseasein 877 (65.3%), 77 (5.7%) and 388 (29%), respectively. Donors were matched related (MRD), matched unrelated (MUD) and mismatched unrelated (MMUD) in 749 (55.8%), 513 (38.2%) and 80 (6%), respectively. Conditioning regimens were various, mostly eitherbusulfan-based (53.7%) or TBI-based (26.7%). Seven hundred and thirty-nine patients (55%) and 603 patients (45%) receivedmyeloablativeconditioning (MAC) and reduced intensity conditioning (RIC), respectively. The main stem cell source was peripheral blood (81%). In vivo T-cell depleted (TCD) methods were used in 665 patients (50%). Median time from diagnosis to transplant was 5.1 months (range 2-387 months) while the median follow-up duration was 35.5 months (range 8-174 months). Results Engraftment occurred in 96.3%, 69.7% and 30.3% had full and mixed donorchimerism, respectively. At 2 year post-transplant, the cumulative incidence (CI) of acute GVHD grade II-IV and grade III-IV was 26.3% and 8.4%, respectively, whereas CI of chronic GVHD was 30.9% with extensive chronic GVHD 17.8%. Leukemia free survival (LFS), overall survival (OS), CI of relapse, non-relapse mortality (NRM) at 2 years for the whole group was 31.3%, 36.8%, 51.1% and 17.6%, respectively, while 2-year GVHD-free, relapse-free survival (GRFS) was 19.8%. LFS, OS, GRFS, CI of relapse and NRM at 2 years for patients transplanted in CR1 was 38.4%, 44.5%, 23.8%, 46% and 15.7%, respectively. For patients with active disease these outcomes were 14.6%, 18.5%, 9.6%, 63.5% and 21.9%, respectively (Figure A, B). Patients ages 40-60 years transplanted in CR1 with MAC demonstrated lower relapse (40.2% vs. 51% with RIC, p=0.005), offset by a higher NRM (18.2% vs 9.8% RIC, p=0.037), associated with higher incidence of acute GVHD, and a non-significant difference in LFS (Figure C, D). In multivariable analysis (MVA) for the entire group, advanced age, transplantation in active disease, secondary AML and presence of deletion or monosomy 5 or 7 predicted poor LFS and OS. All of these factors as well as year of transplant (before 2010) also predicted poor GRFS, while conditioning intensity (MAC vs RIC) and donor type did not influence survival outcomes. Prognostic factors for relapse were age, secondary AML, active disease at transplant and presence of deletion or monosomy 5, while prognostic factors for NRM were older age, active disease, use of a mismatched unrelated donor and deletion or monosomy 7. Conclusions In this largest analysis of complex karyotypes AML patients, relapse remains the most common cause of treatment failure with 45% for patients in CR1 and 63.5% for patients not in remission relapsing after transplant. The only modifiable factorsat this time are performing transplantation in CR1 as soon as the donor is available. Control of GVHD might allow younger patients receiving MAC to have a lower NRM and improved LFS. Novel approaches are needed to decrease relapse rate and improve survival in these patients. Table Multivariable analysis for patients with CK AML. Table. Multivariable analysis for patients with CK AML. Figure A. CI of relapse for all patients and patients in CR; B. LFS for all patients and patients in CR; C. CI of relapse for patients age 40-60 years in CR with MAC, RIC; D. LFS for patients age 40-60 years in CR with MAC, RIC. Figure. A. CI of relapse for all patients and patients in CR; B. LFS for all patients and patients in CR; C. CI of relapse for patients age 40-60 years in CR with MAC, RIC; D. LFS for patients age 40-60 years in CR with MAC, RIC. Disclosures Ciurea: Cyto-Sen Therapeutics: Equity Ownership; Spectrum Pharmaceuticals: Other: Advisory Board. Champlin:Ziopharm Oncology: Equity Ownership, Patents & Royalties; Intrexon: Equity Ownership, Patents & Royalties.

Introduction: Previous trials have shown that autologous stem cell transplantation (ASCT) is superior to conventional chemotherapy in terms of remission rate and PFS in younger MM patients. Concerns about toxicity and potential efficacy of ASCT in older MM patients lead most centers to limit ASCT indications to patients aged Patients and Methods: We prospectively analyzed the outcomes of 56 consecutive MM patients who had received ASCT between September 2012 and September 2014 in 6 institutions in France (protocol ClinicalTrials.gov Identifier: NCT01671826). Patients were newly diagnosed MM. For induction therapy, all patients received a bortezomib-based induction regimen (VD, VTD, VCD, or VRD, 4 to 6 cycles) according to center's local guidelines. Mobilization was performed with G-CSF or G-CSF+cyclophosphamide and plerixafor whenever needed. High-dose chemotherapy consisted of either 140 mg/m2 or 200 mg/m2 Melphalan. A short two months consolidation phase post ASCT was allowed (lenalidomide-dexamethasone, VD, VTD, VCD or VRD). No maintenance treatment was given. Response, disease progression and relapse were defined according to the IMWG uniform response criteria. All patients signed an informed consent form according to the EBMT guidelines. Results: At time of diagnosis, median age was 67 (range, 64-74) years with 23% of patients being >70 years. There were 30 males and 26 females. The immunoglobulin subtype was IgG (n=29), IgA (n=15), light chain (n=10), other (n=2). The Salmon and Durie stage was III in 89% of cases (n=47), and the ISS score was I (n=18; 35%), II (n=19; 37%), III (n=14; 27%). Patients had high risk cytogenetics features (t(4;14) and/or del17p) in 9 cases (16%). 10% of patients had a serum creatinine level >176 micromol/L. None of the patients underwent hemodialysis. The Sorror comorbidity score was 0 (34), 1 (6), 2 (2), 3 (6), 6 (1), unknown (7). The median age at time of ASCT was 68 years, and the median time from diagnosis to ASCT was 5 months. In an intention to treat analysis, out of 56 patients, 6 patients could not proceed to ASCT because of an early infectious death (n=1), serious comorbidity (n=2), disease refractoriness to induction (n=1), and failure to collect an adequate PBSC graft (n=2). A median of 5.31x106/Kg CD34+ cells could be collected. Disease status at time of ASCT was: CR (n=12; 24%), VGPR (n=19; 38%), PR (n=17; 34%), and SD/non-responding (n=2; 4%). The conditioning regimen consisted of 140mg/m² melphalan in 18 cases (36%) and 200mg/m2 in 32 patients (64%). Moreover, 4 patients (8%) received a tandem ASCT. The median time for neutrophils and platelets engraftment was 12 days. The day-100 post ASCT non-relapse mortality was 0% and the 2-year NRM was 4.2% (95% CI:[0.3-18.3]). The overall response rate at day 100 was 96% (CR: 34%, VGPR: 47%, PR: 15%, SD/non-responsive: 4%). At 3 months post ASCT, 82% patients were able to receive the planned post ASCT consolidation treatment. After a median follow-up of 12 months, the estimated progression-free (PFS) and overall survival (OS) rates at 2 years were 76% (95%CI: [61.6-94.1]) and 88% (95%CI: [76.7-100]), respectively. The incidences of infectious complications post ASCT, and response rates were comparable between the two melphalan dose levels (p=0.28). However, in the univariate analysis, the 200 mg/m2 melphalan conditioning group showed a better OS rate compared to the 140 mg/m2 group (1-year OS: 100% vs. 67%; p=0.012). Conclusion: These prospective multicenter results indicate that ASCT is a safe and effective treatment modality for elderly, but fit MM patients at the era of novel induction agents. Of note, patients above age 70 did not experience a worse prognosis. Thus, age per se should not be used as an exclusion criterion for ASCT. Longer follow-up data will be presented, but these results already set the frame for a randomized comparison to the non-transplant approaches in this patients' subgroup. Disclosures Garderet: Bristol-Myers Squibb: Consultancy. Touzeau:AbbVie: Research Funding. Stoppa:Janssen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria. Karlin:Celgene: Honoraria; Janssen: Honoraria; BMS: Honoraria; Amgen: Honoraria; Sandoz: Honoraria, Membership on an entity's Board of Directors or advisory committees. Moreau:Celgene, Janssen, Takeda, Novartis, Amgen: Membership on an entity's Board of Directors or advisory committees.

Introduction: The response rate (partial remission and better) of pomalidomide and low dose dexamethasone in myeloma patients who received prior lenalidomide and bortezomib was 34% (Richardson P, Blood 2011, 118; abs 634). In order to increase the response rate of a pomalidomide based therapy, investigators commonly add oral weekly cyclophosphamide to pomalidomide and dexamethasone (PCD). We conducted a retrospective, single institution, study to analyse the efficacy and toxicity of the PCD combination for relapse/refractory patients. Patients / Methods: Patients had relapsed/refractory myeloma. They received pomalidomide 4 mg PO D1-21, dexamethasone 40 mg PO D1-4 and D15-19 (20mg if older than 75 years) or 40 mg once a week and oral cyclophosphamide 300 mg on D1, 8, 15, 22 of a 28 days cycle. Treatment was given as a bridge to transplantation or until progression. Granulocyte colony stimulating factor support was allowed. Thrombosis and infectious prophylaxis were recommended. Responses were assessed per the IMWG criteria. Results: Twenty patients were analyzed. The median age was 57 (range= 42 -76) years, and 9 were males (45 %). The immunoglobulin subtype was IgG 19, IgA 1. At diagnosis, the SD stage was I (73%) and II (27 %) and 5 missing values. The ISS score was I (50 %), II (30 %), III (20 %). The disease characteristics before PCD were: bone disease in 13 patients (93%, with 6 missing values), median calcemia was 2.3 micromol/L (range= 2.1- 2.6), hemoglobin was 11g/dL (range= 8-14), platelets were 178 000/mm3 (range=7-361), 10 % had a creatinine level >176 micromol/L (no hemodialysis was performed), elevated lactate dehydrogenase (> 470 IU) in 5 cases (25 %), elevated C-reactive protein (> 5 IU), for 6 patients (40%, 5 missing values). The median time from diagnosis to current therapy was 4 years (range= 1-16 years). The median number of prior therapies was 4 (range= 2-6). Prior treatments were chemotherapy (9), thalidomide (10), lenalidomide (20), bortezomib (19), autologous stem cell transplantation (ASCT) (10), double ASCT (1). Five patients were bortezomib refractory and 4 were lenalidomide refractory. The median number of administered cycles was 4 (2-12). The confirmed response rate (more than PR) was 63 % and the median number of cycles to response 3 (range=1-9). The number of responders after the first cycle was 8/19 (42 %). The type of best response were: CR: 1 (5%), VGPR: 3 (16%), PR: 8 (42%), SD: 4 (21%), PD: 3 (16%). With a follow-up of 8.5 months, the median PFS at 1 year is 80.7 % (95% CI: [63.2-100]). Patients without relapse at follow-up are 13 (65%). The causes of PCD withdrawal are: scheduled ASCT (6, 46%), toxicity (3, 23%), disease progression (4, 31%). The treatments after PCD failure were ASCT (4, 21 %), IMiDs (7, 37 %), other (10, 53 %). Response (≥PR) to salvage treatment post PCD was 60 %. At the last follow-up, the status was n=19 alive, and 1 patient lost to follow up. Toxicity was mostly neutropenia (50 %) and one patient had pulmonary aspergillosis. Conclusion: Toxicities were manageable and the PCD regimen had evidence of preliminary efficacy. Almost half of the patients could proceed to salvage ASCT. The IFM is currently conducting a phase II study analyzing the role of PCD for relapsing patients who were initially treated with bortezomib lenalidomide dex and had an ASCT upfront or delayed (IFM 2009/DFCI trial). Disclosures Garderet: Bristol-Myers Squibb: Consultancy.

Allogeneic hematopoietic stem cell transplantation (HSCT) offers a potential cure for a variety of hematological malignancies. Patients without an HLA matched sibling donor can turn to unrelated donor registries to identify a suitably HLA matched donor. In the case where a fully HLA-A, -B, -C, -DRB1 and -DQB1 (10/10) matched donor is unavailable, there are often multiple 9/10 matched donors to select from. However, the prioritization and identification of permissive HLA mismatches in the 9/10 matched setting have proven elusive. Fetal exposure to non-inherited maternal antigens (NIMA) imparts lifelong immune modulating effects leading to tolerance to these antigens. Prior studies have found that matching for non-inherited maternal antigens (NIMA) can lead to lower rates of acute graft versus host disease (aGVHD) and lower treatment-related mortality (TRM) in cord blood HSCT (J.J. van Rood et al., Blood 2002; J. J. van Rood et al., PNAS, 2009; V. Rocha et al., BBMT, 2012). Patients undergoing mismatched HSCT with adult unrelated donors could benefit from NIMA matching by introducing maternal HLA testing during confirmatory typing of the donor and using NIMA matching as a criterion for mismatched donor selection. This joint EBMT-CIBMTR retrospective analysis was designed to evaluate the influence of NIMA matching in HSCT with mismatched adult unrelated donors. Matching criteria were based on HLA-A, -B, -C, -DRB1, -DQB1 at high resolution. Included donor-recipient pairs had 5 loci HLA typing and a minimum of one year follow-up recorded at EBMT or CIBMTR and donors were registered with DKMS German Bone Marrow Donor Center. To obtain maternal HLA typing information, DKMS contacted the respective donors by mail to inform about the study and to provide detailed information, a buccal swab kit and an informed consent form to the donor's mother that the donor could send on. SBT-based HLA typing was performed at the DKMS Life Science Lab, Dresden, Germany once signed informed consent and samples were received. A total of 1735 donors were contacted and maternal samples could be retrieved for 803 cases (46%). A total of 50 NIMA matches (6%) were found reflecting the rate expected from previous studies. Multivariate analyses were performed using Cox proportional hazards models adjusting for significant co-variates for overall survival (OS), disease free survival (DFS), relapse, TRM and acute and chronic GVHD comparing NIMA matched to NIMA mismatched cases. The final analysis population was restricted to 9/10 matched cases (N=452) transplanted for acute myeloid leukemia (N=307) and acute lymphoblastic leukemia (N=145) using myeloablative (N=307) or reduced intensity (N=145) conditioning from 1999-2013. The NIMA matched (N=32) and mismatched (N=420) groups were well balanced for all disease, patient, transplant and donor characteristics. The groups differed by mismatched HLA locus with the NIMA matched group skewed towards more HLA-C mismatches (66% vs. 35%). Univariate analyses did not find any significant differences between the NIMA matched and mismatched groups for any outcomes. TRM rates were similar between the groups at 1 year with 23% (95% CI: 10-40%) and 23% (95% CI: 19-28%) in the NIMA matched and mismatched groups, respectively. No significant associations were observed in multivariate analyses of the NIMA matched versus mismatched groups (Table). In contrast to prior studies of NIMA matched HSCT, no significant associations were found between NIMA matching and any outcomes. However, our findings may be due to the fact that the current study was underpowered to detect the expected difference in TRM observed in prior studies. Investigation on a larger cohort or a prospective trial would be needed. We thank Carlheinz Müller from the German unrelated donor registry ZKRD for providing additional HLA information and the donors and their mothers for their cooperation in this study. Table. Multivariate analysis results of NIMA matched versus mismatched (used as reference) HSCT Table 1.OutcomeHR95% CIp-valueOS0.890.54-1.480.653DFS0.880.53-1.430.598TRM0.740.35-1.600.447Relapse0.890.45-1.750.737aGVHD II-IV0.970.53-1.800.935aGVHD III-IV0.590.19-1.910.382cGVHD1.770.99-3.160.053 Disclosures Lee: Bristol-Myers Squibb: Consultancy; Kadmon: Consultancy. Nagler:Biokine LTD: Consultancy.

Background Allo-HSCT has been shown to increase survival and improve cure in acute leukemia (AL). However, this procedure is accompanied by high rates of morbidity and mortality. Several risk scores based on conventional statistical methods may aid decision regarding whom and how to perform allo-HSCT, but these methods carry inherent limitations, which may lead to sub-optimal candidate selection. Machine learning (ML) is a field in computer science stemming from artificial intelligence and is part of the data mining approach for data analysis. ML algorithms are commonly applied in technological and commercial settings. They allow for coping with complex data scenarios and thus may be suitable for outcome prediction in allo-HSCT. With this background, and using a ML prediction method- the alternating decision tree (ADT) algorithm, we developed an interpretable model for overall mortality (OM) and treatment-related mortality (TRM) at day +100 after allo-HSCT in AL. Patients and Methods 28,995 adult allo-HSCT recipients from the registry of the ALWP of EBMT were analyzed. Twenty two variables were available including year of transplant (range, 2000-2011), diagnosis (Acute Myeloid Leukemia and Acute Lymphoblastic Leukemia), disease status, Karnofsky performance status, conditioning regimen (myeloablative or reduced- intensity conditioning), graft type (peripheral blood, bone marrow or cord blood), donor and recipient HLA compatibility, CMV serostatus, GVHD prophylaxis regimens, etc. Per study definitions, the primary outcomes to be predicted were OM and TRM at day +100 days after allo-HSCT. The complete dataset was split into 3 sets: training set (n=11,600), testing set (n=8,688) and validation set (n=8,707). The ADT prediction model was tested and optimized according to the first 2 subgroups and validated on the last one. Output from the ADT model, included variables selection with assigned scores in a tree-based structure and area under the ROC curve (AUC), a measure for model discrimination Results Each of the ADT models selected 12 out 22 variables for prediction of OM and TRM at day +100. Ten variables were mutual for both prediction models, although different weights were assigned. These included: age, diagnosis, disease status, Karnofsky performance status (all at time of transplant), donor-recipient HLA-matching, number of transplants in each center per year, year of transplant, conditioning regimen and the donor's and patient's CMV serostatus. Variables selected exclusively by the OM prediction model were graft type and donor-patient CMV serostatus match, whereas the TRM model selected time from diagnosis to transplant and donor-recipient sex match. Applying the models on the validation set yielded AUCs of 0.701 (95% confidence interval [CI] 0.691-0.710) for OM prediction and 0.67 (95% [CI] 0.66-0.68) for TRM. The ADT prediction models assigned scores correlating with patient outcome. Patients in each of the validation sets were grouped according to their score range and the prediction success. A Higher score was correlated with higher rate of the measured outcome in both models (figure 1 and figure 2). Conclusions We present two new models, based on the ADT ML algorithm, for prediction of OM and TRM at day +100 after allo-HSCT. The models are robust as they rely on a high number of samples and a large validation set. As shown in the figures, higher scores correlated with a poorer outcome, reaching more than 50% mortality for a score range of 5.76-7 in the OM prediction model. The AUC performance measure was better for OM than TRM, possibly due to a higher event rate in former, making it easier to predict. Improving the predictive ability will probably necessitate evaluation of more variables, as the limitation of the maximal predictive performance is most likely in the information gained from the variables and not from the sample size or algorithm used. This is currently under progress, especially combination with other risk scores linked to comorbidities. In summary, our models can aid candidate selection for allo-HSCT, by providing a measurable score that correlates with transplant success. Disclosures: Schmid: Novartis: Honoraria, Research Funding, travel grant Other; Roche: travel grant, travel grant Other; MSD: Honoraria.

Abstract 4139 The prognosis of patients with AML harboring the FlT3 ITD is known to be poor in those patients treated with chemotherapy alone. However, it remains uncertain whether this abnormality has also an impact on outcome following high dose intensification and autologous stem cell transplantation (ASCT). We addressed this question using the EBMT data base: we initially reported on a total of 134 patients in 2010 (Blood 2010, 3356a). Following further queries, we have now extended our study to a total of 357 patients with AML autografted in CR1 between January 2000 to December 2009, and in whom the information on the presence or the absence of FlT3ITD was available. 258 (136 with a normal karyotype) patients were ITD negative and 99 (63 with a normal karyotype) were ITD positive. 96% of the patients received peripheral blood as a source of stem cells. The median follow up was 30 m. (range, 1–118). Patients who were ITD positive had higher white cell counts at diagnosis (54 vs. 12.5 109/L; p In the univariate analysis, Leukemia-Free Survival (LFS) at 3 years was significantly lower in patients who were ITD positive (34±5% vs. 52±4%; p=0.001) and the relapse incidence was higher (58±5% vs. 42±4%; p=0.002). The Non-Relapse Mortality (NRM) rate was similar (8±3% vs. 6±1%; p= 0.7). By multivariate analysis, the only unfavorable prognostic factors for outcome were failure to achieve CR with more than one induction course (slow remitters), and the presence of an ITD, which were associated with higher relapse incidence (p= 0.006; p=0.03) and lower LFS (p=0.05; p=0.005). In this series, it was interesting to observe that the only group with a significantly lower LFS in univariate analysis, was the group of patients who were FlT3ITD positive without NPM1 mutation (23±11% vs. 56±6% for FLT3ITD negative/NPM non-mutated, 46±8% for FLT3ITD negative/NPM mutated and 48±13% for FLT3ITD positive /NPM mutated; p=0.03). We conclude that in the context of autografting for AML in CR1, the presence of a FLT3ITD is an unfavorable prognostic factor only in less than 50% of the patients corresponding to those with the absence of a NPM1 mutation. This study helps to better define the population of patients with AML that would benefit most from intensification with autologous stem cell transplantation. Disclosures: No relevant conflicts of interest to declare.

Abstract 3004FN2 Clofarabine (CLO), a second generation purine analogue, has demonstrated an efficient anti-leukemia activity while showing a favorable toxicity profile. The aim of our study was to analyse the results of CLO as part of the conditioning regimen prior to allo-SCT for the treatment of patients with AML or ALL. This retrospective multicenter report assessed the outcome of 90 patients who received a clofarabine-containing conditioning regimen allogeneic stem cell transplantation (allo-SCT) for AML (n=69) or ALL (n=21) between November 2006 and September 2010 and reported on the EBMT registry. The median age was 42 years (range: 18–69) at transplant. The majority of patients presented with an active disease at transplant (CR1 n=8; CR2 n=16, active disease n=66). All patients had received a CLO-containing conditioning regimen (RIC n=88; MAC n=2) with the following combinations: CLO/TBI n=27; CLO/Busulfan n=10; CLO/Busulfan/ATG n=32; CLO/others drugs n=21. With a median follow-up of 14 months (range: 1–45), 2-years OS, LFS, relapse incidence, non-relapse mortality (NRM) and chronic GVHD were 28+-5%, 23+-5%, 41+-6%, 35+-5% and 38+-7%, respectively. When comparing AML and ALL patients, OS and LFS were significantly higher for AML patients (OS: 35+-6% vs 0%, p Disclosures: No relevant conflicts of interest to declare.

Abstract 3501 Acute myeloid leukemia (AML) with translocation t(6;9)(p23;q34)/DEK-NUP214(CAN) rearrangement (t(6;9) AML) is a rare but well-characterized entity, associated to a poor prognosis. In this regard, a possible benefit of allogeneic hematopoietic stem-cell transplantation (alloHSCT) has been suggested, based on small series of patients. To investigate the potential role of alloHSCT for the management of t(6;9) AML we analyzed the outcome of patients with this AML subtype submitted to alloHSCT and reported to the ALWP, and compared it to other well-defined cytogenetic categories. Overall, we identified 74 patients (median age: 38, 18–65; 51% male) diagnosed with t(6;9) AML allografted since 1988 (median year of transplant: 2004). Most transplants were performed in complete response (CR1=56, 76%; CR2=8, 11%), whereas only a minority were performed in advanced phase (primary refractory, n=5; relapse, n=5). Donor was an HLA-identical sibling in 43 transplants (58%), and a matched unrelated donor in 24 (32%). Conditioning regimen consisted of a myeloablative regimen in most patients (n=61, 82%), and source of stem-cells was peripheral blood in 41 (55%) and bone marrow in 32 (43%). After a median follow-up of 51 months, 3-year leukemia-free survival (LFS), relapse incidence (RI), and non-relapse mortality (NRM) for patients allografted in CR1 was 51±7%, 19±6%, and 30±7%, respectively, whereas LFS for patients transplanted in other disease status was only 16±10% (p Disclosures: No relevant conflicts of interest to declare.

The cell source for autologous stem cell transplantation has shifted since 1994 from bone marrow (BM) to peripheral blood (PB). However, no study has compared outcomes. We analyzed 2165 adults with acute myelocytic leukemia (AML) and 1545 adults with acute lymphocytic leukemia (ALL) in first complete remission (CR1) who received autografts (AML: 1607 PB and 558 BM, ALL: 1126 PB and 416 BM) from 1994 to 2006. AML: Relative to the time of CR1, PB transplants were performed earlier than BM transplants. Since a poorer outcome was associated with a shorter interval from CR1 to PB transplantation, patients were divided into three groups: BM, early PB (≤ 80 days after CR1) and late PB transplants. BM recipients were younger, and more received total body irradiation. In multivariate analysis, transplant-related mortality was not different among groups, but relapse incidence (RI) was higher for early PB (p = .0006) and late PB (p = .01) compared to BM (56 ± 3%,.46 ± 2%, 39 ± 2% respectively). Earlier PB (p= .02) and later PB transplants (p= .06) were associated with a lower three year LFS rate than marrow (36± 3%, 46 ± 2%, 52± 2% respectively). ALL:: In multi variate analysis the only poor prognostic factors were a high white cell count at diagnosis and cytogenetics (presence of the Phi/bcr-abl). The RI and LFS at 2 years were identical in patients receiving BM and PB ( 45 ± 3% vs 47 ± 2% and 47 ± 3% vs 46 ± 2% respectively) In conclusion, in AML patients autografted in CR1 but not in ALL, risk of relapse was lower with BM than with PB, independent of the CR1 to transplantation interval.

Patients with acute myelocytic leukaemia (AML) with core binding factor mutations (CBF), bearing abnormalities of chromosome 16 or t(8;21) are classified as good risk with chemotherapy regimens including high dose cytosine arabinoside and are not subjected to hemopoietic stem cell transplantation (HSC) front line. However there are limited data from old studies indicating good outcome following HSC, autografting in particular, and there has been recently some concern about higher than expected relapse incidence following conventional chemotherapy in this patient population. From January 1990 to December 2004, a total of 325 adult patients were reported to the EBMT Acute Leukemia registry as receiving a transplant in first remission (CR1). Of these, 159 had an inversion 16, including 124 with no additional chromosome abnormality and 35 with other abnormalities. 166 had a t(8;21) translocation, as the only chromosome abnormality in 106 and associated to other abnormalities in 60. 64 patients with inv 16 and 81 patients with t(8;21) received a geno-identical allograft. 95 patients with inv 16 and 85 patients with t(8;21) translocation received an autograft. In patients with inv 16, following allogeneic and autologous transplantation respectively, the LFS were 59 ± 7% and 66 ± 5% (p=0.5), the RI 27 ± 6% and 32 ± 4% (p=0.45) and the TRM 14 ± 4% and 2 ± 2% (p=0.003). The LFS was significantly higher after January 2001. Female patients had a significantly lower incidence of relapse and a higher LFS. The existence of additional chromosome abnormalities not only did not worsen the prognosis but was associated with less relapses (12±5% vs 34 ± 4%, p= 0.01), and a better LFS (78 ± 7% vs 59 ± 5%, p=0.04). In patients with t(8;21), following allogeneic and autologous transplantation respectively, the LFS were 60 ± 5% and 66 ± 5% (p=0.69), the RI 15 ± 2% and 28 ± 3% (p=0.03) and the TRM 24 ± 3% and 6 ± 1% (p=0.003). Younger age and a lower white cell count at diagnosis were associated with a lower TRM and a better LFS.There was no difference in outcome between female and male patients. Following autologous transplantation as compared to allogeneic, the TRM was significantly lower and the relapse incidence significantly higher. For all adult CBF AML, the LFS did not differ between autologous and allogeneic transplants. Although the reasons why these patients were transplanted are unclear, considering the low TRM of autologous stem cell transplantation and the possibility to monitor in vivo purging by molecular biology, the data support the inclusion of ASCT in the front line treatment of CBF AML and suggest that a randomized prospective trial comparing high dose ARA-C and ASCT would be of interest.