Acute Leukemia Working Party Research Articles

Practice Patterns of Transplant Centers Regarding Maintenance Treatment Post Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia: A Survey on Behalf of the EBMT Acute Leukemia Working Party

Introduction: Disease recurrence in acute myeloid leukemia (AML) remains the major reason of allogeneic hematopoietic cell transplantation (allo-HCT) failure. Strategies to reduce the risk of relapse such as prophylactic pharmacologic interventions post allo-HCT are more frequently applied by some transplant physicians, especially after the growing evidence of its efficacy and tolerability. Others are still being skeptical regarding its implementation due to difficulty proving efficacy by large randomized trials, or concerns of long-term toxicities. The aim of this study was to conduct a survey among the European Society for Blood and Marrow Transplantation (EBMT)-affiliated transplant centers to identify clinical practice patterns regarding maintenance treatment post-allo-HCT in AML. Methods: After the approval of the board of the Acute Leukemia Working Party (ALWP), EBMT-affiliated centers received by email a questionnaire-based survey between January and June 2023. The questionnaire consisted of 13 questions assessing clinical practices regarding maintenance treatment post allo-HCT in AML, specifically the indications of maintenance, the type, the drug used, and the duration of the treatment. Results: A total of 115 (out of 424) EBMT-affiliated centers from 31 countries responded to the survey with a response rate of 27.12%. Overall, 102 (88.8%) centers implement maintenance strategy whether pharmacological intervention or cellular therapy post allo-HCT in AML, most of the centers (N=67, 58.3%) use it based on a personalized decision, 17 (14.8%) use it routinely, and 18 (15.7%) use it exceptionally. Regarding the indication, the majority of the centers recommend maintenance treatment for AML patients in second remission or beyond (N=64, 62.7%) or in AML patients in first remission with high risk of relapse based on cytogenetic or molecular data (N=61, 59.8%), whereas 34 (33.3%) centers recommend it only for FLT3-mutant disease, and 11 (10.8%) centers in all patients regardless of the risk of disease. The majority of centers (N=77, 75.5%) use a combination of pharmacologic and cellular therapies, and 20 (19.6%) centers use only pharmacologic therapies. Among centers using pharmacologic therapies, 62 (63.9%) use hypomethylating agents (HMA) (azacitidine N=51 (82.3%), decitabine N=6 (9.6%), HMA with venetoclax N=23 (37%), HMA with donor lymphocyte infusion (DLI) N=38 (61%), or a combination of modalities in 42 (67.7%)). In general, most centers (N=35; 87.5%) do it pre-emptively either minimal residual disease (MRD) driven or chimerism driven, whereas 22 (55%) centers do it prophylactically. The majority of centers continue HMA for one-year duration (N=37, 59.7%), 15 (24.2%) for two years and only 10 (16.1%) continue until disease recurrence or toxicity. Out of 97 responding centers regarding the use of FLT3 inhibitors as maintenance, 93 (95.9%) are implementing this strategy. The most common choice was sorafenib in 82/93 (88.2%) centers, midostaurin in 28 (30%), and gilteritinib in 30 (32.2%). Among these, 56 (83.5%) centers use FLT3 inhibitors as prophylaxis whereas 28 (41.7%) use a pre-emptive approach. The preferred maintenance duration was for two years in 51 (54.8%) centers, followed by one-year duration in 30 (32.3%) centers, continuous until disease relapse or toxicity in 9 (9.7%) centers, and for five years in only 3 (3.2%) centers. Novel agents are used in 71 (70.2%) centers as maintenance either alone or in combination with HMA, of them 52 (73.2%) use venetoclax, and 13 (13.2%) use enasidenib. Finally, regarding practice patterns, 32 (29.6%) centers claim that maintenance treatment is part of their routine practice, 46 (42.6%) only for FLT3 mutant AML. Others are not routinely implementing maintenance because they are still skeptical and need more evidence by randomized clinical trials (N=8), whereas 5 centers are concerned regarding tolerability, and 16 (14.8%) cannot implement because of regulatory restrictions or lack of access. Conclusion: In this survey, the majority of responding EBMT-affiliated transplant centers is implementing post-transplant AML maintenance treatment, predominantly HMA and FLT3 inhibitors. Further studies are needed to clarify the appropriate strategy and duration of maintenance therapy. The study will help the EBMT to incorporate post-transplant strategies as a routine registry capture parameter.

Outcome of Allogeneic Stem Cell Transplantation in FLT3-TKD-Mutated AML - a Study on Behalf of the Acute Leukemia Working Party of the EBMT

Introduction The overall prognostic impact of point mutations in the tyrosine-kinase domain 1 of FLT3 (FLT3-TKD mut) in patients (pts) with acute myelogenous leukemia (AML) remains controversial. Furthermore, co-occurrence of FLT3-TKD mut and mutated nucleophosmin-1 (NPM1 mut) was shown to have a favorable prognostic impact on AML pts receiving conventional chemotherapy. However, little is known about the outcome of AML pts with FLT3-TKD mut with or without co-occurring NPM1 mut treated with allogeneic stem cell transplantation (alloSCT). Patients and Methods This is a retrospective study of the acute leukemia working party (ALWP) of the European Society for Blood and Marrow transplantation (EBMT) investigating the outcome of adult AML pts with FLT3-TKD mut with or without NPM1 mut after first alloSCT using matched sibling (MSD), unrelated (UD) or haploidentical (haplo) donors between 2005 and 2022. All patients were in first or second complete remission (CR1 of CR2). Information on cytogenetic risk was necessary for inclusion. No ex-vivo T-cell depletion (TCD) was allowed. The primary endpoint was leukemia-free survival (LFS) at two years after alloSCT. Secondary endpoints were overall survival (OS), cumulative incidence of relapse (RI), non-relapse mortality (NRM), acute and chronic graft-versus-host disease (GVHD) and GVHD-free, relapse free survival (GRFS). One hundred and eighty-two adult AML pts with FLT3-TKD mut were identified, of which 74 (40.7%) had a co-occurring mutation in NPM1. Median age was 55.1 years (range 18.6-79.1) and 46.7% were male. Median follow-up was 21.4 months [IQR 13.6-28.1]. 78% of the pts were in CR1. Cytogentic risk was favorable, intermediate and adverse in 12.6%, 75.3% and 12.1% of pts, respectively. Additional FLT3 internal tandem duplication (FLT3-ITD) was present in 25.8% of pts. Information on measurable residual disease (MRD) was available for 68.7% of pts, being positive in 48% of these. Karnofsky performance score was < 90% in 21.1%, and hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was >=3 in 28.1% of pts. 69.6% of pts were cytomegalovirus (CMV) positive. Conditioning was myeloablative in 52.8% and reduced intensity in 47.2% of pts. Stem cell donors were MSD, UD and haplo in 25.8%, 55.5% and 18.7% of cases. Stem cell source was bone marrow in 10.4%, peripheral blood in 87.4% and both in 2.2%. In-vivo TCD was performed in 59.2% of pts. GVHD prophylaxis was calcineurin inhibitor-based in 92.2% of pts. Results Engraftment was achieved in 99.4% of pts with a day-60 absolute neutrophil count (ANC) >0.5 x 10 9/L of 97.7% [95% CI: 93.7-99.2]. Day-180 rates of acute GVHD (aGVHD) grade II-IV and grade III-IV were 26.2% (95% CI:19.9-32.9) and 8.1% (95% CI:4.6-12.8), respectively. At two years, rates of total chronic GVHD (cGVHD) and extensive cGVHD were 30% (95% CI: 22.5-38) and 16.6% (95% CI:10.6-23.7), respectively. Two-year LFS and OS were 66.1% (95% CI: 57.6-73.2) and 74% (95% CI: 65.4-80.8), respectively. Two-year RI, NRM and GRFS were 22.5% (95% CI:16-29.8), 11.4% (95% CI: 7-17), and 51.1% (95% CI: 42.4-59.1), respectively. Cause of death was original disease in 47.5%, infection in 27.5%, GVHD in 22.5% and non-SCT related in 2.5% of cases. In univariate analysis the only factor with significant impact on LFS was donor type (haplo [n=34] vs. others, p=0.006). For GRFS, patient CMV negativity (p=0.014) and in-vivo TCD (p=0.01) were significant. Interestingly, co-occurring mutations in FLT3 (FLT3-ITD) or NPM1 were not identified as having a significant impact on LFS or GRFS. Moreover, MRD status before alloSCT was also not shown to have a significant impact on these outcomes. In multivariate analysis of LFS and GRFS, only donor type (haplo [n=34] vs. others) was shown to be significant for both endpoints, hazard ratio (HR) 2.54; 95% CI: 1.4-4.6; p=0.002, and HR 2.01; 95% CI: 1.18-3.41; p=0.01, respectively. Conclusion Acknowledging the limitations of our retrospective study in this rare entity results are encouraging given the high-risk population (median age 55.1 years, CR2 in 22%, co-occurring FLT3-ITD in 25.8%, positive MRD in 48%, HCT CI >=3 in 28.1%). LFS, OS and GRFS rates were 66.1%, 74% and 51.1%, respectively, and both RI and NRM were comparably low with rates of 22.5% and 11.4%, respectively. No positive prognostic impact of co-occurring mutations in FLT3-TKD and NPM1 was detected, unlike what was found for conventional chemotherapy.

Survival advantage of treosulfan plus fludarabine (FT14) compared to busulfan plus fludarabine (FB4) in active acute myeloid leukemia post allogeneic transplantation: an analysis from the European Society for Blood and Marrow Transplantation (EBMT) Acute Leukemia Working Party (ALWP).

We compared FT14 (fludarabine 150-160 mg/m2, treosulfan 42 g/m2) versus FB4 (fludarabine 150-160 mg/m2, busulfan 12.8 mg/kg) in acute myeloid leukemia (AML) transplanted at primary refractory/relapsed disease. We retrospectively studied: (a) adults diagnosed with AML, (b) recipients of first allogeneic hematopoietic stem cell transplantation (HSCT) from unrelated/sibling donor (2010-2020), (c) HSCT with primary refractory/relapsed disease, (d) conditioning regimen with FT14 or FB4. We studied 346 patients, 113 transplanted with FT14, and 233 with FΒ4. FT14 patients were significantly older, more frequently had an unrelated donor and had received a lower dose of fludarabine. Cumulative incidence (CI) of acute graft-versus-host disease (GVHD) grade III-IV and extensive chronic GVHD was similar. With a median follow-up of 28.7 months, 2-year CI of relapse was 43.4% in FT14 versus 53.2% in FB4, while non-relapse mortality (NRM) was respectively 20.8% versus 22.6%. This led to 2-year leukemia-free survival (LFS) of 35.8% for FT14 versus 24.2% in FB4, and overall survival (OS) of 44.4% versus 34%. Adverse cytogenetics and conditioning regimen independently predicted CI of relapse. Furthermore, conditioning regimen was the only independent predictor of LFS, OS, and GVHD-free/relapse-free survival. Therefore, our real-world multicenter study suggests that FT14 is associated with better outcomes in primary refractory/relapsed AML.

Validation of the Transplant Conditioning Intensity (TCI) Score for Allogeneic Hematopoietic Cell Transplantation

Introduction: Since non-relapse mortality (NRM) after allogeneic hematopoietic cell transplantation (HCT) is influenced by the conditioning regimen, it is essential to precisely calculate its intensity for any patient. Therefore, the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) registry previously developed the Transplant Conditioning Intensity (TCI) score to define conditioning regimens based on the sum of the doses (weight scores) for every component of the pre-transplantation regimen. HCT patients (pts) were stratified by a 3-index scheme with a low [1-2], intermediate [2.5-3.5] or high [4-6] TCI-score. (Bone Marrow Transplantation 2020; 55:1114) When tested in a large registry dataset of acute myeloid leukemia (AML) pts >45 years of age, TCI grouping was highly predictive for early and 2-year NRM, and better compared with the classical 2-index reduced intensity conditioning/ myeloablative conditioning (RIC/MAC) classification. The aim of the current study was to validate using a distinct dataset, the ability of the original TCI classification scheme to predict post-HCT NRM. Methods: TCI score was applied to a timely distinct cohort reported to the EBMT as the one used to establish the TCI classification scheme. We tested the impact of TCI in predicting early (day 180) NRM (defined as any death without previous relapse) in 55-75 years of age AML first complete remission (CR-1) pts who were transplanted between 2018 and 2021. Included pts were allografted with peripheral blood stem cells (PBSC, 96.4%) or bone marrow (BM, 3.6%) from a matched sibling donor (MSD, 25%) or unrelated donor (UD, 75%). NRM at 2 years was a secondary endpoint. Results: 4,312 AML pts (median age 63.4, interquartile range 59.5-67.2) were assigned to a TCI category, as previously described. 49% of the pts received a low [1-2], 47% an intermediate [2.5-3.5] but only 4% of the pts received a high [4-6] TCI-score regimen. As expected, there was an inverse relationship between age, Karnofsky status and hematopoietic cell transplant-specific comorbidity index (HCT-CI) and TCI group (p<0.0001). Besides a higher prevalence of MSD transplantations in the high (40%) as compared to low (21.6%) and intermediate (26.4%) TCI-groups (p<0.0001), pts were well balanced within TCI groups regarding other transplant and patient characteristics. The day (d)100, d180 and 2-year NRM ranged from 4.8-12.5%, 8.9-17%, and 17.4-23.9% between low, intemediate and high TCI scores, respectively. In univariate analysis, TCI provided a highly significant risk stratification for early and 2-year NRM (p<0.0001 for all pairwise comparisons between groups) (Figure 1). In the multivariate Cox regression analysis adjusted for age, Karnofsky status, HCT-CI and other variables, there was a significant increase in risk of early NRM with each TCI group (Table 1). Compared to low TCI, pts receiving intermediate and high score TCI regimens had a significantly increased risk for d180 NRM (hazard ratio [HR] 1.34, 95% CI, 1.03-1.74, p=0.029 and HR 2.37, 1.39-4.06, p<0.002, respectively). The HRs for d180 NRM pts receiving a high TCI [4-6] score regimen was 1.77 (1.06-2.97, p=0.029) when compared to the intermediate TCI [2.5-3.5] group. As expected, early NRM was also significantly influenced by incremental age, Karnofsky status score <90 and HCT-CI >=3. TCI grouping was also significantly associated with overall NRM. Similar results were found when the analysis was restricted to pts aged between 55 and 65 years (N=2,640). There was good concordance between RIC/MAC and low/high TCI score grouping, whereas 49% of the MAC pts and 51% of the RIC pts were re-classified as having received a reduced toxicity conditioning regimen with a TCI score of 2.5-3.5. Conclusion: Here, we validated in an independent patient cohort, the recently proposed 3-group TCI score for its ability to predict early NRM in AML pts >55 years of age. TCI predicts early NRM independently of other known prognostic factors such as age, Karnofsky, or HCT-CI. Compared to the current RIC/MAC classification model, the TCI provides a finer and more precise tool which may be easily calculated for any patient to offer safer transplantation especially in older and unfit pts. TCI may be used as a new, well-defined, and standard terminology for conditioning intensity in registry databases, in the literature and in clinical trials. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Trends in outcome of transplantation in patients with secondary acute myeloid leukemia: an analysis from the Acute Leukemia Working Party (ALWP) of the EBMT.

Trends in outcome of transplantation (HSCT) in secondary acute myeloid leukemia (sAML) are limited. We evaluated results of HSCT in 4224 patients with sAML in complete remission; 1337 were transplanted in 2000-2010 and 2887 in 2011-2020. Median age was 54 (range, 18-74) and 59 (range, 18-78) years, respectively (p < 0.0001). Donors were MSD in 65% vs. 37%, 10/10 UD in 27% vs. 50%, and 9/10 UD in 8% vs. 13%, respectively (p < 0.0001). Conditioning was myeloablative in 46% and 38%, respectively. Two-year non-relapse mortality (NRM) was lower in patients transplanted in 2011-2020 vs. those transplanted in 2000-2010, 18% vs. 21% (hazard ratio (HR) = 0.82, 95% CI: 0.68-0.9; p = 0.04) and modified GVHD-free, relapse-free survival (GRFS) (HR = 0.9, 95% CI: 0.81-0.99; p = 0.04) was better in patients transplanted in the 2011-2020 vs. those transplanted in 2000-2010. Two-year relapse incidence (RI) was similar between the 2 groups with 32% vs. 31%, (HR = 1.05, 95% CI: 0.9-1.22; p = 0.55). Likewise, leukemia-free survival (LFS) (HR = 0.95, 95% CI: 0.84-1.07; p = 0.38) and overall survival (OS) (HR = 0.93, 95% CI: 0.82-1.05; p = 0.26) were not significantly different between the two periods. In conclusion, Incidence of NRM has been significantly reduced and GRFS significantly increased in HSCT for sAML in the last 2 decades.

Measurable residual disease (MRD) status before allogeneic hematopoietic cell transplantation impact on secondary acute myeloid leukemia outcome. A Study from the Acute Leukemia Working Party (ALWP) of the European society for Blood and Marrow Transplantation (EBMT).

Measurable residual disease (MRD) assessment before allogeneic hematopoietic cell transplantation (HCT) may help physicians to identify a subgroup of patients at high risk of relapse for de novo acute myeloid leukemia (AML) but its relevance among patients affected by secondary AML (sAML) is still unknown. We assessed the impact of MRD among 318 adult patients with sAML who received an allogeneic HCT in first complete remission. At the time of HCT, a total of 208 (65%) patients achieved MRD negativity, while 110 (35%) had positive MRD. 2-year overall survival (OS) was 58.8 % (95% CI 52.2-64.9) with leukemia-free survival (LFS) of 50.0 % (95% CI 43.7-56.1), relapse incidence of 34.2% (95% CI 28.4-40.1) and non-relapse mortality (NRM) of 23.3 % (95% CI 19-27.7) for the entire cohort. In multivariate analysis, HCT recipients with KPS ≥ 90 experienced less disease recurrence (HR 0.61, 95% CI 0.4-0.94) with better LFS (HR 0.63, 95% CI 0.44-0.89) and OS (HR 0.58, 95% CI 0.39-0.86). There were no differences in major clinical endpoints between patients with MRD-positive and MRD-negative status at the time of HCT. Pre-transplantation assessment of MRD was not informative on post-HCT outcomes in this retrospective registry-based analysis among patients affected by sAML.

Comparison of fludarabine–melphalan and fludarabine–treosulfan as conditioning prior to allogeneic hematopoietic cell transplantation—a registry study on behalf of the EBMT Acute Leukemia Working Party

In recent years considerable variations in conditioning protocols for allogeneic hematopoietic cell transplantation (allo-HCT) protocols have been introduced for higher efficacy, lower toxicity, and better outcomes. To overcome the limitations of the classical definition of reduced intensity and myeloablative conditioning, a transplantation conditioning intensity (TCI) score had been developed. In this study, we compared outcome after two frequently used single alkylator-based conditioning protocols from the intermediate TCI score category, fludarabine/melphalan 140 mg/m2 (FluMel) and fludarabine/treosulfan 42 g/m2 (FluTreo) for patients with acute myeloid leukemia (AML) in complete remission (CR). This retrospective analysis from the registry of the Acute Leukemia Working Party (ALWP) of the European Society of Bone Marrow Transplantation (EBMT) database included 1427 adult patients (median age 58.2 years) receiving either Flu/Mel (n = 1005) or Flu/Treo (n = 422). Both groups showed similar 3-year overall survival (OS) (54% vs 51.2%, p value 0.49) for patients conditioned with FluMel and FluTreo, respectively. However, patients treated with FluMel showed a reduced 3-year relapse incidence (32.4% vs. 40.4%, p value < 0.001) and slightly increased non-relapse mortality (NRM) (25.7% vs. 20.2%, p value = 0.06) compared to patients treated with FluTreo. Our data may serve as a basis for further studies examining the role of additional agents/ intensifications in conditioning prior to allo-HCT.

Comparative Study of Treosulfan Plus Fludarabine (FT14) with Busulfan Plus Fludarabine (FB4) for Acute Myeloid Leukemia in First or Second Complete Remission: An Analysis from the European Society for Blood and Marrow Transplantation (EBMT) Acute Leukemia Working Party (ALWP)

Comparative Study of Treosulfan Plus Fludarabine (FT14) with Busulfan Plus Fludarabine (FB4) for Acute Myeloid Leukemia in First or Second Complete Remission: An Analysis from the European Society for Blood and Marrow Transplantation (EBMT) Acute Leukemia Working Party (ALWP)

Outcome of Human Umbilical Cord Blood Stem Cell Transplantation (CBT) for Acute Myeloid Leukemia in Patients Achieving First Complete Remission after One Versus Two Induction Courses: A Study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Background: Achieving a first complete remission (CR1) is an important prognostic factor for transplantation outcome. However, there are no data in the setting of cord blood transplantation (CBT) indicating whether the number of induction courses (1 or 2) needed to achieve CR1, is of prognostic significance. As CBT is advantageous for acute myelogenous leukemia (AML) patients (pts) with positive pre transplant measurable residual disease (MRD) (Milano F, NEJM 2016), it is conceivable that in the CBT setting, no difference in transplantation outcome will be observed between pts achieving CR1 after 1 or 2 inductions.Methods: Using the European Society for Blood and Marrow Transplantation (EBMT)/Acute Leukemia Working Party (ALWP) registry, we compared transplantation outcomes of adult pts aged ≥18 years with AML that underwent CBT in 2005-2020 in CR1, achieved following 1 versus (vs) 2 induction courses. Multivariate analysis (MVA) adjusting for differences between the induction groups was performed using a Cox's proportional-hazards regression model for main outcomes.Results: Three hundred and twenty-five pts were included comprising 243 (75%) with 1 and 82 (25%) with 2 induction chemotherapy courses. Median (range) follow-up was 65.4 (57.4-73.5) and 51.0 (34.8-61.5) months, respectively (p=0.6). Median age was 49.4 (19.0-70.9) and 52.1 (19.2-71.5) years (p=0.8), respectively. For patients with 1 and 2 induction courses, respectively, 49.4% and 57.3% were male, 225 (92.6%) and 78 (95.1%) pts had de novo AML, and 18 (7.4%) and 4 (4.9%) had secondary AML (p=0.6). Pts with 1 and 2 induction courses, respectively, were classified by cytogenetic risk as follows: intermediate, 62.0% and 79.2%, adverse, 33.2% and 19.5%, and favorable, 4.8% and 1.3% (p=0.02) (missing data~25%). The FLT3-ITD mutation was harbored by 33.7% and 32.3% of the pts (p=0.8), respectively (missing data ~6%). Conditioning was myeloablative (MAC) in 43.0% and 36.6% and reduced intensity (RIC) in 57.0% and 63.4%, respectively (p=0.31). Karnofsky performance score (KPS) was > 90 in 74.7% and 71% of the pts, respectively (p=0.5). The most frequent anti-graft-versus-host disease (GVHD) prophylaxis was cyclosporin A (CSA) and mycophenolate mofetil (MMF) in 75.6% and 82.5 %, or CSA with or without steroids in 16.1 % and 11.2%, respectively. Anti-thymocyte globulin (ATG) was administered to 32.9% and 25.6% of the CBT recipients, respectively (p=0.2). Engraftment rates were lower for pts achieving CR1 after 1 vs 2 induction courses (91.3% and 98.8% p=0.02) with corresponding day 60 absolute neutrophil count (ANC) > 0.5 x 10 9/L in 89.6% vs 96.3% of the pts (p=0.03).Day 180 incidence of acute GVHD grades II-IV was similar in both induction groups, 38.3% and 37.2% (p=0.8), as was 2-year total chronic GVHD, 23.4% and 27.5 %, respectively (p=0.6). In univariate analysis, the 2–year non-relapse mortality (NRM), relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS) and GVHD-free, relapse-free survival (GRFS) were similar between patients achieving CR1 with 1 vs 2 induction courses with 22.6% vs 23.6% (p=0.87) 25.1% vs 30.4% (p=0.4), 52.3% vs 46.0% (p=0.3), 58.6% vs 50.0% (p=0.2), and 44% vs 44.1% (p=0.66), respectively. Similarly in MVA, there was no significant association between 2 courses of induction and NRM (hazard ratio (HR) = 1.1; 95% CI, 0.6-1.8, p=0.7), RI (HR = 1.4; 95% CI, 0.9-2.3, p=0.1), LFS (HR = 1.3; 95% CI, 0.9-1.8, p=0.2), OS (HR = 1.3; 95% CI, 0.9-1.9, p=0.1), and GRFS (HR = 1.1; 95% CI, 0.8-1.5, p=0.5).Conclusions: In CBT recipients, we did not find any significant differences in outcomes in patients achieving CR1 after one or two induction courses. Notably, engraftment was better in patients receiving two courses of induction chemotherapy. [Display omitted] DisclosuresLabopin: Jazz Pharmaceuticals: Honoraria. Forcade: Novartis: Other: travel grant. Sierra: Amgen: Other: Educational grant; Roche: Other: Educational grant; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alexion: Other: Educational grant; Jazz Pharmaceuticals: Research Funding; Janssen: Other: Educational grant; Novartis: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria; BMS Celgene: Honoraria, Research Funding. Byrne: Incyte: Honoraria. Blaise: Jazz Pharmaceuticals: Honoraria. 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.

Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia with Hyperdiploid Complex Karyotype: A Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

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<0.004). Age was associated with lower OS (p=0.05). Being in remission at the time of allo-HCT was associated with better LFS, OS and GRFS, and lower NRM and RI (all p-values<0.02). Secondary AML, donor type, KPS, and conditioning regimen intensity were not associated with any outcome in multivariate analysis.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. [Display omitted] DisclosuresLabopin: 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.

Post-Transplant Cyclophosphamide in Acute Leukemia Patients Receiving More Than 5/10 HLA-Mismatched Allogeneic Stem Cell Transplantation: A Study on Behalf of the ALWP of the EBMT

BackgroundPost-transplant cyclophosphamide (PTCy) is a powerful strategy to prevent occurrence of graft-versus-host disease (GvHD) following allogeneic hematopoietic stem cell transplantation (HSCT). Initially developed in the setting of haploidentical HSCT, PTCy has been increasingly used for fully HLA-matched transplants with favorable results.The purpose of this retrospective multi-center study is to evaluate PTCy-based GvHD prevention for patients with acute leukemia receiving a traditionally prohibitive highly mismatched HSCT and to describe their outcome.MethodsThis is a registry-based study employing the data set of the Acute Leukemia Working Party (ALWP) of the European Society of Blood and Marrow Transplantation (EBMT). We retrospectively assessed the outcome of adult patients with acute myeloid or lymphoblastic leukemia (AML/ALL), transplanted between 2010 and 2020 with grafts from HLA-mismatched donors with more than 5/10 mismatches using PTCy-based GvHD prophylaxis.ResultsThe study cohort consisted of 59 patients, with a median time of follow up of 20 (95% CI, 14-39) months. The median age was 47 (range, 18-69) years. Forty-four patients had a diagnosis of AML, 14 of ALL and one case of mixed phenotype acute leukemia. At time of transplant, 39 (66%) were in first or second complete remission, 4 (7%) were in later remission and 16 (27%) had active, relapsed or refractory, disease. Conditioning regimens were myeloablative for 54% of cases and peripheral blood was the preferred source of stem cells (64%). All donors were related. Most patients (85%) received a 4/10 HLA-matched transplant, the most commonly mismatched loci were C and DQB1, often with a double mismatch involving the same locus. Two cases of fully mismatched donors were also recorded.PTCy was always associated with other immunosuppressive treatments, especially with the standard combination of calcineurin inhibitors and mycophenolate mofetil. In only 8 cases in vivo T-cell depletion was realized with anti-thymocyte globulin.A large proportion of patients (86%) attained engraftment with a median time of 19 (range, 11-37) days. Only 8 patients did not reach engraftment and all of them died of infection or disease relapse in the first one-hundred days (range, 6-99) after HSCT.Thirty-three patients (58%) did not present any sign of acute GvHD (aGvHD). Cumulative incidence of grade II-IV and grade III-IV aGvHD at day 180 were 30.3% and 14.3%, respectively. At 2 years, the cumulative incidence of chronic GvHD (cGvHD) was 21%, and 7% for extensive cGvHD.Twenty-four patients died during the study period, mostly because of leukemia progression (n=13, 54%), infectious complications (n=6, 25%) and interstitial pneumonia (n=2, 8%). Other causes of death were hemorrhage, GvHD, and another non HSCT-related that accounted for one case (4%) each. At 2 years, the overall survival (OS), leukemia-free survival (LFS), and a GVHD and relapse free survival (GRFS) were 56%, 54% and 47% respectively. Rates of relapse incidence and non-relapse mortality were 28% and 19%, respectively.ConclusionAccording to this preliminary data overview, transplantation in a highly mismatched framework is possible, without unfavorable OS, LFS and GVHD rates. Despite the important limitation of the retrospective non-controlled nature of this analysis, these findings suggest that PTCy-based strategies could help overcome the barrier of HLA-matching and configure a new setting of transplantation, encouraging more in-depth investigations. [Display omitted] DisclosuresLabopin: Jazz Pharmaceuticals: Honoraria. Angelucci: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene BSM: Honoraria, Other: DMC; Blue Bird Bio: Honoraria, Membership on an entity's Board of Directors or advisory committees; Menarini-Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: steering commitee, Speakers Bureau; Vertex Pharmaceuticals: Honoraria, Other: DMC; Crispr therapeutics: Honoraria, Other: DMC; Glaxo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Mohty: Takeda: Honoraria; Jazz: Honoraria, Research Funding; Gilead: Honoraria; Adaptive Biotechnologies: Honoraria; Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Amgen: Honoraria; Astellas: Honoraria.

Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia with Monosomy 7 or Deletion 7q: A Study from the Acute Leukemia Working Party (ALWP) of the European Society of Blood and Marrow Transplantation (EBMT)

▪ INTRODUCTIONMonosomy 7 or deletion 7q (-7/7q-) is the most frequent high-risk cytogenetic feature reported in acute myeloid leukemia (AML) and is associated with a dismal outcome after chemotherapy alone. Allogeneic stem cell transplantation (SCT) appears to be the best consolidation strategy in these patients (pts), thereby significantly improving outcomes. Nevertheless, -7/7q- occurs frequently with other high-risk cytogenetic abnormalities such as complex karyotype (CK), monosomal karyotype (MK), monosomy 5 or deletion 5q (-5/5q-), 17p abnormalities (abn(17p)) or inversion/translocation of chromosome 3q26 (inv(3)). The presence of such abnormalities may further influence the outcomes of SCT in pts with -7/7q-. The purpose of this study was to evaluate the role of SCT in AML with -7/7q- in the context of additional cytogenetic abnormalities. METHODSWe selected adult pts with AML and -7/7q- reported to the EBMT registry with a complete cytogenetic report. We included only first SCT from a sibling or unrelated donor (UD) performed between 2000 and 2016. RESULTSA total of 1109 pts were identified. Median age at SCT was 52 year-old (range, 18-76) and median follow-up was 34 months (range, 0.7-193). A diagnosis of secondary AML was reported in 213 pts (19%). At the time of SCT, 702 patients (63%) were in first remission (CR1), 58 (5%) in subsequent remission and 349 (32%) had active disease. Four hundred ninety-six pts received SCT from a sibling donor (45%). Most pts had a Karnofsky's performance status (KPS) of more than 80% at the time of SCT (93%). A myeloablative conditioning regimen was administered in 50% of the pts. In vivo T-cell depletion was part of the regimen in 56% of the pts.The 2-year probability of leukemia-free survival (LFS) and overall survival (OS) were 30% and 36%, respectively. The 2-year probability of non-relapse mortality (NRM) was 20% and the 2-year cumulative incidence of relapse (RI) was 50%. The cumulative incidence of acute graft-versus-host disease (GvHD) was 31% and the 2-year cumulative incidence of chronic GvHD was 31%. The 2-year probability of GvHD and relapse-free survival (GRFS) was 21%. In multivariate analysis, age was not associated with any outcomes. Active disease was significantly associated with increased NRM and RI, which translated into worse LFS, OS and GRFS. Significant higher NRM was associated with UD. Secondary AML was associated with higher NRM and decreased OS. Better KPS correlated significantly with less NRM and better LFS, OS and GRFS.To evaluate the impact of additional cytogenetic abnormalities, we have been able to sort out 5 different groups within the entire cohort. The first group included 523 pts with -7/7q- with or without CK, but without any of the following chromosomal abnormalities: MK, -5/5q-, abn(17p) or inv(3). One hundred ninety-nine pts belonged to the second group that included pts with -7/7q- within MK but without -5/5q-, abn(17p) or inv(3). The third group included 151 pts with -7/7q- in association with -5/5q- but no abn(17p) or inv(3). Group 4 included 125 pts with -7/7q- and abn(17p) but without inv(3). Finally, 111 pts had inv(3) in addition to 7/7q- and were assigned to the fifth group. NRM was similar across all groups. The 2-year probability of LFS was 39.7% for group 1, 28.5% for group 2, 22.5% for group 3, 16.4% for group 4 and 13.7% for group 5 (p<0.001) (see figure). The 2-year probabilities of OS in the 5 groups were 47.7%, 34.9%, 28.2%, 15.9% and 19.7%, respectively (p<0.001). The corresponding 2-year probability of GRFS was 29.7% for group 1, 16.6% for group 2, 14.5% for group 3, 8.1% for group 4 and 8.9% for group 5 (p<0.001). Multivariate analysis confirmed those significant differences across groups. We observed comparable results when the analysis was focused on CR1 pts. CONCLUSIONSSCT in AML pts with -7/7q- provides durable response in one third of the pts. Disease status at the time of transplantation remains the strongest prognostic factor for poor outcomes. The presence of -7/7q- with or without CK in the absence of MK, -5/5q-, abn(17p) or inv(3) was associated with a better survival after SCT. On the contrary, addition of MK, -5/5q-, abn(17p) or inv(3) identifies a sub-group of pts that benefits less from SCT. In these pts, future efforts should focus on prevention of relapse by therapeutic modalities like early withdrawal of immunosuppression, administration of hypomethylating agents, donor lymphocytes infusion or others. [Display omitted] DisclosuresSocié:Alexion Pharmaceuticals, Inc.: Consultancy. Mohty:Sanofi: Honoraria, Speakers Bureau.

Comparison of Outcome after Allogeneic Stem Cell Transplantation in AML Patients in First or Second Complete Remission Following Either Fludarabin/Busulfan, Flamsa-TBI or Flamsa-Bu Conditioning

IntroductionFludarabin/Busulfan (Flu/Bu) is a widely used reduced intensity conditioning (RIC) regimen for allogeneic stem cell transplantation (alloSCT) in AML. As an alternative, the sequential FLAMSA-TBI RIC regimen has been developed and has shown a substantial activity, particularly in relapsed/refractory AML patients (pts). Recently, FLAMSA-Bu with busulfan replacing TBI has also frequently been used. To evaluate their role, the acute leukemia working party (ALWP) of the EBMT conducted a retrospective study, comparing the outcomes of AML pts transplanted in CR1 or CR2 after conditioning with either Flu/Bu or one of the FLAMSA regimens.Patients and MethodsPts were eligible if they had received an alloSCT for AML in CR1 or CR2 between 1/2005 and 6/2016 after conditioning with either Flu/Bu (fludarabine 5x30 mg/m2, busulfan (8x0.8 mg/kg b.w. i.v.)), FLAMSA-TBI (fludarabine 4x30 mg/m2, cytarabine 4 x 2000 mg/m2, amsacrine 4x100 mg/m2)-TBI(4Gy), cyclophosphamide (2x40-60 mg/kg b.w.) or FLAMSA-Bu, in which TBI is replaced by busulfan (8x0.8 mg/kg b.w.). Data were extracted from the ALWP database. Primary endpoint was leukemia free survival (LFS) at two years. Overall survival (OS), relapse incidence (RI), non-relapse-mortality (NRM), graft-versus-host-disease (GVHD) free relapse free survival (GRFS), and rates of acute and chronic GVHD were secondary endpoints. To allow for potential confounding factors between treatment groups, propensity score matching was performed separately for the Flu/Bu group vs. FLAMSA-TBI and FLAMSA-Bu groups using the ‘MatchIt’ package. Factors included in the model were age per deciles, status at transplant, donor type, cytogenetics risk group, sex matching, pt and donor CMV serology and use of in vivo T cell depletion. Then, comparisons were performed using weighted Cox regression.Results1642 pts in the Flu/Bu group were compared to 174 and 318 in the FLAMSA-TBI and FLAMSA-Bu groups, respectively. Median follow-up of survivors was 20.1 months (0.6 - 129.0). Main differences between groups were: pts in the FLAMSA-Bu group suffered more often from secondary AML (25,7% vs.12.6% and 13.9% for Flu/Bu and FLAMSA-TBI, respectively, p<10-4). In addition, they were less often transplanted from a matched sibling donor (29.3 % vs. 46.7% vs. 38.1%, p<10-4) had more wild type NPM1 (79,1% vs. 60.5% vs. 46.2%. p=0.003) and had received more often in vivo T-cell depletion (98.9% vs. 83.8 % vs. 88.6%, p<10-4). Pts in the FLAMSA-TBI group were younger (median: 48y) than in both other groups (59.6y each p<10-4), and had more often a Karnofsky performance status >=90% (81.9%) as compared to the Flu/Bu and FLAMSA-Bu groups (74.0% and 75.8%, respectively, p=0.014).In univariate analysis, LFS at two years was significantly higher in the FLAMSA-TBI group (60.3%) compared to FLAMSA-Bu (48.7%) and Flu/Bu (50.8%), p=0.003. Also, OS and GRFS were highest in the FLAMSA-TBI group (67% and 46% vs. 53.3% and 38.4% vs. 57.1% and 38.3%, respectively p=0.02 and p=0.02). NRM was higher in the FLAMSA-Bu group (26.6%) compared to FLAMSA-TBI (17.1%) and Flu/Bu (17.8%), p=0.02. RI was lower in both FLAMSA groups (FLAMSA-TBI 22.7%, FLAMSA-Bu 24.6%) compared to Flu/Bu (31.4%), p=10-4). Main cause of death in the FLAMSA-Bu group was infection (41.3 %). This rate was lower in the Flu/Bu and FLAMSA-TBI groups with 17.9% and 18.2%, respectively (p=10-5 and p=0.001).Weighted Cox regression revealed that FLAMSA-Bu compared to Flu/Bu was associated with lower RI (HR 0.53 (95% CI 0.33-0.87), p=0.011), whereas NRM was higher (HR 1.88(95% CI 1.17-3.02), p=0.008). LFS, OS, GRFS, aGVHD II-IV, aGVHD III-IV, cGVHD and ext cGVHD were not different. Comparing FLAMSA-TBI with Flu/Bu there was a trend towards reduced relapse incidence for FLAMSA-TBI (HR=0.72 (95% CI 0.51-1.02), p=0.063), better LFS (HR=0.78 (95% CI 0.59-1.04), p=0.085) and GRFS (HR=0.8 (95% CI 0.62-1.03, p=0.081). All other outcome variables were not significantly different.ConclusionsThis retrospective analysis indicates that FLAMSA-Bu compared to Flu/Bu leads to substantial reduction in RI in AML pts transplanted in CR1 or CR2. Higher NRM, mainly due to infections counterbalance this positive effect. Therefore, LFS and OS are not different. Similarly, FLAMSA-TBI was associated with a trend towards reduced RI as compared to Flu/Bu. These data need confirmation in a prospective trial. DisclosuresSchmid:MoilMed: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees. Scheid:Amgen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Socié:Alexion Pharmaceuticals, Inc.: Consultancy. Savani:Jazz Pharmaceuticals: Speakers Bureau.

Allogeneic Stem Cell Transplantation in Acute Myeloid Leukemia with t(6;9)(p23;q34);dek-NUP214 Is Followed By a Low Relapse Risk and Favorable Outcome in Early Phase- a Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

▪Introduction: Allogeneic stem cell transplantation (allo-SCT) is the best post-remission treatment for patients (pts) with acute myeloid leukemia (AML) harboring high-risk genetic features. AML with translocation t(6;9)(p23;q34) (t(6;9) AML) is a rare but well-characterized AML subtype, commonly associated to FLT3 internal tandem duplication (FLT3 -ITD). It constitutes a high-risk cytogenetic entity, with a reported high relapse risk after conventional chemotherapy. Therefore, allo-SCT in first complete remission (CR1) is now commonly recommended in these pts. However, comprehensive studies analyzing the outcome of allo-SCT in this setting are lacking.Patients and methods: We included 182 adult pts with t(6;9) AML who received an allo-SCT from 2000 to 2015, from matched related (MRD), unrelated (MUD), or cord blood donors. Statistical analyses were performed using R v3.0.1 and SPSS v19. Endpoints included leukemia-free survival (LFS), relapse incidence (RI), non-relapse mortality (NRM), overall survival (OS), acute and chronic GVHD, and GVHD-free/relapse-free survival (GRFS). All outcomes were measured from the time of stem cell infusion.Results: Median age was 42 years (18-65 years) and 51% were male. 166 out of 182 pts (91%) presented as de novo AML. An associated cytogenetic abnormality was documented in 20 pts (11%). Among 63 (34%) pts with available information on FLT3 status, 39 (62%) carried a FLT3-ITD mutation. Status at allo-SCT was first CR (CR1) in 130 pts (71%), CR2 in 14 (8%), and non-CR AML in 38 pts (21%), respectively. The type of conditioning regimen was myeloablative in 121 (66%) of the pts. In most pts (n=129, 71%) graft source was peripheral blood. The donor was a MRD in 85 (47%), MUD in 88 (48%) and an unrelated cord blood in 9 (5%) of the pts, respectively (Table 1). With a median follow-up of 28 months, 2-year LFS was 46.7% (95% CI:38.6-54.8), OS 51.9 % (43.7-60.1), RI 26.4% (19.7- 33.6), NRM 26.9 % (20-34.2) and GRFS 33.7% (25.8-41.6). Acute GvHD grade II-IV and 2-year chronic GvHD were 26.3 % (19.9 - 33.1) and 35.7 % (27.8 - 43.6), respectively. In the univariate analysis, disease status at time of allo-SCT was the most important prognostic factor, with the following 2-year outcomes in CR1, CR2, and non-CR: RI of 19.3% (12.3-27.5), 31% (8.6-57.1) and 48.8% (31-64.4, p<0.001); LFS of 55.6% (45.8-65.3), 31.7% (6.3-57.2) and 22.7% (8.5-36.9, p<0.001); OS of 60% (50.2-69.8), 31.4% (6.1-56.8)], and 33.1% (17-49.2, p<0.001); and GRFS of 40.2% (30.2-50.1), 23.8% (0.4-47.2) and 17.2% (4.4-30.1, p<0.001), respectively (Figure 1). Reduced intensity conditioning (RIC) was associated with an increased risk of RI, without impact on LFS or OS. Secondary leukemia was associated with a reduced LFS. A longer interval (i.e., >median value, 4.8 mos.) from diagnosis to allo-SCT was associated with higher NRM. Finally, FLT3 -ITD status and additional cytogenetic abnormalities did not influence prognosis.In pts in CR1, the main causes of death were NRM (infection, n=15; GVHD, n=9), whereas recurrent of the leukemia was the cause of death in only 12 pts. Of note, pts harboring FLT3 -ITD had a relatively favorable outcome, with a 2-year RI, NRM, LFS, OS, and GRFS of 17.2% (3.7-39.1), 27.7% (8.9-50.5), 55.1% (30.8-79.5), 57.5% (32.1-82.8), and 42.9% (19.2-66.5), respectively. In the multivariate analysis for pts in CR1, RIC was the only significant prognostic factor for RI (HR=5.79, 1.82-18.40; p=0.00293), without impact on LFS or OS.Conclusions: Allo-SCT in patients with t(6;9) AML results in a relatively favorable outcome when performed in CR1, with approximately 17% relapse rate, suggesting the existence of a beneficial GvL effect in this context. Notably FLT3 -ITD did not show a negative impact in this entity. This study supports the recommendation to subject pts with t(6;9) AML to allo-SCT while being in CR and emphasize that allo-SCT in CR as the best current therapeutic option for these pts. [Display omitted] DisclosuresSocié:Alexion Pharmaceuticals, Inc.: Consultancy. Mohty:Sanofi: Honoraria, Speakers Bureau.

Comparative Outcome of Reduced Intensity and Myeloablative Preparative Regimen in HLA Identical Sibling Allogeneic Hematopoietic Stem Cell Transplantation for Patients Older Than 50 Years of Age with Acute Myeloblastic Leukaemia: A Retrospective Survey from the Acute Leukemia Working Party (ALWP) of the European Group for Blood and Marrow Transplantation (EBMT).

Results of reduced intensity preparative regimen (RIC) hematopoietic stem cell transplantation (HSCT) in the HLA identical HSCT setting have not been compared to myeloablative HSCT (MA) in patients with AML over 50 years of age. With this aim, outcomes of 315 RIC were compared with 407 MA HSCT recipients from 182 transplant centers. The majority of RIC was fludarabine-based regimen associated to Busulfan (BU) (53%) or low dose TBI (24%). Multivariate analyses of outcomes were used adjusting for differences between both groups. The median follow-up was 13 months. Cytogenetics, FAB classification, WBC count at diagnosis and status of the disease at transplant were not statistically different between the two groups. However, RIC patients were older (median 57 years versus 54 years), transplanted more recently, and more frequently with peripheral blood allogeneic stem cells as compared to MA recipients. In multivariate analysis, Incidence of grade II-IV acute GvHD (aGvHD) was significantly lower after RIC: 22% compared to 31% after MA HSCT (p=0.003) but not Grade III-IV (8% versus 12%, respectively)(p=0.12). the risk of chronic GVHD was lower following RIC (RR=0.69; 95% CI,=0.51 to 0.94, p=0.02). Transplant-related mortality was significantly decreased(18% versus 32%) (p<10−4; RR=0.48, CI= 0.33 to 0.68), and relapse incidence was significantly higher (41% versus 24%) (p=0.0003; RR=1.78, CI=1.3 to 2.43) after RIC transplantation. Leukaemia-free survival (LFS) was not statistically different between the two groups. These results may set the grounds for prospective trials comparing RIC with other strategies of treatment in elderly AML.

Outcome of haploidentical versus matched sibling donors in hematopoietic stem cell transplantation for adult patients with acute lymphoblastic leukemia: a study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

BackgroundNon-T-cell depleted haploidentical hematopoietic stem cell transplantation (HaploSCT) is being increasingly used in acute lymphoblastic leukemia (ALL) with improving patient outcomes. We have recently reported that outcomes of adult patients (pts) with ALL in complete remission (CR) receiving HaploSCT are comparable to unrelated donor transplants. We now compared HaploSCT and matched sibling donor (MSD) transplants in pts with ALL.AimTo assess transplantation outcomes of HaploSCT and MSD transplants in pts with ALL in CR.MethodsWe retrospectively analyzed adult patients (≥ 18 years) with ALL who underwent their first allogeneic stem cell transplantation (alloSCT) in first or second CR between 2012 and 2018, either from a T cell replete Haplo or MSD donor, and whose data were reported to the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT). Multivariate analysis (MVA) adjusting for differences between the groups was performed using the Cox proportional hazards regression model. Propensity score matching was also performed to reduce confounding effects.ResultsThe analysis comprised 2304 patients: HaploSCT-413; MSD-1891. Median follow-up was 25 months. Median age was 37 (range 18–75) and 38 (18–76) years in HaploSCT and MSD, respectively. HaploSCT patients were transplanted more recently than those transplanted from MSD (2016 vs 2015, p < 0.0001). A higher rate of HaploSCT was in CR2 (33.4% vs 16.7%, p < 0.0001), respectively, and fewer received myeloablative conditioning (68% vs 83.2%, p < 0.0001). Cytomegalovirus (CMV) seropositivity was lower in HaploSCT patients (22% vs 28%, p = 0.01) and donors (27.1% vs 33%, p < 0.02), and a higher proportion of the HaploSCTs were performed using a bone marrow (BM) graft (46.2% vs 18.6%, p < 0.0001). The 2 groups did not differ with regard to gender, Karnofsky performance status score, ALL phenotype, Philadelphia chromosome (Ph) positivity and pre-alloSCT measurable residual disease (MRD). Graft versus host disease (GVHD) prophylaxis was mainly post-transplant cyclophosphamide (PTCy) based (92.7%) in the HaploSCT setting, while it was mostly pharmacologic in the setting of MSD (18.7% received ATG). Cumulative incidence of engraftment at day 60 was higher in MSD transplants compared to HaploSCT (98.7% vs 96.3%, p = 0.001), respectively. Day 180 incidence of acute (a) GVHD II-IV and III-IV was higher in HaploSCT vs. MSD: 36.3% vs 28.9% (p = 0.002 and 15.2% vs 10.5% (p = 0.005), respectively. Conversely, the 2-year chronic (c) GVHD and extensive cGVHD were 32% vs 38.8% (p = 0.009) and 11.9% vs 19.5% (p = 0.001) in HaploSCT vs MSD, respectively. Main causes of death were leukemia (31.8% vs 45%), infection (33.1% vs 19.7%) and GVHD (16.6% vs 19.7%) for HaploSCT and MSD, respectively. Two-year relapse incidence (RI), non-relapse mortality (NRM), leukemia-free survival (LFS), overall survival (OS) and GVHD-free, relapse-free survival (GRFS) were 26% vs 31.6%, 22.9% vs 13%, 51% vs 55.4%, 58.8% vs 67.4% and 40.6% vs 39% for HaploSCT and MSD, respectively. In the MVA, RI was significantly lower in HaploSCT in comparison with MSD, hazard ratio (HR) = 0.66 (95% CI 0.52–0.83, p = 0.004), while NRM was significantly higher, HR = 1.9 (95% CI 1.43–2.53, p < 0.0001). aGVHD grade II-IV and grade III-IV were higher in HaploSCT than in MSD HR = 1.53 (95% CI 1.23–1.9, p = 0.0002) and HR = 1.54 (95% CI 1.1–2.15, p = 0.011), respectively. Extensive cGVHD was lower in HaploSCT compared with MSD, HR = 0.61 (95% CI 0.43–0.88, p = 0.007), while total cGVHD did not differ significantly, HR = 0.94 (95% CI 0.74–1.18, p = 0.58). LFS, OS and GRFS did not differ significantly between the 2 transplant groups, HR = 0.96 (95% CI 0.81–1.14, p = 0.66); HR = 1.18 (95% CI 0.96–1.43, p = 0.11) and HR = 0.93 (95% CI 0.79–1.09, p = 0.37), respectively. These results were confirmed in a matched-pair analysis.ConclusionsOutcomes of adult patients with ALL in CR receiving alloSCT from haploidentical donors are not significantly different from those receiving transplants from MSD in terms of LFS, OS and GRFS.

145 - MRD Status Impact on Secondary Acute Myeloid Leukemia Outcomes after Allogeneic Hematopoietic Cell Transplantation. A Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

145 - MRD Status Impact on Secondary Acute Myeloid Leukemia Outcomes after Allogeneic Hematopoietic Cell Transplantation. A Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Reduced Intensity Vs. Non-Myeloablative Conditioning Regimens for Haploidentical Transplantation in Complete Remission Acute Myeloid Leukemia: A Study from the ALWP of the EBMT

Background: In the context of a haploidentical stem cell transplantation (Haplo-SCT) platform with post transplantation cyclophosphamide (PT-Cy) for acute myeloid leukemia (AML) patients, the optimal conditioning regimen remains unknown. A non-myeloablative conditioning (NMAC) regimen (cyclophosphamide + fludarabine + 2Gy TBI [CyFluTBI]) was initially reported by the Johns Hopkins group as a safe approach in this setting, notably to treat patients of advanced age and/or with comorbid conditions. However, relapse incidence after NMAC Haplo-SCT remains high in AML where it can reach 45%. Alternatively, a reduced intensity conditioning (RIC) regimen containing an antileukemic drug combination like thiotepa and reduced-dose busulfan in addition to fludarabine (TBF) may decrease AML relapse. However, this anticipated benefit may be counterbalanced by a higher incidence of toxicity, graft-versus-host disease (GVHD) and non-relapse mortality (NRM). To date, no study comparing TBF vs. CyFluTBI has been published in complete remission (CR) AML. We performed this retrospective comparison on behalf of the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT). Methods: We retrospectively analyzed 398 patients from the EBMT registry database with the following inclusion criteria: 1) adult patient in CR1 or CR2 AML; 2) T-replete Haplo-SCT with PT-Cy; 3) no in vivo depletion using antithymocyte globulin or alemtuzumab; and 4) receiving either TBF RIC (equivalent of 2-day iv busulfan dose) or CyFluTBI NMAC regimen. We compared separately TBF vs. CyFluTBI in patients younger (n=170, 82 TBF vs. 88 CyFluTBI) and older (n=228, 141 TBF vs. 87 CyFluTBI) than 60 years. Results: In patients younger than 60 years, the 2-year cumulative incidence of relapse (CIR) was significantly lower in the TBF group compared with the CyFluTBI group (TBF vs. CyFluTBI: 14% vs. 43%, p&amp;lt;0.01). No significant increase in 2-year NRM was observed (TBF vs. CyFluTBI: 22% vs. 16%, p=0.15). This led to a significantly higher 2-year leukemia-free survival (LFS) probability in the TBF group (64% vs. 41%, p=0.03). After adjustment in multivariate analysis, CyFluTBI was associated with a higher risk of relapse (hazard ratio [HR] 3.4, 95%CI [1.4-6.9], p&amp;lt;0.01), lower LFS (HR 1.8, 95%CI 1.1-3.0, p=0.03) and lower overall survival (OS) (HR 1.8, 95%CI 1.1-3.1, p=0.02), without significant impact of conditioning regimen on incidence of GVHD and NRM. In patients older than 60 years, univariate analysis did not show any significant difference in outcome according to the type of conditioning regimen (2-year NRM: TBF vs. CyFluTBI: 33% vs. 25%, p=0.23; 2-year CIR: TBF vs. CyFluTBI: 23% vs. 28%, p=0.20; 2-year LFS: TBF vs. CyFluTBI: 44% vs. 47%, p=0.96). Multivariate analysis showed a significant reduction in the risk of NRM after CyFluTBI (HR 0.5, 95%CI [0.2-0.9], p=0.04), while a non-significant increase in the risk of relapse was observed (HR 1.9, 95%CI [0.8-4.2], p=0.13). Finally, there was no significant difference in LFS (HR 0.9, 95%CI [0.5-1.5], p=0.67) and OS (HR 0.9, 95%CI [0.5-1.5], p=0.67). Conclusion: Our study suggests that in CR AML patients aged younger than 60 years, the use of TBF RIC provides better outcomes than NMAC CyFluTBI due to lower incidence of relapse, without significant increase in the risk of NRM. Conversely, it seems that older patients do not benefit from such conditioning intensification, due to a significantly higher risk of NRM after TBF RIC. Thus, in CR AML patients who will not receive a truly myeloablative regimen prior to PT-Cy Haplo-SCT, age could be used for determining the conditioning intensity from the wide variety of reduced toxicity conditioning regimens. Beyond the patient age, further prospective trials should assess patient-based parameters that may be useful for a fine tuning of conditioning intensity in a more individualized approach. Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Blaise:Jazz Pharmaceuticals: Honoraria. Bug:Sanofi: Other: Travel; Neovii: Other: Travel; Jazz: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel; Hexal: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Eurocept: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel. Mohty:Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Stemline: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Evaluation of six different types of sequential conditioning regimens for allogeneic stem cell transplantation in relapsed/refractory acute myelogenous leukemia – a study of the Acute Leukemia Working Party of the EBMT

The Acute Leukemia Working Party (ALWP) of the EBMT assessed the outcome of allogeneic stem cell transplantation (alloSCT) in patients with relapsed/refractory AML (r/rAML) evaluating six sequential conditioning regimens (SR) groups. A total of 2132 patients were included. LFS at 2 years was 28.9%, 33.6%, 35.3%, 20.6%, 24.4%, and 27% for the FLAMSA-TBI4, FLAMSA-Chemo, Mel-Flu-TBI8, Mel-Treo-Flu, Thio-ETO-Cy-Bu2-Flu, and Clo-ARAC-(Bu2/TBI4)-Cy groups, respectively. In patients <55 years of age Mel-Flu-TBI8 had the best LFS, which was statistically significant only in comparison to the Mel-Treo-Flu group, while in patients ≥55 years LFS was best with FLAMSA-Chemo without significant differences compared to FLAMSA-TBI4 and Mel-Flu-TBI8. Furthermore, best NRM rates were obtained with the two FLAMSA regimens groups. Our study suggests that in younger (<55 years) patients a more intense regimen might be used whereas in older (≥55 years) patients the focus might be more on tolerability.

Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Acute Lymphoblastic Leukemia and Poor Karnofsky Performance Status. a Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Recently, an increasing number of patients with acute lymphoblastic leukemia with a poor Karnofsky Performance Status (KPS) score are considered for allogeneic hematopoietic stem cell transplantation (allo-HCT). Nevertheless, there is paucity of available data about outcome of this fragile population. We report here the results of a retrospective study designed to evaluate outcome of ALL patients undergoing allo-HCT with KPS score ≤80%. The analysis included ALL patients aged ≥18 years, undergoing allo-HCT in first remission between 2000 and 2018, with a KPS score of 50% to 80% at the time of transplant. A total of 1,010 patients were identified. Median age at transplant was 43 years (18-76 years). Median year of transplant was 2011. The KPS score was =80% in 83% of the patients and On multivariate analysis, transplant from 10/10 UD was associated with higher incidence of aGVHD (HR 1.8, p In conclusion, allo-HCT is feasible in patients with acute lymphoblastic leukemia in first remission and KPS score ≤80%, with acceptable NRM and survival rates. Transplant from a MSD was associated with reduced risk of NRM and aGVHD as compared to 10/10 UD. Interestingly, despite the poor KPS score of the patients included in the analysis, a MAC protocol was associated with similar NRM, lower relapse and better LFS and GRFS as compared to RIC in the selected population. Finally, administration of ATG was associated with reduced acute and chronic GVHD rates.