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Impact of measurable residual disease on outcomes of unrelated donor haematopoietic cell transplantation with post-transplant cyclophosphamide in AML in first complete remission
Nagler, A., Labopin, M., Dholaria, B., Blaise, D., Bondarenko, S., Vydra, J., Choi, G., Rovira, M., Reményi, P., Meijer, E., et al
British journal of haematology. 2023
Abstract
Pre-transplant measurable residual disease (MRD) predicts relapse and outcome of allogeneic haematopoietic cell transplantation (allo-HCT). The impact of MRD on the outcomes of post-transplant cyclophosphamide (PTCy)-based allo-HCT from a matched unrelated donor (UD) is unknown. This study assessed the impact of MRD in acute myeloid leukaemia (AML) in the first complete remission (CR1). A total of 272 patients (MRD negative [MRD-], n = 165; MRD positive [MRD+], n = 107) with a median follow-up of 19 (range: 16-24) months were studied. The incidence of grades II-IV and grades III-IV acute GVHD at day 180 was 25.2% and 25% (p = 0.99), and 10.6% and 6.8% (p = 0.29), respectively, and 2-year chronic GVHD was 35% and 30.4% (p = 0.96) in MRD+ and MRD- cohorts, respectively. In multivariate analysis, MRD+ status was associated with a higher incidence of relapse (RI) (hazard ratio [HR] = 2.56, 95% CI: 1.39-4.72), lower leukaemia-free survival (LFS) (HR = 2.04, 95% CI: 1.23-3.39), overall survival (OS) (HR = 1.83, 95% CI: 1.04-3.25) and GVHD-free, relapse-free survival (GRFS) (HR = 1.69, 95% CI: 1.10-2.58). MRD status did not have a significant impact on non-relapse mortality (NRM), or acute or chronic GVHD risk. Among patients with AML undergoing UD allo-HCT with PTCy, pre-transplant MRD+ status predicted a higher relapse rate, lower LFS, OS and GRFS.
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Comparison of fludarabine/melphalan (FluMel) with fludarabine/melphalan/BCNU or thiotepa (FBM/FTM) in patients with AML in first complete remission undergoing allogeneic hematopoietic stem cell transplantation - a registry study on behalf of the EBMT Acute Leukemia Working Party
Duque-Afonso, J., Finke, J., Ngoya, M., Galimard, J. E., Craddock, C., Raj, K., Bloor, A., Nicholson, E., Eder, M., Kim, O., et al
Bone marrow transplantation. 2023
Abstract
Conditioning protocols for patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) are being developed continuously to improve their anti-leukemic efficacy and reduce their toxicity. In this study, we compared the conditioning protocol of fludarabine with melphalan 140 mg/m(2) (FluMel) with conditioning protocols based on this same backbone but with an additional alkylating agent i.e., either fludarabine/BCNU (also known as carmustine)/melphalan (FBM), or fludarabine/thiotepa/melphalan (FTM) 110 mg/m(2). We included 1272 adult patients (FluMel, n = 1002; FBM/FTM, n = 270) with acute myeloid leukemia (AML) with intermediate/poor cytogenetic risk in first complete remission (CR) from the registry of the EBMT Acute Leukemia Working Party. Despite patients in the FBM/FTM group were older (64.1 years vs. 59.8 years, p < 0.001) and had a worse Karnofsky performance score (KPS < 90, 33% vs. 24%, p = 0.003), they showed a better overall survival (OS) (2 y OS: 68.3% vs. 58.1%, p = 0.02) and less non-relapse mortality (NRM) (2 y NRM: 15.8% vs. 22.2%, p = 0.009) compared to patients treated with FluMel. No significant differences were observed in relapse incidence (RI) (2 y RI: 24.9% vs. 23.7%, p = 0.62). In conclusion, the addition of a second alkylating agent (BCNU/carmustine or thiotepa) to FluMel as FBM/FTM conditioning, improves OS in AML patients in first CR with intermediate/poor risk cytogenetics after allo-HCT.
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Fludarabine or cyclophosphamide in combination with total body irradiation as myeloablative conditioning prior to allogeneic hematopoietic cell transplantation for acute lymphoblastic leukemia: an analysis by the Acute Leukemia Working Party of the EBMT
Giebel, S., Labopin, M., Socié, G., Aljurf, M., Salmenniemi, U., Labussière-Wallet, H., Srour, M., Kröger, N., Zahrani, M. A., Lioure, B., et al
Bone marrow transplantation. 2023
Abstract
In this registry-based study we retrospectively compared outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) for adult patients with acute lymphoblastic leukemia (ALL) following conditioning with total body irradiation (TBI) combined with either cyclophosphamide (Cy) or fludarabine (Flu). TBI 12 Gy + Cy was used in 2105 cases while TBI 12 Gy + Flu was administered to 150 patients in first or second complete remission. In a multivariate model adjusted for other prognostic factors, TBI/Cy conditioning was associated with a reduced risk of relapse (HR = 0.69, p = 0.049) and increased risk of grade 2-4 acute graft-versus-host disease (GVHD, HR = 1.57, p = 0.03) without significant effect on other transplantation outcomes. In a matched-pair analysis the use of TBI/Cy as compared to TBI/Flu was associated with a significantly reduced rate of relapse (18% vs. 30% at 2 years, p = 0.015) without significant effect on non-relapse mortality, GVHD and survival. We conclude that the use of myeloablative TBI/Cy as conditioning prior to allo-HCT for adult patients with ALL in complete remission is associated with lower risk of relapse rate compared to TBI/Flu and therefore should probably be considered a preferable regimen.
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Fludarabine/TBI 8 Gy versus fludarabine/treosulfan conditioning in patients with AML in first complete remission: a study from the Acute Leukemia Working Party of the EBMT
Bug, G., Labopin, M., Niittyvuopio, R., Stelljes, M., Reinhardt, H. C., Hilgendorf, I., Kröger, N., Kaare, A., Bethge, W., Schäfer-Eckart, K., et al
Bone marrow transplantation. 2023
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Editor's Choice
Abstract
The optimal reduced intensity conditioning (RIC) regimen is a matter of debate. We retrospectively compared conditioning with fludarabine plus fractionated total body irradiation of 8 Gy (FluTBI) and fludarabine plus treosulfan 30, 36 or 42 g/m(2) (FluTreo) in 754 patients with AML above the age of 40 years undergoing an allogeneic hematopoietic stem cell transplant (HSCT) in first complete remission (CR). After balancing patient characteristics by propensity score matching of 115 patients in each group, FluTBI was associated with a significantly lower probability of relapse compared to FluTreo (18.3% vs. 34.7%, p = 0.018) which was counteracted by a higher non-relapse mortality (NRM, 16.8% vs. 5.3%, p = 0.02). Thus, overall survival and graft-versus-host disease-free and relapse-free survival at 2 years were similar between groups (OS 66.9% vs. 67.8%, GRFS 50.3% vs. 45.6%). Univariate analysis by age group demonstrated a higher NRM exclusively in patients ≥55 years of age treated with FluTBI compared to FluTreo (27.6% vs. 5.8%, p = 0.02), while a similarly low NRM was observed in patients <55 years in both groups (6.0% vs. 4.7%, p = ns). We conclude that both conditioning regimens are effective and safe, but FluTBI may better be reserved for younger patients below the age of 55 years.
PICO Summary
Population
Adults above the age of 40 years with AML, undergoing an allogeneic hematopoietic stem cell transplant (HSCT) in first complete remission and reported to the EBMT registry (n=754, pair matched to produce a population of 230)
Intervention
Conditioning with fludarabine plus fractionated total body irradiation of 8 Gy (FluTB, n=115)
Comparison
Conditioning with fludarabine plus treosulfan 30, 36 or 42 g/m(2) (FluTreo, n=115)
Outcome
After balancing patient characteristics by propensity score matching of 115 patients in each group, FluTBI was associated with a significantly lower probability of relapse compared to FluTreo (18.3% vs. 34.7%) which was counteracted by a higher non-relapse mortality (NRM, 16.8% vs. 5.3%). Thus, overall survival and graft-versus-host disease-free and relapse-free survival at 2 years were similar between groups (OS 66.9% vs. 67.8%, GRFS 50.3% vs. 45.6%). Univariate analysis by age group demonstrated a higher NRM exclusively in patients ≥55 years of age treated with FluTBI compared to FluTreo (27.6% vs. 5.8%), while a similarly low NRM was observed in patients <55 years in both groups (6.0% vs. 4.7%).
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Impact of Cytogenetic Risk on Outcomes of Non-T Cell Depleted Haploidentical Hematopoietic Cell Transplantation in Patients with Relapsed or Refractory Acute Myeloid Leukemia
Nagler, A., Labopin, M., Dholaria, B., Ciceri, F., Fraccaroli, A., Blaise, D., Fanin, R., Bruno, B., Forcade, E., Vydra, J., et al
Transplantation and cellular therapy. 2022
Abstract
BACKGROUND Baseline cytogenetics and disease status are key factors predicting the outcomes of allogeneic hematopoietic cell transplantation (HCT) in patients with acute myeloid leukemia (AML). The importance of cytogenetic risk in patients with primary refractory or relapsed (R/R) AML undergoing haploidentical (Haplo) HCT is unknown. We studied the impact of cytogenetic risk in patients with R/R de novo AML with active disease who underwent non-T cell depleted Haplo-HCT with post-transplant cyclophosphamide from 2010-2020. OBJECTIVES Four hundred and forty patients with active disease at transplantation from EBMT database were analyzed [291 (66.1%) with intermediate-risk (AMLint) and 149 (44.1%) with adverse-risk cytogenetics (AMLadv)]. Impact of baseline cytogenetic risk on various transplant outcomes was evaluated. RESULTS Pre-transplant disease status was relapse in 48.1% and 26.8% and primary refractory in 51.9% and 73.2% of the patients with AMLint and AMLadv, respectively (p<0.0001). Two-year leukemia-free survival (LFS, 35.5% vs. 15.5%, p=0.001) and overall survival (OS, 39.2% vs. 20.1%, p=0.001) were better in AMLint versus AMLadv. In multivariate analysis, the relapse rate was significantly higher [hazard ratio (HR)=2.17 (95% CI 1.57-3.0)] and LFS [HR=1.71 (95% CI 1.31-2.22)] and OS [HR=1.69 (95% CI 1.29-2.22)], significantly lower for patients with AMLadv compared to AMLint, conditioning intensity did not affect leukemia relapse rate. Non-relapse mortality [HR=1.1 (95% CI: 0.7-1.74)] and GVHD-free, relapse-free survival [GRFS, HR=1.37 (95% CI: 1.06-1.77)] did not differ significantly between the risk groups. Disease status before transplant (primary refractory versus relapsed) or conditioning intensity did not impact main transplant outcomes. CONCLUSION Baseline cytogenetic risk remains a key prognostic factor for patients with R/R AML with persistent disease before non-T cell depleted Haplo-HCT.
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Impact of conditioning regimen intensity on outcomes of second allogeneic hematopoietic cell transplantation for secondary acute myelogenous leukemia
Nagler, A., Peczynski, C., Dholaria, B., Labopin, M., Valerius, T., Dreger, P., Kröger, N., Reinhardt, H. C., Finke, J., Franke, G. N., et al
Bone marrow transplantation. 2022
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Editor's Choice
Abstract
Limited data is available on factors impacting the outcomes of second hematopoietic cell transplantation (HCT2) in patients with secondary acute myeloid leukemia (sAML). This study aimed to assess HCT2 outcome for sAML comparing reduced-intensity (RIC) to myeloablative (MAC) conditioning. Two hundred and fifteen patients were included: RIC (n = 134), MAC (n = 81). The median follow-up was 41.1 (95% CI: 26.7-69.3) and 28.5 (95% CI: 23.9-75.4) months, respectively. At two years, the relapse incidence (RI) was 58.3% versus 51.1% in RIC and MAC, respectively. The 2-year leukemia free survival (LFS) was 26.6% versus 26%, and the graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) was 16.4% versus 12.1%, while OS was 31.4% and 39.7%, for RIC and MAC respectively. MVA showed a significantly lower RI [hazard ratio (HR) = 0.46 (95% CI, 0.26-0.8, p = 0.006)] and improved LFS [HR = 0.62 (95% CI, 0.39-0.98, p = 0.042)] with MAC versus RIC. The choice of conditioning regimen did not impact non-relapse mortality [HR = 1.14 (95% CI, 0.52-2.5, p = 0.74)], overall survival (OS) [HR = 0.72 (95% CI, 0.44-1.17, p = 0.18)] or GRFS [HR = 0.89 (95% CI, 0.59-1.36, p = 0.6)]. In conclusion, MAC was associated with a lower RI and superior LFS. These results support the use of MAC for eligible patients with sAML who are being considered for HCT2.
PICO Summary
Population
Adult patients with relapsed secondary acute leukaemia (sAML) receiving a second hematopoietic cell transplant (HCT2) from mulitple centre registries across Europe (n=215)
Intervention
Reduced-intensity pre-HCT2 conditioning (RIC, n=134)
Comparison
Myeloablative pre-HCT2 conditioning (MAC, n=81)
Outcome
Median follow-up was 41.1 (RIC, 95% CI: 26.7-69.3) and 28.5 (MAC, 95% CI: 23.9-75.4) months. At two years, the relapse incidence (RI) was 58.3% versus 51.1% in RIC and MAC, respectively. The 2-year leukemia free survival (LFS) was 26.6% versus 26%, and the graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) was 16.4% versus 12.1%, while OS was 31.4% and 39.7%, for RIC and MAC respectively. Multivariate analysis showed a significantly lower RI [hazard ratio (HR) = 0.46 (95% CI, 0.26-0.8)] and improved LFS [HR = 0.62 (95% CI, 0.39-0.98)] with MAC versus RIC. The choice of conditioning regimen did not impact non-relapse mortality [HR = 1.14 (95% CI, 0.52-2.5)], overall survival (OS) [HR = 0.72 (95% CI, 0.44-1.17)] or GRFS [HR = 0.89 (95% CI, 0.59-1.36)].
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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
Duque-Afonso, J., Finke, J., Labopin, M., Craddock, C., Protheroe, R., Kottaridis, P., Tholouli, E., Byrne, J. L., Orchard, K., Salmenniemi, U., et al
Bone Marrow Transplantation. 2022;57(8):1269-1276
Abstract
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/m(2) (FluMel) and fludarabine/treosulfan 42 g/m(2) (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.
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Total body irradiation plus fludarabine versus thiotepa, busulfan plus fludarabine as a myeloablative conditioning for adults with acute lymphoblastic leukemia treated with haploidentical hematopoietic cell transplantation. A study by the Acute Leukemia Working Party of the EBMT
Swoboda, R., Labopin, M., Giebel, S., Angelucci, E., Arat, M., Aljurf, M., Sica, S., Pavlu, J., Socié, G., Bernasconi, P., et al
Bone marrow transplantation. 2022
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Editor's Choice
Abstract
Optimal conditioning for adults with acute lymphoblastic leukemia (ALL) treated with haploidentical hematopoietic cell transplantation (haplo-HCT) and post-transplant cyclophosphamide has not been established so far. We retrospectively compared outcomes for two myeloablative regimens: fludarabine + total body irradiation (Flu-TBI, n = 117) and thiotepa + iv. busulfan + fludarabine (TBF, n = 119). Patients transplanted either in complete remission (CR) or with active disease were included in the analysis. The characteristics of both groups were comparable except for patients treated with TBF were older. In univariate analysis the incidence of non-relapse mortality (NRM) at 2 years was increased for TBF compared to Flu-TBI (31% vs. 19.5%, p = 0.03). There was a tendency towards reduced incidence of relapse after TBF (p = 0.11). Results of multivariate analysis confirmed a reduced risk of NRM using Flu-TBI (HR = 0.49, p = 0.03). In the analysis restricted to patients treated in CR1 or CR2, the use of Flu-TBI was associated with a decreased risk of NRM (HR = 0.34, p = 0.009) but an increased risk of relapse (HR = 2.59, p = 0.01) without significant effect on survival and graft-versus-host disease. We conclude that for haplo-HCT recipients with ALL, Flu-TBI may be preferable for individuals at high risk of NRM while TBF should be considered in cases at high risk of relapse.
PICO Summary
Population
Adults with acute lymphoblastic leukemia (ALL) treated with haploidentical (n=haematopoietic cell transplantation (haplo-HCT) and post-transplant cyclophosphamide (n=236)
Intervention
Fludarabine + total body irradiation conditioning (Flu-TBI, n=117)
Comparison
Thiotepa + iv. busulfan + fludarabine conditioning (TBF, n=119)
Outcome
In univariate analysis the incidence of non-relapse mortality (NRM) at 2 years was increased for TBF compared to Flu-TBI (31% vs. 19.5%). There was a tendency towards reduced incidence of relapse after TBF. Results of multivariate analysis confirmed a reduced risk of NRM using Flu-TBI (HR = 0.49). In the analysis restricted to patients treated in CR1 or CR2, the use of Flu-TBI was associated with a decreased risk of NRM (HR = 0.34) but an increased risk of relapse (HR = 2.59) without significant effect on survival and graft-versus-host disease.
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Development and validation of a disease risk stratification system for patients with haematological malignancies: a retrospective cohort study of the European Society for Blood and Marrow Transplantation registry
Shouval, R., Fein, J. A., Labopin, M., Cho, C., Bazarbachi, A., Baron, F., Bug, G., Ciceri, F., Corbacioglu, S., Galimard, J. E., et al
The Lancet. Haematology. 2021;8(3):e205-e215
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Editor's Choice
Abstract
BACKGROUND Diagnosis and remission status at the time of allogeneic haematopoietic stem-cell transplantation (HSCT) are the principal determinants of overall survival following transplantation. We sought to develop a contemporary disease-risk stratification system (DRSS) that accounts for heterogeneous transplantation indications. METHODS In this retrospective cohort study we included 55 histology and remission status combinations across haematological malignancies, including acute leukaemia, lymphoma, multiple myeloma, and myeloproliferative and myelodysplastic disorders. A total of 47?265 adult patients (aged =18 years) who received an allogeneic HSCT between Jan 1, 2012, and Dec 31, 2016, and were reported to the European Society for Blood and Marrow Transplantation registry were included. We divided EBMT patients into derivation (n=25?534), tuning (n=18?365), and geographical validation (n=3366) cohorts. Disease combinations were ranked in a multivariable Cox regression for overall survival in the derivation cohort, cutoff for risk groups were evaluated for the tuning cohort, and the selected system was tested on the geographical validation cohort. An independent single-centre US cohort of 660 patients transplanted between Jan 1, 2010, and Dec 31, 2015 was used to externally validate the results. FINDINGS The DRSS model stratified patients in the derivation cohort (median follow-up was 2·1 years [IQR 1·0-3·2]) into five risk groups with increasing mortality risk: low risk (reference group), intermediate-1 (hazard ratio for overall survival 1·26 [95% CI 1·17-1·36], p<0·0001), intermediate-2 (1·53 [1·42-1·66], p<0·0001), high (2·03 [1·86-2·22], p<0·0001), and very high (2·87 [2·63-3·13], p<0·0001). DRSS levels were also associated with a stepwise increase in risk across the tuning and geographical validation cohort. In the external validation cohort (median follow-up was 5·7 years [IQR 4·5-7·1]), the DRSS scheme separated patients into 4 risk groups associated with increasing risk of mortality: intermediate-2 risk (hazard ratio [HR] 1·34 [95% CI 1·04-1·74], p=0·025), high risk (HR 2·03 [95% CI 1·39-2·95], p=0·00023) and very-high risk (HR 2·26 [95% CI 1·62-3·15], p<0·0001) patients compared with the low risk and intermediate-1 risk group (reference group). Across all cohorts, between 64% and 65% of patients were categorised as having intermediate-risk disease by a previous prognostic system (ie, the disease-risk index [DRI]). The DRSS reclassified these intermediate-risk DRI patients, with 855 (6%) low risk, 7111 (51%) intermediate-1 risk, 5700 (41%) intermediate-2 risk, and 375 (3%) high risk or very high risk of 14?041 patients in a subanalysis combining the tuning and internal geographic validation cohorts. The DRI projected 2-year overall survival was 62·1% (95% CI 61·2-62·9) for these 14?041 patients, while the DRSS reclassified them into finer prognostic groups with overall survival ranging from 45·7% (37·4-54·0; very high risk patients) to 73·1% (70·1-76·2; low risk patients). INTERPRETATION The DRSS is a novel risk stratification tool including disease features related to histology, genetic profile, and treatment response. The model should serve as a benchmark for future studies. This system facilitates the interpretation and analysis of studies with heterogeneous cohorts, promoting trial-design with more inclusive populations. FUNDING The Varda and Boaz Dotan Research Center for Hemato-Oncology Research, Tel Aviv University.
PICO Summary
Population
Adults with haematological malignancies who received an allogeneic HSCT reported to the European Society for Blood and Marrow Transplantation registry (n=47,265)
Intervention
Disease Risk Stratification System (DRSS)
Comparison
Disease Risk Index (DRI)
Outcome
The DRSS scheme separated patients into 4 risk groups associated with increasing risk of mortality: intermediate-2 risk (hazard ratio [HR] 1·34), high risk (HR 2·03]) and very-high risk (HR 2·26) patients compared with the low risk and intermediate-1 risk group (reference group). Across all cohorts, between 64% and 65% of patients were categorised as having intermediate-risk disease by a previous prognostic system (ie, the disease-risk index [DRI]). The DRSS reclassified these intermediate-risk DRI patients, with 855 (6%) low risk, 7111 (51%) intermediate-1 risk, 5700 (41%) intermediate-2 risk, and 375 (3%) high risk or very high risk of 14,041 patients in a subanalysis combining the tuning and internal geographic validation cohorts. The DRI projected 2-year overall survival was 62·1% for these 14,041 patients, while the DRSS reclassified them into finer prognostic groups with overall survival ranging from 45·7% (37·4-54·0; very high risk patients) to 73·1% (70·1-76·2; low risk patients).
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Improved Outcomes of Haploidentical Hematopoietic Cell Transplantation with Total Body Irradiation-Based Myeloablative Conditioning in Acute Lymphoblastic Leukemia
Dholaria, B., Labopin, M., Angelucci, E., Tischer, J., Arat, M., Ciceri, F., Gülbas, Z., Ozdogu, H., Sica, S., Diez-Martin, J. L., et al
Transplantation and cellular therapy. 2021;27(2):171.e1-171.e8
Abstract
The optimal myeloablative conditioning (MAC) for patients undergoing haploidentical hematopoietic cell transplantation (haplo-HCT) is unknown. We studied the outcomes of total body irradiation (TBI)-based versus chemotherapy (CT)-based MAC regimens in patients with acute lymphoblastic leukemia (ALL). The study included 427 patients who underwent first haplo-HCT with post-transplantation cyclophosphamide (PTCy), following TBI-based (n = 188; 44%) or CT-based (n = 239; 56%) MAC. The median patient age was 32 years. Fludarabine-TBI (72%) and thiotepa-busulfan-fludarabine (65%) were the most frequently used TBI- and CT-based regimens, respectively. In the TBI and CT cohorts, 2-year leukemia-free survival (LFS) was 45% versus 37% (P = .05), overall survival (OS) was 51% versus 47% (P = .18), relapse incidence (RI) was 34% versus 32% (P = .44), and nonrelapse mortality (NRM) was 21% versus 31% (P < .01). In the multivariate analysis, TBI was associated with lower NRM (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.33 to 0.86; P = .01), better LFS (HR, 0.71; 95% CI, 0.52 to 0.98; P =.04), and increased risk for grade II-IV acute graft-versus-host disease (GVHD) (HR, 1.59; 95% CI, 1.08 to 2.34; P = .02) compared with CT-based MAC. The type of conditioning regimen did not impact RI, chronic GVHD, OS, or GVHD-free, relapse-free survival after adjusting for transplantation-related variables. TBI-based MAC was associated with lower NRM and better LFS compared with CT-based MAC in patients with ALL after haplo-HCT/PTCy.