An adapted European LeukemiaNet genetic risk stratification for acute myeloid leukemia patients undergoing allogeneic hematopoietic cell transplant. A CIBMTR analysis.

Cytogenetic and molecular abnormalities are known to influence post-transplant outcomes in acute myeloid leukemia (AML) but data assessing the prognostic value of combined genetic models in the HCT setting are limited. We developed an adapted European LeukemiaNet (aELN) risk classification based on available genetic data reported to the Center for International Blood and Marrow Transplant Research, to predict post-transplant outcomes in 2289 adult AML patients transplanted in first remission, between 2013 and 2017. Patients were stratified according to aELN into three groups: favorable (Fav, N = 181), intermediate (IM, N = 1185), and adverse (Adv, N = 923). Univariate analysis demonstrated significant differences in 2-year overall survival (OS) (Fav: 67.7%, IM: 64.9% and Adv: 53.9%; p < 0.001); disease-free survival (DFS) (Fav: 57.8%, IM: 55.5% and Adv: 45.3; p < 0.001) and relapse (Fav: 28%, IM: 27.5% and Adv: 37.5%; p < 0.001). Multivariate analysis (MVA) revealed no differences in outcomes between the Fav and IM groups, thus they were combined. On MVA, patients in the Adv risk group had the highest risk of relapse (HR 1.47 p ≤ 0.001) and inferior DFS (HR 1.35 p < 0.001) and OS (HR 1.39 p < 0.001), even using myeloablative conditioning or in those without the pre-HCT measurable-residual disease. Novel approaches to mitigate relapse in this high-risk group are urgently needed.

Allogeneic Transplantation to Treat Therapy-Related Myelodysplastic Syndrome and Acute Myelogenous Leukemia in Adults.

Patients who develop therapy-related myeloid neoplasm, either myelodysplastic syndrome (t-MDS) or acute myelogenous leukemia (t-AML), have a poor prognosis. An earlier Center for International Blood and Marrow Transplant Research (CIBMTR) analysis of 868 allogeneic hematopoietic cell transplantations (allo-HCTs) performed between 1990 and 2004 showed a 5-year overall survival (OS) and disease-free survival (DFS) of 22% and 21%, respectively. Modern supportive care, graft-versus-host disease prophylaxis, and reduced-intensity conditioning (RIC) regimens have led to improved outcomes. Therefore, the CIBMTR analyzed 1531 allo-HCTs performed in adults with t-MDS (n = 759) or t-AML (n = 772) between and 2000 and 2014. The median age was 59 years (range, 18 to 74 years) for the patients with t-MDS and 52 years (range, 18 to 77 years) for those with t-AML. Twenty-four percent of patients with t-MDS and 11% of those with t-AML had undergone a previous autologous (auto-) HCT. A myeloablative conditioning (MAC) regimen was used in 49% of patients with t-MDS and 61% of patients with t-AML. Nonrelapse mortality at 5 years was 34% (95% confidence interval [CI], 30% to 37%) for patients with t-MDS and 34% (95% CI, 30% to 37%) for those with t-AML. Relapse rates at 5 years in the 2 groups were 46% (95% CI, 43% to 50%) and 43% (95% CI, 40% to 47%). Five-year OS and DFS were 27% (95% CI, 23% to 31%) and 19% (95% CI, 16% to 23%), respectively, for patients with t-MDS and 25% (95% CI, 22% to 28%) and 23% (95% CI, 20% to 26%), respectively, for those with t-AML. In multivariate analysis, OS and DFS were significantly better in young patients with low-risk t-MDS and those with t-AML undergoing HCT with MAC while in first complete remission, but worse for those with previous auto-HCT, higher-risk cytogenetics or Revised International Prognostic Scoring System score, and a partially matched unrelated donor. Relapse remains the major cause of treatment failure, with little improvement seen over the past 2 decades. These data mandate caution when recommending allo-HCT in these conditions and indicate the need for more effective antineoplastic approaches before and after allo-HCT.

Fludarabine and Melphalan Compared with Reduced Doses of Busulfan and Fludarabine Improve Transplantation Outcomes in Older Patients with Myelodysplastic Syndromes.

Reduced-intensity conditioning (RIC) regimens developed to extend the use of allogeneic hematopoietic stem cell transplantation (HSCT) to older patients have resulted in encouraging outcomes. We aimed to compare the 2 most commonly used RIC regimens, i.v. fludarabine with busulfan (FluBu) and fludarabine with melphalan (FluMel), in patients with myelodysplastic syndrome (MDS). Through the Center for International Blood and Marrow Transplant Research (CIBMTR), we identified 1045 MDS patients age ≥60 years who underwent first HSCT with a matched related or matched (8/8) unrelated donor using an RIC regimen. The CIBMTR's definition of RIC was used: a regimen that incorporated an i.v. busulfan total dose ≤7.2 mg/kg or a low-dose melphalan total dose ≤150 mg/m2. The 2 groups, recipients of FluBu (n = 697) and recipients of FluMel (n = 448), were comparable in terms of disease- and transplantation-related characteristics except for the more frequent use of antithymocyte globulin or alemtuzumab in the FluBu group (39% versus 31%). The median age was 67 years in both groups. FluMel was associated with a reduced relapse incidence (RI) compared with FluBu, with a 1-year adjusted incidence of 26% versus 44% (P ≤ .0001). Transplantation-related mortality (TRM) was higher in the FluMel group (26% versus 16%; P ≤ .0001). Because the magnitude of improvement with FluMel in RI was greater than the improvement in TRM with FluBu, disease-free survival (DFS) was better at 1 year and beyond with FluMel compared with FluBu (48% versus 40% at 1 year [P = .02] and 35% versus 27% at 3 years [P = .01]). Overall survival was comparable in the 2 groups at 1 year (63% versus 61%; P = .4) but was significantly improved with FluMel compared with FluBu at 3 years (46% versus 39%; P = .03). Our results suggest that FluMel is associated with superior DFS compared with FluBu owing to reduced RI in older patients with MDS patients. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Impact of depth of clinical response on outcomes of acute myeloid leukemia patients in first complete remission who undergo allogeneic hematopoietic cell transplantation.

Acute myeloid leukemia (AML) patients often undergo allogeneic hematopoietic cell transplantation (alloHCT) in first complete remission (CR). We examined the effect of depth of clinical response, including incomplete count recovery (CRi) and/or measurable residual disease (MRD), in patients from the Center for International Blood and Marrow Transplantation Research (CIBMTR) registry. We identified 2492 adult patients (1799 CR and 693 CRi) who underwent alloHCT between January 1, 2007 and December 31, 2015. The primary outcome was overall survival (OS). Multivariable analysis was performed to adjust for patient-, disease-, and transplant-related factors. Baseline characteristics were similar. Patients in CRi compared to those in CR had an increased likelihood of death (HR: 1.27; 95% confidence interval: 1.13-1.43). Compared to CR, CRi was significantly associated with increased non-relapse mortality (NRM), shorter disease-free survival (DFS), and a trend toward increased relapse. Detectable MRD was associated with shorter OS, shorter DFS, higher NRM, and increased relapse compared to absence of MRD. The deleterious effects of CRi and MRD were independent. In this large CIBMTR cohort, survival outcomes differ among AML patients based on depth of CR and presence of MRD at the time of alloHCT. Further studies should focus on optimizing post-alloHCT outcomes for patients with responses less than CR.

Impact of Pretransplantation Renal Dysfunction on Outcomes after Allogeneic Hematopoietic Cell Transplantation.

Renal dysfunction is a recognized risk factor for mortality after allogeneic hematopoietic cell transplantation (alloHCT), yet our understanding of the effect of different levels of renal dysfunction at time of transplantation on outcomes remains limited. This study explores the impact of different degrees of renal dysfunction on HCT outcomes and examines whether the utilization of incremental degrees of renal dysfunction based on estimated glomerular filtration rate (eGFR) improve the predictability of the hematopoietic cell transplantation comorbidity index (HCT-CI). The study population included 2 cohorts: cohort 1, comprising patients age ≥40 years who underwent alloHCT for treatment of hematologic malignancies between 2008 and 2016 (n = 13,505; cohort selected given a very low incidence of renal dysfunction in individuals age <40 years), and cohort 2, comprising patients on dialysis at the time of HCT (n = 46). eGFR was measured using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) method. The patients in cohort 1 were assigned into 4 categories-eGFR ≥90 mL/min (n = 7062), eGFR 60 to 89 mL/min (n = 5264), eGFR 45 to 59 mL/min (n = 897), and eGFR <45 mL/min (n=282)-to assess the impact of degree of renal dysfunction on transplantation outcomes. Transplantation outcomes in patients on dialysis at the time of alloHCT were analyzed separately. eGFR <60 mL/min was associated with an increased risk for nonrelapse mortality (NRM) and requirement for dialysis post-HCT. Compared with the eGFR ≥90 group, the hazard ratio (HR) for NRM was 1.46 (P = .0001) for the eGFR 45 to 59 mL/min group and 1.74 (P = .004) for the eGFR <45 mL/min group. Compared with the eGFR ≥90 mL/min group, the eGFR 45 to 59 mL/min group (HR, 2.45; P < .0001) and the eGFR <45 mL/min group (HR, 3.09; P < .0001) had a higher risk of renal failure necessitating dialysis after alloHCT. In addition, eGFR <45 mL/min was associated with an increased overall mortality (HR, 1.63; P < .0001). An eGFR-based revised HCT-CI was also developed and shown to be predictive of overall survival (OS) and NRM, with predictive performance similar to the original HCT-CI. Among 46 patients on dialysis at alloHCT, the 1-year probability of OS was 20%, and that of NRM was 67%. The degree of pretransplantation renal dysfunction is an independent predictor of OS, NRM, and probability of needing dialysis after alloHCT. An eGFR-based HCT-CI is a validated index for predicting outcomes in adults with hematologic malignancies undergoing alloHCT. The outcomes of alloHCT recipients on dialysis are dismal; therefore, one should strongly weigh the significant risks of being on hemodialysis as a factor in determining alloHCT candidacy.

Bortezomib-Based Induction Is Associated with Superior Outcomes in Light Chain Amyloidosis Patients Treated with Autologous Hematopoietic Cell Transplantation Regardless of Plasma Cell Burden.

The benefits of pre-transplant induction chemotherapy in light chain (AL) amyloidosis, a low burden plasma cell (PC) neoplasm associated with multiorgan dysfunction, is debatable, although with the availability of bortezomib, this approach is being increasingly pursued. We analyzed the outcomes of AL amyloidosis patients undergoing autologous hematopoietic cell transplant between 2014 and 2018 that were reported to the Center for International Blood and Marrow Transplant Research database. Of 440 patients, 294 received bortezomib-based induction, and 146 received no induction. Patients receiving induction had greater PC burden compared to no induction (PC 10% or more, 39% versus 11%; P < .01). At 2 years, the induction group compared to no induction had lower relapse/progression: 13% (9% to 18%) versus 23% (16% to 32%) (P = .02); better progression-free survival (PFS): 82% (77% to 87%) versus 69% (61% to 77%) (P < .01); and similar overall survival (OS): 92% (88% to 95%) versus 89% (84% to 94%) (P = .22), findings that were confirmed on multivariate analysis. A subset analysis limited to patients with <10% PC also showed superior relapse/progression (hazard ratio [HR], .43; 95% confidence interval [CI], .24 to .78; P < .01) and PFS (HR, .43; 95% CI, .26 to .72; P < .01) for induction compared to no induction. Thus, we conclude that pre-transplant bortezomib-based induction was associated with improved relapse/progression and PFS in AL amyloidosis. Longer survival follow-up is warranted, as OS was excellent in both cohorts at 2 years.

Benralizumab for adolescent patients with severe, eosinophilic asthma: Safety and efficacy after 3 years of treatment.

BACKGROUND: Adults and adolescents with severe asthma who completed the 48-week SIROCCO and 56-week CALIMA phase III benralizumab trials entered the safety extension study BORA (NCT02258542). The continued safety and efficacy of benralizumab in the first year of BORA (year 2 of treatment) have been reported. OBJECTIVE: We sought to report outcomes for adolescents during years 2 and 3 of treatment in BORA. METHODS: Patients on benralizumab 30 mg every 4 weeks (Q4W) or every 8 weeks (Q8W) in SIROCCO/CALIMA continued their regimens in BORA (Q4W/Q4W and Q8W/Q8W, respectively), whereas placebo patients were rerandomized 1:1 to benralizumab (placebo/Q4W and placebo/Q8W, respectively) for 108 weeks. The primary outcome was safety; secondary outcomes included reduction in annual asthma exacerbation rate and change from baseline in prebronchodilator FEV1. RESULTS: Adolescents (N = 86) were treated with benralizumab Q8W (n = 61) or Q4W (n = 25); 69 completed treatment (Q8W: n = 51; Q4W: n = 18). For Q4W and Q8W regimens, rates of treatment-emergent adverse events were 68% (17 of 25) and 74% (45 of 61), respectively, rates of treatment-emergent adverse events (TEAEs) were 68% (17/25) and 74% (45/61), TEAEs leading to discontinuation were 4% (1/25) and 0%, serious AEs were 8% (2/25) and 7% (4/61), and no deaths occurred. In efficacy analyses, 69% (42 of 61) Q8W patients were exacerbation-free (placebo/Q8W: 62% [18 of 29], Q8W/Q8W: 75% [24 of 32]). Mean ± SD change in FEV1 at week 108 versus BORA baseline was 0.327 ± 0.452 L (placebo/Q8W) and 0.323 ± 0.558 L (Q8W/Q8W). CONCLUSIONS: Safety and efficacy profiles in this 2-year extension study (up to 3 years of benralizumab treatment in adolescents) were consistent with previous findings.

Neighborhood poverty and pediatric allogeneic hematopoietic cell transplantation outcomes: a CIBMTR analysis.

Social determinants of health, including poverty, contribute significantly to health outcomes in the United States; however, their impact on pediatric hematopoietic cell transplantation (HCT) outcomes is poorly understood. We aimed to identify the association between neighborhood poverty and HCT outcomes for pediatric allogeneic HCT recipients in the Center for International Blood and Marrow Transplant Research database. We assembled 2 pediatric cohorts undergoing first allogeneic HCT from 2006 to 2015 at age ≤18 years, including 2053 children with malignant disease and 1696 children with nonmalignant disease. Neighborhood poverty exposure was defined a priori per the US Census definition as living in a high-poverty ZIP code (≥20% of persons below 100% federal poverty level) and used as the primary predictor in all analyses. Our primary outcome was overall survival (OS), defined as the time from HCT until death resulting from any cause. Secondary outcomes included relapse and transplantation-related mortality (TRM) in malignant disease, acute and chronic graft-versus-host disease, and infection in the first 100 days post-HCT. Among children undergoing transplantation for nonmalignant disease, neighborhood poverty was not associated with any HCT outcome. Among children undergoing transplantation for malignant disease, neighborhood poverty conferred an increased risk of TRM but was not associated with inferior OS or any other transplantation outcome. Among children with malignant disease, a key secondary finding was that children with Medicaid insurance experienced inferior OS and increased TRM compared with those with private insurance. These data suggest opportunities for future investigation of the effects of household-level poverty exposure on HCT outcomes in pediatric malignant disease to inform care delivery interventions.

Community health status and outcomes after allogeneic hematopoietic cell transplantation in the United States.

BACKGROUND: The association of community factors and outcomes after hematopoietic cell transplantation (HCT) has not been comprehensively described. Using the County Health Rankings and Roadmaps (CHRR) and the Center for International Blood and Marrow Transplant Research (CIBMTR), this study evaluated the impact of community health status on allogeneic HCT outcomes. METHODS: This study included 18,544 adult allogeneic HCT recipients reported to the CIBMTR by 170 US centers in 2014-2016. Sociodemographic, environmental, and community indicators were derived from the CHRR, an aggregate community risk score was created, and scores were assigned to each patient (patient community risk score [PCS]) and transplant center (center community risk score [CCS]). Higher scores indicated less healthy communities. The impact of PCS and CCS on patient outcomes after allogeneic HCT was studied. RESULTS: The median age was 55 years (range, 18-83 years). The median PCS was -0.21 (range, -1.37 to 2.10; standard deviation [SD], 0.42), and the median CCS was -0.13 (range, -1.04 to 0.96; SD, 0.40). In multivariable analyses, a higher PCS was associated with inferior survival (hazard ratio [HR] per 1 SD increase, 1.04; 99% CI, 1.00-1.08; P = .0089). Among hematologic malignancies, a tendency toward inferior survival was observed with a higher PCS (HR, 1.04; 99% CI, 1.00-1.08; P = .0102); a higher PCS was associated with higher nonrelapse mortality (NRM; HR, 1.08; 99% CI, 1.02-1.15; P = .0004). CCS was not significantly associated with survival, relapse, or NRM. CONCLUSIONS: Patients residing in counties with a worse community health status have inferior survival as a result of an increased risk of NRM after allogeneic HCT. There was no association between the community health status of the transplant center location and allogeneic HCT outcomes.

Myeloablative Conditioning for Allogeneic Transplantation Results in Superior Disease-Free Survival for Acute Myelogenous Leukemia and Myelodysplastic Syndromes with Low/Intermediate but not High Disease Risk Index: A Center for International Blood and Marrow Transplant Research Study.

Compared with reduced-intensity conditioning (RIC), myeloablative conditioning (MAC) is generally associated with lower relapse risk after allogeneic hematopoietic cell transplantation (HCT) for acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS). However, disease-specific risk factors in AML/MDS can further inform when MAC and RIC may yield differential outcomes. We analyzed HCT outcomes stratified by the Disease Risk Index (DRI) in 4387 adults (age 40 to 65 years) to identify the impact of conditioning intensity. In the low/intermediate-risk DRI cohort, RIC was associated with lower nonrelapse mortality (NRM) (hazard ratio [HR], .74; 95% confidence interval [CI], .62 to .88; P < .001) but significantly greater relapse risk (HR, 1.54; 95% CI, 1.35 to 1.76; P < .001) and thus inferior disease-free survival (DFS) (HR, 1.19; 95% CI, 1.07 to 1.33; P = .001). In the high/very high-risk DRI cohort, RIC was associated with marginally lower NRM (HR, .83; 95% CI, .68 to 1.00; P = .051) and significantly higher relapse risk (HR, 1.23; 95% CI, 1.08 to 1.41; P = .002), leading to similar DFS using either RIC or MAC. These data support MAC over RIC as the preferred conditioning intensity for patients with AML/MDS with low/intermediate-risk DRI, but with a similar benefit as RIC in high/very high-risk DRI. Novel MAC regimens with less toxicity could benefit all patients, but more potent antineoplastic approaches are needed for the high/very-high risk DRI group.

Comparison of outcomes of HCT in blast phase of BCR-ABL1- MPN with de novo AML and with AML following MDS.

Comparative outcomes of allogeneic hematopoietic cell transplantation (HCT) for BCR-ABL1- myeloproliferative neoplasms (MPNs) in blast phase (MPN-BP) vs de novo acute myeloid leukemia (AML), and AML with prior myelodysplastic syndromes (MDSs; post-MDS AML), are unknown. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we compared HCT outcomes in 177 MPN-BP patients with 4749 patients with de novo AML, and 1104 patients with post-MDS AML, using multivariate regression analysis in 2 separate comparisons. In a multivariate Cox model, no difference in overall survival (OS) or relapse was observed in patients with MPN-BP vs de novo AML with active leukemia at HCT. Patients with MPN-BP in remission had inferior OS in comparison with de novo AML in remission (hazard ratio [HR], 1.40 [95% confidence interval [CI], 1.12-1.76]) due to higher relapse rate (HR, 2.18 [95% CI, 1.69-2.80]). MPN-BP patients had inferior OS (HR, 1.19 [95% CI, 1.00-1.43]) and increased relapse (HR, 1.60 [95% CI, 1.31-1.96]) compared with post-MDS AML. Poor-risk cytogenetics were associated with increased relapse in both comparisons. Peripheral blood grafts were associated with decreased relapse in MPN-BP and post-MDS AML (HR, 0.70 [95% CI, 0.57-0.86]). Nonrelapse mortality (NRM) was similar between MPN-BP vs de novo AML, and MPN-BP vs post-MDS AML. Total-body irradiation-based myeloablative conditioning was associated with higher NRM in both comparisons. Survival of MPN-BP after HCT is inferior to de novo AML in remission and post-MDS AML due to increased relapse. Relapse-prevention strategies are required to optimize HCT outcomes in MPN-BP.

Age no bar: A CIBMTR analysis of elderly patients undergoing autologous hematopoietic cell transplantation for multiple myeloma.

BACKGROUND: Upfront autologous hematopoietic stem cell transplantation (AHCT) remains an important therapy in the management of patients with multiple myeloma (MM), a disease of older adults. METHODS: The authors investigated the outcomes of AHCT in patients with MM who were aged ≥70 years. The Center for International Blood and Marrow Transplant Research (CIBMTR) database registered 15,999 patients with MM in the United States within 12 months of diagnosis during 2013 through 2017; a total of 2092 patients were aged ≥70 years. Nonrecurrence mortality (NRM), disease recurrence and/or progression (relapse; REL), progression-free survival (PFS), and overall survival (OS) were modeled using Cox proportional hazards models with age at transplantation as the main effect. Because of the large sample size, a P value <.01 was considered to be statistically significant a priori. RESULTS: An increase in AHCT was noted in 2017 (28%) compared with 2013 (15%) among patients aged ≥70 years. Although approximately 82% of patients received melphalan (Mel) at a dose of 200 mg/m2 overall, 58% of the patients aged ≥70 years received Mel at a dose of 140 mg/m2 . On multivariate analysis, patients aged ≥70 years demonstrated no difference with regard to NRM (hazard ratio [HR] 1.3; 99% confidence interval [99% CI], 1-1.7 [P = .06]), REL (HR, 1.03; 99% CI, 0.9-1.1 [P = 0.6]), PFS (HR, 1.06; 99% CI, 1-1.2 [P = 0.2]), and OS (HR, 1.2; 99% CI, 1-1.4 [P = .02]) compared with the reference group (those aged 60-69 years). In patients aged ≥70 years, Mel administered at a dose of 140 mg/m2 was found to be associated with worse outcomes compared with Mel administered at a dose of 200 mg/m2 , including day 100 NRM (1% [95% CI, 1%-2%] vs 0% [95% CI, 0%-1%]; P = .003]), 2-year PFS (64% [95% CI, 60%-67%] vs 69% [95% CI, 66%-73%]; P = .003), and 2-year OS (85% [95% CI, 82%-87%] vs 89% [95% CI, 86%-91%]; P = .01]), likely representing frailty. CONCLUSIONS: The results of the current study demonstrated that AHCT remains an effective consolidation therapy among patients with MM across all age groups.

Timing of allogeneic hematopoietic cell transplantation (alloHCT) for chronic myeloid leukemia (CML) patients.

While TKI are the preferred first-line treatment for chronic phase (CP) CML, alloHCT remains an important consideration. The aim is to estimate residual life expectancy (RLE) for patients initially diagnosed with CP CML based on timing of alloHCT or continuation of TKI in various settings: CP1 CML, CP2 + [after transformation to accelerated phase (AP) or blast phase (BP)], AP, or BP. Non-transplant cohort included single-institution patients initiating TKI and switched TKI due to failure. CIBMTR transplant cohort included CML patients who underwent HLA sibling matched (MRD) or unrelated donor (MUD) alloHCT. AlloHCT appeared to shorten survival in CP1 CML with overall mortality hazard ratio (HR) for alloHCT of 2.4 (95% CI 1.2-4.9; p = .02). In BP CML, there was a trend toward higher survival with alloHCT; HR = 0.7 (0.5-1.1; p = .099). AlloHCT in CP2 + [HR = 2.0 (0.8-4.9), p = .13] and AP [HR = 1.1 (0.6-2.1); p = .80] is less clear and should be determined on a case-by-case basis.

Risk Factors for Graft-versus-Host Disease in Haploidentical Hematopoietic Cell Transplantation Using Post-Transplant Cyclophosphamide.

Post-transplant cyclophosphamide (PTCy) has significantly increased the successful use of haploidentical donors with a relatively low incidence of graft-versus-host disease (GVHD). Given its increasing use, we sought to determine risk factors for GVHD after haploidentical hematopoietic cell transplantation (haplo-HCT) using PTCy. Data from the Center for International Blood and Marrow Transplant Research on adult patients with acute myeloid leukemia, acute lymphoblastic leukemia, myelodysplastic syndrome, or chronic myeloid leukemia who underwent PTCy-based haplo-HCT (2013 to 2016) were analyzed and categorized into 4 groups based on myeloablative (MA) or reduced-intensity conditioning (RIC) and bone marrow (BM) or peripheral blood (PB) graft source. In total, 646 patients were identified (MA-BM = 79, MA-PB = 183, RIC-BM = 192, RIC-PB = 192). The incidence of grade 2 to 4 acute GVHD at 6 months was highest in MA-PB (44%), followed by RIC-PB (36%), MA-BM (36%), and RIC-BM (30%) (P = .002). The incidence of chronic GVHD at 1 year was 40%, 34%, 24%, and 20%, respectively (P < .001). In multivariable analysis, there was no impact of stem cell source or conditioning regimen on grade 2 to 4 acute GVHD; however, older donor age (30 to 49 versus <29 years) was significantly associated with higher rates of grade 2 to 4 acute GVHD (hazard ratio [HR], 1.53; 95% confidence interval [CI], 1.11 to 2.12; P = .01). In contrast, PB compared to BM as a stem cell source was a significant risk factor for the development of chronic GVHD (HR, 1.70; 95% CI, 1.11 to 2.62; P = .01) in the RIC setting. There were no differences in relapse or overall survival between groups. Donor age and graft source are risk factors for acute and chronic GVHD, respectively, after PTCy-based haplo-HCT. Our results indicate that in RIC haplo-HCT, the risk of chronic GVHD is higher with PB stem cells, without any difference in relapse or overall survival.