Comparison of Outcomes of Hematopoietic Cell Transplants from T-Replete Haploidentical Donors Using Post-Transplantation Cyclophosphamide with 10 of 10 HLA-A, -B, -C, -DRB1, and -DQB1 Allele-Matched Unrelated Donors and HLA-Identical Sibling Donors: A Multivariable Analysis Including Disease Risk Index

Abstract Outcomes of 475 consecutive patients undergoing first allogeneic transplantation for hematologic malignancy performed using T-replete HLA-haploidentical donors and post-transplantation cyclophosphamide (HIDT; n = 116) were compared with contemporaneous patients transplanted from 10 of 10 HLA allele-matched unrelated donors (MUDT; n = 178) or HLA-identical sibling donors (MRDT; n = 181). Uniform supportive care measures and assessments were used. Median follow-up was 45 months. HIDT patients were more likely than MUDT patients to be black (44% versus 2%; P < .001). At 2 years after transplantation, estimates of overall survival were 57% for HIDT, 59% for MUDT, and 72% for MRDT ( P not significant [NS] for HIDT versus MUDT; P = .02 for HIDT versus MRDT); corresponding disease-free survival rates were 54%, 50%, and 56% ( P NS for both comparisons). The respective cumulative incidences (CIs) of nonrelapse mortality were 17%, 16%, 14%, and those of relapse were 29%, 34%, and 30% ( P NS for all). The respective CIs of acute graft-versus-host disease (GVHD) grade II-IV were 41%, 48%, and 28% ( P = NS for HIDT versus MUDT; P = .005 for HIDT versus MRDT). At 2 years, the respective CIs of moderate/severe chronic GVHD were 31%, 47%, and 44% ( P = .004 for HIDT versus MUDT; P = .032 for HIDT versus MRDT) and 19% of HIDT recipients, 42% of MUDT recipients, and 35% of MRDT recipients were on systemic immunosuppressive treatment ( P = .007 for HIDT versus MUDT). In recipients of peripheral blood stem cell grafts, the incidence of moderate-severe chronic GVHD was significantly lower in HIDT recipients compared with MUDT recipients (2-year CI, 25% versus 48%; P = .002). In a multivariate analysis incorporating Disease Risk Index and other significant covariates, survival (hazard ratio [HR], 1.31; P = .15) and disease-free survival (HR, 0.96; P = .79) were not significantly different between HIDT and MUDT recipients, but the incidence of chronic GVHD was lower in HIDT recipients (moderate-severe, HR, 0.59; P = .007). HIDT produced similar long-term survival with lower rates of chronic GVHD than optimally matched MUDT. HIDT should be considered a standard of care option for patients lacking a matched sibling donor.