Post-relapse survival after haploidentical transplantation vs matched-related or matched-unrelated hematopoietic cell transplantation.

Relapse remains a major cause of mortality among patients receiving allogeneic hematopoietic cell transplantation (HCT). The impact of donor type on post-relapse survival (PRS) has not been widely examined. We compared the survival outcomes for patients relapsing after haploidentical donor transplantation (HIDT) using post-transplant cyclophosphamide with those relapsing after matched-related donor transplantation (MRDT) or matched-unrelated donor transplantation (MUDT) at our institution. Two hundred and thirty-seven consecutive HCT recipients with relapse occurring after HIDT (N=48), MUDT (N=87) and MRDT (N=102) were included in this analysis. Median age was 49 years (19-77 years) and the median time to relapse was 156 days (12-2465) after HCT. HIDT recipients had similar median time to relapse (5.8 vs 4.8 vs 5.5 months, P=0.638) compared with MUDT and MRDT, respectively. One-year PRS was worse among HIDT recipients compared with MRDT and MUDT (17% vs 46% vs 40%, P<0.05). In a multivariate analysis, time to relapse (<3 vs >3 months post transplant), no use of donor lymphocyte infusion (DLI) following relapse, higher Dana Farber disease risk index and HCT comorbidity index scores at the time of transplant and delayed platelet engraftment post transplant were all predictive of worse PRS. This analysis shows that 1-year PRS is inferior among HIDT when compared with MRDT or MUDT. Lower use of DLI after HIDT may have contributed to this inferior survival.