Outcomes of PTCY-Based Haploidentical Transplants and Donor Factors Affecting Outcomes: A 12-year Experience from India.

Outcomes of haploidentical transplantation have been reported to be comparable to HLA-matched transplants in several studies; however, data from low- and middle-income countries remain limited. In this retrospective study, we evaluated outcomes of 71 patients who underwent haploidentical transplantation for malignant indications using post-transplant cyclophosphamide (PTCy) between July 2010 and March 2022 and analyzed donor factors influencing outcomes. All patients received peripheral blood stem cell grafts with standard PTCy/calcineurin inhibitor/mycophenolate mofetil prophylaxis. Graft failure occurred in seven patients (9.8%), with a higher incidence observed in those with 0-1 mismatch in the graft versus host direction (p=0.011). The incidences of grade II-IV acute graft versus host disease (GVHD) and chronic GVHD were 42.3% and 47.7%, respectively. Overall transplant related mortality (TRM) was 42.3%. Donor killer-cell immunoglobulin-like receptor haplotype BX with 2DS2 and the Bw6Bw6 ligand in recipients were associated with a reduced risk of relapse. The 5-year overall survival was 31.9%. On multivariate analysis, female donors were associated with improved overall survival (hazard ratio 0.465 [95% confidence interval 0.222-0.974], p=0.042). Transplant outcomes were primarily limited by a high incidence of TRM. These findings warrant validation in larger multicenter studies.