Haploidentical hematopoietic stem cell transplantation to adults with hematologic malignancies: analysis of 66 cases at a single Japanese center

Sixty-six adult patients with hematologic malignancies underwent haploidentical hematopoietic stem cell transplantation (haplo-HSCT) without T cell depletion. The patients were preconditioned with a reduced intensity regimen, and tacrolimus was used for graft-versus-host disease (GVHD) prophylaxis. Successful engraftment occurred in 60 patients (90.1%) and graft rejection in only 4 patients (6.1%). Among the 60 engrafted patients, only 5 developed severe (grade III or IV) acute GVHD. Twenty patients, including 19 relapse-free patients were alive at a median follow-up of 48 months (range 6–77 months). The overall survival (OS) at 6 years was 29.3%. The OS of 45 patients <60 years of age was 43.6%, which was superior to that of 21 patients who were 60 years of age and older (9.5%) (P < 0.01). The OS of 11 patients from human leukocyte antigen (HLA) 1 locus-mismatched donors (63.6%) was higher than that of 28 patients from HLA 3 loci-mismatched donors (12.5%) (P < 0.01). Organ injury and infection were the main causes of mortality. Notably, immunosuppressive therapy could be successfully stopped in 9 patients transplanted from HLA 2 or 3 loci-mismatched donors with a median duration of 45 months (range 5–71 months). These data suggest that haplo-HSCT is a promising treatment for patients who need urgent allogeneic transplantation but lack HLA-identical family donors.