T-cell-replete haploidentical stem cell transplantation using low-dose antithymocyte globulin in children with relapsed or refractory acute leukemia.

We evaluated the efficacy and toxicity of T-cell-replete haploidentical stem cell transplantation (TCR-haploSCT) using low-dose antithymocyte globulin (ATG) in children with refractory/relapsed (R/R) acute leukemia. From October 2009 to April 2016, 39 consecutive patients with R/R acute leukemia who underwent TCR-haploSCT were included. At the time of TCR-haploSCT, 17 patients were in complete remission (CR), but 22 had active disease. Thirty-three patients received a myeloablative regimen and six received a reduced-intensity conditioning regimen. Graft-versus-host disease (GvHD) prophylaxis comprised tacrolimus, methotrexate, prednisolone, and low-dose ATG (thymoglobulin 2.5 mg/kg). Neutrophil engraftment (> 0.5 × 109/L) was 95% after a median of 13 days. The median follow-up period was 527 days, with mean 3-year overall and disease-free survival rates of 45.1% [standard deviation (SD), ± 8.5%) and 33.8% (SD, ± 7.9%), respectively. The cumulative incidence of acute GvHD was 73.0%, but that of grade III-IV acute GvHD was 34.1%. The 3-year cumulative incidences of relapse and transplant-related mortality were 50.3 and 15.9%, respectively. Age < 10 years at transplantation was associated with a better overall survival in the multivariate analysis. These data suggest that TCR-haploSCT using a low-dose ATG combined with the GvHD prophylaxis described here has a significant anti-leukemic activity, particularly in younger patients.