Reduced-toxicity alternate-donor stem cell transplantation with posttransplant cyclophosphamide for primary immunodeficiency disorders.

We describe here the outcomes of reduced-toxicity alternate-donor stem cell transplant (SCT) with posttransplant cyclophosphamide (PTCy) for primary immunodeficiency disorders (PIDs) in eight children (haploidentical-seven and matched unrelated donor-one). The conditioning was with serotherapy (alemtuzumab-3/rabbit-anti-thymoglobulin-5); fludarabine, cyclophosphamide, and total body irradiation-5 (additional thiotepa-3); fludarabine and treosulfan-2; and fludarabine and busulfan-1. All received PTCy 50 mg/kg on days 3 and 4 as graft versus host disease prophylaxis along with tacrolimus and mycophenolate. Mean CD34 dose was 13.8 × 106 /kg. Two children died because of PIDs. Acute graft versus host disease up to grades I and II was seen in three children. All six survivors are fully donor and disease free at median follow-up of 753 days. Alternate donor SCT with PTCy is feasible in PID and has good outcomes.