Successful Reduced Intensity Conditioning Alternate Donor Stem Cell Transplant for Wiskott-Aldrich Syndrome

There are very few reports of reduced intensity conditioning (RIC) hematopoietic stem cell transplant (HSCT) with alternate donor for Wiskott-Aldrich syndrome (WAS) and there is no report of RIC with posttransplant cyclophosphamide (PTCy) in WAS. There is only 1 report of T cell receptor and CD19-depleted haploidentical HSCT for WAS. Here we report successful outcome in 3 children with WAS who underwent successful RIC alternate donor HSCT of whom 2 (matched unrelated donor and T-cell replete haploidentical) received PTCy and 1 underwent T cell receptor and CD19-depleted haploidentical HSCT. We modified conditioning used by Luznik for haploidentical HSCT by adding thiotepa 8mg/kg and Campath or rabbit antithymoglobulin for 2 cases who received PTCy. In third case we gave fludarabine, thiotepa, and treosulfan-based conditioning. The mean duration of follow-up for these patients was 23.6 months posttransplant (range, 21 to 26mo). All 3 patients are transfusion independent. Acute graft versus host disease (GVHD) grade I occurred in 1 and none had chronic GVHD. Chimerism of all 3 was fully donor (>95% donor) at D+30 and D+100 posttransplant. All are alive, healthy, and doing well. Our 3 cases highlight that with newer conditioning and GVHD prophylaxis approach alternate donor HSCT in WAS can become a safe and effective treatment option.