Haploidentical bone marrow transplant with post-transplant cyclophosphamide plus thiotepa improves donor engraftment in patients with sickle cell anemia: results of an international learning collaborative.

•Multicenter learning collaborative model of haploidentical bone marrow transplantation (BMT) for sickle cell disease (SCD).•Using haploidentical BMT as curative therapy for SCD increases the donor pool.•Haploidentical BMT with post-transplantation cyclophosphamide (PTCy) plus thiotepa increases donor engraftment in SCD.•Event-free survival and overall survival are improved following haplo-BMT with PTCy plus thiotepa.