Nonmyeloablative, HLA-Haploidentical Bone Marrow Transplantation with High Dose, Post-Transplantation Cyclophosphamide

Allogeneic stem cell transplantation (SCT) from an HLA-haploidentical relative provides a potentially curative treatment option for hematologic malignancies patients who lack a suitably HLA-matched donor. The greatest challenge to performing HLA-haploidentical SCT has been high rates of graft failure and severe graft-versus-host disease (GVHD). Our group has been exploring high dose, post-transplantation cyclophosphamide (Cy) as prophylaxis of GVHD after nonmyeloablative, HLA-haploidentical bone marrow transplantation, or <i>mini-haplo</i>BMT. Among 210 recipients of mini-haploBMT, 87% of patients have experienced sustained donor cell engraftment. The cumulative incidences of grades II-IV acute GVHD and chronic GVHD are 27% and 13%, respectively. Five-year cumulative incidence of non-relapse mortality is 18%, relapse is 55%, and actuarial overall survival and event-free survivals are 35% and 27%, respectively. These outcomes suggest that mini-haploBMT with post-transplantation Cy is associated with acceptably low toxicities and can provide longterm survival, if not cure, for many patients with advanced hematologic malignancies.