David J. Curtis, Geoffrey R. Hill
ABSTRACT: The use of posttransplant cyclophosphamide was initially pioneered as a means of permitting haploidentical transplantation across HLA barriers. This approach has now become a standard of care for the prevention of significant acute and chronic graft-versus-host disease (GVHD) after related and unrelated HLA-matched allogeneic peripheral blood stem cell transplant across a full spectrum of conditioning intensities. This article discusses recent advances, the mechanisms of action, and important unresolved questions in the prevention of GVHD that will help inform new prospective clinical studies.