[Allogeneic hematopoietic stem cell transplantation using posttransplant cyclophosphamide]

Posttransplant cyclophosphamide (PTCy) was initially developed by the Johns Hopkins group as a graft-versus-host disease (GVHD) prophylaxis for human leukocyte antigen (HLA)-haploidentical stem cell transplantation. Recently, PTCy has been attempted in HLA-matched transplantation. In HLA-haploidentical hematopoietic transplantation, several retrospective studies have compared HLA-matched transplantation with HLA-haploidentical hematopoietic transplantation using PTCy. In these reports, transplantation outcomes have been comparable. Therefore, PTCy- based haploidentical transplantation is a viable alternative to HLA-matched transplantation. Moreover, In HLA-matched transplantation, PTCy alone may be sufficient in the prevention of GVHD in HLA-matched bone marrow transplantation. Although PTCy alone is not enough in HLA-matched peripheral blood stem cell transplantation, PTCy has demonstrated excellent GVHD inhibition when combined with several immunosuppressive agents, such as calcineurin inhibitor and mycophenolate mofetil. Furthermore, PTCy also playing a significant role in other areas, such as aplastic anemia, salvage transplantation for graft failure, and allogeneic transplantation after checkpoint inhibitor use. PTCy can be performed inexpensively and without any special equipment or techniques at any institution. It is expected that PTCy will continue to spread worldwide in the future.