There is growing recognition of post-transplant cyclophosphamide (PTCy) as the new standard prophylaxis for graft-versus-host disease (GVHD) in HLA-matched peripheral blood stem cell transplants with reduced intensity conditioning, based on recent results of randomized phase III trials of PTCy. Allogeneic hematopoietic cell transplantation (HCT) with PTCy is thought to have GVHD-dependent and -independent graft-versus-tumor (GVT) effects. Its GVHD-dependent effects may be attenuated by PTCy-induced alloreactive T cell dysfunction and preferential recovery of regulatory T cells after HCT, but its GVT effects do not appear to be significantly impaired in patients in remission or with indolent disease. As patients not in remission are often also candidates for transplantation in Japan, it will be necessary to use PTCy as a platform to establish a strategy that could also be effective in patients not in remission and to revise the donor selection algorithm.