Post-transplant cyclophosphamide was safely conjugated with 1 of the most-used GVHD prophylaxis regimens. Nonrelapse mortality was contained to 3% at 2 years. Extremely low acute and chronic GVHD rates (17% and 7%) allowed limited steroid and immunosuppressive drug use. Most nonrelapsing patients can live without chronic GVHD therapy. The presented strategy appears to be widely reproducible across most transplant centers.