High-dose melphalan allows durable engraftment of allogeneic bone marrow

Conditioning regimens for allogeneic bone marrow transplantation are designed to eradicate malignant cells and to provide sufficient immunosuppression for engraftment of donor marrow. Total body irradiation and high-dose cyclophosphamide are the most established immunosuppressive agents used for this purpose. It is uncertain whether other alkylating agent-based conditioning regimens are sufficiently immunosuppressive to allow engraftment of allogeneic marrow. We report four patients who had prompt engraftment after conditioning with melphalan-based chemotherapy regimens (BEAM or busulfan/melphalan). Two patients survived without disease for a prolonged period, indicating that these melphalan regimens are sufficiently immunosuppressive to allow sustained engraftment and donor hematopoiesis.