Toxicity of busulfan and cyclophosphamide (BU/CY₂) in patients with hematologic malignancies

Between July 1991 and January 1994, 52 patients with hematologic malignancies underwent BMT using BU/CY₂ as conditioning regimen. Median patient age was 38 years. Eleven patients underwent autologous BMT, 22 HLA-identical allogeneic BMT, and 19 patients underwent a MUD or an allogeneic mismatched BMT. GVHD prophylaxis was with cyclosporine/methylprednisone in 26 patients; T cell depletion was used in 15 patients. VOD was observed in 7.5% of patients, IP in 12%, seizures in 4%. The overall incidence of grade II-IV acute GVHD was 35%. Delayed platelet engraftment was observed in seven of 11 patients who underwent autologous BMT. Graft failure was seen in seven of 19 (37%) patients who underwent MUD or allogeneic mismatched BMT. Six of the seven patients received T cell depletion as GVHD prophylaxis. BU/CY₂ transplantation from an unrelated or family-mismatched donor with T cell depletion is associated with a high incidence of graft failure.