BONE-MARROW ENGRAFTMENT FOLLOWING UNRELATED DONOR TRANSPLANTATION UTILIZING BUSULFAN AND CYCLOPHOSPHAMIDE PREPARATORY CHEMOTHERAPY

Two major problems of unrelated donor transplantation have been an inc reased incidence of GVHD and graft failure, Even with HLA identity by microlymphocytotoxicity assay and non-reactive MLC, URD marrow transpl ant recipients have a higher incidence of graft rejection and GVHD, Th e preparative regimen busulfan 16 mg/kg and cyclophosphamide 120 mg/kg (BuCy2) has been shown to be at least as effective in preparation of recipients with CML of HLA-indentical sibling grafts as cyclophosphami de and total body irradiation (Cy/TBI), However, concern about a high rejection rate in URD transplants has prevented most centers from usin g BuCy2 in this setting, From March 1990 to March 1994, 26 patients un derwent URD transplantation following preparation with BuCy2, Patients received either standard cyclosporine and methotrexate or cyclosporin e and methylprednisolone for GVHD prophylaxis, Two patients died on da y 16 and 20 without evidence of hematopoietic engraftment, Of the 24 p atients evaluable for engraftment, 23 (96%) had evidence of donor engr aftment defined as an ANC >0.5 x 10(9)/l, No patient who had initial e ngraftment had late graft failure, Within our study group the risk of graft rejection or graft failure does not appear to be higher than tha t reported for URD transplants utilizing TBI-containing regimens.