UNRELATED ALLOGENEIC BONE-MARROW TRANSPLANTATION USING HIGH-DOSE BUSULFAN AND CYCLOPHOSPHAMIDE (BU-CY) FOR THE PREPARATIVE REGIMEN

This study reviews results of a radiation-free preparative regimen con sisting of busulfan and cyclophosphamide in 65 unrelated allogeneic bo ne marrow transplant recipients, Thirty-eight patients had chronic mye logenous leukemia (17 patients chronic phase, 13 patients accelerated phase, eight patients blast phase), 19 patients had acute leukemia (se cond complete remission or relapse) and eight patients had myelodyspla sia, The patients were transplanted at four different medical centers from July 1988 to November 1992, Ages ranged 4-48 years (median 32), F ifty-seven patients received busulfan 16 mg/kg and cyclophosphamide 12 0 mg/kg, and eight received busulfan at doses between 15 and 17 mg/kg and cyclophosphamide at doses 100-200 mg/kg as preparative regimens, A ll patients received cyclosporine for graft-versus-host disease prophy laxis; in addition 46 patients received corticosteroid, 38 methotrexat e, six anti-CDS ricin A-immuno-toxin, and four T cell-depleted bone ma rrow, Median follow-up of survivors was 53 months (range 15-68 months) , Four year actuarial survival was 24 +/- 12%, Four-year survival base d on disease was 29 +/- 27% for chronic myelogenous leukemia (CML) in chronic phase, 20 +/- 9% for chronic myelogenous leukemia in accelerat ed phase, 0% for chronic myelogenous leukemia in blast phase, 32 +/- 4 0 % for acute leukemia, and 38 +/- 34 % for myelodysplasia, Actuarial survival was 66 +/- 40% in patients age <20 years, vs 23 +/- 13% for p atients ages 20 to 40, and 10 +/- 14% for patients age >40 years. Fift y patients (88%) engrafted, Graft failure occurred in eight patients, Acute graft-versus-host disease grade II-IV occurred in 36 (72%), Two patients relapsed after engraftment,vith the donor cells and died of l eukemia within a month of relapse, The most common causes of death wer e graft-versus-host disease (37%), and transplant-related toxicity (59 %); relapse (4%) was a rare cause of death, Busulfan/cyclophosphamide is an effective preparative regimen in unrelated bone marrow transplan tation permitting adequate engraftment and a low relapse rate, Best re sults are observed in patients less than 20 years old.