Standard conditioning regimen and T-depleted donor bone marrow for transplantation in chronic myeloid leukemia.

Abstract Between January 1984 to June 1985, 18 Ph 1 positive chronic myeloid leukemia (CML) patients in chronic phase (CP) underwent allogeneic bone marrow transplantation (BMT) from HLA identical and MLC negative siblings. The median age was 32.5 yr and median disease duration of CML at time of BMT was 19.3 months. The pretransplant conditioning regimen consisted of cyclophosphamide (CTX) (120 mg/kg) and 10.20 Gy total body irradiation (TBI) at 6 doses of 1.7 Gy each, administered in 3 daily fractions over 2 days at a dose rate of 15–20 cGy/min. To prevent graft-vs-host disease (GvHD) we used methotrexate (MTX) in one patient and cyclosporin-A (CYA) in the other 17 patients. In addition to CYA, given until day +365, 10 patients received donor marrow depleted of T cells with CAMPATH-1. The residual marrow lymphocytes were always Of the other 8 patients transplanted with untreated marrow, 5 are alive after a median followup of 19.3 months (range 3.7–24) and the actuarial survival is 63.8%. This pilot study seems to demonstrate that T-cell depletion of donor bone marrow with CAMPATH-1 is effective to prevent GvHD, while the risk of graft failure can be avoided using a “standard” conditioning regimen including a fractionated TBI with a fast dose rate and a prolonged administration of CYA at the maximum tolerable dosage. While the high frequency of relapses suggests the employ of more aggressive anti-leukemic conditioning regimens in CAMPATH-1 treated marrow recipients.