Purpose: We evaluated the efficacy and toxicity of a conditioning regimen designed to overcome the increased risk of rejection and relapse associated with T-cell-depleted bone marrow transplants.
Patients and methods: Fifty-four patients with acute leukemia received an allogeneic T-depleted bone marrow transplant from an HLA-matched (n=52) or one locus mismatched (n=2) sibling donor between June 1989 and November 1993. Nineteen acute myeloid leukemia patients and 17 acute lymphoid leukemia patients were in complete remission, and 11 acute myeloid leukemia patients and 7 acute lymphoid leukemia patients were in relapse. Patients were preconditioned with hyperfractionated total body irradiation of 1.2 Gy three times a day on days -9 to -6 (total 14.4 Gy), 10 mg/kg thiotepa on day -5, 4 mg/kg rabbit antithymocyte globulin on days -4 to -1, and 50 mg/kg cyclophosphamide on days -3 and -2.
Results: All patients were fully engrafted at a median of 15 days after transplant. No patient rejected the transplant or developed acute or chronic graft-versus-host disease. Of 19 patients with acute myeloid leukemia in complete remission, 14 survive. Four of the 11 patients with acute myeloid leukemia in relapse survive. Twelve acute myeloid leukemia patients died (three of relapse, eight of toxicity, one of other causes). Eleven of 24 patients with acute lymphoid leukemia (one treated in relapse) are alive in complete remission; the other 13 died (nine of relapse, four of toxicity). Interstitial pneumonia, the main cause of toxic death, occurred in 9.26% of total patients. The median follow-up time at this writing is 30 months.
Conclusions: The absence of rejection and graft-versus-host disease and the relatively low relapse and toxicity rates are evidence for the efficacy of our conditioning regimen.