Improved outcome with T-cell-depleted bone marrow transplantation for acute leukemia

Purpose: To eliminate the risk of rejection and lower the risk of relapse a fter T-cell-depleted bone marrow transplants in acute leukemia patients, we enhanced pretransplant immunosuppression and myeloablation. Patients and Methods: Antithymocyte globulin and thiotepa were added to sta ndard total-body irradiation/ cyclophosphamide conditioning. Donor bone mar rows were depleted ex vivo of T lymphocytes by soybean agglutination and E- rosetting. This approach was tested in 54 consecutive patients with acute l eukemia who received transplants from HLA-identical sibling donors or, in t wo cases, from family donors mismatched at D-DR. No posttransplant immunosu ppressive treatment wets given as graft-versus-host disease (GVHD) prophyla xis. Results: Neither graft rejection nor GVHD occurred. Transplant-related deat hs occurred in six(16.6%) of 36 patients in remission and in seven (38.8%) of 18 patients in relapse at the time of transplantation. The probability o f relapse was .12 (95% confidence interval [CI], 0 to .19)far patients with acute myeloid leukemia and .28 (95% Cl, .05 to .51) for patients with acut e lymphoblastic leukemia who received transplants at the first or second re mission. At a median follow-up of 6.9 years (minimum follow-up, 4.9 years), event-free survival for patients who received transplants while in remissi on was .74 (95% Cl, .54 to .93) for acute myeloid leukemia patients and .59 (95% Cl, .35 to .82) for acute lymphoblastic leukemia patients. All surviv ing patients have 100% performance status. Conclusion: Adding antithymocyte globulin and thiotepa to the conditioning regimen prevents rejection of extensively T-cell-depleted bone marrow. Even in the complete absence of GVHD, the leukemia relapse rate is not higher t han in unmanipulated transplants. J Clin Oncol 17:1545-1550. (C) 1999 by Am erican Society of Clinical Oncology.