Low-intensity conditioning is sufficient to ensure engraftment in matched unrelated bone marrow transplantation

Objective. Matched unrelated bone marrow transplantation (BMT) for patients with hematological malignancies is associated with a high incidence of tra nsplant-related complications due to high doses of chemoradiotherapy admini stered pre-PMT to ensure engraftment. The aim of this study was to investig ate the feasibility of low-intensity conditioning for BMT from matched unre lated donors. Patients and Methods. Sixteen patients with hematologic malignancies underw ent non-T-cell-depleted BMT following a low-intensity conditioning regimen consisting of fludarabine monophosphate 30 mg/m(2)/day for 6 days, busulfan 4 mg/kg/day for 2 days, anti-T lymphocyte globulin 10 mg/kg/day for 4 days . Seven of the patients suffered from chronic myelogenous leukemia, four fr om acute lymphoblastic leukemia, four from acute myelogenous leukemia, and one from Ki-1 non-Hodgkin's lymphoma, Three of the patients had secondary l eukemia and two were post-autologous BMT (ABMT). All patients were transpla nted from fully matched unrelated donors. Results. Fifteen of the 16 patients had 100% donor chimerism; no graft reje ction was observed. None of the patients developed >Grade II veno-occlusive disease, sepsis, multiorgan failure, or renal or pulmonary toxicity. Four patients died posttransplant; one of thrombocytopenia and severe hemorrhagi c cystitis, one of central nervous system toxicity, one of Grade IV graft-v s-host disease, and one following relapse (9 months post-BMT), Survival and disease-free survival at 36 months are 75% (95% confidence interval 46-90% ) and 60% (95% confidence interval 30-80%), respectively. Conclusion. These results indicate that low-intensity conditioning is suffi cient to ensure stable engraftment of bone marrow grafts in a matched unrel ated setting. (C) 2001 International Society for Experimental Hematology. P ublished by Elsevier Science Inc.