Effect of short-term interferon therapy on the outcome of subsequent HLA-identical sibling bone marrow transplantation for chronic myelogenous leukemia: an analysis from the International Bone Marrow Transplant Registry

Allogeneic bone marrow transplantation (BMT) is the only curative therapy f or chronic myelogenous leukemia (CML), though several studies indicate that prolonged survival can result from interferon-alpha (IFN-alpha) treatment. IFN-alpha is now often used as initial therapy for CML, before donor avail ability is known. Because identifying potential donors can take several wee ks to months, it is important to know whether IFN-alpha adversely affects o utcome of a subsequent BMT. If it does, initiation of IFN-alpha therapy mig ht be delayed until donor availability is determined and avoided in patient s for whom BMT is planned. We studied 873 patients who received HLA-identic al sibling BMI for chronic-phase CML in 153 centers participating in the In ternational Bone Marrow Transplant Registry. The object was to compare outc ome in the 664 who received only hydroxyurea before BMT with outcome in the 209 who received IFN-alpha with or without hydroxyurea. The median duratio n of IFN-alpha therapy was 2 months (range, 1 to 39 months). Cox proportion al hazards analysis was used to compare engraftment, graft-versus-host dise ase (GVHD), nonrelapse mortality, relapse, survival, and leukemia-free surv ival after adjustment for other prognostic variables. We found a higher ris k of nonengraftment among patients given IFN-alpha than among those given h ydroxyurea alone (2% versus 0.2%; P = 0.01). Patients who received IFN-alph a had a lower risk of relapse (relative risk, 0.17; 95% confidence interval , 0.04-0.70), Probabilities of GVHD, nonrelapse mortality, survival, and le ukemia-free survival were similar in the two treatment groups, These result s suggest that a short course of IFN-alpha does not adversely affect surviv al after a subsequent HLA-identical sibling BMT for chronic-phase CML. (Blo od, 2000;95:410-415) 2000 by The American Society of Hematology.