PROSPECTIVE EVALUATION OF UNRELATED DONOR BONE-MARROW TRANSPLANTATION

The International Marrow Unrelated Search and Transplant (IMUST) Study has prospectively assessed outcome of unrelated donor BMT (UD-BMT) in comparison with a matched cohort of patients treated by HLA-identical sibling BMT (ID-BMT). We report an interim analysis of the first 165 UD-BMT and 368 ID-BMT. Eighty-two percent of UD-BMT pairs were matched by serology for HLA-A, B and DR, 10% were less well matched and HLA m atching data was incomplete in 8%. The Kaplan-Meier estimated probabil ity of survival until day 400 was 0.42 (95% confidence limits 0.33-0.5 1) after UD-BMT and 0.62 (0.56-0.68) after ID-BMT (p = < 0.001). Proba bility of engraftment by day 100 was 0.90 (0.85-0.95) and 0.95-0.99) a fter UD-BMT and ID-BMT, respectively (p = < 0.001). Cumulative probabi lity of acute GVHD by day 100 was 0.52 (0.45-0.60) and 0.42 (0.37-0.47 ) after UD-BMT and ID-BMT, respectively (p = 0.009). After UD-BMT, 52% of patients with early disease survived until day 400 (40-64%) and 27 %) (14-40%) with advanced disease (p = < 0.001). Multifactorial analys is of survival showed success was related to the centre's experience o f UD-BMT and this effect was modified by conditioning protocol. Increa sed probability of survival after UD-BMT in centres with most experien ce of the procedure is a novel finding. We conclude UD-BMT is a more d ifficult procedure than ID-BMT but results are acceptable in patients with early disease and when UD-BMT is carried out in experienced centr es.