UNRELATED DONOR BONE-MARROW TRANSPLANTATION FOR CHILDREN WITH RELAPSED ACUTE LYMPHOBLASTIC-LEUKEMIA IN SECOND COMPLETE REMISSION

Allogeneic sibling bone marrow transplantation (BMT) is the recommende d treatment for relapsed childhood acute lymphoblastic leukaemia (ALL) , but appropriate donors are only available in 30% of cases. Unfortuna tely, BMT from unrelated donors (UD) has been associated with high rat es of severe graft-versus-host disease (GvHD) and transplant-related m ortality (TRM). In an attempt to improve outcome in UD-BMT we have ass essed the impact of T-cell depletion using CAMPATH-1 (anti-CD52) monoc lonal antibodies in 50 consecutively referred patients with relapsed A LL in second remission. All were previously treated according to MRC p rotocols UKALL X and XI, and then given chemotherapy on MRC R1 from re lapse until UD-BMT. 19 patients had relapsed on and 31 off therapy. Pa tients and donors were fully matched at HLA-A. -B, -DR and -DQ loci in 29 cases and mismatched in 21 (four mismatched for more than one anti gen). Pre-transplant conditioning comprised CAMPATH-1G, cyclophosphami de and total body irradiation. Bone marrow was T-cell depleted in vitr o using CAMPATH-1 antibodies. Additional GvHD prophylaxis consisted of cyclosporin A (42 cases), cyclosporin plus methotrexate (four) or non e (four). 47 patients engrafted. The incidence of acute GvHD was very low: two patients with grade II disease in the matched group, four wit h grade II-IV in the mismatched group. Only four chronic GVHD. The act uarial event-free have (EFS) at 2 years is 53%, with no significant di fference between the matched and mismatched group. Further leukaemic r elapse was the most important cause of failure. These results are simi lar to the most favourable published reports for HLA-matched sibling B MT in relapsed ALL.