Bone marrow transplantation for the treatment of leukemia.

Marrow transplantation from a syngeneic (monozygous twin) or allogeneic [homologous leucocytic antibody (HLA)-identical sibling] donor allows the administration of aggressive antileukemic therapy without regard to marrow toxicity. Until 1975 marrow transplantation was carried out only in patients with advanced relapse after failure of all other therapy. Six of sixteen patients given syngeneic marrow grafts and 13 of 100 patients with allogeneic marrow grafts are still in remission after 51/2-10 years (Thomas et al. 1977a,b). An actuarial survival curve according to the method of Kaplan and Meier of the first 100 patients grafted in Seattle after treatment with cyc1ophosphamide (60 mg/kg/dayX 2) and total body irradiation (1000 rad at 5-8 radi min) showed three periods of interest: (1) during the first 4 months the slope was steep because many patients died due to advanced illness, graft-versus-host disease, infections (in particular interstitial pneumonias), and recurrent leukemia; (2) from 4 months to 2 ys the curve showed a much slower rate of decline, primarily due to death from recurrent leukemia; and (3) from 2 to 10 years the curve was almost horizontal with a negligible loss of patients and no recurrent leukemia. This flat portion of the curve corresponded to 13 % of the patients, and it is likely that the majority of these survivors are cured of their disease (Thomas et al. 1977b). A number of transplant groups, including our own, made attempts at reducing the