High-dose melphalan with or without marrow transplantation: a study of dose-effect in patients with refractory and/or relapsed acute leukemias.

Dose-effect relationships of high-dose melphalan were evaluated in 37 patients with measurable relapsed or refractory acute leukemias. Thirteen patients (Group 1) received 70-100 mg/m2 of melphalan without marrow rescue and 24 patients (Group 2) received 140-180 mg/m2 of melphalan followed by marrow transplantation. Patients in both groups were comparable with respect to age, sex, diagnosis, and status of the leukemia. The complete remission rate was 23% in Group 1 versus 75% in Group 2 (P less than 0.01). Hematological recovery of remission patients was not statistically different in either group. Nonhematological toxicity was comparable in the two dose ranges examined. These results demonstrate the existence of a dose-response effect of high-dose melphalan regimens in relapsed acute leukemias, without marked increases in nonhematological toxicity with these doses.