Chemotherapy for relapsed and resistant acute nonlymphoblastic leukemia. Effect of ATA, an amsacrine-containing regime.

Twenty-nine evaluable patients with acute nonlymphoblastic leukemia (ANLL), either in relapse or resistant to initial induction therapy (ara C, daunorubicin + etoposide), received the ATA regime consisting of 100 mg/m2 per day Ara C by i.v. infusion for 4-5 days, 100 mg/m2 per day thioguanine orally for 4-5 days, and 100 mg/m2 per day amsacrine i.v. for 2-5 days. Each patient received 1-6 courses (median, 2) of the regime. There were 7 (24%) complete responders, and their duration of responses were 2, 2, 2, 5, 9+, 19, and 24+ months. The complete remission (CR) rate of patients who had a previous CR beyond 6 months (6/13, 46%) was significantly better (X2 = 4.25, p less than 0.05) than that of those who had previously relapsed within 6 months or were refractory to primary induction chemotherapy (1/16, 6%). The two groups of patients had similar patterns of treatment failure. Myelosuppression was the major toxic side effect, and nonhematological toxicities were mild and acceptable.