A new combination of two intercalating agents (mitoxantrone + daunomycin) in adult refractory acute leukemia: the DON protocol.

A combination of two intercalating agents, mitoxantrone and daunorubicin with vincristine (the DON regimen) was studied in 16 patients with refractory acute leukemia, including three patients with myeloblastic transformation of refractory anemia with excess of myeloblasts after the failure of first-line chemotherapy and one additional patient with AML relapsing while off therapy. All patients had been heavily pretreated prior to receiving the DON regimen, and all but two had previously received high-dose anthracyclines. Of the 17 patients, nine (53%) who achieved complete remissions (CR) had myeloblastic leukemia. The three patients with acute lymphocytic leukemia did not achieve CR. Cardiac toxicity occurred in two patients and contributed to death in one. These results in very poor risk leukemia suggest a possible synergism in the action of the two intercalating agents and absence of increased cardiotoxicity.