Preliminary observations on intravenous idarubicin (4-demethoxydaunorubicin) in the chronic and accelerated phase of chronic myelogenous leukemia.

The study included 13 patients with chronic myelogenous leukemia (8 in the chronic phase with high WBC counts at onset, and 5 in the accelerated phase, poorly responding to conventional drugs for the chronic phase). They were treated with 4-demethoxydaunorubicin (idarubicin), a new anthracycline analog more active than daunorubicin (DNR) and doxorubicin (DX) in experimental tumor models which offers a higher therapeutic index than existing anthracyclines. Idarubicin was administered i.v. at the dose of 8 mg/m2 on days 1, 3 and 5. All patients in the chronic phase (8/8) developed significant leukopenia. Five of these 8 patients showed complete reduction of splenomegaly, and 4 of hepatomegaly as well. In all the other cases, hepato-splenomegaly was reduced by more than 70%. Three of the 5 patients in the accelerated phase of chronic myelogenous leukemia also showed massive cytolysis. More important, all of them showed complete or major reduction of hepato-splenomegaly and renewed responsiveness to conventional drugs for the chronic phase of the disease. Idarubicin was fairly well tolerated by all patients with only minor gastrointestinal side effects and no liver damage or acute cardiotoxic effects. These findings indicate that idarubicin--although it cannot replace established drugs for the chronic phase of the disease--represents an added therapeutic resource for producing rapid cytolysis at onset and, above all, in the accelerated phase of chronic myelogenous leukemia.