Acute toxicity and effectiveness of idarubicin in childhood acute lymphoblastic leukemia.

Anthracyclines have become important components of multi-agent remission induction and continuation therapy of acute lymphoblastic leukemia (ALL). New anthracycline derivatives are being investigated in an attempt to shift the balance of side effects and antileukemic potency. To evaluate the toxicity and efficacy of idarubicin (IDA) in childhood ALL, a prospective multicenter phase-II study was performed. A total of 51 children with prognostically poor recurrences of ALL were enrolled, all of whom had been exposed to anthracyclines during front-line treatment. A single 48-h continuous infusion of IDA at 24 mg/m2 was started on the first day of salvage treatment without concomitant systemic cytostatic agents. The response was assessed by reduction of leukemic blasts in the bone marrow and other compartments 2 wk later. IDA monotherapy caused complete and partial remissions in 5 and 20 patients, respectively (49%). Delays of treatment with subsequent polychemotherapy courses were frequent and mainly caused by prolonged intervals of myelosuppression and high rates of systemic infection. Non-hematological toxicities including acute cardiac reactions were transient and moderate. Our findings suggest that IDA is an effective drug for remission induction in children with ALL, with acute hematological toxicity being dose-limiting.