High efficacy and low toxicity of APL induction with concurrent idarubicin/ATRA followed by a novel and simplified outpatient post-remission therapy using single doses of idarubicin and intermittent ATRA.

Acute promyelocytic leukemia (APL) is one of the most curable myeloid malignancies because of its great sensitivity to all-trans retinoic acid (ATRA) and response to anthracycline therapy. In an attempt to simplify post-remission therapy, deliver adequate dose of anthracycline and reduce treatment related toxicity, we entered 26 consecutively newly diagnosed, previously untreated APL patients in a pilot treatment program consisting of concurrent induction using idarubicin/ATRA followed by an exclusive outpatient post-remission therapy using single dose of idarubicin and intermittent ATRA, every 4 weeks. Of 25 evaluable patients, two (8%) died early during induction due to hemorrhagic complications, and 23 (92%) achieved complete remission. Overall survival at 4.2 years was 90% (CI 76.4-100), and 3.6 years disease-free survival was 78% (CI 60.6-95.4). The treatment outcome of this program is encouraging; however, the result of this study needs to be validated in larger cohort of patients and optimally in a randomized comparison with other current post-remission approaches.