CLINICAL TRIALS AND OBSERVATIONS Arsenic trioxide improves event-free and overall survival for adults with acute promyelocytic leukemia: North American Leukemia Intergroup Study C9710

Arsenic trioxide (As2O3) is a highly effective treatment for patients with relapsed acute promyelocytic leukemia (APL); its role as consolidation treatment for patients in first remission has not been defined. We randomized 481 patients (age > 15 years) with untreated APL to either a standard induction regimen of tretinoin, cytarabine, and daunorubicin, followed by 2 courses of consolidation therapy with tretinoin plus daunorubicin, or to the same induction and consolidation regimen plus two 25-day courses of As2O3 consolidation immediately after induction. After consolidation, patients were randomly assigned to one year of maintenance therapy with either tretinoin alone or in combination with methotrexate and mercaptopurine. Ninety percent of patients on each arm achieved remission and were eligible to receive their assigned consolidation therapy. Event-free survival, the primary end point, was significantly better for patients assigned to receive As2O3 consolidation, 80% compared with 63% at 3 years (stratified logrank test, P < .0001). Survival, a secondary end point, was better in the As2O3 arm, 86% compared with 81% at 3 years (P .059). Disease-free survival, a secondary end point, was significantly better in the As2O3 arm, 90% compared with 70% at 3 years (P < .0001). The addition of As2O3 consolidation to standard induction and consolidation therapy significantly improves event-free and diseasefree survival in adults with newly diagnosed APL. This trial was registered at clinicaltrials.gov (NCT00003934). (Blood. 2010;116(19):3751-3757)