Improved Outcomes With Retinoic Acid and Arsenic Trioxide Compared With Retinoic Acid and Chemotherapy in Non-High-Risk Acute Promyelocytic Leukemia: Final Results of the Randomized Italian-German APL0406 Trial

The initial results of the APL0406 trial showed that the combination of all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) is at least not inferior to standard ATRA and chemotherapy (CHT) in first-line therapy of low- or intermediate-risk acute promyelocytic leukemia (APL). We herein report the final analysis on the complete series of patients enrolled onto this trial. Patients and Methods: The APL0406 study was a prospective, randomized, multicenter, open-label, phase III noninferiority trial. Eligible patients were adults between 18 and 71 years of age with newly diagnosed, low-or intermediate-risk APL (WBC at diagnosis # 10 3 109/ L). Overall, 276 patients were randomly assigned to receive ATRA-ATO or ATRA-CHT between October 2007 and January 2013. Results Of 263 patients evaluable for response to induction, 127 (100%) of 127 patients and 132 (97%) of 136 patients achieved complete remission (CR) in the ATRA-ATO and ATRA-CHT arms, respectively (P =.12). After a median follow-up of 40.6 months, the event-free survival, cumulative incidence of relapse, and overall survival at 50months for patients in the ATRA-ATO versus ATRA-CHT arms were 97.3% v 80%, 1.9% v 13.9%, and 99.2% v 92.6%, respectively (P<.001, P =.0013, and P =.0073, respectively). Postinduction events included two relapses and one death in CR in the ATRA-ATO arm and two instances ofmolecular resistance after third consolidation, 15 relapses, and five deaths in CR in the ATRACHT arm. Two patients in the ATRA-CHT arm developed a therapy-related myeloid neoplasm. Conclusion: These results show that the advantages of ATRA-ATO over ATRA-CHT increase over time and that there is significantly greater and more sustained antileukemic efficacy of ATO-ATRA compared with ATRA-CHT in low-and intermediate-risk APL. (C) 2016 by American Society of Clinical Oncology