Long-term efficacy and safety of all-trans retinoic acid/arsenic trioxide-based therapy in newly diagnosed acute promyelocytic leukemia.

All-trans retinoic acid (ATRA)/arsenic trioxide (ATO) combination-based therapy has benefitted newly diagnosed acute promyelocytic leukemia (APL) in short-term studies, but the long-term efficacy and safety remained unclear. From April 2001, we have followed 85 patients administrated ATRA/ATO with a median follow-up of 70 months. Eighty patients (94.1%) entered complete remission (CR). Kaplan-Meier estimates of the 5-year event-free survival (EFS) and overall survival (OS) for all patients were 89.2% +/- 3.4% and 91.7% +/- 3.0%, respectively, and the 5-year relapse-free survival (RFS) and OS for patients who achieved CR (n = 80) were 94.8% +/- 2.5% and 97.4% +/- 1.8%, respectively. Upon ATRA/ATO, prognosis was not influenced by initial white blood cell count, distinct PML-RARalpha types, or FLT3 mutations. The toxicity profile was mild and reversible. No secondary carcinoma was observed, and 24 months after the last dose of ATRA/ATO, patients had urine arsenic concentrations well below the safety limit. These results demonstrate the high efficacy and minimal toxicity of ATRA/ATO treatment for newly diagnosed APL in long-term follow-up, suggesting a potential frontline therapy for de novo APL.