Phase II Study of Single-Agent Arsenic Trioxide for the Front-Line Therapy of Acute Promyelocytic Leukemia

Purpose The long-term follow-up results of patients with acute promyelocytic leukemia (APL) treated with all-trans retinoic acid and chemotherapy show high cure rates. Several studies have shown high efficacy of single-agent arsenic trioxide in newly diagnosed APL. However, long-term follow-up results are needed. Patients and Methods One hundred ninety-seven patients with newly diagnosed APL were treated with arsenic trioxide 0.15 mg/kg daily intravenous infusion until complete remission (CR). After achieving CR, the patients received one to four more courses of therapy with arsenic trioxide as consolidation and were observed with reverse-transcriptase polymerase chain reaction studies from peripheral blood (to detect of minimal residual disease) every 3 months or until relapse or death. Results The morphologic CR rate was 85.8%. The most common cause of remission failure was early death owing to APL differentiation syndrome (13.2%). The most important prognostic factor for early mortality was a high WBC count at presentation. The 5-year disease-free survival (DFS) rate was 66.7% +/- 4% (SE). Relapse after 5 years in CR was rare. The 5-year overall survival (OS) rate by intention-to-treat analysis was 64.4% +/- 4%. In patients who achieved CR, OS and DFS were identical. Conclusion The long-term follow-up of newly diagnosed patients with APL treated with single-agent arsenic trioxide shows high rates of DFS and OS.