Single-agent arsenic trioxide in the treatment of newly diagnosed acute promyelocytic leukemia: durable remissions with minimal toxicity.

Arsenic trioxide, as a single agent, has proven efficacy in inducing molecular remission in patients with acute promyelocytic leukemia (APL). There is limited long-term outcome data with single-agent As2O3 in the management of newly diagnosed cases of APL. Between January 1998 to December 2004, 72 newly diagnosed cases of APL were treated with a regimen of single-agent As2O3 at our center. Complete hematologic remission was achieved in 86.1%. At a median follow-up of 25 months (range: 8-92 months), the 3-year Kaplan-Meier estimate of EFS, DFS, and OS was 74.87% +/- 5.6%, 87.21% +/- 4.93%, and 86.11% +/- 4.08%, respectively. Patients presenting with a white blood cell (WBC) count lower than 5 x 10(9)/L and a platelet count higher than 20 x 10(9)/L at diagnosis (n = 22 [30.6%]) have an excellent prognosis with this regimen (EFS, OS, and DFS of 100%). The toxicity profile, in the majority, was mild and reversible. After remission induction, this regimen was administered on an outpatient basis. Single-agent As2O3, as used in this series, in the management of newly diagnosed cases of APL, is associated with responses comparable with conventional chemotherapy regimens. Additionally, this regimen has minimal toxicity and can be administered on an outpatient basis after remission induction.