OBJECTIVETo study whether all-trans retinoic acid (ATRA) combined with arsenic trioxide (As(2)O(3)) in acute promyelocytic leukemia (APL) treatment could further improve the clinical and molecular remission rate.

METHODThirty one newly-diagnosed APL patients of whom 15 were males, 16 females and median age 35.4 years entered into the study. They were treated with ATRA 25 mg x m(-2) x d(-1) combined with As(2)O(3) 0.16 mg x kg(-1) x d(-1) until complete remission (CR). The doses were adjusted according to white blood cell (WBC) counts, occurrence of RA syndrome and the status of liver function. CR rate, time of reaching clinical and molecular remission and side effects were observed.

RESULTTwo patients died 2 approximately 3 days after the treatment due to intracranial hemorrhage, and 29 (93.5%) achieved CR. The average time for achieving CR was 25.1 +/- 3.9 days. Hyperleukocytosis emerged in 66.5% and hepatic damages in 65.5% of the patients, they were ameliorated within one week after reduction of the As(2)O(3) dose or its suspension. The PML/RAR alpha fusion gene that was positive in all 29 patients before treatment turned negative only in 3 cases (10.3%) after obtaining CR (CR1) and in 10/13 cases (77%) after consolidation treatment. Up to now (1-8 months follow-up), all 29 patients remain in CR1.

CONCLUSIONATRA combined with As(2)O(3) in de novo APL treatment can yield a high CR rate without intolerable side effects. Long term effect needs further observation.