Use of all-trans retinoic acid plus arsenic trioxide as an alternative to chemotherapy in untreated acute promyelocytic leukemia

We examined whether combining alltrans retinoic acid (ATRA) and arsenic trioxide (ATO) might be an alternative to ATRA plus chemotherapy in untreated acute promyelocytic leukemia (APL). Twenty-five low-risk patients (white blood cell [WBC] count less than 10 x 10(9)/L [10 000/mu L]) received ATRA (45 mg/m(2) daily) and ATO (0.15 mg/kg daily, beginning day 10 of ATRA), and in complete remission (CR) received ATO plus ATRA, without chemotherapy, unless they were reverse transcriptase-polymerase chain reaction (RT-PCR)-positive 3 months from CR date or had molecular relapse. Nineteen high-risk patients were treated identically, but received chemotherapy, generally 9 mg/m(2) gemtuzumab ozogamycin (GO) on day 1 of induction. The CR rate was 39 of 44 (24 of 25 in low-risk, 15 of 19 in high-risk). Disease recurred at 9, 9, and 15 months, respectively, in 3 high-risk patients. The median follow-up time from CR date in the 36 patients alive in first CR is 16 months (15 months in low-risk, 20 months in high-risk), with 9 patients followed for at least 24 months. Each of the 36 patients was PCR-negative at last follow-up. Thus, none of the low-risk patients has received chemotherapy, and only 3 high-risk patients (the 3 with relapsed disease) have received chemotherapy past induction. ATRIA plus ATO may serve as an alternative to chemotherapy in low-risk untreated APL (eg, in older patients) and, when combined with GO, may improve outcome in high-risk patients.