PF258 REAL‐WORLD DATA ON DOSE‐RELATED EFFECT OF ARSENIC TRIOXIDE IN THE RELAPSE OF ACUTE PROMYELOCYTIC LEUKEMIA

Abstract

Background:Acute promyelocytic leukemia (APL) has evolved from a highly fatal to a highly curable disease because of all‐trans retinoic acid (ATRA) based regimens. Although the cure rate has been improved with the addition of arsenic trioxide (ATO), the relapse rate is still 1–10%. It is not known whether ATO dosage is related to the relapse rate in real‐world.Aims:This study was designed to elucidate the relationship between the dosage of ATO in post‐remission therapy and relapse rate in APL, and to explore the optimum dosage of ATO.Methods:According to 2019 NCCN guideline, the recommended ATO dosage in post‐remission therapy is 12 mg/kg in low‐risk and 7.95–12 mg/kg in high‐risk APL. 112 patients with newly diagnosed APL, receiving the combination of ATRA and anthracycline‐based chemotherapy and different dose of ATO for variable cycles, were divided into the high‐dose group (ATO dosage ≥12 mg/kg) and low‐dose group (ATO dosage <12 mg/kg). The 4‐year cumulative relapse‐free survival(RFS) was compared. Receiver operating characteristic (ROC) curve was used to determine the cutoff value.Results:Based on the total ATO dosage in post‐remission therapy, 72 (64.3%) patients were in the low‐dose group, whereas 40 (35.7%) patients were in the high‐dose group. There was no significant difference in the baseline characteristics between the two groups. After a median follow‐up time of 53 months, the 4‐year cumulative relapse‐free survival was 83% in the low‐dose group and 100% in the high‐dose group respectively (p = 0.008). ROC analysis indicated if the dose of ATO in post‐remission reached 5.49 mg/kg, the relapse rate had no significant difference with the dose of ATO more than 12 mg/kg (p < 0.001). In the binary logistic regression analysis, an increased ATO dosage has an independent protective factor in terms of probability of relapse (odds ratio = 0.67, 95%CI, 0.51–0.88, p = 0.004). Age, WBC count, and the occurrence of differentiation syndrome had no relationship with relapse rate (p > 0.05).Summary/Conclusion:The results indicate that the relapse rate of APL is significantly associated with the dosage of ATO in post‐remission therapy. Regardless of low or high‐risk APL, the ATO dosage should be 12 mg/kg or at least more than 5.49 mg/kg.image