Realgar Indigo Formula Plus ATRA As Postremission Treatment in an Rral and Chemo-Free Model for High-Risk Acute Promyelocytic Leukemia Patients: A Prospective, Multicenter, Phase II Study

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▪Background:Low-risk patients with acute promyelocytic leukemia (APL) can be cured using only ATRA and arsenic trioxide (ATO), without chemotherapy(Lo-Coco F, et al. NEJM 2013) .Our group simplified the protocol by replacing iv ATO with oral arsenic, referred to as RIF, allowing for outpatient, oral and chemotherapy-free treatment for an increasing number of APL patients (Zhu HH, et al. NEJM 2014; 371:2239-41;Zhu HH, et al. Lancet Oncol 2018;19:871-879; Zhu HH, et al. Blood 2019;134:597-605). We also reported a promising single-center results using chemo-free postremission treatment for high-risk APL patients (Zhu HH, Blood 2018;131:2987-2989), which need to be confirmed in a well designed multi-center trial.Objective:To evaluate the efficacy of safety Realgar indigo formula plus retinoic acid as postremission treatment in an oral and chemo-free model for high-risk APL patients .Design, setting and participants:a prospective, multicenter, single-arm, phase II clinical trial conducted in the First Affiliated Hospital, Zhejiang University College of Medicine, China. Eligible patients (>18 years old) with newly diagnosed APL and achieved complete remission(CR) were enrolled since May 2019, with final follow-up in July 31,2021.Interventions:The consolidation therapy included realgar-Indigo naturalis formula (60 mg/kg daily in an oral divided dose) in a 4-week-on and4-week-off regimen for 4 cycles and ATRA (25 mg/m 2 daily in anoral divided dose) in a 2-week-on and 2-week-off regimen for 7 cycles. The primary endpoint was the 2-year DFS. Secondary endpoints included complete molecular remission (CMR) defined as the absence of detectable PML-RARA transcripts., event-free survival (EFS), OS, and safety.Main outcomes and measures:38 eligible patients were enrolled including 18 males and 20 females and the median age was 41 years old (18-77 years). The median of WBC count is 25.39（10.2-113.9）×109/L[ >50×10 9/L n=10; (20-50)×10 9/L n=14，(10-20)×10 9/L n=14].All the patients achieved CMR during post-remission treatment phase (7 months). Until now, no molecular, hematologic recurrence,and central nervous system leukemia has happened with median follow-up of 13 months. What's more, this chemotherapy-free, completely oral regimen was well tolerated.Conclusions:These exciting results proved that RIF plus retinoic acid as postremission treatment of high-risk APL was effective, safe and convenient. The study is ongoing, and the effective of this regimen need to be evaluated by more patients and longer time.Figure 1. The overall survival(OS) and disease-free survival (DFS) of high-risk APL patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.