摘要Introduction:There is currently no standard treatment for relapsed and arsenic trioxide(ATO)-resistant acute promyelocytic leukemia(APL).Here,we report a case series of realgar-indigo naturalis formula(RIF)for the successful treatment of patients with relapsed and ATO-resistant APL.Case presentation:Two patients in the first relapse and one in the second relapse failed to achieve hema-tologic complete remission(HCR)when reinduced by ATO;the other five patients progressed to relapse during ATO-based regimens for post-remission therapy.These eight patients received RIF in three doses per day totaling 130 mg/kg(≤ 30 pills)as induction therapy and achieved HCR at a median time of 46.5 days.They received 5 years of post-remission therapy,which consisted of combined chemotherapy followed by RIF.During this period,the patients did not experience renal dysfunction or QT interval pro-longation.At the last follow-up,three patients survived without relapse,two patients survived with a second or third relapse and third or fourth remission,and the other three patients relapsed for a third or fourth time and died.The 5-year overall survival and event-free survival rates were 75.0％(95％confi-dence interval[CI]:31.5-93.1)and 37.5％(95％CI:5.6-71.7),respectively.Conclusion:RIF for induction therapy and RIF combined with chemotherapy for post-remission therapy may represent an effective and safe protocol for the treatment of patients with relapsed and ATO-resistant APL.