Realgar-indigo naturalis formula for the treatment of patients with relapsed and arsenic trioxide-resistant acute promyelocytic leukemia: A case series

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 hematologic 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 prolongation. 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% confidence 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. Please cite this article as: Fang YG, Huang SL, Chen NN. Realgar-indigo naturalis formula for the treatment of patients with relapsed and arsenic trioxide-resistant acute promyelocytic leukemia: a case series.