[Efficacy and safety of IAC regimen for relapse/refractory acute myeloid leukemia: a prospective randomized controlled study]

Objective: To evaluate the efficacy and toxicity profiles of idarubicin, cytarabine, and cyclophosphamide (IAC) in relapse/refractory acute myeloid leukemia (AML) . Methods: This study was a prospective, randomized controlled clinical trial with the registration number NCT02937662. The patients were randomly divided into two groups. The experimental group was treated with an IAC regimen, and the regimen of the control group was selected by doctors according to medication experience. After salvage chemotherapy, allogeneic hematopoietic stem cell transplantation (allo-HSCT) was conducted as far as possible according to the situation of the patients. We aimed to observe the efficacy, safety, and toxicity of the IAC regimen in relapse/refractory AML and to explore which is the better regimen. Results: Forty-two patients were enrolled in the clinical trial, with a median age of 36 years (IAC group, 22 cases and control groups, 20 cases) . ①The objective response rate was 71.4% in the IAC group and 40.0% in the control group (P=0.062) ; the complete remission (CR) rate was 66.7% in the IAC group and 40.0% in the control group (P=0.121) . The median follow-up time of surviving patients was 10.5 (range:1.7-32.8) months; the median overall survival (OS) was 14.1 (range: 0.6-49.1) months in the IAC group and 9.9 (range: 2.0-53.8) months in the control group (P=0.305) . The 1-year OS was 54.5% (95%CI 33.7%-75.3%) in the IAC group and 48.2% (95%CI 25.9%-70.5%) in the control group (P=0.305) , with no significant difference between these two regimens. ②The main hematologic adverse events (AEs) were anemia, thrombocytopenia, and neutropenia. The incidence of grade 3-4 hematologic AEs in the two groups was 100% (22/22) in the IAC group and 95% (19/20) in the control group. The median time of neutropenia after chemotherapy in the IAC group and control group was 20 (IQR: 8-30) and 14 (IQR: 5-50) days, respectively (P=0.023) . ③The CR rate of the early relapse (relapse within 12 months) group was 46.7% and that of the late relapse (relapse after 12 months) group was 72.7% (P=0.17) . The median OS time of early recurrence was 9.9 (range:1.7-53.8) months, and that of late recurrence patients was 19.3 (range: 0.6-40.8) months (P=0.420) , with no significant differences between the two groups. The 1-year OS rates were 45.3% (95%CI 27.2%-63.3%) and 66.7% (95%CI 40.0%-93.4%) , respectively (P=0.420) . Survival analysis showed that the 1-year OS rates of the hematopoietic stem cell transplantation group and non-hematopoietic stem cell transplantation group were 87.5% (95%CI 71.2%-100%) and 6.3% (95%CI 5.7%-18.3%) , respectively. The OS rate of the hematopoietic stem cell transplantation group was significantly higher than that of the non-hematopoietic stem cell transplantation group (P<0.001) . Conclusion: The IAC regimen is a well-tolerated and effective regimen in relapsed/refractory AML; this regimen had similar efficacy and safety with the regimen selected according to the doctor's experience for treating relapsed/refractory AML. For relapsed/refractory patients with AML, allogeneic hematopoietic stem cell transplantation should be attempted as soon as possible to achieve long-term survival.