Propensity-score matched comparison of salvage chemotherapy regimens in relapsed/refractory acute myeloid leukemia

Abstract Background Relapsed/refractory acute myeloid leukemia (R/R AML) confers a poor prognosis, and there is no single standard of care first-line salvage regimen. FLAG (fludarabine, cytarabine, and granulocyte colony-stimulating factor) is a common salvage regimen with a favorable toxicity and efficacy profile in poor-risk AML. Materials and Methods We conducted a single-center, retrospective analysis of first relapse/primary refractory AML patients that received salvage chemotherapy from January 2009 to July 2019. We 1:1 propensity-score matched patients (based on age at diagnosis, cytogenetic risk group, Charlson Comorbidity index, de novo versus secondary AML, and whether or not they received an allogeneic stem cell transplant in first complete remission) into two groups, FLAG (Group 1) or non-FLAG (Group 2) as first-line salvage regimen, with 66 patients in each group. The primary endpoint was overall response rate (complete response (CR) and complete response (CRi) with incomplete hematological recovery) Results Median patient age was 59 years (range 19-80). Patients treated with FLAG had a higher overall response rate (CR/CRi) (71.2% versus 50.0%, odds ratio [OR] = 2.47, 95% confidence interval [CI] 1.21-5.08, p=0.013), longer event-free survival (8.9 versus 2.1 months, hazard ratio [HR] = 0.58, 95% CI 0.39-0.86, p=0.005), and longer overall survival (14.2 versus 5.9 months, HR = 0.62, 95% CI 0.41-0.93, p=0.019). Patients who received FLAG had a shorter median duration of neutropenia (22 versus 34 days, HR = 0.43, 95% CI 0.29-0.64, p Conclusion This analysis supports the FLAG regimen as an effective and well-tolerated salvage therapy for patients with relapsed/refractory AML