P578: GILTERITINIB FOR RELAPSED/REFRACTORY FLT3 MUTATED ACUTE MYELOID LEUKEMIA A REAL-WORLD, MULTI-CENTER, MATCHED ANALYSIS

Abstract

Background: Patients with FLT3-mutated relapsed or refractory (R/R) acute myeloid leukemia (AML) have a dismal prognosis. Gilteritinib is a FLT3 tyrosine kinase inhibitor (TKI) recently approved for patients with R/R AML. Aims: We aimed to characterize real-world data regarding gilteritinib treatment in FLT3-mutated R/R AML and to compare outcomes with matched FLT3-mutated R/R AML patients treated with chemotherapy-based salvage regimens. Methods: Survival analysis was performed by Kaplan Meyer with log rank test to compare between subgroups. Cox proportional hazards regression models were fitted to predict effect of covariates on overall survival (OS) and event free survival (EFS). All statistical analyses used 2-sided p value with a threshold of 0.05. Results: Twenty-five patients from six academic centers were treated with gilteritinib for FLT3-mutated R/R AML. The median age was 58 (IQR1-3 47-73) years, 80% (n=20) were treated with a prior intensive induction regimen and 40% of them received prior TKI therapy. After a median time of seven months post gilteritinib initiation (range 1-34), 12 patients (48%) achieved complete response (CR) with gilteritinib (figure 1A). The estimated median overall survival (OS) of the entire cohort was eight (CI 95% 0-16.2) months and was significantly higher in patients who achieved CR compared to those who did not (16.3 months, CI 95% 0-36.2 vs. 2.6 months, CI 95% 1.47-3.7; p value=0.046, figure 1B). In a multivariate cox regression analysis, achievement of CR was the only predictor for longer OS (HR 0.33 95% CI 0.11-0.97, p=0.044). Prior TKI exposure did not affect OS but was associated with better event-free survival (HR 0.15 95% CI 0.03-0.71, p=0.016). An age and ELN-risk matched comparison between patients treated with gilteritinib and intensive salvage revealed similar response rates (50% in both groups); median OS was 9.6 months (CI 95% 2.3-16,8) vs. 7 months (CI 95% 5.1-8.9) in gilteritinib and matched controls, respectively (p = 0.869, figure 1C). Image:Summary/Conclusion: In the real-world setting gilteritinib is effective, including in heavily pre-treated, TKI exposed patients.