French Retrospective Database Analysis of Patient Characteristics and Treatment Patterns in Patients with R/R FLT3-Mutated AML: A Registry-Based Cohort Study

Abstract

Introduction: There is a dearth of evidence to document treatment of FMS-like tyrosine kinase 3 (FLT3)-mutated acute myeloid leukemia (AML) in real-world settings before the introduction of FLT3 inhibitors. A retrospective cohort study was conducted to understand treatment practices prior to the availability of FLT3 inhibitors in patients with FLT3-mutated AML from two registries in France. Methods: Patient data from January 1, 2009 to December 31, 2017 were collected from the Hauts-de-France and Midi-Pyrénées registries. Patients aged ≥ 18 years at diagnosis with FLT3-mutated AML were included. Demographic and disease characteristics of patients with FLT3-mutated AML and relapsed or refractory (R/R) FLT3-mutated AML were documented. Treatment regimens, overall survival (OS), and event-free survival were assessed in patients with R/R FLT3-mutated AML who did not participate in clinical trials. Results: Overall, 819 and 1244 adult patients with AML from the Midi-Pyrénées and Hauts-de-France cohorts, respectively, underwent FLT3 mutation testing; 172 (21.0%) and 263 (21.1%) patients, respectively, had a FLT3 mutation. Primary R/R status was identified in 41.3% (n = 71/172) of the Midi-Pyrénées and 34.6% (n = 91/263) of the Hauts-de-France cohorts. Before R/R AML diagnosis, 82.0% and 97.5% of patients in the Midi-Pyrénées and Hauts-de-France cohorts, respectively, achieved complete remission (CR) or CR with incomplete hematologic recovery (CRi) following induction chemotherapy; after diagnosis of R/R AML, CR/CRi rates with salvage therapy were 33.3% and 28.1%, respectively. Median OS (interquartile range) in patients receiving salvage therapy (n = 49, n = 78) was 5.2 (2.3–11.1) and 6.1 (2.5–35.2) months, in the Midi-Pyrénées and Hauts-de-France cohorts, respectively. Across both cohorts, patients with R/R FLT3-mutated AML had low rates of CR/CRi with salvage therapy and a median OS of approximately 6 months. Conclusion: Before FLT3 inhibitor availability, real-world treatment patterns and outcomes in French patients with R/R FLT3-mutated AML were consistent with clinical trial data, highlighting a poor prognosis and unmet need for effective treatment.