Assessment of Molecular Response to Gilteritinib in FLT3 Mutation–Positive Relapsed/Refractory Acute Myeloid Leukemia

In prior studies, gilteritinib, a selective FLT3/AXL inhibitor, displayed clinical activity in FLT3 mutation–positive relapsed/refractory acute myeloid leukemia (AML). In this analysis, researchers assessed molecular response to gilteritinib in a clinical trial subpopulation.

Molecular response was assessed in adult patients with FLT3 mutation–positive AML treated with gilteritinib 120 or 200 mg daily. Response was evaluated at baseline and at least 1 subsequent time point. A Cox regression model of overall survival (OS) by Kaplan-Meier estimation was utilized to determine an internal tandem duplication (ITD) signal ratio indicative of improved survival.

A total of 80 patients with FLT3 mutation–positive AML who received gilteritinib 120 or 200 mg daily were included in the analysis. Median age was 61 years; 22 (28%) patients had prior FLT3 tyrosine kinase inhibitor therapy. A total of 20 (25%) patients showed a molecular response to treatment. Of these 20 patients, 18 had a ratio of ≤10−3, indicative of major molecular response, and 13 had a ratio of ≤10−4, indicative of minimal residual disease–negative status. These patients had significantly longer median OS than those who did not.

In this first demonstration of molecular response to an FLT3 inhibitor in relapsed/refractory AML, molecular responses to gilteritinib correlated with clinical response and improved OS. Although further investigation is warranted, the preliminary data suggest that the ITD signal ratio may predict the durable clinical benefit of gilteritinib.

Altman JK, et al. ASCO Abstract 7003.

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