Effect of gilteritinib on survival in patients with FLT3-mutated (FLT3mut+) relapsed/refractory (R/R) AML who have common AML co-mutations or a high FLT3-ITD …

7000 Background: The FLT3 inhibitor, gilteritinib, showed superior response and overall survival (OS) compared with salvage chemotherapy (SC) in patients (pts) with FLT3mut+ R/R AML in the phase 3 ADMIRAL study. We analyzed the impact of baseline co-mutations and FLT3-ITD allelic ratio (AR) on response and OS. Methods: A total of 37 recurrently mutated genes in AML (Archer Core Myeloid Panel) were analyzed by next-generation sequencing; the cutoff for co-mutation positivity (co-mut+) was ≥0.027. Baseline FLT3-ITD AR ( FLT3-ITD to FLT3 wild-type DNA) was measured by the LeukoStrat CDx FLT3 Mutation Assay. The median FLT3-ITD AR value of 0.77 was used to define high (≥0.77) vs low (<0.77) FLT3-ITD AR. Results: Analysis of 361 FLT3mut+ pts identified four major co-mutation cohorts, each with ≥10% of pts: NPM1 (n=173; 47.9%), DNMT3A (n=115; 31.9%), DNMT3A/NPM1 (n=86; 23.8%) , and WT1 (n=65; 18.0%). In addition, seven pts (1.9%) had all three co-mutations (ie, NPM1, DNMT3A, and WT1). The gilteritinib arm had superior response rates and OS across all four major co-mutation cohorts, with the greatest survival benefit in pts with DNMT3A/NPM1 co-mut+ (Table). In FLT3-ITD AR analyses (n=335), gilteritinib conferred longer OS than SC in pts with a high or low FLT3-ITD AR (gilteritinib: high FLT3-ITD AR, 7.1 mos vs low FLT3-ITD AR, 10.6 mos; SC: high FLT3-ITD AR, 4.3 mos vs low FLT3-ITD AR, 6.9 mos). In both arms, OS was longer in the low FLT3-ITD AR cohort than the high FLT3-ITD AR cohort but the difference in the gilteritinib arm was not statistically significant (gilteritinib: HR=1.341, P=0.0712; SC: HR=2.01, P=0.0021). Conclusions: The ADMIRAL trial shows that the clinical benefit of gilteritinib in FLT3mut+ R/R AML is maintained regardless of NPM1, DNMT3A, DNMT3A/ NPM1, or WT1 co-mut+ or high FLT3-ITD AR. Clinical trial information: NCT02421939. [Table: see text]