Real-world adherence and tolerability of FLT3 inhibitors as post-allogeneic transplant maintenance therapy in older adults with AML: A Medicare claims data cohort study.

e18505 Background: The use of allogeneic hematopoietic cell transplantation (alloHCT) is increasing in older adults with acute myeloid leukemia (AML). Although FLT3 tyrosine kinase inhibitor (FLT3-TKI) use for post-alloHCT maintenance is recommended by the NCCN Clinical Practice Guidelines in Oncology for AML (v.1.2025), real-world data in this setting is limited, especially in older adults. Methods: An observational cohort study assessed healthcare resource utilization (HRU), treatment adherence (proportion of days covered [PDC]), and dose modifications among patients with AML who received alloHCT with FLT3-TKI (gilteritinib, midostaurin or sorafenib) maintenance therapy. Patients were identified from Medicare claims databases from Jan 1, 2016–Jun 30, 2024. Index date was the first FLT3-TKI claim within 100 days post alloHCT, with follow up until relapse, death or end of study. Data were summarized descriptively. Results: Of 150 patients, mean age was 70.5 years and Charlson Comorbidity Index score was 4.5. Mean time to FLT3-TKI maintenance initiation was 56.2 days post-alloHCT; 82 (54.7%) received gilteritinib, 36 (24.0%) midostaurin and 32 (21.3%) sorafenib. Relative to patients who received midostaurin or sorafenib, gilteritinib patients were older (57.3% vs. 45.6% ≥70 years) and a greater proportion received low-intensity induction chemotherapy (50.0% vs. 19.1%). A similar proportion of patients had relapsed/refractory (R/R) AML prior to alloHCT; 54.9%, 58.3%, and 46.9% for gilteritinib, midostaurin, and sorafenib, respectively. The greatest HRU overall was outpatient physician visits (mean 3.2 per patient per month), with no differences in either outpatient visits or hospitalizations among treatment groups. Mean PDC was 47% overall (54% gilteritinib, 43% midostaurin and 34% sorafenib); adherence was better for patients with vs. without a history of R/R AML pre-alloHCT at 52% vs. 41%. Rate of dose reductions were low on maintenance with gilteritinib; 84% of patients maintained or increased their gilteritinib dose during follow-up and no gilteritinib dose change was observed in 36.1% and 28.9% of patients with and without a history of R/R AML pre-alloHCT, respectively. Dose modification results were blinded for midostaurin/sorafenib groups. Switching among FLT3-TKIs was also uncommon: all patients initiated on gilteritinib remained on gilteritinib, while <32% and 38% of patients initiated on midostaurin or sorafenib, respectively, switched to an alternative FLT3-TKI. Conclusions: Real-world treatment patterns suggest gilteritinib maintenance is well-tolerated among older adult alloHCT recipients with AML. While the low sample size limits interpretability of some study results, gilteritinib may be associated with improved adherence and tolerability relative to other FLT3-TKIs.