Real-world patterns of maintenance therapy after allogeneic transplant in older adults with acute myeloid leukemia: A Medicare cohort study.

[INTRODUCTION] Older adults represent the majority of patients with acute myeloid leukemia (AML), and an increasing proportion receive allogeneic hematopoietic cell transplantation (alloHCT). Mutations in the FMS-like tyrosine kinase 3 gene (FLT3) confer high relapse risk, and post-transplant maintenance with FLT3 tyrosine kinase inhibitors (FLT3-TKIs) is guideline-recommended. However, real-world utilization, adherence, and tolerability of FLT3-TKIs in older adults remain poorly characterized.

[MATERIALS AND METHODS] Using 100% Medicare claims (Parts A/B/D and Medicare Advantage encounter data), we conducted a retrospective cohort study of beneficiaries ≥65 years old with AML who received alloHCT between January 1, 2016 and June 30, 2024, and initiated FLT3-TKI maintenance (gilteritinib, midostaurin, or sorafenib) within 100 days post-transplant. Baseline demographics, comorbidities, prior therapy, and health care resource utilization (HCRU) were captured from 2010 through the index date. Adherence was assessed using proportion of days covered (PDC). Dose modification, FLT3-TKI switching, and post-transplant HCRU were evaluated descriptively. Centers for Medicare & Medicaid Services suppression rules were applied throughout.

[RESULTS] Of 7403 eligible older adults with AML undergoing alloHCT, 150 (2.0%) initiated FLT3-TKI maintenance (gilteritinib: 54.7%, midostaurin: 24.0%, sorafenib: 21.3%). Mean age was 70.5 years, and 59.3% had Charlson Comorbidity Index ≥4. Utilization of post-transplant FLT3-TKIs was sustained from 2020 onwards at approximately 20% of eligible patients annually. Overall adherence was modest, with a mean PDC of 47% and very few patients achieving PDC ≥80%. Higher mean PDC was observed in patients ≥70 years of age, those with fewer comorbidities, those previously treated with low-intensity chemotherapy, and those who received gilteritinib as maintenance. Among patients treated with gilteritinib, two-thirds had no evidence of dose change, and no patients switched to an alternative FLT3-TKI. Across all patients, post-alloHCT HCRU was predominantly outpatient visits, with low hospitalization rates across FLT3-TKIs.

[DISCUSSION] In this first real-world analysis of post-alloHCT FLT3-TKI maintenance in older adults, utilization was low and adherence was modest, although not impaired by age alone. Gilteritinib demonstrated the highest adherence and appeared to have favorable tolerability. Strategies to improve adherence and prospective data in older adults are needed to maximize the benefits of FLT3-TKI maintenance in this population.