Transfusion burden among older US patients with relapsed FLT3-mutated Acute Myeloid Leukemia treated with gilteritinib: A Medicare claims-based cohort study

Abstract Background : Older patients with relapsed acute myeloid leukemia (AML) often require transfusion support due to persistent cytopenias from both disease progression and targeted therapy. Gilteritinib is an approved treatment for adults with relapsed or refractory AML with FLT3 mutations, yet real-world data on transfusion burden during its use remains limited. This study characterizes transfusion burden among Medicare beneficiaries with relapsed AML receiving gilteritinib. Understanding transfusion burden is critical, as high transfusion dependence has been associated with increased healthcare utilization, reduced quality of life, and poorer clinical outcomes in this population. Methods : This retrospective observational cohort study analyzed Medicare beneficiaries aged ≥65 years with relapsed AML using claims data from the Centers for Medicare & Medicaid Services, including both Medicare Fee-for-Service (Parts A, B, and D) and Medicare Advantage (Part C) enrollees. The study period was from July 1, 2016, to December 31, 2024 (Part C: January 1, 2017, to December 31, 2022). Eligible patients had a confirmed AML diagnosis, evidence of relapse, and a prescription for gilteritinib following relapse. Patients were required to have ≥180 days of continuous enrollment prior to diagnosis and no prior history of acute promyelocytic leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia or allogeneic hematopoietic cell transplantation. Transfusion independence was defined as a continuous 56-day period without any red blood cell or platelet transfusions, assessed on a rolling basis. Results : Among 169,642 Medicare beneficiaries diagnosed with AML, 962 met the study's eligibility criteria, of whom 799 initiated gilteritinib for relapsed disease. The median follow-up duration was 136 days [Interquartile range (IQR)=71-320] and the median age at diagnosis was 74 years (IQR=70-78) in all patients. The majority of patients were male (52.9%, n=423) and White (84.7%, n=677). Patients had a mean Charlson Comorbidity Index score of 2.9 (SD=1.46), including common comorbidities: 28.9% (n=231) with congestive heart failure, 27.7% (n=221) with chronic pulmonary disease, 27.4% (n=219) with renal disease, and 25.0% (n=200) with peripheral vascular disease. Among other comorbidities of interest, anemia (93.7%, n=749) and thrombocytopenia (79.7%, n=637) were the most prevalent, followed by kidney-related conditions such as kidney failure (47.1%, n=376), acute kidney issues (38.7%, n=309), and chronic kidney disease (26.7%, n=213). Most patients (76.0%, n=607) received an initial gilteritinib dose of 120 mg, followed by 12.3% (n=98) who received 80 mg, and 11.8% (n=94) who received other doses. Within 56 days prior to treatment initiation (baseline), 56.0% (n=444) of patients were red blood cell transfusion independent (RBC-TI) and 64.0% (n=514) of patients were platelet transfusion independent (PLT-TI). During the first 8 weeks of follow-up, 74.8% (n=332) of RBC TI and 75.1% (n=386) of PLT TI patients maintained independence, while 26.8% (n=95) of initially RBC transfusion-dependent (RBC-TD) and 30.9% (n=88) of PLT transfusion-dependent (PLT-TD) patients achieved TI. A substantial proportion of patients maintained TI over time. At ≥8 weeks, 63.9% of patients achieved RBC TI and 65.7% achieved platelet TI. These strong results continued across longer durations, with over half of patients remaining transfusion-independent at ≥16 weeks (50.0% for RBC and 50.9% for platelets). Even at ≥24 weeks, a notable 40.5% (RBC) and 41.6% (platelets) sustained TI. Conclusions : In this real-world study of older Medicare beneficiaries with relapsed AML, many patients receiving gilteritinib experienced periods of transfusion independence for both RBCs and platelets, suggesting low transfusion burden.