Abstract
This study aimed to characterize real-world treatment patterns among patients in the United States with triple-negative breast cancer (TNBC) eligible for pembrolizumab treatment, including patients eligible for Medicare (aged ≥65 years). This retrospective study analyzed treatment utilization among patients with TNBC using two United States (US)-based electronic health record (EHR) databases (Flatiron Health Research Database and N-Power Medicine's Breast Analytical Dataset). Patients were stratified by Medicare insurance status or age ≥65 years. Treatment uptake was analyzed in cohorts of patients with a metastatic diagnosis on or after 1 January 2021, and defined by FDA-approved pembrolizumab indications in TNBC. Overall, 133 patients with metastatic TNBC (mTNBC) and 392 patients with early-stage TNBC (esTNBC) were included; 33.9-39.1% were Medicare-eligible. Programmed Death-Ligand 1 (PD-(L)1) inhibitors were the most used therapy class across all Medicare-eligible cohorts with TNBC (79.0-85.0%). Use of pembrolizumab-containing regimens was observed across TNBC cohorts (77.0-85.0%). Treatment patterns in Medicare-eligible patients were consistent with the overall population. This real-world analysis demonstrates high uptake of PD-(L)1 inhibitors, including pembrolizumab, among Medicare-eligible patients with TNBC. These findings provide real-world insights into how regulatory approvals in TNBC have shaped clinical practice in the US.