OBJECTIVES : CDK4/6i are used with hormonal therapies to treat patients with HR+/HER2- aBC/mBC, but little is known about the characteristics of patients receiving treatment and their prescribing physicians in the US. This analysis describes characteristics among female patients (and their prescribing oncologist) with HR+/HER2- a/mBC who received CDK4/6i plus endocrine therapy (ET) and were enrolled Medicare Fee-for-Service (FFS), Medicare Advantage (MA), Managed Medicaid (MM), or commercial insurance.

METHODS : A retrospective cohort analysis was conducted to provide a comprehensive picture across all payer types using the 100% sample Medicare FFS beneficiaries and a convenience sample of MA, commercial, and MM plan members from the MORE² Registry®. Inclusion criteria included: diagnosed with a/mBC and treated with a CDK4/6i plus ET anytime between 2015-2018, and ≥6 months of pre/ ≥2 post index data. Baseline characteristics of treated patients and their prescribing oncologist were analyzed.

RESULTS : A total of 25,590 patients qualified for analysis; 93.7% received palbociclib plus ET; remainder received abemaciclib or ribociclib plus ET. The majority of patients were identified in Medicare FFS (78.2%); the remainder were in commercial (9.9%), MM (6.4%), and MA (5.5%). Mean age: 69.2 years (±11.3); highest in Medicare FFS (72.1 years [±9.4]) and lowest in MM: (53.8 years [±9.8]). Across all payer types, CDK4/6i was most commonly prescribed by oncologists with ≥20 years of experience (61.5%), located in metropolitan statistical areas, and >200% above the US Federal poverty level. Medicare FFS beneficiaries were more commonly treated by hospital-based oncologists whereas non-Medicare populations were more commonly treated in community settings (68.6% MA, 65.6% Commercial, 57.5% MM).

CONCLUSIONS : Characteristics of patients with a/mBC who receive CDK4/6i plus ET therapy and their prescribers differ by type of insurance coverage. Additional research is needed to measure the association between insurance coverage and CDK4/6i selection and patient outcomes.