Abstract PS10-46: Real-world patient characteristics, utilization patterns, and outcomes of US patients with HR+/HER2- metastatic breast cancer treated with abemaciclib

• Published in: Cancer research (Chicago, Ill.) Ill.), 2021-02, Vol.81 (4_Supplement), p.PS10-46-PS10-46
• Main Authors: Saverno, Kimberly R., Beyrer, Julie, Smyth, Emily Nash, Abedtash, Hamad, DeLuca, Angelo, Zhu, Yajun Emily, Rybowski, Sarah
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS20-PS10-46

Background Abemaciclib is the most recent oral cyclin-dependent kinase 4 and 6 inhibitor (CDK4&6i) to receive FDA approval to treat hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer (MBC). We used administrative claims data to describe patient characteristics, real-world utilization patterns, and outcomes in a US patient cohort upon initiating abemaciclib treatment for HR+, HER2- MBC.Methods This retrospective observational study analyzed medical and pharmacy claims from the IBM® MarketScan® Research Databases (Commercial and Medicare Supplemental) between 1-Jan-2007 to 31-Jan-2020. Patients (≥18 years) newly initiating abemaciclib between 1-Sept-2017 and 31-Oct-2019 were included if they had ≥2 breast cancer diagnoses, ≥2 secondary neoplasm diagnoses, evidence of HR+ disease, continuous enrollment ≥6 months before and ≥90 days after abemaciclib initiation (index date), and absence of therapies suggesting HER2 positivity. Patients were grouped by concomitant therapy (+aromatase inhibitor [AI], +fulvestrant [F], 200mg abemaciclib monotherapy [200mgMono], or +other), and stratified by prior CDK4&6i use (yes/no). Line of therapy (LoT) and reason for discontinuation were not able to be determined from this dataset. Baseline demographic, clinical, and treatment characteristics were summarized with descriptive statistics. Kaplan-Meier methods assessed time-to-discontinuation, defined as a gap of 60-days without an abemaciclib fill, following exhaustion of days’ supply from prior fills, or initiation of a different CDK4&6i (ie, palbociclib or ribociclib).Results There were 454 patients included in this analysis (mean [SD] age=57.7 years [10.8]; 98.9% female). Prevalence of new abemaciclib initiators was 29.3% (n=133) in the +AI group, 35.0% (n=159) in the +F group, 10.4% (n=47) in the 200mgMono group, and 25.3% (n=115) in the +other group. Prior CDK4&6i use within each regimen ranged from 37.6% (+AI) to 60.0% (+other). Visceral metastases were present in 50.4% in the +AI group; 49.7% in the +F group; 55.3% in the 200mgMono group; and 47.8% in the +other group. Nearly 75% (n=331) of all abemaciclib initiators began treatment with a 150 mg dose. Chemotherapy use in the 6-month pre-index period was observed for 18.8% in the +AI group; 21.4% in the +F group; 51.1% in the 200mgMono group; and 21.7% in the +other group. Median length of follow-up for all abemaciclib initiators was 321 days (I