Factors impacting treatment with abemaciclib + endocrine therapy in high risk early-stage HR+/HER2- breast cancer patients.

Abstract

e12521 Background: The inhibitor of cyclin-dependent kinases 4 and 6, abemaciclib (abema), in combination with endocrine therapy (ET) is indicated for the adjuvant treatment of breast cancer (bc) patients (pts) with hormone receptor positive (HR+), human epidermal growth factor receptor-2 negative (HER2-), node-positive, early bc at a high risk of recurrence. High risk of recurrence is defined as pts with >4 positive lymph nodes, or 1-3 positive lymph nodes with either grade 3 disease or a tumor size > 5cm either pre-operatively or at surgery. This real-world study sought to understand the factors for whether pts receive abema+ET among early-stage high risk HR+/HER2- bc. Methods: This was a retrospective, observational analysis of data from pts in the IntegraConnect PrecisionQ real-world de-identified database. The study included adults (age ≥18 years) with HR+/HER2- bc at high risk of recurrence who initiated adjuvant therapy between January 1, 2023 and September 30, 2024 with follow-up through November 30, 2024. Pts were assessed to see whether age of pt, eastern cooperative group status (ECOG), race, volume of pts treated by a provider, or risk grouping of pt impacted whether a pt received adjuvant abema+ET. Data are presented using descriptive statistics and comparisons were performed using chi-squared analyses. Results: Of the 1267 pts with HR+/HER2- bc at high risk of recurrence who initiated adjuvant therapy included in the analysis, most were female (96.7%) and white (56.0%) with a median age of 63 [IQR ]. Among eligible pts, 45% received abema+ET. Pts who > 65 years of age at diagnosis (N = 557) 34.8% received abema+ET whereas pts < 65 years of age at diagnosis (N = 710) 53.8% received abema+ET (p < 0.01). Among pts with ECOG < 1, the use of abema+ET was 47.8% (N=1029), while pts with ECOG>2, abema+ET use was 29.9% (N=67) (p <0.01). Among White pts use of abema+ET was 46.1% (N=709), whereas among Black/African American pts use of abema+ET was 51.9% (N=108) (p>0.05). Among pts with > 4 positive nodes (N = 602) 49.7% received abema+ET, 1-3 positive nodes with grade 3 and tumor size of > 5cm (N = 60) 51.7% received abema+ET, 1-3 positive nodes with grade 3 and tumor size < 5cm (N = 294) 35.0% received abema+ET, and 1-3 positive nodes with tumor size > 5cm (N = 311) 46.0% received abema+ET (p < 0.01). Regarding pts who had >4 nodes, no notable differences were found abema+ET use based on tumor size. Of 337 providers who saw <5 pts (N = 628) 37.9% prescribed abema+ET, among 72 providers who saw 5-10 pts (N = 501) 45.1% prescribed abema+ET and among 10 providers who saw >10 pts (N = 138) 51.4% prescribed abema+ET (p<0.01). Conclusions: Pts with HR+/HER2- bc at high risk of recurrence who initiated adjuvant therapy were more likely to receive abema+ET if they were younger (< 65 years of age), had better performance status (ECOG <1), had >4 positive nodes, 1-3 positive nodes with a tumor >5cm, or were treated by a provider with >10 high risk pts.