Presenting Author: Erich Brechtelsbauer, PharmD, MS, Eli Lilly and Company, Indianapolis, IN
Co-Authors: Kathryn Hudson, MD, Texas Oncology, Austin, TX; Wambui Gathirua-Mwangi, PhD, Zhanglin Lin Cui, Brenda Grimes, PhD, Astra M. Liepa, PharmD, Raisa Volodarsky, PharmD, and Katheryn Moreira, MD, MBA, Eli Lilly and Company, Indianapolis, IN; Madeline Richey, MPH, and Jingru Wang, Flatiron Health, New York City, NY; Hatem Soliman, MD, Moffitt Cancer Center and Research Institute, Tampa, FL
BACKGROUND: Abemaciclib in combination with endocrine therapy is approved for adjuvant treatment of adult patients with hormone receptor (HR)-positive/HER2-negative, node-positive early breast cancer at high risk of recurrence. The monarchE trial established the efficacy of abemaciclib and endocrine therapy for early breast cancer, with the highest rates of early discontinuation observed in the first few months. The use of abemaciclib in the real-world early breast cancer setting can provide insight into treatment patterns and inform adverse event (AE) management strategies. This retrospective study describes clinical characteristics and treatment persistence in patients with HR-positive/HER2-negative, node-positive early breast cancer starting abemaciclib.
METHODS: Data were accessed from Flatiron Health electronic database. Adult patients with node-positive, stage I-III early breast cancer starting abemaciclib October 2021 (FDA approval) to November 2022 at 150 mg twice daily were analyzed. Persistence rate was defined as the percentage of patients remaining on abemaciclib at 3 months, allowing for ≤60-day medication gap.
RESULTS: A cohort of 354 patients with a median follow-up time from abemaciclib initiation of 8.8 months were selected. The median age was 56 years, 25.4% were aged ≥65 years, 12.7% were Black, 4.0% were Asian, and most patients (80.8%) received care in a community setting. More than half (55.4%) of patients were postmenopausal; 57.9% had an ECOG Performance Status 0; whereas 25.1% had ECOG Performance Status 1. Approximately 33.9% had ≥1 comorbidity, and 12.1% had ≥2 comorbidities, with diabetes (14.1%) being the most frequent. Most patients had stage II (41.8%) or III (38.4%) disease, nodal status N1 (45.2%) or N2 (35.3%), and tumor grade 2 (52.3%). Abemaciclib was initiated at a median of 11.1 months after early breast cancer diagnosis. Before abemaciclib initiation, most patients received radiotherapy (96.3%) and chemotherapy (83.1%), with 46.3% receiving neoadjuvant chemotherapy. Most patients (74.0%) initiated endocrine therapy 1.6 months before abemaciclib initiation. The median time to abemaciclib initiation from breast surgery was 6.7 months. The most frequent regimen was abemaciclib and aromatase inhibitors (91.0%). At 3 months, 81.6% of patients were persistent; 5.6% resumed abemaciclib after >60-day interruption and 11.3% discontinued due to AEs. Additional information on dose modifications will be presented.
CONCLUSION: In this real-world study of utilization of abemaciclib in the first year after approval for early breast cancer, an older, less fit, and more racially diverse population than participated in the monarchE trial, as well as a higher proportion of patients with lower nodal status, was observed. The high 3-month persistence rate suggests abemaciclib for early breast cancer is well-tolerated in routine clinical practice.
This abstract was previously presented at the 2024 San Antonio Breast Cancer Symposium.