Presenting Author: Astra Liepa, PharmD, BS, Eli Lilly and Company, Indianapolis, IN
BACKGROUND: In patients with hormone receptor (HR)-positive, HER2-negative, node-positive early breast cancer (EBC) at high risk of recurrence, 2 years of adjuvant abemaciclib plus endocrine therapy is approved and guideline recommended. In initial real-world studies, the high rate (>85%) of treatment persistence beyond 3 months suggests that adjuvant abemaciclib is well tolerated in routine clinical practice.1,2
OBJECTIVE: To describe 6-month treatment persistence and dosing patterns in patients with EBC receiving abemaciclib 150 mg twice daily.
METHODS: Retrospective data were accessed from the US deidentified Flatiron Health Research Database. Adults with HR-positive, HER2-negative, node-positive EBC who received abemaciclib 150 mg twice daily from January 2022 to June 2024 were eligible. Data cutoff was December 2024. The persistence rate was the proportion of patients receiving abemaciclib ≥6 months, allowing for a ≤60-day medication gap within this period. Subgroup analyses were conducted in patients meeting the monarchE high-risk criteria regarding axillary lymph nodes (N2, N3, or N1 plus grade 3 and/or tumor ≥5 cm).
RESULTS: Of 1063 eligible patients, median age was 56 years (interquartile range [IQR], 47-65). Most had N1 (48%) or N2 (34%) disease. Median follow-up was 17.5 months (IQR, 11-25). Treatment persistence at 6 months was 75%. Most discontinuations were due to adverse events (AEs; 19%), and <1% were due to recurrence. Approximately 50% of patients (n=536) had ≥1 dose reduction. Persistence was 85% in patients with ≥1 dose reduction and 64% in those with no dose reductions. In all, 70% of patients who discontinued abemaciclib by 6 months did not have a dose reduction. Median time from the start of abemaciclib to the first dose change and/or hold was 49 days (IQR, 23-111). During the first 30 days of treatment and days 31 to 90, discontinuations due to AEs were lower in patients with dose reductions versus those with no dose reductions (0-30 days: 7% [overall], 1% [≥1 dose reduction], 12% [no dose reduction]; 31-90 days: 7% [overall], 4% [≥1 dose reduction], 10% [no dose reduction]; 91-182 days: 5% [overall], 6% [≥1 dose reduction], 5% [no dose reduction]). Persistence and use of dose reductions were similar in patients meeting the monarchE high-risk criteria.
CONCLUSION: In US clinical practice, 75% of patients who initiated adjuvant abemaciclib continued abemaciclib beyond 6 months. Treatment persistence was higher among patients with dose reductions versus those with no dose reductions, and rates of early discontinuations due to AEs were low in patients with dose reductions. Given that dose reductions in monarchE were not associated with reduced efficacy,3 these additional real-world data support the use of early dose modifications to improve tolerability and treatment persistence for adjuvant abemaciclib in patients with high risk of recurrence.
- Hudson K, Gathirua-Mwangi W, Williams LA, et al. Abemaciclib persistence in patients with HR+, HER2-, node-positive early breast cancer: a real-world analysis. Oncol Ther. 2025;13:1105-1118. doi:10.1007/s40487-025-00385-9
- Gorantla V, Choski R, Rosenfeld S, et al. Dose reduction impacts persistence on abemaciclib: a retrospective analysis of real-world data from the IntegraConnect PrecisionQ de-identified database. Clin Cancer Res. 2025;31(12Suppl):P1-11-21. doi:10.1158/1557-3265.SABCS24-P1-11-21
- Goetz MP, Cicin I, Testa L, et al. Impact of dose reductions on adjuvant abemaciclib efficacy for patients with high-risk early breast cancer: analyses from the monarchE study. NPJ Breast Cancer. 2024;10:34. doi:10.1038/s41523-024-00639-1