Key Clinical Summary:

• Design/Population: A retrospective real-world analysis of the Flatiron Health Database included 1063 patients with high-risk HR-positive, HER2-negative early breast cancer who initiated adjuvant abemaciclib between January 2022 and June 2024.
• Key Outcomes: Treatment persistence at 6 months was 75%, with most discontinuations due to adverse events. Dose reductions occurred in about 50% of patients and were associated with higher persistence. Early dose modification reduced discontinuation rates due to adverse events, and 70% of early discontinuations occurred without prior dose reduction.
• Clinical Relevance: Early dose modifications with adjuvant abemaciclib improve tolerability and treatment persistence without compromising efficacy, supporting proactive dose management strategies to optimize outcomes in high-risk early breast cancer.

Real-world data from the US Flatiron Health Research Database demonstrate that most patients with HR-positive, HER2-negative early breast cancer remain on adjuvant abemaciclib at 6 months, with dosing strategies playing a critical role in treatment continuation. 

These results were presented at the Hematology/Oncology Pharmacy Association (HOPA) Annual Meeting in New Orleans, Louisiana, by Astra Liepa, PharmD, Eli Lilly and Company, Indianapolis, Indianna. 

 “In patients with at high risk of recurrence, 2 years of adjuvant abemaciclib plus endocrine therapy is approved and guideline recommended,” stated Dr Liepa. “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.” 

In this retrospective study, researchers collected data from 1063 patients who initiated 150 mg of twice daily abemaciclib between January 2022 and June 2024. The primary end point was persistence rate, defined as the proportion of patients receiving abemaciclib for ≥6 months (allowing for a ≤60-day medication gap). Subgroup analyses assessed outcomes in patients who meet monarchE high-risk criteria (N2, N3, or N1 axillary lymph nodes plus grade 3 and/or tumor ≥5 cm). 

At a median follow-up of 17.5 months, the 6-month treatment persistence rate was 75%. Treatment discontinuations were mainly due to adverse events (19%) and disease recurrence (<1%) and half of patients experienced ≥1 dose reduction. Persistence rates were 85% in patients who underwent ≥1 dose reduction and 64% in patients who underwent no dose reductions. Of note, 70% of patients who discontinued treatment by 6 months did not experience a dose reduction. 

The median time to first dose change and/or hold was 49 days. During the first 30 days, adverse events led to discontinuation in 1% of patients who underwent dose reductions and in 12% of patients who did not undergo dose reductions. In the following 60 days, discontinuation rates were 4% and 10%, respectively. 

Similar persistence and dosing patterns were observed in patients meeting monarchE high-risk criteria.

“Given that dose reductions in monarchE were not associated with reduced efficacy, 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,” concluded Dr Liepa. 

Source:

Liepa A. Treatment persistence and dose modifications in US patients with hormone receptor–positive, HER2-negative, node-positive, early breast cancer treated with adjuvant abemaciclib. Presented at HOPA Annual Conference. March 25-27, 2026. CR20.