Overall survival with abemaciclib in early breast cancer

The phase III monarchE trial evaluated adjuvant abemaciclib combined with endocrine therapy for patients with HR-positive, HER2-negative, node-positive, high-risk early breast cancer. An updated analysis, recently presented at the European Society for Medical Oncology 2025 Congress, focused on overall survival (OS), in contrast to the previously evaluated endpoints of invasive disease–free survival (IDFS) and distant recurrence–free survival (DRFS). This analysis extends the 5-year data, providing updated IDFS and DRFS results after a median follow-up of 6.3 years, as well as new data for OS. The inclusion of OS is particularly relevant, as the 5-year data did not demonstrate statistical significance for this endpoint. In this updated analysis, abemaciclib plus endocrine therapy resulted in a statistically significant improvement in OS in the intent-to-treat population.