Abemaciclib plus endocrine therapy in HR-positive, HER2-negative high-risk early breast cancer: efficacy in nodal subgroups

Background In monarchE, 2 years of abemaciclib plus endocrine therapy (ET) significantly reduced the risk of recurrence and mortality in patients with node-positive, high-risk hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer. This analysis provides additional efficacy data based on nodal subgroups.Patients and methods Three nodal subgroups were analyzed in cohort 1, a population comprising 91% of the patients in monarchE: N1 high-risk (1-3 positive nodes with grade 3 tumors and/or tumor size ≥5 cm), N2 [4-9 positive axillary lymph node (ALN)], and N3 (≥10 positive ALN). Median follow-up was 76.8 months. Efficacy outcomes for invasive disease-free survival (IDFS) and distant recurrence-free survival (DRFS) using Kaplan-Meier methods and baseline characteristics are reported for nodal subgroups.Results Kaplan-Meier analyses for IDFS and DRFS highlighted consistent and durable efficacy across nodal subgroups. Within the N1 high-risk group, 68.6% of tumors were grade 3; 57.6% of grade 3 tumors were Conclusions The similar recurrence risk for patients in the N1 high-risk and N2 subgroups, and consistent efficacy across nodal subgroups, support addition of 2 years of adjuvant abemaciclib to ET to improve outcomes in patients meeting monarchE cohort 1 N1 high-risk, N2, or N3 criteria.