The U.S.Food and Drug Administration (FDA) has approved Eli Lilly and Company's Verzenio® (abemaciclib), in combination with endocrine therapy (tamoxifen or an aromatase inhibitor), for the adjuvant treatment of adult patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), node-positive, early breast cancer (EBC) at high risk of recurrence and a Ki-67 score of =20% as determined by an FDA-approved test. Ki-67 is a marker of cellular proliferation. Verzenio is the first and only CDK4/6 inhibitor approved for this patient population. The Verzenio Phase 3 monarchE trial is a randomized (1:1), open-label, two cohort, multicenter study in adult women and men with HR+ HER2-, node-positive, resected EBC with clinical and pathological features consistent with a high risk of disease recurrence. In the trial, patients were randomized to receive two years of Verzenio 150 mg twice daily plus physician's choice of standard endocrine therapy, or standard endocrine therapy alone. Patients in both treatment arms were instructed to continue to receive adjuvant endocrine therapy for up to 5-10 years as recommended by their clinician. The primary endpoint of the study is invasive disease-free survival (IDFS) and was met at a pre-specified interim analysis in the intent-to-treat (ITT) population, with a statistically significant improvement in IDFS for patients treated with Verzenio plus ET compared to those treated with ET alone. Consistent with expert guidelines, IDFS was defined as the length of time before breast cancer comes back, any new cancer develops, or death. Having achieved the study's primary endpoint in the entire enrolled population, a pre-specified analysis of IDFS was also conducted in patients with high-risk clinical and pathological factors and a Ki-67 score =20%. This subgroup analysis (N=2,003) included patients with =4 positive axillary lymph nodes (ALN), or 1-3 positive ALN with either Grade 3 disease and/or tumor size =5 cm, and whose tumors had a Ki-67 score of =20%. There was also a statistically significant improvement in IDFS for this pre-specified subgroup of patients receiving Verzenio plus ET compared to those who received ET alone (HR=0.643, 95% CI: 0.475, 0.872, p=0.0042).1,3. This approval is based on efficacy results from an analysis of this subgroup with additional follow-up, conducted post-hoc. In this analysis, Verzenio given in combination with ET continued to demonstrate a clinically meaningful benefit, with a 37 percent decrease in the risk of breast cancer recurrence or death compared to standard adjuvant ET alone for patients with high risk clinical and pathological features and a Ki-67 score =20% (HR: 0.626 [95% CI: 0.49-0.80]), and an absolute benefit in IDFS event rate of 7.1 percent at three years. The number of IDFS events at the time of this analysis was 104 with Verzenio plus ET compared to 158 with ET alone. Overall survival data were not mature and additional follow up is ongoing.