Based on the efficacy results in cohort 1 patients with high Ki-67 scores at the additional follow-up analysis, the US Food and Drug Administration approved abemaciclib in combination with ET for patients with HR + /HER2-, node-positive, early breast cancer at high risk of recurrence and a Ki-67 score of ≥ 20%65; ASCO and NCCN have also updated their guidelines to include use of adjuvant abemaciclib plus ET in patients with ER + /HER2- early breast cancer and a Ki-67 score ≥ 20%32,64,66. Here, ESR1 is linked to breast cancer.