ESR1 and breast cancer: Median PFS was 16 months in the placebo group and 25.3 months in the ribociclib arm (hazard ratio (HR), 0.568; 95% confidence interval (CI): 0.457–0.704; p = 9.63 × 10−8)32, resulting in the approval of ribociclib for use in patients with ER+ breast cancer.