To gain a better understanding of the efficacy and safety of abemaciclib in Japanese breast cancer patients, the current analysis examined the Japanese subpopulation of MONARCH 2, a phase 3 study of abemaciclib plus fulvestrant in a global population of patients with HR+ , HER2− ABC who had progressed on prior ET [12, 13, 23]. The gene discussed is ERBB2; the disease is breast cancer.