ERBB2 and breast carcinoma: Also, laboratory‐based and clinical studies have revealed that the addition of CDK4/6 inhibitors to endocrine therapy results in synergistic effects and significantly improved progression‐free survival and overall survival in patients with advanced HR+/HER2− breast cancer.[5] Thus, CDK4/6 inhibitors in combination with endocrine therapy has become the standard therapeutic approach for patients with HR+/HER2− MBC.[6] Nevertheless, resistance is inevitable in the advanced setting.