Patient with hormone receptor‑positive Her2‑negative metastatic breast cancer with visceral crisis with good response to abemaciclib and letrozole: A case report and review of the literature

Combined chemotherapy is typically the preferred treatment for patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) experiencing a visceral crisis. However, the emergence of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) has introduced a potential alternative: The combination of CDK4/6i with endocrine therapy (ET). The present study reported a case of HR+/HER2-MBC with extensive liver and bone metastases who responded well to abemaciclib and letrozole. The patient achieved a rapid partial response and continuous clinical stabilization and the progression-free survival of this patient reaches 30 months and counting. Furthermore, the side effects were manageable and no dose reductions were necessary during treatment. These findings suggest that the combination of CDK4/6i and ET in the treatment of HR+/HER2-advanced breast cancer cannot be underestimated.