Pyrotinib in Combination With Fulvestrant in Patients With HER2 Positive，HR-Positive Metastatic Breast Cancer

HR+/HER2+（Human epidermal growth factor receptor 2 positive and hormone receptor positive）metastatic breast cancer is a special subtype of HER2+breast cancer. Conventional guidelines recommend chemotherapy combined with trastuzumab targeted therapy for this subtype of patients. However, the choice of treatment for these patients after treatment progress is a research hotspot in this field. Pyrotinib is a new class I small molecule Tyrosine kinase inhibitors（TKI） drug with high efficacy and low toxicity after the progress of trastuzumab therapy. Fulvestrant is the most preferred single-drug therapy for HR + metastatic breast cancer recommended unanimously by the guidelines, and fulvestrant and small molecule TKI have synergistic effects. Therefore, we envisage that fulvestrant combined with Pyrotinib in the treatment of HR+/HER2+ metastatic breast cancer in clinical practice has the advantages of improving efficacy and survival. To this end, we intend to conduct a prospective, multi-center, phase II clinical trial to evaluate the efficacy and safety of erlotinib in combination with fulvestrant in patients with human epidermal growth factor receptor 2 (HER2) positive，hormone receptor-positive metastatic breast cancer.