Efficacy and Safety of Inetetamab Plus Pyrotiniband and Capecitabine in HER2-positive Metastatic Breast Cancer Patients With or Without Brain Metastasis

This study intends to include HER2-positive metastatic breast cancer patients (with or without brain metastasis) who have become resistant to previous treatment with trastuzumab. It will use pertuzumab in combination with pyrotinib and capecitabine to observe efficacy and safety. The choice of capecitabine as the chemotherapy drug is mainly based on the following reasons: ① it has been less commonly used as neoadjuvant treatment, making it less prone to cross-resistance; ② its oral formulation is convenient for administration, making it more acceptable to patients; ③ previous studies have shown good efficacy when combined with pyrotinib; ④ previous research in breast cancer patients with brain metastasis has also demonstrated certain effectiveness. It is hoped that through this study, preliminary evidence can be provided for the dual-target treatment of original Chinese drugs, as well as the treatment of HER2+ MBC after resistance to trastuzumab, and the addition of new data for patients with brain metastasis.