A Study to Evaluate Inetetamab + Pyrotinib + Chemotherapy in Previously Untreated HER2-Positive Metastatic Breast Cancer

"Inetetamab: was administered as an intravenous (IV) loading dose of 8mg/kg q3w on Day 1 of Cycle 1 (1 Cycle length = 21 days), and 6mg/kg q3w on Day 1 of subsequent cycles, until investigator-assessed radiographic or clinical progressive disease, unmanageable toxicity, or study termination.~pyrotinib: 400 mg once daily orally within 30 minutes after a meal at the same time each day.~chemotherapy:Taxanes (paclitaxel, docetaxel, liposomal paclitaxel, nabpaclitaxel), vinorelbine, capecitabine, eribulin, and other chemotherapeutic agents indicated in advanced breast cancer are permitted. Refer to the appropriate package insert for dosage and administration recommendations."