Abstract
BACKGROUND: Breast cancer is the most common tumor among women worldwide, which human epidermal growth factor receptor 2 (HER2)-positive subtype accounts for approximately 15-20%. Although anti-HER2 agents have already diversified in recent years, a highly effective and more affordable treatment option is urgently needed. Inetetamab is a new antibody exhibiting efficacy in managing HER2-positive advanced breast cancer (ABC) through antibody-dependent cellular cytotoxicity (ADCC). Pyrotinib is a second-line treatment specifically targeting HER2. Given that pyrotinib could exhibit strong HER2 antagonism and synergize with monoclonal antibodies to boost ADCC effect, herein we investigated the effects and safety of first to third line of combined treatments utilizing inetetamab plus vinorelbine and pyrotinib in dealing with HER2-positive ABC. METHODS: This is a multicenter, retrospective, real-world study. During the period of July 2020 to October 2023, 76 participants at 17 centers with HER2-positive ABC received the triple regimen and were evaluated for progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and clinical benefit rate (CBR). Data regarding treatment-associated adverse events (TAAEs) were also collected. RESULTS: The median age of the participants enrolled was 53 years. Among the participants, 53 (69.7%) were diagnosed to suffer from visceral metastases, while 35 (46.1%) possessed hormone receptor-positive lesions. The median PFS (mPFS) of the cohort was 10.03 months [95% confidence interval (CI): 6.80 to 13.27]. The ORR and CBR were respectively 61.8% (47/76) and 97.4% (74/76). The TAAE with highest incidence was diarrhea (77.6%). Grades III and IV TAAEs with highest incidences were leukopenia (19.7%), neutropenia (19.7%), and diarrhea (17.1%). No severe TAAEs were observed during the investigation. CONCLUSIONS: The triple regimen of inetetamab plus pyrotinib and vinorelbine exhibited promising therapeutic effects and was tolerable for participants with HER2-positive ABC.