{Reference Type}: Journal Article {Title}: Mechanisms of resistance to trastuzumab in HER2-positive gastric cancer. {Author}: Li Z;Zhao H;Hu H;Shang H;Ren Y;Qiu W;Su H;Lyu H;Chen X; {Journal}: Chin J Cancer Res {Volume}: 36 {Issue}: 3 {Year}: 2024 Jun 30 {Factor}: 4.026 {DOI}: 10.21147/j.issn.1000-9604.2024.03.07 {Abstract}: Gastric cancer is one of the most prevalent cancers worldwide, and human epidermal growth factor receptor 2 (HER2)-positive cases account for approximately 20% of the total cases. Currently, trastuzumab + chemotherapy is the recommended first-line treatment for patients with HER2-positive advanced gastric cancer, and the combination has exhibited definite efficacy in HER2-targeted therapy. However, the emergence of drug resistance during treatment considerably reduces its effectiveness; thus, it is imperative to investigate the potential mechanisms underlying resistance. In the present review article, we comprehensively introduce multiple mechanisms underlying resistance to trastuzumab in HER2-positive gastric cancer cases, aiming to provide insights for rectifying issues associated with resistance to trastuzumab and devising subsequent treatment strategies.