The following innovative HER2-targeted agents for advanced metastatic GC are currently under investigation (Table 4): monoclonal antibodies (mAbs) (e.g., margetuximab), bispecific antibodies (BsAbs) (e.g., ZW25, KN026), antibody–drug conjugates (ADCs) (e.g., T-DXd, Disitamab vedotin, ARX788), tyrosine kinase inhibitors (TKIs) (e.g., tucatinib), and other novel therapeutic approaches. The gene discussed is ERBB2; the disease is gastric cancer.