Several novel HER2-targeted agents for GC are currently in development to overcome trastuzumab resistance, including bispecific antibodies (zanidatamab) [54,55], chimeric antibodies with augmented antibody-dependent cellular cytotoxicity (ADCC) (margetuximab) [56], and small molecule kinase inhibitors (afatinib, neratinib, and tucatinib) [57,58,59]. The gene discussed is ERBB2; the disease is gastric cancer.