ERBB2 and gastric cancer: Several novel HER2-targeted drugs for GC are under development, including bispecific antibodies (zanidatamab) [58], antibody–drug conjugates (trastuzumab deruxtecan) [59], and small-molecule kinase inhibitors (afatinib, neratinib, and tucatinib) [60,61,62], which have been designed to overcome this resistance [63].