ERBB2 and gastric cancer: As such, EGFR and ERBB2 have been the focus of extensive drug development efforts and are the targets of both small-molecule tyrosine kinase inhibitors (TKIs) and antibody-based therapies that are FDA-approved for treating a variety of indications, including breast (BrCa), lung, colorectal, head and neck, and gastric cancers (GCa) [2].