HER2 amplification, but mostly HER2 protein overexpression by IHC, has been shown by several key studies (MyPathway, HERIZON-BTC-01, SGNTUC-019, DESTINY-PanTumor02) to be a valid therapeutic target for anti-HER2 monoclonal antibodies, TKIs, and antibody-drug conjugates, with ORRs averaging 40% in a tumor-agnostic population including BTC [25,26,27,28]. Here, ERBB2 is linked to neoplasm.