Trastuzumab Deruxtecan (T-DXd), a HER2-directed antibody and topoisomerase inhibitor conjugate, showed impressive responses in patients with previous BTC and HER2-positive (IHC 3+, IHC 2+/ISH+) and HER2-low (IHC/ISH of 0/+, 1+/+, 2+/−) cancers, during the first data presentation at the ASCO 2022. The gene discussed is ERBB2; the disease is cancer.