ERBB2 and cancer: The inhibitory activity of T‐DXd against cell cancer growth in vitro was compared to two other approved anti‐HER2 agents, trastuzumab (Herceptin) and T‐DM1 (Kadcyla) in the FaDu cell line since it exhibited the highest HER2 expression in the HNSCC cell lines we tested (IHC 1+, 18.2% via flow and in vivo SBR = 7.41 ± 3.28 using optically labeled trastuzumab).