Albeit having an improved therapeutic index than traditional chemotherapies, anti-HER2 ADCs still retain some class-related AEs, many in common with the general profile of chemotherapeutic agents (myelotoxicity, hepatotoxicity) and trastuzumab profile (cardiotoxicity), but some depending on the class of the cytotoxic warhead (mainly GI toxicity with T-Dxd and ocular toxicity with trastuzumab–duocarmazine), altogether with potentially life-threatening AEs, such as ILD. This evidence concerns the gene ERBB2 and interstitial lung disease.