ERBB2 and neoplasm: Trastuzumab deruxtecan (T-DXd) is an ADC that binds an anti-HER2 monoclonal antibody to a cytotoxic agent through a cleavable tetrapeptide-based linker, creating a dual-action mechanism that combines targeted therapy with chemotherapeutic cytotoxicity.(13) This drug complex works by releasing the deruxtecan payload into tumor cells, inducing DNA damage and apoptosis.