ENHERTU 100 mg Injection ENHERTU contains Fam-trastuzumab deruxtecan-nxki, a HER2-targeted antibody-drug conjugate (ADC) composed of a humanized anti-HER2 IgG1 monoclonal antibody linked to DXd, a topoisomerase I inhibitor payload, via a tetrapeptide-based cleavable linker. Upon binding to HER2 on tumor cells, the ADC is internalized and cleaved by lysosomal enzymes, releasing DXd. DXd causes DNA damage and apoptotic cell death, while also exerting a bystander antitumor effect on neighboring tumor cells. It is indicated for the treatment of adult patients with unresectable or metastatic HER2-positive or HER2-low breast cancer, HER2-mutated non-small cell lung cancer (NSCLC), and HER2-positive gastric or gastroesophageal junction adenocarcinoma.