patritumab deruxtecan

**Patritumab deruxtecan** is an investigational HER3-directed antibody-drug conjugate developed by Daiichi Sankyo and jointly developed with Merck. It comprises patritumab, a fully human anti-HER3 IgG1 monoclonal antibody, covalently linked through a tetrapeptide-based cleavable linker to DXd, an exatecan-derived topoisomerase I inhibitor payload. Following HER3-mediated tumor-cell binding and internalization, intracellular linker cleavage releases DXd, causing topoisomerase I inhibition and DNA damage. The program has been studied most extensively in previously treated EGFR-mutated locally advanced or metastatic non-small cell lung cancer and is also in development across other HER3-expressing solid tumors. Its U.S. BLA for EGFR-mutated NSCLC was voluntarily withdrawn in May 2025 after the confirmatory HERTHENA-Lung02 phase 3 trial did not demonstrate statistically significant overall survival. ([daiichisankyo.com](https://www.daiichisankyo.com/files/news/pressrelease/pdf/202505/20250529_E.pdf))

Other names

HER3-DXdHER-3-DXdHER 3-DXdHE3-DXdHE-3-DXdHE 3-DXd