LY4175408

LY4175408 is an investigational **antibody-drug conjugate (ADC)** developed by Eli Lilly & Co. for the treatment of solid tumors. It consists of an **Fc-silenced IgG1 monoclonal antibody targeting PTK7 (protein-tyrosine kinase 7)** conjugated to a **topoisomerase I inhibitor payload (exatecan)** using a proprietary polysaccharide linker technology acquired from Mablink Bioscience. The ADC format is designed to deliver the cytotoxic topoisomerase I inhibitor selectively to PTK7-expressing tumor cells, providing targeted antineoplastic activity. LY4175408 has demonstrated preclinical activity across a range of PTK7-expressing tumors, including those with low to moderate PTK7 expression. The compound entered its first-in-human Phase 1 trial in July 2025 to assess safety, pharmacokinetics, and preliminary efficacy in participants with advanced cancers[1][2][3][7][8][10].