BAY 3713391

BAY 3713391 is a humanized monoclonal antibody designed to target Glypican-3 (GPC3), a cell-surface oncofetal antigen that is highly expressed in hepatocellular carcinoma (HCC) but has limited expression in normal adult tissues. It serves as the targeting moiety for the targeted alpha therapy (TAT) program **BAY 3547926**. In this therapeutic configuration, BAY 3713391 is conjugated to a chelator and labeled with the alpha-emitting radioisotope **Actinium-225** (225Ac). The antibody specifically binds to GPC3 on the surface of tumor cells, facilitating the internal delivery of the radioactive payload. The resulting alpha radiation induces potent, localized DNA damage, specifically double-strand breaks, leading to cancer cell death while minimizing damage to surrounding healthy tissues due to the short range of alpha particles. BAY 3713391 is being developed by Bayer and is currently being evaluated in Phase 1 clinical trials for the treatment of advanced GPC3-positive hepatocellular carcinoma as the radiolabeled drug product BAY 3547926.