XL210

XL210 is a preclinical-stage HER2-targeted imaging agent developed by XL-protein using its proprietary PASylation technology. The molecule consists of a Fab fragment specific for the Human Epidermal Growth Factor Receptor 2 (HER2) genetically fused to a PAS sequence—a conformationally disordered polypeptide comprising Proline, Alanine, and Serine. This modification significantly increases the hydrodynamic volume of the antibody fragment, extending its circulation half-life while maintaining the rapid tissue penetration and high target specificity characteristic of small antibody fragments. XL210 is designed for use in oncology imaging to visualize HER2-positive tumors, potentially aiding in patient stratification and monitoring of HER2-targeted therapies.