TX1351

TX1351 is a humanized VHH-Fc fusion molecule developed by Tectonic Therapeutic using its proprietary GEODe™ platform. It functions as a potent and selective antagonist of the apelin receptor (APJ), a G protein-coupled receptor (GPCR) that plays a critical role in angiogenesis and vascular stability. In the context of Hereditary Hemorrhagic Telangiectasia (HHT), loss of ALK1 signaling leads to upregulated apelin/APJ signaling, which promotes pathological hypervascularization and the formation of arteriovenous malformations (AVMs). TX1351 is designed to block this pathway, thereby reducing bleeding and anemia. Preclinical data presented at the EHA 2026 Congress demonstrated that TX1351 significantly reduced retinal AVMs and gastrointestinal bleeding in mouse models of HHT, showing durable efficacy compared to standard anti-VEGF approaches.