Diagonal Therapeutics’ innovative clustering antibodies for vascular diseases

What It Covers

Patrick Andre, CSO of Diagonal Therapeutics, explains how the company's clustering antibody platform targets the root cause of hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension. Lead program DIAG-723 holds FDA and EMA orphan drug designation and is entering clinical trials mid-2026, backed by a $125M Series B.

Key Questions Answered

• •Clustering antibody mechanism: Unlike conventional antibodies that bind a single receptor, clustering antibodies force co-association of four receptors — two ALK1 and two BMPR2 — into a functional tetramer, replicating the signaling complex that nature requires for endothelial integrity. This distinction means the therapy restores normal biology rather than modulating a downstream compensatory pathway.
• •HHT disease burden and unmet need: Approximately 330,000 patients across the US and EU have HHT, yet zero drugs are approved specifically for the disease. Nearly 100% of patients experience recurrent nosebleeds, over 60% develop anemia requiring iron infusion or transfusion, and 20–70% develop arteriovenous malformations in the brain, liver, or lungs.
• •AI-accelerated antibody discovery: Diagonal's platform uses a computational algorithm developed at the University of Texas at Austin to screen billions of epitope combinations across four receptor domains. This narrows wet-lab testing to 200–400 representative antibodies, with roughly 30% demonstrating the desired signaling activity, compressing the discovery cycle to approximately six months.
• •Preclinical proof of disease reversal: In mouse and rat HHT models developed with the Finchten Institute, DIAG-723 both prevented and reversed arteriovenous malformation formation. It also reversed anemia and reduced mortality from blood loss. Human patient-derived cells with loss-of-function mutations confirmed the antibody restores receptor clustering and normal downstream signaling.
• •Clinical and pipeline milestones funded by Series B: The $125M round led by Sanofi and Janice Anderson funds a single ascending dose trial in HHT patients starting mid-2026, with proof-of-concept data expected by end of 2027. Proceeds also advance four early-discovery programs toward drug candidate nomination in 2026 and at least one IND filing by 2027.