Diagonal secures an additional $125M to advance ‘clustering’ antibody therapeutics

Diagonal Therapeutics Secures $125 Million to Advance Innovative Antibody Therapy

Diagonal Therapeutics, a biotechnology company, has announced the successful completion of a $125 million Series B funding round. This new investment will enable the company to move its leading drug candidate into clinical trials within the year.

Unlike traditional antibody drugs that typically block disease-related signaling pathways—such as those involved in cancer or immune disorders—Diagonal is developing unique “clustering” antibodies. These engineered molecules attach to cell receptors and bring them together in a precise formation, which can trigger alternative cellular signals. This approach may help restore pathways that have been disrupted by disease.

The company’s primary focus is on its first drug candidate, DIAG723. This therapy targets two serious conditions: hereditary hemorrhagic telangiectasia, a rare inherited disorder, and pulmonary arterial hypertension, which affects both the lungs and heart. Initially, Diagonal planned to create separate treatments for each disease. However, research revealed that a single clustering antibody could potentially treat both by reactivating a signaling complex known as ALK1, according to CEO Alex Lugovskoy.

“By addressing the underlying defect in these diseases, we believe our approach could offer significant benefits to patients,” Lugovskoy explained.

Hereditary hemorrhagic telangiectasia impacts around 150,000 individuals across the U.S. and Europe. The disorder causes the formation of abnormal blood vessels, which can rupture and result in bleeding and persistent anemia. Current treatments only manage symptoms, highlighting the need for a therapy like DIAG723 that could tackle the disease at its source.

In the field of pulmonary arterial hypertension, competition is stronger. Recently, Merck & Co.’s Winrevair received approval, joining other established treatments such as Johnson & Johnson’s Opsumit and Uptravi, as well as United Therapeutics’ Tyvaso, all of which help manage symptoms. Nevertheless, Lugovskoy believes DIAG723 could work alongside these therapies, offering additional benefits to patients.

Beyond DIAG723, Diagonal’s pipeline includes early-stage candidates aimed at treating iron overload and chronic kidney disease.

The Series B funding was co-led by Sanofi Ventures and Janus Henderson Investors, with participation from over a dozen investors. Lugovskoy noted that Sanofi’s expertise in hematology and Janus Henderson’s deep understanding of drug development made them ideal partners for this round.

• Other investors included Deep Track Capital, Atlas Venture, RA Capital Management, Frazier Life Sciences, and Viking Global Investors.

Since emerging from stealth mode in 2024, Diagonal Therapeutics has raised over $250 million to support its mission of developing novel therapies for challenging diseases.