# Diagonal Therapeutics

> Diagonal Therapeutics is a Watertown, Massachusetts biotech building 'clustering antibodies' - multi-specific, agonist antibodies that bind two or more cell-surface receptors at once to switch broken signaling pathways back on. Its DIAGONAL Product Engine combines computational and experimental screening to sift billions of antibody combinations for the rare ones that restore receptor activity. The lead program, DIAG723, restores dysregulated ALK1 signaling to address the root cause of hereditary hemorrhagic telangiectasia (HHT) and pulmonary arterial hypertension (PAH). Founded by Alex Lugovskoy with Atlas Venture, the company launched in 2024 with a $128M Series A and raised an oversubscribed $125M Series B in January 2026 to push DIAG723 into the clinic.

- **Founded:** 2022
- **Headquarters:** Watertown, Massachusetts, United States
- **Founders:** Alex Lugovskoy (Co-Founder & Chief Executive Officer)
- **Team size:** ~28 employees
- **Products:** DIAGONAL Product Engine, DIAG723, Disease-modifying antibody pipeline
- **Notable:** Raised a combined ~$253 million across Series A ($128M, 2024) and Series B ($125M, 2026)., Built the DIAGONAL Product Engine to systematically discover rare agonist 'clustering' antibodies., Advanced DIAG723 with disease-modifying activity in multiple preclinical models of HHT and PAH.

## Products & services

- **DIAGONAL Product Engine** — A proprietary platform that combines computational and experimental techniques to search billions of antibody combinations for rare clustering/agonist antibodies that bind two or more receptors and reactivate impaired signaling pathways.
- **DIAG723** — Lead program: a first-in-class clustering antibody that restores dysregulated ALK1 receptor signaling to address the root cause of hereditary hemorrhagic telangiectasia (HHT) and pulmonary arterial hypertension (PAH). A first-in-human trial in HHT was expected to begin in the first half of 2026.
- **Disease-modifying antibody pipeline** — A broader pipeline of multi-specific, signal-restoring antibodies aimed at conditions where receptor signaling has been disrupted.

## Achievements

- Raised a combined ~$253 million across Series A ($128M, 2024) and Series B ($125M, 2026).
- Built the DIAGONAL Product Engine to systematically discover rare agonist 'clustering' antibodies.
- Advanced DIAG723 with disease-modifying activity in multiple preclinical models of HHT and PAH.
- Moved from stealth toward a planned first-in-human trial in HHT in the first half of 2026.
- Attracted a syndicate including Atlas Venture, BVF Partners, Sanofi Ventures, and Janus Henderson.

## Latest updates

- **2026-01** — Announced an oversubscribed $125M Series B co-led by Sanofi Ventures and Janus Henderson to advance DIAG723 and the clustering-antibody pipeline; Paulina Hill of Sanofi Ventures joined the board.
- **2024-10** — Presented at Cure HHT's 15th International Scientific Conference.
- **2024-04** — Emerged from stealth with a $128M Series A co-led by BVF Partners and Atlas Venture to build the DIAGONAL platform and pipeline.

## Links

- Website: https://diagonaltx.com
- LinkedIn: https://www.linkedin.com/company/diagonal-therapeutics

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Profile page: https://yespress.io/diagonal-therapeutics
Published by YesPress — https://yespress.io
Last updated: 2026-06-15