# Zag Bio

> Zag Bio is a Cambridge, Massachusetts biotechnology startup pioneering thymus-targeted medicines for autoimmune disease. Founded and incubated by Polaris Partners and launched in October 2025 with an $80M Series A, the company designs bifunctional antibodies that ferry self-antigens directly into the thymus - the organ that trains immune cells - to re-teach the body to tolerate its own tissue rather than attack it. Its lead program, ZAG-101, aims to prevent or delay Type 1 diabetes by inducing durable, antigen-specific central tolerance instead of broad immunosuppression.

- **Founded:** 2025
- **Headquarters:** Cambridge, Massachusetts, United States
- **Founders:** Alan Crane (Co-Founder & Chair; Entrepreneur Partner at Polaris Partners), Diane Mathis (Co-Founder; Professor of Immunobiology, Harvard Medical School), John Kulman (Co-Founder & Chief Scientific Officer), Jo Viney (Co-Founder; autoimmune disease drug-development executive)
- **Team size:** ~26 employees
- **Products:** Thymus-targeted bifunctional antibody platform, ZAG-101, Discovery pipeline
- **Notable:** Launched in October 2025 with an $80M Series A, Attracted three major pharma venture arms - AbbVie, Sanofi, and Regeneron - into a single round, Co-founded by Harvard Medical School immunobiologist Diane Mathis

## Products & services

- **Thymus-targeted bifunctional antibody platform** — Engineered bifunctional antibodies that deliver self-antigens to specialized antigen-presenting cells inside the thymus, expanding antigen-specific thymic regulatory T cells (Tregs) while depleting self-reactive T effector cells to induce durable central tolerance.
- **ZAG-101** — Lead program for Type 1 diabetes; delivers pancreatic beta-cell antigens to the thymus as a tolerogenic therapy to prevent or delay disease onset. IND-enabling studies underway with a goal of entering the clinic around late 2026.
- **Discovery pipeline** — Earlier-stage thymus-targeted programs aimed at other antigen-specific autoimmune diseases.

## Achievements

- Launched in October 2025 with an $80M Series A
- Attracted three major pharma venture arms - AbbVie, Sanofi, and Regeneron - into a single round
- Co-founded by Harvard Medical School immunobiologist Diane Mathis
- Advancing ZAG-101 through IND-enabling studies toward a clinic goal around late 2026
- Developed a novel approach to make the previously drug-inaccessible thymus a therapeutic target

## Latest updates

- **2025-10** — Zag Bio launched publicly with $80M in Series A financing and named Jason F. Cole, J.D., as CEO; outlined ZAG-101 for Type 1 diabetes.

## Links

- Website: https://zagbio.com
- LinkedIn: http://www.linkedin.com/company/zag-bio

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Profile page: https://yespress.io/zag-bio
Published by YesPress — https://yespress.io
Last updated: 2026-06-10