What Zag Bio does

Zag Bio is a Cambridge, Massachusetts-based, privately held biotechnology company developing thymus-targeted bifunctional antibody medicines designed to restore immune tolerance in autoimmune diseases. The company's scientific premise is that the thymus is the only site where self-antigens are presented to induce central T cell tolerance, and that disruption of this process underlies autoimmunity. Its platform engineers antibodies with a thymus-targeting variable domain, an engineered Fc region, and a peripherally fused self-antigen, enabling systemic delivery of disease-relevant antigens to thymic antigen-presenting cells. This promotes deletion of autoreactive T cells and generation of antigen-specific, epigenetically stable regulatory T cells (Tregs) that home to affected tissues and exert localized anti-inflammatory effects without broad immunosuppression.

The company's lead program, ZAG-101, targets pancreatic beta-cell antigens for the disease-modifying treatment of Type 1 diabetes, addressing the approximately 1.5 million U.S. and 9.5 million global patients who currently rely on lifelong insulin therapy without correcting the underlying autoimmune pathology. First-in-human clinical studies are targeted for late 2026, with CMC manufacturing established through a January 2026 partnership with ProBioGen. Discovery-stage programs are also underway in autoimmune indications affecting the gastrointestinal tract, skin, and nervous system, leveraging the platform's modular design.

Zag Bio is pre-revenue and funded by an $80 million Series A closed in October 2025, co-led by Polaris Partners and T1D Fund with participation from AbbVie Ventures, Sanofi Ventures, Regeneron Ventures, Lightspeed Ventures, Mission BioCapital and others. The company is led by CEO Jason F. Cole, CMO Jan Hillson (formerly of Provention Bio), COO Alison Conlon, and CSO and co-founder John Kulman (formerly of CRISPR Therapeutics), with scientific co-founder Diane Mathis of Harvard Medical School providing the foundational immunology expertise. Long-term revenue is expected to be generated through pharmaceutical sales of approved biologics distributed via specialty pharmacy networks and direct provider channels.

Name

Zag Bio

Legal name

Zag Bio, Inc.

Website

https://zagbio.com

Company type

Private

Founded year

2025

Operating status

Operating

Headcount range

11–50 employees

Short description

Zag Bio is a Cambridge, MA-based pre-clinical biotechnology company developing thymus-targeted bifunctional antibody therapies to restore immune tolerance in autoimmune diseases, with lead program ZAG-101 advancing toward first-in-human studies in Type 1 diabetes by late 2026.

Ownership category

akta.pro rank

Product category

Autoimmune Disease Biologics

NAICS

Medical and Diagnostic Laboratories (62151), Medical Laboratories (621511)

SIC

In Vitro & In Vivo Diagnostic Substances (2835)

akta.pro primary industry

Monoclonal Antibody Therapeutics (mAbs) (HLAAAAAA)

Keywords

• Thymus-targeted antibodies
• Autoimmune disease therapy
• Bifunctional antibody medicines
• Central immune tolerance
• Biologic drug development

Headquarters

HQ city

Cambridge

HQ country

United States

HQ region

North America

Offices2 records

Markets served

GTM type

B2C

Offering type

Hardware or Manufacturing

Cost components

Personnel, Technology or R&D, Operations, Marketing or Sales, Infrastructure

Revenue model

1. Pharmaceutical Product Sales: Pre-revenue development stage biotech company. Revenue would be generated through sales of ZAG-101 and future thymus-targeted therapies for autoimmune diseases once approved. Typical biotech commercialization model with pricing based on therapeutic value and patient access programs.

Go-to-market motion1 record

Distribution channels3 records

Marketing channels5 records

Core offering

Zag Bio designs thymus-targeted bifunctional antibody medicines that deliver self-antigens directly to thymic antigen-presenting cells, inducing central T cell tolerance to address the root cause of autoimmunity rather than broadly suppressing the immune system. The lead clinical candidate ZAG-101 is being developed as a disease-modifying therapy for Type 1 diabetes, with the platform enabling additional pipeline programs across gastrointestinal, skin, and nervous system autoimmune indications.

Product overview

Zag Bio is a biotechnology company pioneering thymus-targeted medicines to treat and prevent autoimmune diseases. The company's core offering consists of ZAG-101, a lead disease-modifying therapy for Type 1 diabetes currently advancing toward clinical development (anticipated first-in-human study in late 2026), built upon a proprietary thymus-targeted bifunctional antibody platform. The platform enables the delivery of self-antigens to the thymus to induce central immune tolerance. Discovery programs are underway for autoimmune diseases affecting the gastrointestinal tract, skin, and nervous system.

Differentiator

Problem solved

Functional benefit

Products and services

• ZAG-101 A first-in-class, disease-modifying bifunctional antibody therapy for Type 1 diabetes that delivers pancreatic beta cell antigens to the thymus to restore immune tolerance, expand antigen-specific regulatory T cells, and protect beta cells from destruction in newly diagnosed or at-risk patients who still have functional beta cells.

Quantifiable outcome

• Antigen-specific Tregs uniquely suppress pathogenic immune responses at the site of autoantigen expression without broad immunosuppression
• +2 more outcomes

Segments2 records

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature4 records

Partnerships

One partnership is on record.

• ProBioGencoreStrategic or Co-development Partner · 7 January 2026ProBioGen signed a master service agreement with Zag Bio for cell line development, process development, and GMP manufacturing for Zag Bio's lead product ZAG-101, aimed at preventing or delaying Type 1 diabetes. Clinical development is targeted for late 2026.

Scale indicators4 records

Recent moves7 records

Expansion highlights5 records

Broad incumbents

• AbCellera Biologics: AbCellera is a public antibody discovery platform company partnering with pharma to generate therapeutic antibodies, including for autoimmune indications. Comparable as a bifunctional/therapeutic antibody platform company serving immunology markets.
• Vertex Pharmaceuticals: Vertex is advancing VX-880, a stem-cell-derived beta cell replacement therapy for T1D that, if successful, would address the disease by replacing destroyed cells rather than modulating immune response. Represents a competing modality in the same T1D indication Zag Bio targets.

Emerging players

• CRISPR Therapeutics: CRISPR Therapeutics developed Casgevy (the first CRISPR-based therapy), where Zag Bio CSO John Kulman previously served on executive leadership. Comparable as a gene-editing/biologics platform developing first-in-class therapies approved through novel mechanisms.
• SalioGen Therapeutics: SalioGen Therapeutics was a gene-insertion therapy company where Zag Bio CEO Jason Cole previously served as CEO and Chair. While SalioGen operated in a different modality, it represents prior leadership experience at a similar stage autoimmune/genetic-medicine biotech.

Direct peers

• Alpine Immune Sciences: Alpine Immune Sciences developed engineered protein therapies modulating immune pathways for autoimmune disease, recently acquired by Vertex for $4.9B. Listed as a previous employer of Zag Bio's CMO Jan Hillson, indicating overlap in clinical development expertise.
• Provention Bio (Sanofi): Provention Bio developed and commercialized Tzield (teplizumab), the only FDA-approved disease-modifying therapy for Type 1 diabetes. Zag Bio's CMO Jan Hillson led Tzield's clinical development there, making Provention the most directly relevant T1D therapeutic competitor.
• Abata Therapeutics: Abata Therapeutics develops Treg-based cell therapies for autoimmune diseases, including Type 1 diabetes, with co-founder Diane Mathis (same as Zag Bio) providing foundational tolerance biology. Direct peer in T1D tolerance-induction approach with shared scientific lineage.
• Trex Bio: Trex Bio is a Treg cell therapy company co-founded by Diane Mathis (also Zag Bio co-founder). Focuses on tissue-specific regulatory T cells for autoimmune disease, sharing scientific foundation and tolerance-induction approach with Zag Bio.
• Seismic Therapeutic: Seismic Therapeutic is an immunology-focused biotech co-founded by Zag Bio co-founder Jo Viney (current CEO). Develops biologics for autoimmune and inflammatory diseases, making it a closely aligned peer in stage, focus, and founding team overlap.
• Pandion Therapeutics: Pandion Therapeutics developed engineered Tregs and immune-modulating biologics for autoimmune diseases, founded by Zag Bio co-founders Alan Crane and Jo Viney, and acquired by Merck for $1.85B. Represents a successful prior instantiation of the autoimmune tolerance approach.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat4 records

Key risks5 records

Key highlights6 records

Customer concentration

• LinkedInlinkedin.com/company/zag-bio

Revenue estimate

Valuation estimate

Number of profiles

Profiles7 records

Funding overview

Funding rounds2 records

Investors10 records

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Zag Bio