Zag Bio Recruits Experienced Immunologist as Chief Medical Officer

Jan Hillson brings expertise in autoimmune disease biology to lead clinical development of thymus-targeted therapies

Published on Feb. 24, 2026

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Klein Hersh, a life sciences and healthcare executive search firm, has recruited Jan Hillson as the new chief medical officer of Zag Bio, a biotechnology company pioneering thymus-targeted medicines in Cambridge, MA. Hillson is a physician-scientist and rheumatologist with over 20 years of clinical development experience in autoimmune and inflammatory diseases. She will oversee Zag's clinical strategy and pipeline advancement as the company prepares to advance its lead program, ZAG-101 for Type 1 diabetes, into the clinic.

Why it matters

Zag Bio is taking a novel approach to treating autoimmune diseases by targeting the thymus to restore immune tolerance, which has the potential to address the underlying drivers of conditions like Type 1 diabetes where durable disease-modifying treatments remain limited. Hillson's deep expertise in immunology and autoimmune disease biology will be critical as Zag moves its lead candidate towards the clinic.

The details

As chief medical officer, Hillson will lead Zag's clinical team and guide the development strategy and execution for the company's pipeline of thymus-targeted therapies. Her prior experience includes senior roles at Provention Bio, Climb Bio, GlycoEra, and other biotechs where she helped advance therapies for autoimmune and inflammatory diseases. Hillson will be instrumental in preparing Zag's lead program, ZAG-101 for Type 1 diabetes, for a first-in-human study anticipated in late 2026.

  • Zag Bio expects to initiate a first-in-human study for its lead program ZAG-101 in late 2026.

The players

Jan Hillson

A physician-scientist and rheumatologist with over 20 years of clinical development experience in autoimmune and inflammatory diseases, who will serve as the new chief medical officer of Zag Bio.

Jason Cole

The CEO of Zag Bio, a biotechnology company pioneering thymus-targeted medicines in Cambridge, MA.

Zag Bio, Inc.

A biotechnology company advancing a novel approach to treating autoimmune diseases by targeting the thymus to restore immune tolerance.

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What they’re saying

“Jan joins Zag at a pivotal moment as we transition from research into clinical development. She brings extensive expertise in immunology and rheumatology, along with firsthand experience advancing disease-modifying therapies for Type 1 diabetes. Jan's deep understanding of autoimmune disease biology will be critical as we prepare ZAG-101 for the clinic and build a broader pipeline of thymus-targeted therapies.”

— Jason Cole, CEO, Zag Bio (huntscanlon.com)

“Zag is advancing a fundamentally different approach to treating autoimmune disease by targeting the thymus to restore immune tolerance. This strategy has the potential to address the underlying drivers of autoimmunity rather than simply managing the metabolic outcomes for Type 1 diabetes, a disease with significant unmet need where durable disease-modifying treatments remain limited. I'm excited to join the team as Zag moves toward the clinic and works to build a pipeline designed to retrain the immune system and change the course of autoimmune disease.”

— Jan Hillson, Chief Medical Officer, Zag Bio (huntscanlon.com)

What’s next

Zag Bio expects to initiate a first-in-human study for its lead program ZAG-101 in late 2026 as the company advances its novel thymus-targeted approach to treating autoimmune diseases.

The takeaway

Zag Bio's recruitment of an experienced immunologist and rheumatologist as chief medical officer underscores the company's commitment to developing innovative, disease-modifying therapies for autoimmune conditions like Type 1 diabetes where current treatments remain limited.