Medicine Nobel 2025 awarded to Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi — all about the US-Japanese trio

Three scientists have been jointly awarded the Nobel Prize in Physiology or Medicine for their pioneering discoveries concerning the immune system. These findings have opened up new avenues for research and the development of therapies for cancer and autoimmune diseases.

The Nobel Assembly at the Karolinska Institutet in Stockholm announced on Monday that Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi will share the 11 million-krona ($1.2 million) prize.

2025 Nobel Laureates in Medicine: All you need to know

Mary E. Brunkow (US): She holds the position of Senior Program Manager at the Institute for Systems Biology in Seattle, US. She and Fred Ramsdell were credited with the key discovery of the FOXP3 gene, which shows that a mutation in this gene causes a severe autoimmune disease (IPEX) and is crucial for Treg cell function.

• Fred Ramsdell (US): He is the Chief Scientific Officer at Sonoma Biotherapeutics, a company based in San Francisco that focuses on developing engineered regulatory T cell therapies. Ramsdell's work, alongside Brunkow, was central to linking the FOXP3 gene to immune regulation.
• Shimon Sakaguchi (Japan): He is a Distinguished Professor at the Immunology Frontier Research Center (IFReC) at Osaka University, Japan. He is best known for his initial discovery and characterisation of regulatory T cells, demonstrating their indispensable role in maintaining self-tolerance.

The three scientists were recognized “for their groundbreaking discoveries concerning peripheral immune tolerance that prevents the immune system from harming the body”, the Nobel Committee said.

They “identified the immune system’s security guards, regulatory T cells, thus laying the foundation for a new field of research”.

In a social media post on X, the official handle of The Nobel Prize said: “Mary Brunkow and Fred Ramsdell – who have been awarded the 2025 Nobel Prize in Physiology or Medicine – gained decisive insights into how autoimmune diseases arise. Brunkow and Ramsdell made a key discovery in 2001, when they presented the explanation for why a specific mouse strain (named scurfy) was particularly vulnerable to autoimmune diseases.”

“The medicine laureates had discovered that the mice have a mutation in a gene that they named Foxp3. They also showed that mutations in the human equivalent of this gene cause a serious autoimmune disease, IPEX,” it added.

The discoveries have also led to the development of potential medical treatments that are now being evaluated in clinical trials, the Committee observed.