The Karolinska Institute in Sweden announced that the 2025 Nobel Prize in Physiology or Medicine will be awarded to Professor Shimon Sakaguchi of Osaka University, Dr. Mary Brankou of the Institute for Systems Biology, and Dr. Fred Ramsdell of Sonoma Biotherapeutics. Professor Sakaguchi discovered “regulatory T cells,” which act as brakes to suppress immune responses. This discovery paves the way for developing new treatments for diseases such as allergies, autoimmune disorders like type 1 diabetes, and cancer.

This marks the 26th Nobel Prize in the natural sciences awarded to a Japanese national (including those with U.S. citizenship), following Senior Researcher Toshio Manabe of Princeton University, who won the 2021 Physics Prize. It is the sixth Physiology or Medicine Prize for a Japanese recipient, following Special Professor Tasuku Honjo of Kyoto University in 2018. With the 2024 Peace Prize awarded to the Japan Confederation of A- and H-Bomb Sufferers Organizations, this makes two consecutive years of Nobel Prizes for Japan.