Nobel Prize Win Starts to Feel Real for Sakaguchi; Laureate Hopes to Apply Findings to Medical Treatments

The Yomiuri Shimbun

16:37 JST, October 7, 2025

It was starting to feel real to Shimon Sakaguchi on Tuesday — he did in fact win the 2025 Nobel Prize in Physiology or Medicine.

“I’m a bit sleep-deprived, because I kept reading congratulatory messages from a lot of people, but today I finally started to realize that I actually won the prize,” said Sakaguchi, 74, as he was greeted with applause by about 80 students and others at the University of Osaka in Suita, Osaka Prefecture.

Sakaguchi is a specially appointed professor at the University of Osaka. Informed Monday that he had received the prize, he went to the university on Tuesday to report his award to its president and others.

The prize was jointly awarded to Sakaguchi, Mary Brunkow and Fred Ramsdell for “their discoveries concerning peripheral immune tolerance.”

Hepatitis treatment

In an exclusive interview with The Yomiuri Shimbun on Tuesday, Sakaguchi talked about his enthusiasm for applying his research findings to medical treatment.

“Next year, I want to advance to the medical applications of my research findings,” said Sakaguchi, who is aiming to treat hepatitis caused by autoimmune diseases. He has established a startup called RegCell, Inc. to realize such applications.

The regulatory T cells (Tregs) he discovered help maintain immune tolerance and prevent autoimmune diseases.

“Research is advancing worldwide toward treating various autoimmune diseases. The immune system is also involved in the organ rejection that can occur after organ and bone-marrow transplants. [Tregs] are expected to have a broad range of applications, including for the treatment of type 1 diabetes and rheumatoid arthritis,” he said.

Research is also advancing on improving cancer immunotherapy by reducing the Tregs surrounding cancer cells. More than 200 clinical trials involving Tregs are currently underway worldwide.

People with autoimmune diseases and others have shared with Sakaguchi their hopes for progress in treatments, and their worries about the illnesses. He said he wants them to keep up hope — “Medicine and science move forward. We’ll find better treatments than what existed decades ago.”

Shimon Sakaguchi

Born in 1951, Sakaguchi is from Nagahama, Shiga Prefecture. He graduated from Kyoto University’s Faculty of Medicine in 1976 and earned his MD from the university in 1983. He was appointed professor at the University of Osaka’s Immunology Frontier Research Center in 2011 and became a specially appointed professor at the center in 2016. He won the Japan Academy Prize in 2012, the Canada Gairdner International Award in 2015, the Crafoord Prize in 2017 and the Robert Koch Award in 2020. He was awarded the Order of Culture in 2019.