Brunkow, Ramsdell, Sakaguchi Win 2025 Nobel for Tolerance

The 2025 Nobel Prize in Physiology or Medicine was awarded jointly to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi for uncovering how the immune system enforces “peripheral immune tolerance” via regulatory T cells (Tregs); the award was announced Oct. 6 in Stockholm. Sakaguchi first identified Tregs in 1995, and Brunkow and Ramsdell in 2001 traced a mutation in the FOXP3 gene that disrupts Treg development and causes the severe autoimmune disorder IPEX. Their discoveries explain why the immune system usually avoids attacking the body and opened a field that is driving development of therapies for autoimmune diseases, cancer and transplant rejection, with some approaches now in clinical trials. Nobel Committee chair Olle Kämpe called the work decisive and emphasized its therapeutic potential, while the committee stressed the prize recognizes a foundational basic-science breakthrough rather than a single marketed therapy; widely used drugs directly based on these findings have not yet been established. The three laureates — Brunkow (Seattle), Ramsdell (Sonoma Biotherapeutics) and Sakaguchi (Japan) — will share the 11 million Swedish kronor prize.