Tasuku Honjo (born 1942) is a Japanese physician-scientist and immunologist from Kyoto. After graduating from Kyoto University’s Faculty of Medicine, he conducted research at the Carnegie Institution and the US National Institutes of Health, later serving as a professor at Osaka University and Kyoto University. His research clarified mechanisms through which antibodies diversify their functions, and in 1992 his team discovered PD-1, a protein that restrains immune-cell activity. Blocking this molecular brake enabled the immune system to attack cancer cells and led to the development of a new class of cancer immunotherapies. Honjo shared the 2018 Nobel Prize in Physiology or Medicine with James P. Allison for this achievement. His representative book, “Gan Men’eki Ryōhō to wa Nani ka,” traces the path from the discovery of PD-1 to the development of treatments and explains the mechanisms, clinical effects, and remaining challenges of cancer immunotherapy.
