The Nobel Assembly at Karolinska Institutet has awarded the 2018 Nobel Prize in Physiology or Medicine to James P. Allison and Tasuku Honjo for discovering how the immune system can fight off cancer.
James P. Allison studied a known protein that operates as a brake on the immune system. He figured out how this brake could be utilized as a weapon to pounce on tumors. With his discovery, he eventually came up with new treatment approach.
Tasuku Honjo also discovered a protein on immune cells that functions as a brake, but with a different mechanism of action.
Source: The Nobel Prize