The Nobel Prize in Physiology or Medicine 2018 is jointly awarded to American James P. Allison and Japanese Tasuku Honjo. They were awarded for their discovery of cancer therapy by inhibition of negative immune regulation. In other words they discovered how to harness and manipulate the immune system to fight cancer. James P.Allison studied a protein that functions as a brake on the immune system. He realised the potential of releasing the brake and unleashing our immune cells to attack tumours. He developed this concept into a new approach for treating patients. Tasuku Honjo discovered a protein on immune cells and revealed that it also operates as a brake, but with a different mechanism of action. Therapies based on his discovery proved to be strikingly effective in the fight against cancer.