Wolchok said "an untold number of lives ... have been saved by the science that they pioneered". Releasing the brake allowed immune cells to attack tumors, he found.
Following the discovery of the protein in 1992, Honjo presented his research in 2002 showing that a drug that prevents the unification of cancer cells and the PD-1 protein is effective against cancer in animals.
"Everybody wanted to do chemotherapy and radiation". They are caused by an overactive immune response leading to autoimmune reactions but are usually manageable.
Allison, chair of Immunology and executive director of the Immunotherapy Platform at the University of Texas MD Anderson Cancer Center, studied a protein that functions as a brake on the immune system.
For more than 100 years scientists attempted to engage the immune system in the fight against cancer. "A driving motivation for scientists is simply to push the frontiers of knowledge".
He showed that PD-1 functions as a brake on T-cell function. Around the same time, Honjo discovered a similar role for another immune checkpoint, PD-1.
A member of his golf club approached him and thanked him for his efforts, he said. "That was a blissful moment".
"I never dreamed my research would take the direction it has".
The winners of this year's physics prize will be announced on Tuesday, followed by the chemistry prize on Wednesday.
CHECKPOINT INHIBITORS Drugs known as checkpoint inhibitors can physically block the checkpoint, which frees the immune system to attack the cancer.
Tasuku Honjo of Kyoto University heads to the venue for a press conference in Kyoto.
"I don't know if I could have accomplished this work anywhere else than Berkeley", Allison said in the press release. Many checkpoint therapy trials are now underway against most types of cancer, and new checkpoint proteins are being tested as targets. The prizes for achievements in science, literature and peace were created in accordance with the will of dynamite inventor and businessman Alfred Nobel and have been awarded since 1901. No literature prize is being given this year.
Heintz reported from Moscow.
Allison went into cancer research because he always wanted to be the first person to figure something out.