"Allison and Honjo showed how different strategies for inhibiting the brakes on the immune system can be used in the treatment of cancer", the Nobel Assembly at Sweden's Karolinska Institute said, on awarding 9 million Swedish crowns ($1.28 million Cdn).
"By stimulating the inherent ability of our immune system to attack tumor cells this year's Nobel Laureates have established an entirely new principle for cancer therapy", the Nobel Prize Foundation said in a statement.
The discoveries by Allison, 70, and Honjo, 76, "absolutely paved the way for a new approach to cancer treatment", Dr. Jedd Wolchok, chief of the melanoma and immunotherapeutics service at the Memorial Sloan Kettering Cancer Center in NY, told The Associated Press.
US drugmakers Merck & Co and Bristol-Myers Squibb now lead the field after winning drug approvals in 2014, but Roche, AstraZeneca, Pfizer and Sanofi are also fielding rivals. Such treatment is also called "checkpoint therapy", a term that inspired the name of the Checkpoints, a musical group of cancer researchers in which Allison plays harmonica.
Allison's interest in the immune system was deepened by an experiment he conducted on mice when he was a graduate student.
Unlike more traditional forms of cancer treatment that directly target cancer cells - often with severe side-effects - Allison and Honjo figured out how to help the patient's own immune system tackle cancer more quickly.
"I was doing basic science to do basic science, but you know, I had the good opportunity to see it develop into something that actually does people good", Allison has said.
Research by Allison's team has meanwhile led to the development of a monoclonal antibody drug, which was approved by the US Food and Drug Administration (FDA) in 2011 for the treatment of melanoma.More news: Krishna Raj Kapoor passes away
More news: Liverpool boss Klopp: Sarri style gives us chance at Chelsea
More news: Mental health struggles surface for Vikings' Everson Griffen
Charles Swanton, chief clinician at the charity Cancer Research UK, said the scientists' work had revolutionised cancer and immunotherapy.
"When Dana showed me the results, I was really surprised", Allison said.
Meanwhile, Allison left UC Berkeley in 2004 for Memorial Sloan Kettering research center in NY to be closer to the drug companies shepherding his therapy through clinical trials, and to explore in more detail how checkpoint blockade works.
In this video about UC Berkeley's new Immunotherapeutics and Vaccine Research Initiative (IVRI), Allison discusses his groundbreaking work on cancer immunotherapy. In 2013, Science magazine named cancer immunotherapy its Breakthrough of the Year, citing Allison's work as crucial to immunotherapy's rapid advancement, and The Economist honoured him with its Innovations Award in Bioscience.
"In some patients, this therapy is remarkably effective", Jeremy Berg, editor-in-chief of the Science family of journals, told the AP.
Lanier adds he has nominated Allison for the Nobel several times, but that it probably took the committee some time to figure out who deserved to receive it alongside him. The academy hopes to award both the 2018 prize and the 2019 literature prize next year.
The Nobel Prize is the world's most prestigious annual award for outstanding work in physics, chemistry, physiology or medicine, literature and promotion of peace.