Nobel Prize won by scientists who discovered revolutionary way to attack cancer cells

The Nobel Prize for Medicine has been given to two scientists who found a revolutionary new way of treating cancer.

American James P Allison and Japanese Tasuku Honjo found that the body's own immune system could be turned on cancers, marking a major breakthrough in our fight against the disease.

Professor Allison studied a protein that functions as a brake on the immune system. He realised the potential of releasing the brake and unleashing immune cells to attack tumours, and developed this concept into a new approach for treating patients.

Professor 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," the Nobel committee wrote in their citation.

They will share the prize, which is worth 9 million Swedish kronor or roughly £800,000.

"Cancer kills millions of people every year and is one of humanity’s greatest health challenges. By stimulating the inherent ability of our immune system to attack tumour cells this year’s Nobel Laureates have established an entirely new principle for cancer therapy," the Nobel committee wrote.

Scientists have long thought that it might be possible to use the immune system – which has the central job of finding things that don't belong in the body and getting rid of them – and turn it on cancerous cells in the body. Despite numerous attempts, that has yielded few practical results, in part because the "brake" in the body stops immune cells from attacking cancers.

But the discovery of the two new Nobel laureates was a way of taking off that brake, allowing the body to attack its own cancerous tumours. It has already had spectacular results.

"For more than 100 years scientists attempted to engage the immune system in the fight against cancer," the committee wrote. "Until the seminal discoveries by the two laureates, progress into clinical development was modest. Checkpoint therapy has now revolutionized cancer treatment and has fundamentally changed the way we view how cancer can be managed."

Professor Allison said in a statement that he had made the discovery while simply looking to expand human knowledge.

"I'm honored and humbled to receive this prestigious recognition," he said. "A driving motivation for scientists is simply to push the frontiers of knowledge. I didn't set out to study cancer, but to understand the biology of T cells, these incredible cells that travel our bodies and work to protect us."

Last year, the same prize was given to three scientists – Jeffrey C Hall, Michael Rosbash and Michael W Young – who made pioneering discoveries about how the body clock works in humans. Those same discoveries could help vastly improve the way people sleep.

The physics prize will be awarded on Tuesday, with chemistry the following day. The Nobel Peace Prize will be given on Friday and the economics winner will be announced on Monday.

There is no literature prize given this year, because of an ongoing scandal over sex abuse allegations. Instead, the 2018 winner will be given the prize alongside the 2019 winner.