Cancer Immunologists Win Nobel Prize in Medicine
20 November 2018
Researchers James Allison and Tasuku Honjo have won the 2018 Nobel Prize in Medicine or Physiology for their pioneering work on cancer immunotherapy.
Hailed as a revolution in the treatment of cancer, immunotherapy works by boosting the body’s natural defences against cancer. The immune system has an innate ability to seek out and destroy cancer cells. However, cancer cells can develop cunning ways to avoid this surveillance system.
One trick used by cancer cells is to hijack immune “checkpoints” – systems normally put in place to dampen down immune responses after infection. Two such checkpoints involve proteins called CTLA-4 and PD-1, which were studied by Allison and Honjo, respectively, in the 1990s. First in animal experiments and later in clinical trials, they found that, by blocking CTLA-4 or PD-1, the brakes on the immune system could be released, giving immune cells back the power to fight cancer. The results were dramatic; in a cohort of advanced melanoma patients treated with a CTLA-4-blocking drug, over 20% survived for 10 years or more. This compares to a historical 5 year survival rate of less than 10%, making it the first drug to extend the lives of patients with late-stage melanoma. In 2011, the U.S. Federal Drug Administration approved a CTLA-4-blocking therapy for the treatment of melanoma, while a PD-1-blocking drug received regulatory approval in 2014.
The remarkable success of checkpoint-inhibiting therapies has sparked a revolution in the way cancer is viewed and treated. Immunotherapy now stands alongside chemotherapy, radiotherapy and surgery as a mainstay of cancer treatment. Nevertheless, immunotherapy is currently only effective in a subset of patients, and for a subset of cancer types. The next step for researchers is to increase the number of patients who could benefit from this approach.
With funding from Cancer Research UK and PsiOxus therapeutics, scientists from the Department of Oncology at the University of Oxford are developing innovative cancer immunotherapies based on viruses. Cancer-killing, or “oncolytic”, viruses are able to infect and destroy cancer cells while leaving normal cells unharmed. Crucially, the way in which oncolytic viruses kill cancer cells can be very inflammatory, meaning that the immune system is alerted to the presence of a tumour. Because the viruses kill cancer cells based on many more characteristics than can be targeted by any single drug, they have the potential to treat even more patients with different types of cancer.
It is hoped that, with continued research, the remarkable achievements of the new Nobel Laureates can be built upon, and the enormous potential of cancer immunotherapy realised.