In research published on Tuesday in the prestigious Nature journal, researchers from Melbourne’s Peter Doherty Institute and Telethon Kids Institute revealed they had discovered that the T cells had the ability to halt the growth of melanoma cells.
The cells were able to control the tumour in mice for the life of the animal, which was likely to equate to decades of protection in humans, said the paper’s lead author Simone Park.
“What we found was that the cells are capable of basically inducing a state of dormancy of the tumour, like putting the cancer to sleep,” Ms Park said.
“The cancer cells aren’t completely killed. They are still there, but they are held in check by the tissue-resident memory T cells.”
Ms Park, a PhD student with the University of Melbourne, said the breakthrough was made using a novel system whereby scientists were able to monitor melanoma cells and T cells under the microscope using fluorescent markers.
“What we could see was that the T cells were constantly patrolling the skin and watching over these melanoma tumour cells,” she said.
The scientists were also able to remove the T cells from mice with dormant melanomas and found that once the cells were gone the tumours were then able to escape or grow, highlighting the importance of the immune cells in controlling the spread of cancer.
Melanoma remains the fourth most commonly diagnosed cancer in Australia, behind breast cancer, prostate cancer and colorectal cancer. Australia and New Zealand have the world’s highest incidence rate for melanoma.
Although it has a promising survival rate of more than 90 per cent at five years, it still kills an estimated 1900 Australians every year, most of them men.
This year it is expected that a further 14,320 Australians will be diagnosed with the skin cancer.
Ms Park said it was hoped that the research could help lead to better treatment for melanoma tumours in the future.
“By showing these cells are important for controlling cancer … we’ve shown that they are going to be good targets for future design of immunotherapy,” she said.
“And this is something we are actively investigating.”
The paper’s senior author, Associate Professor Thomas Gebhardt, said an increase of tissue-resident memory T cells had already been associated with better outcomes in cancer patients, but the way they worked was unknown.
“We now have a much better understanding of which T cells are important in controlling skin cancers and how these cells are working, but there is still much more work to do to make these cells work even better,” he said.
Aisha Dow reports on health for The Age and is a former city reporter.