People who received a personalised melanoma skin cancer vaccine on top of a standard treatment were 44 per cent less likely to die over the study period than those who had the standard treatment alone
15 December 2022
Custom-made cancer vaccines that prime an individual’s immune system to attack the unique biology of their tumour have halted the progression of melanoma skin cancer in almost half the people taking part in a randomised clinical trial.
We may typically think of vaccines as being used to prevent infections, but there is growing interest in using them to treat medical conditions, particularly cancer. The idea of a vaccine is to help the immune system battle a foreign agent, be it a virus or cancer cell.
The trial was carried out by the pharmaceutical company Moderna, which made the personalised cancer vaccines using similar mRNA technology to its covid-19 vaccines. The trial was made up of 157 people in the US and Australia who had recently undergone surgery to remove melanomas but were at a high risk of developing new tumours because some cancer cells had spread to other parts of their body.
All of the participants received an existing melanoma immunotherapy treatment called pembrolizumab, sold under the brand name Keytruda. Two-thirds were also injected with a personalised cancer vaccine.
The vaccines were made by first identifying the unique set of proteins on each participant’s melanoma. Researchers then created mRNA that would instruct the participant’s cells to make snippets of up to 34 of these proteins once the mRNA is injected. The vaccine therefore trained the individual’s immune system to recognise and attack cancer cells expressing these proteins.
The participants who received a personalised vaccine plus pembrolizumab were 44 per cent less likely to develop new tumours or die over the follow-up period of up to three years, compared with those who were treated with pembrolizumab alone, according to a Moderna news release.
“The exciting thing is that you’re using people’s own tumours as the triggers for the vaccination so hopefully there will be better [cancer] outcomes in the long term because it’s tumour-specific,” says Kerwin Shannon at Chris O’Brien Lifehouse, a cancer hospital in Sydney, Australia.
The vaccine, which was injected nine times across a year, was also safe, says Georgina Long at the University of Sydney, who was involved in the Australian arm of the trial. Side effects included redness at the injection site or flu-like symptoms for a few days, she says.
Vaccines for treating cancer have been in development for decades but have mostly failed due to the variability between people’s tumours.
To overcome this challenge, several research groups have been developing personalised cancer vaccines since around 2014, with generally promising results. Moderna’s trial is the largest reported so far and the only one with a randomised controlled design.
The company is planning a trial of 1000 people with melanoma that should begin in 2023.
Most trials of personalised cancer vaccines have been in people with melanoma, since this type of cancer expresses a wide range of proteins on its surface that can be targeted with vaccines. Moderna has said it plans to rapidly expand its personalised vaccines to target additional tumour types following these promising melanoma results.
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