A personalised cancer vaccine given alongside a widely used immunotherapy drug cut the risk of death or recurrence from melanoma by 42% in a large clinical trial, in results researchers say could mark a turning point for personalised cancer treatment.
The trial enrolled 1,137 adults who had already had their melanoma tumours surgically removed. All received Keytruda, an established immunotherapy drug, while about two-thirds also received intismeran, an experimental vaccine that uses the same mRNA technology as some Covid-19 jabs. Unlike a conventional vaccine, intismeran is personalised: it is built from information drawn from each patient's own tumour to train their immune system to recognise and attack cancer cells if they return.
'A fabulous technology'
Two years after starting treatment, 82% of patients who received the vaccine alongside Keytruda were alive without recurrence, compared with 70% of those who received Keytruda and a placebo — a 42% reduction in the risk of death or recurrence. The combination also cut the risk of the cancer spreading to a new part of the body by 38% over the same period.
"Personalisation is the next step up and it's really exciting, it's a fabulous technology," said Professor Pippa Corrie, a consultant medical oncologist who helped run part of the study at Addenbrooke's Hospital in Cambridge. "The question is how much can we really demonstrate it's worth, and this trial was the first proof of principle." One of her patients, 75-year-old Tony Chapman, enrolled after his melanoma returned following initial surgery in 2019; three years on, he remains cancer-free, though like other participants he still does not know whether he received the vaccine or a placebo. "This just seemed like a really good example of moving science forward," he said.
Drugmakers Merck (known as MSD outside the US) and Moderna said the treatment effect, while strong, was somewhat less pronounced than in an earlier, smaller Phase 2 trial, which had shown a 49% reduction in risk. Independent experts, including Professor Alan Melcher of the Institute of Cancer Research in London, called the Phase 3 results "very impressive" but cautioned that "we shouldn't get ahead of the evidence" on whether the approach ultimately extends patients' lives, since the trial will continue tracking participants over time.
Both companies said they are now in discussions with regulators and could seek approval as soon as next year, with the full data submitted to the New England Journal of Medicine. The same approach is already being tested against kidney, bladder and lung cancers, though wider rollout will hinge on cost: each dose requires a patient's tumour to be individually sequenced and a vaccine manufactured specifically for them.