Landmark vaccine stops cancer returning in trial

Thousands of patients could benefit from personalised jab produced by 
Moderna and Merck to keep people free of the disease


A cancer vaccine personalised for each patient has succeeded in a large 
final-stage trial, raising hopes that a new generation of tailor-made 
treatments could benefit thousands of people.

The experimental vaccine, developed by Moderna and Merck, was given to 
patients with high-risk melanoma, a type of skin cancer, after they had 
surgery. The vaccine, named Intismeran, was accompanied by Keytruda, an 
immunotherapy drug already prescribed by the NHS for a dozen types of 
cancer.

The companies said the combination, compared with Keytruda alone, 
significantly extended the time patients remained free of cancer and 
also reduced the risk of the disease spreading to other organs.

Moderna and Merck are testing similar personalised vaccines for lung, 
bladder and kidney cancers. Lung cancer trials have reached the final 
stage 3 phase, while kidney and bladder studies are in phase 2. The hope 
is that the technology can work across many tumour types.

Researchers will want to see a more detailed breakdown of the results. 
However, shares in both companies surged in New York.

Stéphane Bancel, the Moderna chief executive, said that the latest 
results marked “a pivotal moment for the field of cancer research”.

He added: “For many years, the idea of creating an mRNA treatment 
designed specifically for an individual patient’s cancer was 
aspirational. We are now helping turn that vision into a reality.”

Professor Marco Gerlinger, of the Barts Cancer Institute, said: “I think 
it is fair to call it a breakthrough as it is the first phase 3 study 
that shows that a vaccine can protect against recurrences of one of the 
deadliest cancer types. This is certainly good news for patients with 
melanoma, but the study has much wider implications. It provides proof 
of principle that personalised cancer vaccines work.”

In the UK, half of people with melanoma skin cancer die within a year of 
diagnosis if it is spotted at stage 4. The disease claims about 2,300 
lives in total each year.

More than 1,000 patients took part in the phase 3 trial after having 
melanomas surgically removed. The patients had high-risk stage 2, 3 or 4 
melanoma, meaning they ranged from having large but localised tumours to 
cancers that had spread to other parts of the body.

Although the companies have not released detailed results, they said the 
study met both its principal goal of improving recurrence-free survival 
and an important secondary goal of preventing the cancer from spreading.

Cancer is becoming more common but fewer people are dying from it
The vaccine uses mRNA, a technology that became well known through Covid 
vaccines. Unlike conventional vaccines, which are usually designed to 
prevent infection, the treatment is made individually for each patient. 
After surgery, scientists analyse a sample of the tumour to identify 
mutations unique to its cancer cells.

They then encode selected targets into strands of mRNA, producing a 
vaccine designed to teach the immune system — particularly 
cancer-killing T cells — to recognise and attack any tumour cells that 
remain. Manufacturing each dose takes about six weeks. Patients begin 
treatment with Keytruda while their personalised vaccine is prepared.

Earlier results from a smaller study found that the combination reduced 
the risk of melanoma returning or patients dying by 49 per cent and cut 
the risk of the cancer spreading to other parts of the body or the 
patient dying by 59 per cent compared with Keytruda alone.

Important questions remain, including the size of the benefit, 
side-effects and the cost and complexity of manufacturing a bespoke 
vaccine for every patient.

Nevertheless, the trial appears to represent a milestone. If regulators 
approve the treatment, Moderna has said it hopes it could reach patients 
as early as next year.

Moderna and Merck will provide more details at a medical conference 
later this year. High costs could limit the drug’s accessibility if it 
is eventually approved by regulators.

Professor Georgina Long of the University of Sydney, who is the study’s 
principal investigator and also medical director of the Melanoma 
Institute Australia, said the results represented “a landmark moment”.

She added that the combination of Intismeran and Keytruda “has the 
potential to establish a new treatment paradigm” that would help 
patients remain cancer-free for longer.

Dr Lennard Lee of the University of Oxford, a consultant oncologist who 
is advising the NHS and the government on cancer vaccines, said that it 
was an “important moment that scientists have been working towards for 
many years”.

He added: “There is also a wider story here about what happened after 
the pandemic. In 2020, enormous global investment accelerated mRNA 
technology, vaccine science and manufacturing, and it started in the 
United Kingdom. The question afterwards was whether that capability 
could be redirected towards other major diseases.

“In 2022, the UK made an early strategic decision to pursue that 
opportunity in cancer, launching a national cancer vaccine advance to 
accelerate clinical trials of mRNA cancer vaccines. Since then, the UK 
has developed into one of the world’s leading environments for cancer 
vaccine trials.”

One mRNA vaccine trial now active in the UK involves patients with 
high-risk stage 2 or stage 3 colon or rectal cancer whose tumours have 
been surgically removed, but who still have traces of tumour DNA 
detectable in their blood, suggesting a high chance that the cancer 
could return. BioNTech developed that treatment.

The first English patient received the vaccine in Birmingham in 2024 
through the Cancer Vaccine Launch Pad, a scheme for connecting eligible 
NHS cancer patients with clinical trials of new cancer vaccines. British 
patients are also involved in personalised vaccine trials for pancreatic 
cancer, being run by BioNTech and Genentech.


Rhys Blakely