Melanoma is one of the more aggressive forms of skin cancer, and patients with high-risk disease remain at risk of recurrence even after successful surgery. New results from a phase III trial suggest that may be about to change for some patients.
Merck (known as MSD outside the US) and Moderna have announced that a personalised mRNA vaccine, given alongside the immunotherapy drug Keytruda, extended the time high-risk melanoma patients remained cancer-free after surgery, compared with Keytruda alone. It also reduced the risk of the disease spreading to other organs. The findings were reported by the BBC.
Inside the INTerpath-001 Trial
The phase III trial enrolled more than 1,000 patients with high-risk stage two, three or four melanoma. All had undergone surgery to remove their tumours before joining the study. Patients were randomised to receive either Keytruda alone, the current standard adjuvant treatment for this group, or Keytruda combined with the new vaccine, called intismeran.
Melanoma at this stage remains at risk of returning or spreading, even after the visible tumour has been removed. Comparing the two groups allowed researchers to assess whether adding the vaccine improved outcomes beyond what Keytruda achieves on its own.
What is Intismeran?
Intismeran is described by its developers as a personalised cancer vaccine. Rather than targeting a generic tumour marker shared across patients, it is manufactured specifically for each individual based on the mutations found in their own tumour.
How does the vaccine work?
During surgery, a small sample of the patient’s tumour is removed, and its DNA and RNA are sequenced. This process identifies mutations unique to that patient’s cancer, known as neoantigens. Scientists then use mRNA technology, the same approach behind several Covid-19 vaccines, to build a vaccine that trains the patient’s immune system to recognise and attack any remaining cancer cells carrying those mutations.
Prof Peter Johnson, National Clinical Director for Cancer at NHS England, described the approach as a shift from broadly activating the immune system to directing it with precision at a patient’s specific cancer.
What did the trial find?
Patients who received the vaccine alongside Keytruda remained cancer free for longer than those who received Keytruda alone, and had a lower risk of the melanoma spreading to other organs. The exact duration of that benefit is not yet known, as the companies have only released early results so far.
Caution and Next Steps
The results are interim. They have not yet been peer-reviewed, a process in which independent experts scrutinise a study’s methods and conclusions before they are considered established. Full findings are due to be presented at a medical conference in October.
Dr Talisia Quallo, head of prevention and early detection at Cancer Research UK, said the research shows promise but that the interim data still needs full review. Dr Lennard Lee, a consultant medical oncologist and associate professor at the University of Oxford, called the result proof of principle that personalised cancer vaccines work, adding that the study has implications reaching beyond melanoma alone. Merck and Moderna are already testing similar personalised vaccines for lung, bladder and kidney cancers.
Even if the full data holds up, intismeran would still need regulatory approval before reaching patients, followed by a separate appraisal process before it could be made available on the NHS.
Partner with Simbec-Orion for Your Next Phase III Oncology Trial
News like this is a reminder of what phase III trials are built to do: test whether an early signal of benefit holds up in a large, randomised patient population. Delivering a trial at this scale demands coordinated multi-site enrolment, robust data integrity and biometrics, and clear regulatory submission support, all without losing the oversight that keeps a programme on track.
Simbec-Orion’s oncology team brings Phase III delivery experience across solid tumours and haematological malignancies, backed by integrated laboratory capability and Senior Leadership Team oversight maintained even as trials scale. For sponsors preparing to take a promising therapy through late-stage development, that combination of scientific rigour and lean, accountable delivery is what keeps a large trial on course.
Speak to our oncology experts today.
Frequently Asked Questions
Does this vaccine prevent melanoma in healthy people?
No. Intismeran is a therapeutic vaccine, given to patients who have already had melanoma surgically removed, to reduce the chance of it returning. It is not a preventative vaccine for people without cancer.
Does this replace Keytruda?
No. In the trial, intismeran was given alongside Keytruda, not instead of it. The combination was compared against Keytruda alone.
When might intismeran be available on the NHS?
Not for some time. The treatment still needs full peer-reviewed data, regulatory approval, and a separate NHS appraisal process before it could be offered to patients.