Melanoma Was Less Likely to Come Back With a Personalized Cancer Vaccine

For decades, a vaccine against cancer was an idea that lived in the future tense. New trial results suggest that the future just moved a good deal closer for people who have been treated for melanoma.

A personalized cancer vaccine given with a standard immunotherapy drug cut the risk of melanoma returning or patients dying by 42 per cent, according to late-stage results released by Moderna and Merck and reported by The Associated Press through CTV News. The experimental vaccine, called intismeran, is made for each patient from the genetic fingerprint of their own tumour. It teaches the immune system to recognize those cancer cells and attack them if they try to come back.

Key takeaways

The trial enrolled 1,137 people whose high-risk melanoma had been removed by surgery, and all of them received the immunotherapy drug Keytruda.

Two years in, 82 per cent of people who also got the vaccine were still free of melanoma, compared with 70 per cent on Keytruda alone.

The combination also lowered the risk of the cancer spreading to distant parts of the body by 38 per cent.

The full results have not yet appeared in a peer-reviewed journal, and researchers are still tracking whether the vaccine helps people live longer.

Catching melanoma early is still the strongest protection, and a doctor can assess most new or changing spots in a single visit.

What did the late-stage trial actually show?

The late-stage trial, called INTerpath-001, enrolled 1,137 people whose melanoma had been surgically removed, the point where the biggest worry is the invisible cells that might remain. Everyone received Keytruda, an established immunotherapy that helps the immune system fight cancer, while 757 people also received the vaccine and 380 received a placebo.

Two years after treatment began, 82 per cent of the people on the vaccine plus Keytruda remained free of melanoma, compared with 70 per cent of those on Keytruda alone, according to the companies' detailed results. The combination also cut the risk of melanoma spreading to distant organs by 38 per cent. The side effects were mainly a sore arm, fatigue, and other reactions typical of mRNA COVID-19 vaccines, one of the trial's researchers told The Associated Press.

Two honest caveats belong next to the excitement. The full results have not yet appeared in a peer-reviewed journal, since the data were first presented at a European Society for Medical Oncology meeting in Madrid, though the companies say The New England Journal of Medicine has accepted them for publication. Researchers are also still following patients to learn whether the vaccine helps people live longer as well as stay free of cancer.

Two years after surgery, more people who received the vaccine with Keytruda were still free of melanoma

How is a custom vaccine built for one person?

Most vaccines you have had were identical for everyone, and this one is built very differently. Scientists sequence the patient's tumour to find mutations unique to that cancer, which produce abnormal proteins the body would not normally make. They then encode up to 34 of those targets into an mRNA vaccine, which is what makes it a personalized cancer vaccine in the most literal sense.

Patients receive the custom vaccine as nine doses, three weeks apart, alongside Keytruda. The whole process, from analyzing the tumour to finished doses, can take roughly six weeks and sometimes longer, Moderna's president told The Associated Press.

It uses the same mRNA technology behind the COVID-19 vaccines, which a major review found safe and effective. These detailed numbers also follow the August announcement that the trial had succeeded, so the headline result is now backed by the full figures.

Who stands to benefit first?

The people likely to benefit first are those who have been treated for high-risk melanoma, for whom a 12-point gain in staying cancer-free at two years is a genuinely big number. The companies say they are talking with regulators about next steps, and no Canadian approval has been announced.

The bigger story is the platform behind it. A vaccine built from a patient's own tumour is personalized medicine in its most literal form, and custom cancer vaccines are also being tested against lung, kidney, and pancreatic cancer, the AP reported.

Why does an early skin check still matter most?

For everyone else, this news changes nothing about the basics, and an early skin check is still the most powerful tool most people have. Melanoma rates in Canada keep climbing, especially in men, according to Canadian Cancer Society figures cited by the New Brunswick Health Council.

The good news is that melanoma announces itself where you can see it, as a mole that changes size, shape, or colour, a new spot that stands out from its neighbours, or a sore that will not heal. Our guide to the skin cancer signs that do not look like the pictures shows the ones people miss most often.

A vaccine that helps after surgery is wonderful, though catching a spot early enough that surgery is simple is better still. That idea sits at the heart of the prevention habits worth keeping in 2026.

Raise it at your next appointment. If you or someone you love has had melanoma, ask the oncology team whether this research or a related clinical trial could shape follow-up care.

Know your own skin. Look over your skin once a month, using a mirror or a partner for your back, so you notice when a spot is new or changing.

Take photos. Photograph any mole you are unsure about so you can compare it in a few months.

Keep sunscreen in rotation. Use it even as the days get darker, and skip tanning beds entirely, as our look at what deliberate tanning does to your skin explains.

Get odd spots checked early. Book a family doctor or skin clinic visit for anything new, changing, or strange, and book early, since a skin check can take months to land.

Frequently asked questions

How does a vaccine made for one patient work?

A personalized cancer vaccine is a treatment made for one patient from the mutations in their own tumour. It trains the immune system to recognize proteins found only on that person's cancer cells, so it can attack them if the cancer returns. It treats people who already have cancer and does not prevent cancer in healthy people.

Can you get this vaccine in Canada now?

The vaccine is still experimental and is not approved in Canada or anywhere else. Moderna and Merck are discussing the results with regulators, and access for now runs through clinical trials. If you have had high-risk melanoma, your oncology team can tell you whether a trial is open and whether you might qualify.

Does the vaccine replace sunscreen or skin checks?

The trial tested the vaccine in people whose melanoma had already been removed, so it does nothing to prevent a first melanoma. Sun protection, monthly self-checks, and prompt visits for new or changing spots remain the best ways to stop melanoma early, when it is easiest to treat with a simple procedure.

Your next step

Science is building better safety nets for melanoma, though the earliest catch still wins. The Medimap Health Hub has more on skin health, and you can find a dermatology clinic near you or book a walk-in clinic visit to get that spot checked this week.

Disclaimer: This article is for general information only and is not medical advice. It does not replace a conversation with a doctor or other qualified health professional who knows your history. If you think you are having a medical emergency, call 911 or go to the nearest emergency department.