Skin cancer treatment could be entering a new era.
A personalised vaccine, used alongside an existing cancer drug, has been shown to help stop tumours coming back in patients with melanoma, the most aggressive form of skin cancer, responsible for around 2,600 deaths a year in the UK. For a disease that’s historically been notoriously difficult to treat once it spreads, this combination therapy represents one of the more promising developments in years.
Melanoma is a scary and serious diagnosis.
Melanoma develops in the cells that produce melanin, the pigment responsible for skin colour, and while it’s far less common than other forms of skin cancer, it’s by far the most dangerous. It has a tendency to spread aggressively to other parts of the body if not caught early, which is part of why outcomes for advanced cases have remained so poor for so long. Currently, only around a third of patients diagnosed with the most severe form of the disease survive five years after diagnosis, a statistic that highlights just how much room there is for improvement in treatment options.
What the vaccine is and how it performs
The experimental treatment, known as intismeran, is an mRNA-based vaccine developed jointly by pharmaceutical companies Merck and Moderna. Unlike a typical vaccine designed to prevent infection, this one is built individually for each patient rather than mass-produced for widespread use.
It was tested on people with high-risk melanoma, and early results suggest it can extend how long patients stay cancer-free following treatment. Researchers don’t yet know exactly how long that protection might last, since the trial is still relatively early in tracking long-term outcomes, but the initial signs are being described as encouraging.
How the trial was run
This phase three trial, the stage of testing that typically comes right before a treatment could be approved for wider use, involved more than a thousand patients with advanced melanoma. Participants varied in how far their cancer had progressed. Some had large tumours confined to one specific area of the body, while others had cancer that had already spread to multiple different sites, making their cases considerably harder to treat with standard approaches alone.
How a personalised cancer vaccine actually works
According to a consultant medical oncologist at the University of Oxford, personalised cancer vaccines represent a different way of approaching cancer treatment altogether. Rather than giving every patient the same standard medicine regardless of their specific diagnosis, this approach designs a treatment built entirely around one individual and the unique genetic makeup of their particular tumour.
The process begins with doctors surgically removing the patient’s tumour. From there, the DNA within that tissue sample is closely analysed to identify any mutations present in the cancer cells. These mutations can produce unusual proteins, known as neoantigens, which don’t normally appear in healthy cells and can potentially be recognised by the immune system as foreign or threatening. The vaccine itself uses mRNA technology, the same underlying science behind several Covid-19 vaccines, to essentially hand the body a set of instructions matching these specific neoantigens. The goal is to train the patient’s own immune system, and particularly a type of white blood cell called T cells, to identify and actively attack any cancer cells still carrying those markers.
How the treatment is actually given to patients
Patients receive nine separate doses of the vaccine, spaced three weeks apart from one another. Alongside this, they also receive regular doses of an already-established immunotherapy drug called Keytruda, also administered every three weeks throughout the treatment course. Each personalised vaccine used in this particular trial was designed to target up to 34 different neoantigens unique to that patient’s own tumour, meaning no two patients technically receive an identical treatment.
In fairly simple terms, the two treatments work together but tackle different parts of the problem. The vaccine effectively teaches the immune system exactly what to look for within the body, giving it a precise target. Keytruda, meanwhile, works by releasing the natural brakes that would otherwise hold the immune system’s response back, allowing it to respond more aggressively once it’s spotted something worth attacking.
Could this approach treat other cancers too?
Merck and Moderna aren’t stopping their research at melanoma alone. Similar personalised vaccines built on the same underlying technology are already being tested for lung, bladder, and kidney cancers. Of these, the lung cancer version has progressed furthest, having already reached the final phase three stage of testing, the same stage as the melanoma trial. Trials for kidney and bladder cancers remain at an earlier phase two stage, meaning they’re still some way off from potential approval, but the fact that multiple cancer types are being explored simultaneously suggests real confidence in the underlying approach.
Researchers are broadly hopeful that this style of personalised, mRNA-based vaccine could eventually prove useful across a much wider range of tumour types beyond just these four. According to the Director of Immunotherapy at the Icahn School of Medicine at Mount Sinai, this represents an exciting period for cancer immunotherapy as a whole. She noted that vaccines of this kind are likely to make the biggest practical difference in situations where a patient’s overall cancer burden is relatively low, suggesting they may prove most valuable as a way of preventing recurrence after initial treatment, rather than as a first-line treatment for advanced, widespread disease.
What this could mean going forward
While it’s still early days for this particular treatment, the combination of a personalised vaccine and an established immunotherapy drug marks a meaningful change in how doctors are beginning to think about cancer care. Rather than relying purely on one-size-fits-all treatments, this approach points toward a future where a patient’s own tumour effectively provides the blueprint for their treatment. For a disease like melanoma, where survival rates for advanced cases have remained stubbornly low for years, any real progress toward keeping more patients cancer-free for longer represents a significant step forward.
