IT’S NOW SEEMING POSSIBLE TO VACCINATE AGAINST CANCER WITH NEW BREAKTHROUGH

Results from a large trial of a personalised cancer vaccine for melanoma have raised hopes that doctors could eventually use vaccines to train the immune system to prevent a range of cancers from returning – and perhaps, one day, to treat them more broadly.

Merck and Moderna said their personalised mRNA vaccine, given alongside the immunotherapy drug Keytruda, reduced the risk of melanoma returning or spreading in more than 1,000 patients whose tumours had been surgically removed but who remained at high risk of recurrence.

Experts say the significance extends beyond melanoma. Unlike chemotherapy, which attacks rapidly dividing cells and can damage healthy tissue, personalised cancer vaccines are designed to target mutations found specifically in a patient’s tumour. The aim is to teach the immune system to recognise those mutations and destroy the cancer cells carrying them.

Dr Ryan Sullivan, a melanoma specialist at Mass General Brigham Cancer Institute, described the findings as a major development for the field, saying they could encourage investment in approaches that might change cancer treatment more broadly.

Dr Julie Gralow, chief medical officer of the American Society of Clinical Oncology, called the results a major advance for mRNA technology in cancer treatment.

The treatment, known as intismeran autogene, combines Keytruda with a customised mRNA vaccine.

Scientists analyse a patient’s tumour to identify mutations that distinguish the cancer from healthy cells. The vaccine then delivers instructions designed to help the immune system recognise those targets.

The idea is not to prevent cancer in the same way as vaccines against infections such as HPV. Instead, the treatment is personalised for people who already have cancer – or who have had a tumour removed but remain at risk of the disease returning.

Earlier five-year results from a mid-stage trial of the customised vaccine were encouraging. Patients receiving the vaccine alongside Keytruda had about half the risk of their melanoma returning and a 59 per cent lower risk of the cancer spreading to other parts of the body compared with those receiving Keytruda alone.

The companies said adding the vaccine did not produce new safety concerns.

The trial is still ongoing, and researchers will need to follow patients for longer to determine whether the treatment also improves overall survival.

The biggest test, however, will be whether the technology works against other cancers.

Merck and Moderna are already running large trials in non-small-cell lung cancer. They are also studying the approach in bladder and kidney cancers, as well as in early-stage trials involving pancreatic and stomach cancers.

Moderna president Stephen Hoge said several trial results are expected over the next two years.

Roche and BioNTech are also testing their own personalised mRNA vaccine, autogene cevumeran, in patients with colon and pancreatic cancers following surgery. Results from the colon cancer trial are expected in 2027, while the pancreatic cancer study is expected later.

If several of these trials succeed, the implications could be substantial.

Dr Robert Vonderheide, director of Penn Medicine’s Abramson Cancer Center, said the melanoma results gave researchers reason to hope that other studies could also produce positive findings.

One of the most important effects of personalised vaccines could be on what happens after a tumour has been removed.

Doctors often have to decide whether the potential benefit of additional immunotherapy outweighs the risk of side effects. That calculation can be particularly difficult when a patient has a relatively low chance of their cancer returning.

A vaccine that further reduces that risk could change the balance.

Dr Elizabeth Buchbinder, a melanoma specialist at Mass General Brigham, said the additional benefit “may change that math”.

Melanoma has been a particularly attractive target because its cells often contain many mutations, giving the immune system numerous potential targets. But other cancers also carry multiple mutations, suggesting the technology could have applications well beyond skin cancer.

For the first time, personalised cancer vaccines are being tested at scale across several tumour types. If the results continue to be positive, cancer treatment could move towards something much more individualised: a vaccine designed not simply for the type of cancer someone has, but for the particular genetic fingerprint of their tumour.

The idea of vaccinating against cancer is no longer quite so far-fetched. The next few years may show whether it can become a routine part of cancer care.