Personalised cancer jab cuts risk of melanoma returning by 42% in landmark trial

A personalised cancer vaccine given alongside a widely used immunotherapy drug has cut the risk of patients dying or their skin cancer returning by 42% in a major clinical trial.

Researchers say the results could mark a turning point in cancer treatment, bringing tailor-made medicine a significant step closer for patients. The combination also reduced the risk of melanoma spreading around the body by 38% over two years, compared with immunotherapy alone.

The drug makers MSD, known as Merck in the United States, and Moderna say the same approach is already being tested against other cancers, including kidney, bladder and lung tumours.

Independent experts described the findings as impressive, but cautioned that longer-term studies are still needed to show whether the treatment helps most patients live longer.

How the vaccine works

The treatment is aimed at patients whose tumour has already been removed by surgery but who remain at high risk of the cancer coming back.

In the trial, 1,137 adults with melanoma, the most dangerous form of skin cancer, were given Keytruda, an established immunotherapy drug that helps the immune system find and attack cancer cells. About two-thirds also received the experimental vaccine, while the remainder were given a placebo.

The vaccine, called intismeran, uses the same messenger RNA technology as some Covid jabs. Each dose is made individually. Scientists sequence the genetic material of the patient’s own tumour to identify the mutations unique to it, then build a vaccine that teaches the immune system to recognise those features and destroy any cancer cells that return.

Two years after starting treatment, patients who received the vaccine were far less likely to have seen their melanoma come back or spread.

“Personalisation is the next step up and it’s really exciting, it’s a fabulous technology,” said Prof Pippa Corrie, a consultant medical oncologist who helped run part of the study at Addenbrooke’s Hospital in Cambridge. “The question is how much can we really demonstrate its worth and this trial was the first proof of principle.”

‘What’s to lose?’

Among the patients Prof Corrie treated was Tony Chapman, 75, from Corby in Northamptonshire. He was diagnosed with melanoma in 2019 and had the tumour removed from his chest, but a lump later appeared under his arm. He was told the cancer had returned and spread to his lymph nodes, and that he needed a second operation.

He then volunteered for the study. Like every other participant, he still does not know whether he received the vaccine or the placebo alongside his immunotherapy.

“This just seemed like a really good example of moving science forward, as well as getting some benefit for yourself, so what’s to lose?” he said. Three years on, he has check-ups every six months and remains cancer-free.

Caution from experts

Professor Alan Melcher, of the Institute of Cancer Research in London, who was not involved in the research, described the results as “very impressive”.

“It is an important proof of principle for the field, although we shouldn’t get ahead of the evidence,” he said. “We can’t assume from one melanoma trial that the same approach will work across all cancers, and longer follow-up will be important to understand the effect on overall survival.”

The full results are due to be presented at the European Society for Medical Oncology congress in Madrid on Saturday. They have not yet been published in a peer-reviewed journal, where independent scientists will be able to scrutinise the data.

Investors had reacted strongly to earlier signs of success. Shares in both MSD and Moderna rose sharply after the companies first hinted at the outcome in the summer, but fell on Thursday after analysts said the latest figures were not quite as strong as those from an earlier, much smaller trial.

When could NHS patients get it?

Both companies say they are now “engaging with authorities”, suggesting they could apply to medicines regulators for approval as early as next year.

Widespread use on the NHS would depend on cost as well as approval. Because every patient needs their tumour genetically analysed and a unique vaccine manufactured, the treatment is likely to be expensive and logistically complex compared with conventional drugs. The NHS has already signed agreements to fast-track thousands of cancer patients in England into trials of personalised vaccines, with the aim of making the technology available more quickly if it proves effective.

Melanoma is mainly caused by ultraviolet light from the sun or sunbeds. It is less common than other skin cancers but more aggressive, and can spread to other organs. People with pale skin that burns easily, many moles or freckles, or a history of sunburn are at higher risk. Doctors advise anyone who notices a new mole, or a change in the shape, colour or size of an existing one, to have it checked promptly.

The trial will continue so that patients can be monitored for years to come, both to see whether the cancer returns over a longer period and to establish whether the vaccine ultimately helps them live longer.