Personalised cancer vaccine shows promise in preventing melanoma recurrence

A personalised cancer vaccine developed by Merck and Moderna has shown promise in preventing high-risk melanoma from returning after surgery, with early-stage results indicating greater benefits when used alongside the companies' Keytruda immunotherapy.

According to the BBC, the vaccine, called Intismeran, uses messenger RNA (mRNA) technology to target genetic mutations specific to an individual patient's tumour. In a phase three trial involving more than 1,000 patients with high-risk stage two, three or four melanoma, the combination of Intismeran and Keytruda significantly increased the time patients remained cancer-free and reduced the risk of the disease spreading to other organs compared with Keytruda alone.

The vaccine is designed for each patient. After a tumour is surgically removed, a sample is analysed to identify its genetic mutations. Scientists then use that information to produce a personalised vaccine designed to instruct the immune system to recognise and attack cancer cells carrying those mutations.

The approach uses the same underlying mRNA technology employed in several Covid-19 vaccines, but applies it to the mutations found in an individual patient's cancer.

The trial included patients with a range of high-risk melanoma, from large tumours that had not spread beyond the original site to cancers that had already metastasised to other parts of the body.

Experts have cautioned that the findings should be interpreted carefully. It is not yet clear how long the treatment will keep patients cancer-free, while the full results of the trial have not yet been peer-reviewed or published in full.

The treatment would also need to clear regulatory hurdles before it could become widely available. Even after clinical trials are completed, regulatory approval and further processes would be required before the vaccine could be offered through the UK's National Health Service.

Medical experts have described the results as a "pivotal moment" in cancer research and a "proof of principle" that personalised cancer vaccines can work.

The implications could extend beyond melanoma. Merck and Moderna are also testing personalised mRNA cancer vaccines for other cancers, including lung, bladder and kidney cancers.

Shares in both companies rose following the announcement of the trial results.