Intismeran Personalised Cancer Vaccine Cuts Melanoma Recurrence Risk 42%

What changed

A personalised mRNA vaccine given alongside Keytruda reduced the risk of melanoma returning or patients dying by 42% over two years in a trial of 1,137 adults. It also reduced the risk of the cancer spreading by 38%; each vaccine was built from genetic information taken from the patient’s own tumour.

Why it matters

This is a meaningful shift in what happens after surgery. Instead of giving every patient the same extra treatment, doctors are testing whether the immune system can be trained against the particular cancer that was removed.

The vaccine, Intismeran, was given to about two-thirds of participants, while the rest received a placebo alongside Keytruda. Because patients do not know which group they were in, the trial can provide a cleaner test of whether the personalised vaccine adds something to established immunotherapy.

The results are promising, but the bigger question is still open: whether the treatment helps people live longer on average. The study is continuing, and longer follow-up is needed.

There is also a practical hurdle. Every patient would need tumour genetic analysis and an individually manufactured vaccine. MSD and Moderna are already testing the same approach in kidney, bladder and lung cancers, and may seek regulatory approval as soon as next year. Availability through the NHS would still depend on approval and cost.