LONDON: An experimental personalised cancer vaccine developed by Moderna in combination with Merck’s immunotherapy Keytruda has met its main goal in a late-stage trial involving patients with high-risk melanoma, the companies said on Wednesday.
The interim results showed that the treatment, known as intismeran autogene or intismeran, reduced the risk of melanoma returning and also met a secondary goal related to preventing the cancer from spreading to other parts of the body, according to the companies.
The trial is still ongoing. Moderna and Merck said no new safety signals had emerged.
The results sent Moderna shares about 60% higher in pre-market trading. Merck shares also rose 7.5% before the market opened.
Cancer vaccine targets tumour mutations
Intismeran is an investigational messenger RNA (mRNA)-based personalised neoantigen therapy jointly developed by Moderna and Merck.
The vaccine is made specifically for each patient. It uses a sample of the patient’s tumour to identify mutations unique to their cancer.
Moderna and @Merck today announced positive topline results from the Phase 3 INTerpath-001 trial evaluating adjuvant treatment with intismeran autogene, a novel investigational mRNA-based individualized neoantigen therapy jointly developed by Merck and Moderna, in combination… pic.twitter.com/v4DjH0r823
— Moderna (@moderna_tx) August 19, 2026
The treatment is then designed to produce an mRNA vaccine encoding up to 34 neoantigens. These are tumour-specific targets that can help the immune system recognise and attack cancer cells.
After the vaccine is administered, the encoded neoantigens are produced in the body and presented to the immune system. This is intended to stimulate a targeted T-cell response against cancer cells.
Over 1,100 melanoma patients enrolled
The late-stage study enrolled 1,137 patients with high-risk stage IIB to IV melanoma whose tumours had been surgically removed, the companies said.
Participants were randomly assigned to receive either Keytruda combined with up to nine doses of the personalised vaccine or Keytruda alone for about one year.
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The interim analysis found that the combination met the trial’s primary endpoint of reducing cancer recurrence. It also met a secondary endpoint assessing the prevention of cancer spreading to other parts of the body.
Long-term benefit
The latest findings build on results from a mid-stage trial announced by the companies in January.
That study found that the combination reduced the risk of melanoma recurrence or death by 49% after five years, according to Moderna and Merck.
The companies are now evaluating the treatment in the larger late-stage study as they work towards potential regulatory submissions.
If approved, intismeran could become a new personalised approach to treating melanoma after surgery by combining an individualised vaccine with an established immunotherapy.
