Moderna’s Mrna Shot Cuts Melanoma Recurrence Risk by 40%+

WHO:

Wired - Moderna and Merck developed the personalized mRNA vaccine intismeran.

Nature - Merck is based in Rahway, New Jersey; Moderna is headquartered in Cambridge, Massachusetts.

Nature - Trial leader Georgina Long is an oncologist at Melanoma Institute Australia in Sydney.

Nature - Kristen Radford is an immunotherapist at Mater Research in Brisbane; Seth Cheetham is a geneticist at the University of Queensland in Brisbane; and Jessamy Tiffen is a cancer geneticist at the Centenary Institute in Sydney.

Nature - Evan Seigerman is a health-care financial analyst at BMO Capital Markets in New York City.

WHAT:

Wired - A Phase 3 trial found that a personalized mRNA vaccine reduced the risk of melanoma recurrence by more than 40%; the article describes the result as another example of mRNA vaccines’ potential in cancer treatment.

Nature - Used alongside pembrolizumab, intismeran reduced the risk of melanoma returning or the recipient dying by 42%.

Nature - The Phase III trial enrolled 1,137 people with moderate to advanced melanoma at 157 centres. Participants were randomly assigned to receive either intismeran plus pembrolizumab or pembrolizumab plus an inactive placebo.

Nature - Long said the therapy caused no major harmful side effects. Participants have been followed for around 25 months and will continue to be monitored for several years to assess overall survival.

Nature - Radford said a 10% risk reduction is substantial; Cheetham said a reduction of more than 40% “would send many researchers over the Moon.”

Nature - Long said nearly 55% of people with advanced melanoma are now effectively cured with targeted drugs or immunotherapies. About 15 years ago, people with advanced melanoma typically survived only months.

Nature - Tiffen said the results are exciting but that longer follow-up is needed to determine effectiveness beyond two years; she also noted that some people did not respond to the vaccine.

WHERE:

Nature - The trial was conducted across 157 centres; the article does not specify their locations.

Nature - The European Society for Medical Oncology meeting where trial data will be presented is in Madrid.

WHEN:

Nature - The trial data presentation is scheduled for 24 October.

Nature - The companies announced early positive results in August; the data leak occurred on 22 October.

WHY:

Nature - Intismeran is intended to prevent melanoma from returning after patients have had surgery to remove tumours; it is not designed to prevent melanoma from developing initially.

Nature - The combination is intended for people whose cancer could return after surgery and who do not respond to immunotherapy alone.

HOW:

Nature - Researchers sequenced DNA from each participant’s tumour to identify cancer-cell mutations that can produce neoantigens, proteins that help distinguish cancer cells from healthy cells.

Nature - Intismeran is a tailor-made vaccine used with pembrolizumab, an immunotherapy drug already used to treat melanoma.

Nature - After the trial data leaked online, the companies released key results. Moderna’s stock price dropped by around 25% after the leak; Seigerman told Forbes the market reaction probably reflected “inflated expectation into the full data release, rather than a true indictment on the efficacy of the combo therapy”.

(UPDATED October 24, 2026 12:00 UTC)

A personalized mRNA vaccine developed by Moderna and Merck cut the risk of melanoma returning or patients dying by 42 percent when used with the immunotherapy drug pembrolizumab, according to a Phase 3 trial. The study enrolled 1,137 people with moderate to advanced melanoma across 157 centres, comparing the combination with pembrolizumab and an inactive placebo. Intismeran is designed to prevent cancer returning after surgery, not to stop melanoma from developing in the first place. Researchers tailor each dose by sequencing a patient’s tumour DNA and targeting mutations that produce proteins distinguishing cancer cells from healthy ones. Trial leader Georgina Long said there were no major harmful side effects. Patients have been followed for about 25 months, but longer monitoring is needed to assess survival and determine how well the vaccine works beyond two years. Some patients did not respond. The results are being presented at a meeting in Madrid.