A personalized melanoma vaccine from U.S. drugmakers Merck and Moderna helped keep skin cancer from returning after surgery, phase 3 results show. Patients who got it with Keytruda, an immunotherapy drug also called pembrolizumab, were less likely to relapse or die than those who got Keytruda alone. The results came out Oct. 22, and the therapy is still investigational.
At a glance
- Result: Among 1,137 people with surgically removed melanoma, the risk of recurrence or death fell 42%. At two years, 82.2% on the combination were alive and recurrence-free, versus 70.0% on Keytruda alone.
- Design: Each dose is made from a patient’s own tumor. It codes for up to 34 neoantigens, which are markers specific to that tumor.
- Status: The treatment is not approved, and overall survival data are not yet mature.
What the trial found
About 112,000 new melanoma cases and more than 8,500 deaths are expected in the United States in 2026 C.E., Merck’s release said. The trial tested the combination after surgery. The goal is to keep the cancer from coming back.
The INTerpath-001 trial enrolled adults with fully removed melanoma, from stage IIB to stage IV. Two of every three patients got the vaccine plus Keytruda, and the rest got a placebo plus Keytruda. Median follow-up was 24.6 months, Targeted Oncology reported.
The combination cut the risk of recurrence or death by 42%, with a hazard ratio of 0.58. It also cut the risk of distant spread or death by 38%. That means fewer cancers reached other organs, with two-year rates of 88.5% versus 80.2%.
The lead investigator, Prof. Georgina Long of Melanoma Institute Australia, said the results could bring a “foundational shift.” The data were set for presentation Oct. 24 at the ESMO Congress in Madrid. They have been accepted for publication in the New England Journal of Medicine.
How the melanoma vaccine works
The therapy is called intismeran autogene. It is made from a patient’s own tumor sample. Information from the tumor and from normal DNA is used to design it.
Each dose carries synthetic mRNA that codes for up to 34 neoantigens. The body makes them and shows them to the immune system, which can trigger a targeted T-cell response, Merck said. Patients got a dose every three weeks, up to nine doses, along with Keytruda.
The trial builds on an earlier phase 2b study. Its five-year follow-up was presented at the 2026 C.E. American Society of Clinical Oncology meeting, Merck said. The companies first said on Aug. 19 that the phase 3 trial met its goals, without giving figures, Pharmacy Times reported.
What remains unknown
The melanoma vaccine is investigational and not approved. Merck and Moderna sponsored the trial. They say they are “engaging with regulatory authorities,” and whether it reaches patients depends on that review.
Overall survival, which shows whether patients live longer, is not yet mature, though the data show a favorable trend. The two groups also looked alike in the first six months, because the vaccine began only after each custom dose was made. Keytruda started right away.
The combination also adds side effects. Fever hit 52.2% of patients on it versus 8.2% on Keytruda alone, and injection-site pain hit 51.0% versus 9.5%. Serious treatment-related events were similar, at 14.2% and 13.4%.
Read more
For more on this story, see: Merck and Moderna announcement and Targeted Oncology
For more from Good News for Humankind, see:
- U.S. FDA approves hepatitis B drug that offers some patients a functional cure
- Burkina Faso’s malaria vaccine rollout cuts cases 32%, deaths 44%
- The Good News for Humankind archive on public health
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