Last updated: October 17, 2026
Quick Summary
- A personalized mRNA vaccine called intismeran autogene (also known as V940 or mRNA-4157) is being developed by Moderna and Merck to stop melanoma from coming back after surgery.
- In August 2026, it became the first positive Phase 3 result for an individualized neoantigen therapy and for an mRNA-based cancer therapy. pulse2
- It is not yet approved. Full Phase 3 numbers will be presented at the ESMO conference on October 24, 2026.
What Is the mRNA Melanoma Vaccine?
A treatment, not a preventive shot
Most vaccines prevent illness. This one is for people who already had melanoma, a serious skin cancer, and have had it surgically removed. It is typically given after surgery to help keep cancer from returning. curetoday
The names you will see
You may see it called intismeran autogene, V940 or mRNA-4157. They are all the same product. It is an investigational, individualized mRNA-based neoantigen therapy. nordiclifescience
How Does It Work?
The basic idea
Cancer cells carry mutations that healthy cells do not. Some mutations create markers called neoantigens. Because no two tumors have exactly the same mutations, no two people’s neoantigens are exactly alike. The vaccine teaches the immune system to recognize those markers and attack leftover cancer cells. curetoday
How each dose is made
Step 1: A tumor sample is collected
The sample is taken during the patient’s surgery.
Step 2: The tumor’s DNA is sequenced
Scientists look for the mutations unique to that tumor.
Step 3: Targets are chosen
Up to 34 neoantigens are chosen as targets. curetoday
Step 4: A custom mRNA vaccine is built
The mRNA carries instructions for the body to produce those neoantigens, a bit like giving a sniffer dog the scent of one specific target. It uses the same family of technology as some COVID-19 vaccines.
Why it is given with Keytruda
Keytruda (pembrolizumab) is an immunotherapy that releases a brake on the immune system so it can attack cancer more freely. The vaccine aims the immune system, and Keytruda amplifies the response. In the Phase 3 trial, people received the vaccine every three weeks for up to nine doses, along with Keytruda for about one year. curetodaycuretoday
The History: From Idea to Phase 3
Phase 1 and early safety work
Early studies tested whether the personalized vaccine was safe and could trigger an immune response. Later trial reports said adverse events were consistent with those earlier findings.
Phase 2b: KEYNOTE-942 (2022 onward)
KEYNOTE-942 is a randomized, open-label Phase 2b trial that enrolled 157 patients with high-risk stage III/IV melanoma. It was described as the first demonstration of efficacy for an investigational mRNA cancer treatment in a randomized clinical trial. The results were later published in The Lancet in 2024. biospacemerck
Longer follow-up (2024 and 2026)
- At about three years, the combination resulted in a 49% reduction in the risk of recurrence or death and a 62% reduction in the risk of distant spread or death, compared with Keytruda alone. merck
- At five years (shown at ASCO 2026), patients had a 49% lower risk of recurrence or death, and a 59% lower risk of the cancer spreading to distant organs or death. bio-itworldcuretoday
Phase 3: INTerpath-001 (August 2026)
This is the big one, covered below.
The Phase 3 Trial: INTerpath-001
Who took part
The trial enrolled 1,137 patients with high-risk cutaneous melanoma who had undergone complete surgical resection and had not received prior systemic therapy. That covers stages IIB through IV, a wider group than the earlier study. americanpharmaceuticalreview
How it was designed
Participants were randomly assigned two-to-one to receive intismeran plus Keytruda or Keytruda alone. americanpharmaceuticalreview
What was announced
The study met its primary endpoint of recurrence-free survival and a key secondary endpoint of distant metastasis-free survival. In plain terms, the combination kept cancer from coming back, and from spreading, for longer than Keytruda alone. americanpharmaceuticalreview
What we still don’t know
- The exact numbers have not been released yet; they will be shared at ESMO. curetoday
- The trial is still tracking overall survival, meaning whether patients actually live longer.
How Effective Is It?
What the evidence shows so far
Across the Phase 2b and Phase 3 trials, adding the vaccine to Keytruda has beaten Keytruda alone on keeping melanoma away. The five-year follow-up suggests the benefit lasts.
Caveats to keep in mind
- The Phase 2b trial was small (157 patients) and open-label, so patients and doctors knew who got the vaccine.
- Phase 3 headline results come from company announcements. Independent review of the full data is still ahead.
- Longer survival has not been proven yet.
Is the mRNA Melanoma Vaccine Safe?
Common side effects
In the Phase 2b study, the most common side effects of the combination were fatigue (59.6%), pain at the injection site (59.6%) and chills (51%). One trial participant described the injection soreness as similar to a regular flu shot. curetoday
Serious side effects
- The majority of treatment-related events were grade 1 or 2, and grade 3 or higher events were similar between the arms (25% vs 18%). dermatologytimes
- No grade 4 or 5 events related to the vaccine were reported. dermatologytimes
- Immune-related side effects occurred at similar rates with the combination (45.2%) and with Keytruda alone (44%). curetoday
Phase 3 safety
The companies said the safety profile was consistent with prior studies, with no new safety signals. americanpharmaceuticalreview
What Is the Impact?
For melanoma patients
Keytruda is already a standard treatment after surgery. A vaccine that adds benefit on top of it could establish a new treatment paradigm, which is how the trial’s lead investigator described the potential. pulse2
For cancer treatment overall
If a personalized mRNA vaccine works in melanoma, the same approach could work in other cancers. The program covers nine Phase 2 and Phase 3 trials in melanoma, non-small cell lung cancer, bladder cancer and renal cell carcinoma. americanpharmaceuticalreview
For the mRNA industry
This result is the reason Moderna’s stock has been in the headlines, as covered in our stock explainer.
What Happens Next?
ESMO presentation on October 24
Researchers will share the full results on Saturday, Oct. 24, at 10:30 a.m. EDT during the Presidential Symposium at the ESMO Congress 2026. curetoday
Regulatory approval
Merck and Moderna plan to share the findings with regulators and are preparing to file for approval. Approval would make this the first mRNA cancer vaccine on the market.
Challenges ahead
Each dose is custom-made for one patient. Making that process fast, reliable and affordable at scale is a hurdle. Pricing has not been announced.
Can Patients Get It Now?
Only through clinical trials
Intismeran is not FDA approved, so it is not available outside a clinical trial. curetoday
Questions to ask your oncologist
- Am I eligible for a personalized cancer vaccine clinical trial?
- Is my tumor sample suitable for this testing?
- How do the results compare with my current treatment?
You can search for open trials at ClinicalTrials.gov.
Frequently Asked Questions
Is there an mRNA vaccine for melanoma?
Yes, but only an investigational one. It is in late-stage trials and not yet approved.
Does the vaccine cure melanoma?
No. It aims to lower the chance of melanoma returning after surgery.
Is it the same as the COVID vaccine?
It uses similar mRNA technology, but each cancer vaccine is custom-made from a patient’s own tumor.
What are the side effects?
Mostly tiredness, injection-site pain and chills, usually mild to moderate.
When could it be approved?
No date has been announced. The companies are preparing regulatory filings after the Phase 3 results.
Bottom Line
The mRNA melanoma vaccine has a strong track record from Phase 2b through five years and a positive Phase 3 headline result. The full numbers on October 24 will show how large the benefit really is and whether it holds up under scrutiny.
This article is for information only and is not medical advice. Talk to a qualified doctor about treatment decisions.
Sources: CURE · Merck/Moderna 5-year data · American Pharmaceutical Review · Pulse 2.0 · Merck Phase 2b release · Dermatology Times · Nordic Life Science