The mRNA Melanoma Vaccine: What the 2026 Intismeran Results Mean for Patients in Canada

Last updated: November 3, 2026.

Medical disclaimer: This article is for general education only. It is not medical advice and does not replace a consultation with your doctor or oncologist. Intismeran autogene is an investigational treatment. As of November 3, 2026, it is not approved by Health Canada, the U.S. FDA or any other regulator, and it is only available through clinical trials. Do not stop, delay or change any treatment based on this article.

Quick answer: Intismeran autogene (also called V940 or mRNA-4157) is a personalized mRNA "cancer vaccine" made by Moderna and Merck. In the Phase 3 INTerpath-001 trial of 1,137 people with high-risk melanoma that had been completely removed by surgery, adding intismeran to the immunotherapy drug Keytruda (pembrolizumab) lowered the risk of the cancer coming back or death by 42% compared with Keytruda alone (Merck, October 2026). It is the first personalized mRNA cancer vaccine to succeed in a Phase 3 trial (CURE). It is not yet approved in Canada or anywhere else.

Key takeaways

• What it is: a custom-made mRNA treatment built from the genetic mutations in one person's own tumour. It treats people who already have melanoma. It does not prevent melanoma in healthy people.
• Main result: after a median follow-up of 24.6 months, 82.2% of people who got intismeran plus Keytruda were alive without their melanoma returning, compared with 70.0% of people who got Keytruda alone.
• Spread to other organs: the combination lowered the risk of distant spread (metastasis) or death by 38%.
• Survival: it is too early to know whether it helps people live longer. Overall survival data are not yet mature.
• Side effects: fever, injection-site pain, fatigue and flu-like symptoms were more common with the vaccine. Severe treatment-related side effects were similar in both groups (14.2% vs 13.4%).
• Who it's for (so far): adults with stage IIB, IIC, III or IV skin melanoma that was fully removed by surgery.
• Availability in Canada: not approved. Seven Canadian hospitals took part in the Phase 3 trial, including Sunnybrook and Princess Margaret in Toronto and William Osler in Brampton, but the trial is no longer recruiting.
• The role of surgery: the vaccine is built from tumour tissue, and in the trials it was given only after the melanoma had been completely removed. Finding and removing melanoma early is still the most important step.

What is the mRNA melanoma vaccine (intismeran autogene)?

Intismeran autogene is an individualized neoantigen therapy: a single mRNA medicine designed for one patient, based on the mutations found in that patient's tumour. Moderna and Merck are developing it together. Its earlier code names are mRNA-4157 and V940 (Moderna).

The word "vaccine" can be confusing. This is not a shot that protects healthy people from getting melanoma, like a flu or measles vaccine. It is a treatment for people who have already been diagnosed with melanoma. Its job is to train the immune system to recognize and destroy any melanoma cells that may be left in the body after surgery, so the cancer is less likely to come back (CURE).

Because each dose is designed for one specific person, no two patients receive the same product.

How does a personalized mRNA cancer vaccine work?

The vaccine teaches your immune system to recognize the unique "flags" on your own cancer cells, and Keytruda takes the brakes off the immune response. Moderna and CURE describe the process in these steps (Moderna; CURE):

1. Tumour sample. A sample of the melanoma is collected, usually from tissue removed during surgery. (Curious what happens to removed tissue? See what happens to the tissue after a mole is removed.)
2. Normal sample. A blood sample is taken so scientists can compare your normal DNA with your tumour's DNA.
3. Sequencing. Both samples are sequenced to find mutations that exist only in the cancer cells.
4. Choosing targets. Computer methods select up to 34 neoantigens. These are abnormal protein pieces made by the tumour's mutations that are predicted to trigger a strong immune response.
5. Making the mRNA. The chosen targets are written into a single mRNA sequence. This is the same basic technology used in some COVID-19 vaccines.
6. Treatment. The mRNA is injected. Your cells read the instructions, make the neoantigen pieces and show them to the immune system. This trains T cells (a type of white blood cell) to find cells carrying those flags.
7. Paired with Keytruda. Pembrolizumab (Keytruda) is an anti-PD-1 immunotherapy drug. It blocks a signal that can restrain T cells, so the newly trained T cells can act against the cancer.

What are neoantigens? Neoantigens are new protein fragments found on cancer cells because of the mutations inside them. Healthy cells don't carry these specific mutations, which makes them useful targets for aiming the immune system at the cancer.

How long does it take to make? In the Phase 3 trial, intismeran was successfully manufactured for more than 99% of the 757 patients assigned to receive it, and the median time to the first intismeran dose was 64 days (CancerNetwork).

What did the Phase 3 INTerpath-001 trial find?

Adding intismeran to Keytruda lowered the risk of melanoma coming back, or death, by 42% compared with Keytruda alone. Merck and Moderna announced the topline result on August 19, 2026 (Dermatology Times). The full data were presented as late-breaking abstract LBA1 at Presidential Symposium I of the ESMO Congress 2026 (October 23–27, 2026, Madrid) by principal investigator Professor Georgina Long of Melanoma Institute Australia, and have been accepted for publication in The New England Journal of Medicine (CancerNetwork; Merck).

Who was in the trial?

According to Dermatology Times and the trial's ClinicalTrials.gov record:

• 1,137 adults with completely removed (resected) stage IIB, IIC, III or IV skin (cutaneous) melanoma who had not had any drug treatment for melanoma beyond surgery.
• Patients had to start Keytruda within 13 weeks of the surgery that left them cancer-free.
• People with melanoma of the eye (ocular) or of mucous membranes (mucosal) were excluded.
• Patients were randomly assigned 2 to 1 to receive intismeran plus Keytruda, or placebo plus Keytruda, in a double-blind design.

How was the treatment given?

Per Merck:

• Intismeran: 1 mg injected every 3 weeks, for up to 9 doses.
• Keytruda: 400 mg every 6 weeks, for up to 9 cycles (about one year).

The main results

All results below come from the intention-to-treat analysis (everyone who was randomized), at a median follow-up of 24.6 months (Merck).

• Recurrence-free survival (the main goal): hazard ratio 0.58 (95% CI 0.45–0.75; p<0.001). That's a 42% lower risk of the melanoma coming back or death.
• 2-year recurrence-free survival: 82.2% with intismeran plus Keytruda vs 70.0% with Keytruda alone.
• Distant metastasis-free survival: hazard ratio 0.62 (95% CI 0.45–0.85; p=0.002). That's a 38% lower risk of the melanoma spreading to distant organs, or death.
• 2-year distant metastasis-free survival: 88.5% vs 80.2%.
• Overall survival: not yet mature. The hazard ratio was 0.77 (95% CI 0.45–1.31; p=0.33), which is not statistically significant. Follow-up continues (CancerNetwork).

What does "hazard ratio 0.58" mean? A hazard ratio compares how often an event, here recurrence or death, happens in one group vs another over time. A value of 1.0 means no difference. A value of 0.58 means the event happened at about 58% of the rate seen in the comparison group, which is a 42% reduction.

The benefit appeared after about six months

One of the most interesting findings is about timing. In a pre-specified analysis, there was no difference between the groups in the first six months (recurrence-free survival hazard ratio 0.99). After six months, the gap widened: the hazard ratio was 0.42 for recurrence-free survival and 0.50 for distant metastasis-free survival (Merck).

This pattern is consistent with how a personalized vaccine is delivered. Each one has to be designed and made first (the median time to the first dose was 64 days), and the immune system then needs time to respond.

Did it work across different stages?

The benefit was seen in both lower- and higher-risk groups (CancerNetwork). For a refresher on what each stage means, see melanoma stages explained.

• Stage IIB, IIC, IIIA or IIIB: recurrence-free survival hazard ratio 0.60
• Stage IIIC, IIID or IV: recurrence-free survival hazard ratio 0.57
• Under 65: hazard ratio 0.65
• 65 and older: hazard ratio 0.53

Caveats worth knowing

• Survival isn't proven yet. Staying cancer-free longer is a meaningful benefit, but researchers don't yet know whether the treatment helps people live longer (Cancer Research Institute).
• Some subgroups are small. In the U.S. subgroup, the distant metastasis result had a hazard ratio of 1.77 based on only 10 events, with a very wide confidence interval (0.38–8.35). No conclusion can be drawn from it (CancerNetwork).
• Results don't automatically carry over to other cancers. The Cancer Research Institute notes that a separate Phase 2 trial of a personalized mRNA vaccine given without checkpoint immunotherapy in colorectal cancer was discontinued. Results depend on the cancer and the combination (Cancer Research Institute).
• The full peer-reviewed paper is still to come. The NEJM paper had been accepted but not yet published when this article was last updated.

What did the earlier Phase 2b trial (KEYNOTE-942) show?

The Phase 2b trial showed that the benefit lasted for five years. This smaller, randomized, open-label study enrolled 157 people with high-risk stage III or IV melanoma after complete surgery. Five-year results were presented at the 2026 ASCO Annual Meeting and published in the Journal of Clinical Oncology (Merck, June 2026; Journal of Clinical Oncology).

At a median follow-up of 60.3 months (about five years):

• Recurrence-free survival: hazard ratio 0.51 (95% CI 0.294–0.887). That's a 49% lower risk of recurrence or death with intismeran plus Keytruda vs Keytruda alone.
• Distant metastasis-free survival: hazard ratio 0.411 (95% CI 0.200–0.843). That's a 59% lower risk.
• Overall survival (exploratory): hazard ratio 0.471 (95% CI 0.165–1.345), described as an encouraging trend but not statistically proven.

On February 22, 2023, based on earlier Phase 2b data, the U.S. FDA gave the combination Breakthrough Therapy designation for adjuvant treatment of high-risk melanoma (Drugs.com). This designation speeds up development and review. It is not an approval.

What are the side effects of the mRNA melanoma vaccine?

The most common side effects are short-lived flu-like symptoms, fever, injection-site pain and tiredness. In the Phase 3 trial, the rates of common side effects (from any cause) were (CancerNetwork):

• Fever (pyrexia): 52.2% with the combination vs 8.2% with Keytruda alone
• Injection-site pain: 51.0% vs 9.5%
• Fatigue: 38.5% vs 29.7%
• Flu-like illness: 25.4% vs 9.2%

Investigators described the flu-like symptoms as low-grade and short-lived.

Other safety points from the Phase 3 trial (Merck; CancerNetwork):

• Serious (grade 3–5) treatment-related side effects were similar in both groups: 14.2% with the combination vs 13.4% with Keytruda alone.
• Two treatment-related deaths (0.3%) occurred in the combination group. Both were attributed to Keytruda.
• Stopping treatment because of side effects happened in 14.0% vs 8.7% of patients.
• About 70% of patients in both groups completed the planned treatment (69.8% vs 69.1%).
• The companies reported no new safety signals.

In the five-year Phase 2b data, most side effects attributed to intismeran were grade 1 (mild) or grade 2 (moderate). The most common grade 3 event was fatigue (4.8%), and no grade 4 or 5 events were reported. Immune-related side effects were similar with the combination (45.2%) and Keytruda alone (44%) (Merck, June 2026).

Immunotherapy drugs like Keytruda can cause immune-related side effects, so anyone receiving them is monitored closely by an oncology team.

Is the mRNA melanoma vaccine approved in Canada?

No. As of November 3, 2026, intismeran autogene is not approved by Health Canada, the U.S. FDA or any other regulator. It remains investigational and is available only through clinical trials (Cancer Research Institute; Drugs.com).

Here's what is publicly known about its regulatory status:

• The companies are talking to regulators. After the Phase 3 results, Merck and Moderna said they are engaging with regulatory authorities. They did not give filing dates (Merck).
• A 2027 approval is an expectation, not a guarantee. Moderna's investor materials mention "the potential for approval of intismeran in 2027." That is a forward-looking statement, and Moderna warns it may not happen (Moderna).
• There is no announced Canadian submission. We found no public announcement of a Health Canada filing. In Canada, a new drug must be authorized by Health Canada before it can be sold. After that, public coverage of a new cancer drug typically involves separate reviews of its value and price, and then a decision by each province.

Can I get it now? Outside a clinical trial, no. The Phase 3 INTerpath-001 trial included seven Canadian sites (ClinicalTrials.gov):

• Sunnybrook Research Institute (Toronto)
• Princess Margaret Cancer Centre (Toronto)
• William Osler Health System (Brampton)
• Cross Cancer Institute (Edmonton)
• BC Cancer Vancouver
• CHUM (Montreal)
• CHU de Québec (Quebec City)

That trial is active but no longer recruiting (status checked November 3, 2026). Intismeran is being studied in other trials, including first-line metastatic melanoma and lung, kidney and bladder cancers. If you have melanoma, ask your oncologist whether any open trial fits your situation (here's how to go about finding a melanoma oncologist in Toronto), and search ClinicalTrials.gov for open studies.

How much will it cost? No price has been announced. Any claim about the cost of intismeran is speculation until a regulator approves it and a price is set.

Who might benefit from the mRNA melanoma vaccine?

Based on the Phase 3 trial, the people most likely to be considered are adults with stage IIB to stage IV skin melanoma that has been completely removed by surgery. These are people with no visible cancer left but a meaningful risk of it coming back (ClinicalTrials.gov).

Here's what those stages mean in plain language, based on the AJCC staging system (Patient.info):

• Stage IIB: a melanoma 2.01–4.0 mm thick with ulceration (the skin over the tumour has broken down), or more than 4.0 mm thick without ulceration. It hasn't spread to lymph nodes.
• Stage IIC: a melanoma more than 4.0 mm thick with ulceration. It hasn't spread to lymph nodes.
• Stage III: melanoma that has spread to nearby lymph nodes, or to skin or tissue close to the original tumour (satellite or in-transit spots).
• Stage IV: melanoma that has spread to distant parts of the body, such as distant skin, lungs or other organs. In the trial, patients had to have had all of it surgically removed.

The trial did not include people with stage 0, stage I or stage IIA melanoma, so there is no evidence yet on whether the vaccine would help them. It also excluded eye (ocular) and mucosal melanoma. For more on the later stages, see advanced melanoma stages and whether stage 3 melanoma is a death sentence.

Why surgery and early detection still matter most

Every patient in these trials had one thing in common: their melanoma had been completely removed by surgery first. The personalized vaccine is designed from the patient's tumour, and it was given only after a surgeon had left the patient cancer-free (ClinicalTrials.gov; CURE). That means the new treatment adds to surgery. It doesn't replace it. (Learn more about melanoma surgery in Toronto and wide local excision.)

• Catching melanoma early matters. The Canadian Dermatology Association notes that melanoma survival rates are high compared with most other forms of cancer (Canadian Dermatology Association). The vaccine trials focused on thicker or more advanced melanomas because those carry a higher risk of coming back.
• Melanoma is common in Canada. The Canadian Cancer Society estimated that about 9,700 Canadians would be diagnosed with melanoma in 2023 and about 1,250 would die from it (Canadian Cancer Society).
• Self-checks help. The American Academy of Dermatology recommends watching for the ABCDE warning signs (AAD). See our ABCDEs of melanoma guide and how to check your skin for melanoma at home.
  • A – Asymmetry: one half doesn't match the other.
  • B – Border: the edges are uneven, scalloped or blurry.
  • C – Colour: the colour varies, with shades of tan, brown or black, or patches of white, red or blue.
  • D – Diameter: usually larger than 6 mm (about the size of a pencil eraser), though some melanomas are smaller.
  • E – Evolving: the spot changes in size, shape or colour, or looks different from your other spots.
• Don't wait on a changing spot. If a mole is new, changing, bleeding, itchy or doesn't look like your other moles, have it checked by a doctor. You can book a mole check without a referral in Toronto.

Where The Minor Surgery Center fits

The Minor Surgery Center does not offer intismeran, immunotherapy or oncology treatment. Our role comes earlier: assessing suspicious spots and surgically removing skin cancers.

• Assessment and removal: our board-certified plastic and reconstructive surgeons assess suspicious moles and remove skin cancers at five GTA clinics, including our North York skin cancer clinic.
• OHIP coverage: skin cancer removal (basal cell carcinoma, squamous cell carcinoma and melanoma) is covered by OHIP at our clinics, with no referral needed.
• Pathology: removed tissue can be sent for pathology to confirm the diagnosis. See mole biopsy and pathology in Toronto.
• What happens after a diagnosis: a melanoma diagnosis is usually followed by staging. For higher-risk melanoma, a medical oncologist is the right person to discuss immunotherapy and clinical trials like the ones described here. Read more about melanoma follow-up care in Ontario.

If you have a spot you're worried about, call (647) 614-1611 or book a free consultation.

What's next for personalized mRNA cancer vaccines?

The main things to watch are the full NEJM publication, regulatory decisions, longer survival data and results in other cancers. The intismeran program includes nine Phase 2 and Phase 3 trials (Merck, June 2026):

• INTerpath-001: continues to follow patients for longer-term outcomes, including overall survival.
• INTerpath-002, INTerpath-009 and INTerpath-014: Phase 3 trials in non-small cell lung cancer.
• INTerpath-004: Phase 2 trial after surgery for kidney (renal cell) cancer.
• INTerpath-005 and INTerpath-011: Phase 2 trials in bladder cancer.
• INTerpath-012: Phase 2 trial of first-line treatment for metastatic melanoma.
• INTerpath-013: Phase 2 trial of first-line treatment for metastatic squamous non-small cell lung cancer.

Outside these trials, the Cancer Research Institute says researchers are working on better ways to choose vaccine targets, deliver vaccines to immune cells and understand why some tumours resist vaccine-driven immune responses (Cancer Research Institute). For the bigger picture of where melanoma care is heading, see our melanoma research roundup and how neoadjuvant immunotherapy is changing stage III melanoma care.

Frequently asked questions

Is there a vaccine for melanoma?

There's no approved vaccine that prevents melanoma. Intismeran autogene is an investigational, personalized mRNA treatment for people who already have high-risk melanoma that was removed by surgery. In a 2026 Phase 3 trial, it lowered the risk of recurrence or death by 42% when added to Keytruda. It has not been approved by any regulator.

Is the Moderna melanoma vaccine approved in Canada?

No. As of November 3, 2026, intismeran autogene is not approved by Health Canada or the U.S. FDA. Merck and Moderna say they are engaging with regulators. Moderna has mentioned a potential 2027 approval, but that is not guaranteed.

How effective is the mRNA melanoma vaccine?

In the Phase 3 INTerpath-001 trial, 82.2% of patients on intismeran plus Keytruda were alive and melanoma-free at two years, compared with 70.0% on Keytruda alone. That's a 42% reduction in the risk of recurrence or death. It is not yet known whether it helps people live longer.

Does the melanoma vaccine prevent melanoma?

No. It does not prevent melanoma in healthy people. It is a treatment given after surgery to people who have already had high-risk melanoma, to lower the chance that it comes back. Sun protection and regular skin checks remain the best prevention.

Who is eligible for the mRNA melanoma vaccine?

In the Phase 3 trial, it was studied in adults with stage IIB, IIC, III or IV skin melanoma that was completely removed by surgery, who hadn't had other drug treatment for melanoma. Eligibility for any future approved use will be set by regulators.

How is a personalized melanoma vaccine made?

Scientists sequence the DNA of a tumour sample and a blood sample. They pick up to 34 mutation-based targets (neoantigens) unique to that patient's cancer, write them into a single mRNA medicine and inject it to train the immune system. In the Phase 3 trial, the median time to the first vaccine dose was 64 days.

What are the side effects of the melanoma mRNA vaccine?

The most common side effects were fever, injection-site pain, fatigue and flu-like symptoms. Serious treatment-related side effects were similar to Keytruda alone, at about 14%.

How much does the mRNA melanoma vaccine cost?

No price has been announced because it isn't approved. In Canada, public coverage of a new cancer drug depends on Health Canada approval, then separate value, price and provincial coverage decisions.

Can I get the melanoma vaccine in Toronto?

Not outside a clinical trial. Sunnybrook and Princess Margaret in Toronto, and William Osler in Brampton, were sites for the Phase 3 trial, which is no longer recruiting. Ask your oncologist about other open trials.

Is the melanoma vaccine the same as the COVID vaccine?

It uses the same basic mRNA technology, but it is a completely different product. It is designed from one person's tumour, carries instructions for up to 34 cancer-specific targets and is given as a cancer treatment alongside immunotherapy.

Does the vaccine work without Keytruda?

In melanoma, it has been studied only in combination with Keytruda (pembrolizumab). The trials compared the combination with Keytruda alone, so there's no evidence on how intismeran works on its own in melanoma.

Do I still need surgery if this vaccine is approved?

Yes. In the trials, the vaccine was given only after the melanoma had been completely removed, and it is designed from the patient's tumour. Surgery remains the main treatment for melanoma.

Questions to ask your care team

• What stage is my melanoma, and what is my risk of it coming back?
• Am I a candidate for treatment after surgery, such as immunotherapy?
• Is there an open clinical trial, including a personalized vaccine trial, that I might qualify for?
• Is my tumour tissue stored, and could it be used for future testing?
• What follow-up skin checks and scans do I need, and how often?

References

All sources were accessed on November 3, 2026.

1. Merck & Co. "Merck and Moderna Will Present Results From Landmark Phase 3 INTerpath-001 Trial for Intismeran Autogene Plus KEYTRUDA (pembrolizumab) at ESMO 2026 Presidential Symposium." News release, October 22, 2026.
2. Dermatology Times. "Personalized mRNA-Based Melanoma Vaccine Meets Primary Endpoints in Landmark Phase 3 Trial." August 20, 2026.
3. Moderna. "IR Insights: Recapping the Phase 3 INTerpath-001 Results."
4. CURE. "What Is a Personalized Cancer Vaccine? What Patients Should Know." October 13, 2026.
5. CancerNetwork. "INTerpath-001 Data Detail Survival, Subgroup, and Safety Findings in Melanoma."
6. ClinicalTrials.gov. "INTerpath-001: V940 plus pembrolizumab in high-risk melanoma (NCT05933577)." Status, locations and eligibility checked November 3, 2026.
7. Cancer Research Institute. "Cancer Vaccine Results in Melanoma: What the Data Show and What's Next."
8. Merck & Co. "Moderna and Merck Present 5-Year Data for Intismeran Autogene in Combination With KEYTRUDA (pembrolizumab) in Patients With High-Risk Stage III/IV Melanoma Following Complete Resection at the 2026 ASCO Annual Meeting." News release, June 1, 2026.
9. Journal of Clinical Oncology. "Intismeran Autogene Plus Pembrolizumab Versus Pembrolizumab Alone in High-Risk Resected Melanoma: 5-Year Update of the Randomized Phase IIb KEYNOTE-942 Study."
10. Drugs.com. "Intismeran autogene: What is it and is it FDA approved?"
11. Patient.info. "Malignant Melanoma of Skin" (AJCC stage groupings).
12. Canadian Cancer Society. "Melanoma skin cancer statistics."
13. Canadian Dermatology Association. "Melanoma Fact Sheet."
14. American Academy of Dermatology. "What to look for: ABCDEs of melanoma."

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