The battle against the most dangerous type of skin cancer has made a huge leap forward, and it could dramatically change the way aggressive cancers are treated. In early June 2026, significant clinical trial data were released at the annual meeting of the American Society of Clinical Oncology (ASCO) and published in the Journal of Clinical Oncology, showing that an experimental, personalized mRNA cancer vaccine from Moderna and Merck has cut in half the risk of melanoma returning or spreading after five years, reports NBC News.

This news is being described as “paradigm-shifting” because melanoma can be a very serious diagnosis. When melanoma reaches an advanced stage, it may have already spread to nearby lymph nodes or tissues, making it more difficult to treat and increasing the risk that the cancer could return even after surgery. As a result, any major advance in treating or preventing recurrence is considered highly significant. The five-year follow-up results from this historic trial reveal that an mRNA vaccine tailored to each individual’s cancer, combined with conventional immunotherapy, achieved complete cancer-free status in nearly 70% of patients.

How the personalized vaccine works

Unlike vaccines used to treat infectious diseases, this therapeutic cancer vaccine is a highly specialized medical treatment tailored to a patient’s specific needs after diagnosis. It does not forewarn of skin cancer in the first place, but it is a search-and-destroy mission for hidden cells in the body.

Surgical removal is always the initial step in fighting melanoma, according to the National Institutes of Health (NIH). Still, after surgery, melanoma cancer cells are often microscopic and remain hidden in the body. To remove these stragglers, scientists have taken a tissue sample from the patient’s unique tumor and mapped its genetic mutations. These mutations lead to the production of unique, abnormal proteins, called neoantigens, that are only present on the surface of cancer cells.

Then, the personalized vaccine can be produced using mRNA technology, which provides precise genetic instructions to the patient’s immune system against up to 34 of the most prominent neoantigens detected in the patient’s tumor.

After injection, the vaccine helps educate a type of immune cell, known as T cells, to recognize the tumor’s unique “signature.” This education enables the T-cells to seek out, recognize and kill any remaining or recurring cancer cells, even years after surgery.

“Generally, what we have seen is that if we layer more drugs with immunotherapy, it causes more toxicity but not more benefit. So that is where the results of this trial are promising,” Dr. Shailender Bhatia, director of the melanoma team at Fred Hutch Cancer Center in Seattle says.

Common side effects

The side-effect profile is very predictable and well-tolerated as this personalized cancer vaccine is based on the same mRNA platform as the COVID-19 vaccines used worldwide.

Information gathered from the five-year clinical trial reveals that the physical side effects are far more likely to be mild to moderate and usually occur within 24 to 48 hours of the injection, resolving independently within a few days.

The most common side effects reported by people in the trials were mild pain, swelling and redness at the injection site in the arm. This mild pain is a good indicator that your local cells are responding to the vaccine instructions and starting to build up a defense.

When the immune system starts to become more active and educates your T-cells to target tumor markers, you may have some low-grade, systemic side effects that may last for a short while. Common symptoms include a mild headache, chills, low-grade fever, muscle pain and general fatigue that resolve within a couple of days.

Rare or serious side effects

One of the amazing benefits of this individualized mRNA vaccine is its unusually low toxicity profile compared with traditional, highly aggressive oncology treatments.

Over the years, the Mayo Clinic says, oncology researchers have discovered that adding several drugs to standard cancer immunotherapy can greatly increase toxic side effects without a corresponding increase in survival. This mRNA vaccine, however, is highly specific in targeting unique tumor neoantigens, thereby avoiding widespread damage to healthy tissues.

Although serious or long-term adverse events remain exceedingly rare, clinical trial investigators are closely monitoring for rare immune-mediated adverse events, including severe inflammation of the lungs (pneumonitis), colon (colitis) or endocrine glands, because the vaccine is administered alongside a strong immunotherapy agent called pembrolizumab (Keytruda).

What to do if you notice symptoms

If you experience common, anticipated symptoms such as low-grade fever, muscle pain or a mild headache, healthcare providers recommend getting plenty of rest, drinking plenty of fluids and taking over-the-counter pain relievers or fever reducers as prescribed.

If you have any unusual or serious symptoms, including a sudden high fever or a cough that doesn’t go away, severe abdominal pain, shortness of breath that worsens or a widespread skin rash, contact your oncology clinic right away. By keeping your medical personnel in the loop, you can be sure that any immune-mediated reactions to the accompanying immunotherapy are caught early and treated appropriately.

Alternatives or complementary options

Personalized mRNA vaccines are a promising approach for the treatment of skin cancer. Still, for the time being, patients have access to highly effective, FDA-approved standard therapies and important lifestyle measures.

The current standard frontline treatment for high-risk Stage 3 melanoma is surgical removal of the tumor followed by single-agent immunotherapy, which uses drugs that target the immune system to “unmask” cancer cells, allowing the immune system to attack them, according to the Centers for Disease Control and Prevention (CDC).

Skin protection from ultraviolet (UV) radiation is of utmost importance as a complementary line of defense against the development of new mutations. This means using a broad-spectrum sun protection factor (SPF) 30+ sunscreen every day, wearing sun protection clothing, avoiding indoor tanning beds altogether and getting an annual, professional full-body skin exam by a board-certified dermatologist.

How to stop melanoma from spreading

The absolute best way to prevent melanoma from spreading to your vital internal organs is to detect it early and have it removed by surgery, before it invades deeper into the skin. Doctors consider the “Breslow thickness” of the mole when deciding whether it has grown deep enough into your skin to reach your blood vessels or lymphatic system, according to the Mayo Clinic.

After a high-risk tumor has been removed, these routine doctor’s visits, imaging tests and advanced adjuvant treatments, such as standard immunotherapy or experimental neoantigen vaccines, are crucial for detecting and killing circulating cancer cells before they colonize other parts of the body.

When will the melanoma vaccine be available?

During the recent clinical trial, patients were treated with their custom vaccines four to six weeks after surgery, which coincided with their third or fourth course of conventional immunotherapy. Looking ahead, the top trial investigators will continue to explore methods to make genetic sequencing even smaller and more efficient, enabling the production of these highly personalized mRNA formulations in as few as three to four weeks, enabling doctors to provide this powerful immune boost even sooner in a patient’s treatment window.

Dr. Justus Rabach, MD, tells Blavity Health, “Although this data from the five-year Phase 2 trial is very encouraging, the personalized melanoma vaccine is now undergoing a large-scale Phase 3 clinical trial in the U.S., Australia and Europe to secure final approval from regulators. With all participants in this broader trial having already finished their courses, the researchers are working around the clock to compile the final data; they estimate that the personalized vaccine could be commercially approved and offered to high-risk patients by the end of 2027 or the beginning of 2028, depending on the final speed of the FDA review process.”

Bottom line

When used in combination with conventional immunotherapy, a personalized mRNA vaccine designed based on a patient’s tumor genomic makeup has been shown to reduce the likelihood of melanoma recurrence or spread by half after five years. The treatment involves teaching T-cells to target 34 distinct tumor surface proteins, enabling the immune system to attack those cancer cells that remain hidden after surgery, and with only minor flu-like side effects. These are amazing results, and if the continuing Phase 3 clinical trials confirm these findings, it will be a whole new ballgame in contemporary oncology, providing a fantastic tool to defeat melanoma and other fatal solid tumors.

Frequently Asked Questions

At what stage is melanoma not curable?

Melanoma is generally considered incredibly difficult to cure completely once it reaches Stage 4, meaning the cancer cells have successfully traveled through the bloodstream to deeply invade distant organs like the brain, lungs or liver.

How close are we to curing melanoma?

We are closer than ever before, as modern checkpoint-inhibitor immunotherapies combined with these newly developed personalized mRNA vaccines are successfully shifting advanced melanoma from a highly fatal diagnosis into a manageable, highly survivable condition.

Citations

Sullivan K. A personalized vaccine for melanoma cut the risk of cancer returning after five years. NBC News. Published June 2026. https://www.nbcnews.com/health/cancer/personalized-vaccine-melanoma-cut-risk-cancer-returning-five-years-rcna347424

Verma K, Lewis DJ, Siddiqui FS, Dane A. Mohs Micrographic Surgery Management of Melanoma and Melanoma In Situ. Nih.gov. Published August 28, 2024. https://www.ncbi.nlm.nih.gov/books/NBK606123/

Ferrara N. Mayo Clinic research finds immune system responds to mRNA treatment for cancer. Mayo Clinic Comprehensive Cancer Center Blog. Published January 11, 2022. https://cancerblog.mayoclinic.org/2022/01/11/mayo-clinic-research-finds-immune-system-responds-to-mrna-treatment-for-cancer/

Naik PP. Current Trends of Immunotherapy in the Treatment of Cutaneous Melanoma: A Review. Dermatology and Therapy. 2021;11(5):1481-1496. doi:https://doi.org/10.1007/s13555-021-00583-z

Mayo Clinic. Melanoma – Diagnosis and treatment – Mayo Clinic. Mayoclinic.org. Published December 30, 2023. https://www.mayoclinic.org/diseases-conditions/melanoma/diagnosis-treatment/drc-20374888