Scientists have reported promising long-term results from a study that combines a personalized mRNA vaccine with a leading immunotherapy drug to help stop melanoma from returning.
The research, led by investigators at NYU Langone Health and its Perlmutter Cancer Center, suggests that the treatment may significantly improve survival and reduce the risk of cancer spreading. The study was presented at the 2026 American Society of Clinical Oncology meeting and published in the Journal of Clinical Oncology.
Cancer treatment has changed dramatically in recent years. In the past, surgery, chemotherapy, and radiation were the main options available to patients. Today, doctors increasingly use immunotherapy, a treatment approach that helps the body’s own immune system fight cancer.
Immunotherapy has transformed care for many melanoma patients, but it does not work equally well for everyone. Some cancers learn how to avoid immune attacks and return months or years after treatment.
Researchers wanted to find a way to give the immune system extra help. Their answer was a personalized vaccine called intismeran. Unlike a traditional vaccine that protects against viruses, this vaccine is created specifically for each patient.
Scientists analyze a patient’s tumor after surgery and identify dozens of abnormal proteins called neoantigens. These proteins act like fingerprints that distinguish cancer cells from healthy cells.
Using mRNA technology, researchers create a custom vaccine containing instructions related to these unique tumor markers. Once injected, the vaccine teaches the immune system to recognize those markers. The goal is to train immune cells to hunt down and destroy any remaining melanoma cells before they can grow into new tumors.
The vaccine was tested alongside pembrolizumab, a widely used immunotherapy medicine. Pembrolizumab works by blocking a protein called PD-1, which cancer cells often exploit to avoid detection. By blocking PD-1, the drug helps restore the immune system’s ability to identify cancer cells.
The clinical trial enrolled patients in the United States and Australia between 2019 and 2021. All participants had already undergone surgery to remove their melanoma. Researchers compared outcomes between patients who received the vaccine plus pembrolizumab and those who received pembrolizumab alone.
Five years later, the differences between the groups were striking. Patients receiving the combination treatment had much better outcomes.
Nearly seven out of ten remained cancer-free, while fewer than half of those receiving only pembrolizumab achieved the same result. Researchers found that the combined approach reduced the risk of recurrence or death by almost half.
The treatment also reduced the likelihood that melanoma would spread to distant organs. This is important because metastatic melanoma is much harder to treat and is responsible for many cancer-related deaths. Survival rates were also notably higher among patients who received the personalized vaccine.
The study offers one of the strongest pieces of evidence so far that mRNA technology can be successfully used against cancer.
While mRNA became famous during the global pandemic, cancer researchers have spent years exploring its potential. One advantage of mRNA is flexibility. Scientists can rapidly design treatments tailored to the unique genetic features of an individual’s tumor.
Researchers say this personalized approach may be particularly valuable for cancers such as melanoma because these tumors often carry large numbers of mutations. The more unique markers a tumor contains, the more targets the immune system may have once it is properly trained.
The safety profile was encouraging. Most side effects were manageable and included fatigue, chills, and discomfort at injection sites. Serious safety concerns did not emerge during the study.
Even with these positive findings, experts caution that more research is needed. The trial was a Phase IIb study, which means larger studies are still necessary before doctors can routinely offer the treatment. Fortunately, a Phase III international trial is already underway and will provide stronger evidence about the vaccine’s effectiveness.
From a scientific perspective, the results are highly significant. They suggest that personalized vaccines can enhance existing immunotherapies rather than replace them. This combination strategy may become an important model for future cancer treatments.
At the same time, the study’s relatively small size means the findings should be interpreted carefully until larger trials are completed. If future research confirms these benefits, personalized mRNA vaccines could represent one of the most important advances in cancer care in recent decades and potentially be adapted to treat many different types of cancer.
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Source: NYU Langone Health.
