Results from a large trial of a personalized melanoma vaccine have raised hopes that doctors could eventually use vaccines to train the immune system to prevent a variety of cancers from coming back and perhaps, one day, treat them more broadly.
Merck and Moderna said their personalized mRNA vaccine, given alongside the immunotherapy drug Keytruda, reduced the risk of melanoma coming back or spreading in more than 1,000 patients whose tumors had been surgically removed but who remained at high risk of recurrence.
Experts say the importance extends beyond melanoma. Unlike chemotherapy, which attacks rapidly dividing cells and can damage healthy tissue, personalized cancer vaccines are designed to target mutations found specifically in a patient’s tumor. The goal is to teach the immune system to recognize these mutations and destroy the cancer cells that carry them.
Dr. Ryan Sullivan, a melanoma specialist at Mass General Brigham Cancer Institute, described the findings as a major advance for the field and said they could encourage investment in approaches that could change cancer treatment more broadly.
Dr. Julie Gralow, medical director of the American Society of Clinical Oncology, called the results an important advance for mRNA technology in cancer treatment.
The treatment, known as intismeran autogene, combines Keytruda with a personalized mRNA vaccine.
Scientists analyze a patient’s tumor to identify mutations that distinguish cancer from healthy cells. The vaccine then provides instructions designed to help the immune system recognize those targets.
The idea is not to prevent cancer in the same way as vaccines against infections such as HPV. Instead, treatment is personalized for people who already have cancer, or who have had a tumor removed but remain at risk of the disease returning.
Previous five-year results from a mid-stage trial of the personalized vaccine were encouraging. Patients who received the vaccine along with Keytruda had about half the risk of their melanoma coming back and a 59 percent lower risk of the cancer spreading to other parts of the body compared to those who received Keytruda alone.
The companies said adding the vaccine did not raise new safety concerns.
The trial is still ongoing and researchers will need to follow patients longer to determine if the treatment also improves overall survival.
However, the most important test will be whether the technology works against other cancers.
Merck and Moderna are already conducting large trials in non-small cell lung cancer. They are also studying targeting bladder and kidney cancers, as well as early-stage trials involving pancreatic and stomach cancers.
Moderna President Stephen Hoge said several trial results are expected in the next two years.
Roche and BioNTech are also testing their own personalized mRNA vaccine, autogene cevumeran, in patients with colon and pancreatic cancer after surgery. Results from the colon cancer trial are expected in 2027, while the pancreatic cancer study is expected later.
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If several of these trials are successful, the implications could be substantial.
Dr. Robert Vonderheide, director of Penn Medicine’s Abramson Cancer Center, said the melanoma results gave researchers reason to hope that other studies could also produce positive results.
One of the most important effects of personalized vaccines could be what happens after a tumor is removed.
Doctors often have to decide whether the potential benefit of additional immunotherapy outweighs the risk of side effects. That calculation can be particularly difficult when a patient has a relatively low chance of their cancer coming back.
A vaccine that further reduces that risk could shift the balance.
Dr. Elizabeth Buchbinder, a melanoma specialist at Mass General Brigham, said the added benefit “may change that math.”
Melanoma has been a particularly attractive target because its cells often contain many mutations, providing the immune system with numerous potential targets. But other cancers also have multiple mutations, suggesting the technology could have applications far beyond skin cancer.
For the first time, personalized cancer vaccines are being tested at scale in multiple tumor types. If the results remain positive, cancer treatment could move toward something much more individualized: a vaccine designed not simply for the type of cancer someone has, but for the particular genetic fingerprint of their tumor.
The idea of ​​vaccinating against cancer is no longer so far-fetched. The next few years could show whether it can become a routine part of cancer care.
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