Cancer Vaccine Slashes Melanoma Risk, Spurs Push to Broaden Use

WHO:

ScienceAlert - Georgina Long, medical oncologist at Melanoma Institute Australia (MIA), was the global principal investigator and presented the trial results.

ScienceAlert - Robert Vonderheide, president-elect of the American Association for Cancer Research, was not involved in the trial; he described its results to The New York Times as being among “our biggest breakthroughs.”

ScienceAlert - Moderna and Merck developed the personalized mRNA vaccine.

ScienceAlert - Alex Menzies, a medical oncologist at MIA, said the approach might benefit melanoma patients with advanced disease and patients with other cancers where immunotherapies work poorly.

STAT - James Larkin of London’s Royal Marsden Hospital was scientific co-chair of the European Society for Medical Oncology meeting.

STAT - Vinod Balachandran of Memorial Sloan Kettering Cancer Center described the history of cancer-vaccine development as “long and sordid.”

WHAT:

ScienceAlert - In the phase 3 INTerpath-001 trial, a personalized mRNA vaccine combined with Keytruda reduced the risk of melanoma recurrence or death by 42% compared with Keytruda alone.

STAT - The customized mRNA treatment intismeran, developed by Merck and Moderna, improved outcomes when combined with Merck’s checkpoint inhibitor Keytruda.

ScienceAlert - The phase 3 trial involved more than 1,100 patients at 157 sites worldwide and supported positive phase 2 findings published in 2024.

ScienceAlert - Among patients who remained cancer-free six months after starting treatment, the risk of recurrence or death was reduced by 58% compared with pembrolizumab alone.

ScienceAlert - Trial results were presented at the European Society for Medical Oncology Congress 2026 and are set to be published in the New England Journal of Medicine.

STAT - Specialists are discussing how to adopt the treatment and how widely personalized cancer vaccines can be deployed.

ScienceAlert - The vaccine was not yet available to patients in Australia or the United States; its results had entered regulatory review, which could take several years depending on the country.

WHERE:

ScienceAlert - The phase 3 trial included sites around the world; the results were presented at the European Society for Medical Oncology Congress.

STAT - The European Society for Medical Oncology meeting was held in Madrid.

ScienceAlert - Australia has one of the world’s highest melanoma rates, and one person there dies from melanoma every six hours.

WHY:

ScienceAlert - The vaccine is designed to prevent melanoma from returning after surgery by helping the immune system identify and attack cancer cells.

STAT - James Larkin said the approach may be applicable to other types of tumors.

HOW:

ScienceAlert - Researchers sequence each patient’s tumor and identify features distinguishing it from healthy cells, then use that information to create a personalized mRNA vaccine.

ScienceAlert - The mRNA prompts the patient’s cells to display tumor-specific markers to the immune system.

ScienceAlert - The vaccine is combined with pembrolizumab (Keytruda), which blocks cancer’s immune-evasion mechanism and enables immune cells to recognize and attack it.

ScienceAlert - Long said the INTerpath-001 trial showed that treatment based on a patient’s tumor signature, combined with checkpoint inhibitor immunotherapy, can help the immune system find and destroy remaining cancer cells.

ScienceAlert - The article noted that several randomized mRNA-vaccine trials for colorectal and head and neck cancers had failed to reduce recurrence.

(UPDATED October 26, 2026 07:30 UTC)

A personalized mRNA vaccine combined with Keytruda reduced the risk of melanoma returning or causing death by 42%, compared with Keytruda alone, in a large phase 3 trial. Developed by Moderna and Merck, the treatment is tailored to each patient’s tumor, helping the immune system recognize cancer cells, while Keytruda blocks a mechanism tumors use to evade immune defenses. The international trial enrolled more than 1,100 patients at 157 sites. Georgina Long, the study’s global principal investigator, presented the findings at a cancer meeting in Madrid. The results build on earlier positive findings, though several other cancer-vaccine trials have failed to prevent recurrence. Specialists are now considering how widely the approach could be used, including for other cancers. The vaccine is not yet available in Australia or the United States, where regulatory review is underway.