WEDNESDAY, Oct. 28, 2026 (HealthDay News) — A personalized cancer vaccine can significantly improve survival odds for patients with advanced melanoma, a new clinical trial has found.
Adding the vaccine to immunotherapy after surgery reduced the risk of death or cancer recurrence by 42% among later-stage melanoma patients, researchers reported Saturday at a meeting of the European Society for Medical Oncology (ESMO) in Madrid.
The vaccine, called intismeran, is crafted to specifically target an individual’s stray cancer cells that may be left over after standard surgery. The vaccine is based on a genetic analysis of the melanoma removed through surgery, researchers said.
“This is the first phase 3 study to show that a treatment built from the unique ‘fingerprint’ of a patient’s own tumor can reduce the risk of recurrence or death from cancer,” lead researcher Dr. Georgina Long, medical director and chair of Melanoma Institute Australia, said in an ESMO news release.
“That fingerprint is read by [gene-] sequencing the tumor, then a ‘wanted poster’ of the cancer is made as mRNA, showing the immune system exactly what to look for and attack,” Long explained.
For the new study, researchers recruited 1,137 adults who’d had later-stage melanomas removed through surgery.
All of the patients also received pembrolizumab, a drug that inhibits cancer cells’ ability to evade detection and attack by the immune system. However, many melanoma patients can still see their cancer return, despite treatment with the drug.
As an add-on to surgery and immunotherapy, two-thirds of the patients (757) also received a dose of intismeran, while the other 380 received a placebo.
Each personalized dose of intismeran contains up to 34 different genetic signals that the immune system can use to find and kill cancer cells, researchers said.
After a median of two years, adding intismeran cut the risk of cancer recurrence or death by 42%, the research showed, with more than 82% of patients who got the vaccine still alive and cancer-free, versus 70% of those who only got pembrolizumab.
Side effects were about the same between the two groups – nearly 24% in patients who got the combo experienced side effects, versus 20% among those who got pembrolizumab alone. The most common side effects were fever, injection-site pain and fatigue.
The researchers cautioned that the study group needs to be tracked longer to fully understand the vaccine’s impact on survival.
“For a patient, more time free of melanoma is a meaningful benefit in its own right,” Long said, but “longer follow-up is needed to show an impact on melanoma-specific and overall survival, as well as whether the early benefit we are seeing across stages and subgroups holds, and which patients benefit most.”
Researchers also are investigating whether this sort of vaccine could help people with lung, bladder and kidney cancers, noted Dr. James Larkin, scientific co-chair of the ESMO meeting.
The current clinical trial results “represent a major advance for the adjuvant treatment of stage 2 and 3 melanoma; the reduction in risk of relapse is clinically significant and, from the perspective of side effects, intismeran in combination with pembrolizumab is very well tolerated,” said Larkin, who was not involved in the study.
Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
More information
The International Multispecialty Journal of Health has more on mRNA cancer vaccines.
SOURCE: European Society for Medical Oncology, news release, Oct. 24, 2026
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