Melanoma vaccine reduces death or cancer recurrence by 42%

by Melanoma Institute Australia

edited by Sadie Harley, reviewed by Andrew Zinin

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In a world-first international trial, adding intismeran, a type of personalized therapeutic cancer vaccine made from each patient's own tumor, to pembrolizumab immunotherapy after surgery for high-risk melanoma reduced the risk of recurrence or death by 42%.

Professor Georgina Long AO, medical director at Melanoma Institute Australia (MIA) and chair of melanoma medical oncology and translational research at The University of Sydney, presented the results of the Phase III INTerpath-001 clinical trial at the ESMO (European Society for Medical Oncology) Congress 2026.

"These findings are a foundational shift in our approach to cancer: harnessing the immune system in a more personalized way to reduce the risk of melanoma recurrence or death. This has not been achieved before in the history of cancer drug development. It is the coming together of technology, our biological understanding of cancer and the immune system, and the courage to take this idea into the clinic," said Long

This clinical trial included 1,137 patients whose melanoma had been surgically removed, but who were at very high risk of it returning (stage IIB to IV). These patients had not previously received any cancer drug treatment. The trial compared treatment with a type of personalized therapeutic cancer vaccine, intismeran, given with pembrolizumab immunotherapy versus treatment with pembrolizumab alone.

Unlike a traditional vaccine that prevents disease in healthy people, intismeran is a therapeutic vaccine, designed for people after a cancer diagnosis who are at high risk of the cancer returning after surgery. It helps the immune system find and kill melanoma cancer cells, so the cancer is less likely to return or to spread to an advanced stage.

A melanoma is considered high risk if it has invaded a deeper layer of skin, has spread to nearby tissue and structures such as lymph nodes, or has metastasized to other areas of the body such as organs.

A 42% reduction in risk

The INTerpath-001 results are a landmark moment for cancer treatment. The trial showed adding intismeran to pembrolizumab reduced the risk of melanoma recurrence or death by 42% (hazard ratio [HR] 0.58; 95% confidence interval [CI] 0.45–0.75; p<0.001) compared with pembrolizumab alone. For patients who remained recurrence-free beyond six months from the start of treatment, the reduction in the risk of recurrence or death was even greater, at 58% (HR 0.42) compared with pembrolizumab alone.

Pembrolizumab side effects were not increased by the vaccine. Treatment was generally well tolerated in patients, with the vaccine causing transient low-grade side effects (injection-site pain, headache and chills in some patients).

"These results showed that patients with earlier-stage melanoma can be treated after surgery in a fundamentally new way. But these results are more than a landmark for melanoma; they mark a foundational shift for cancer medicine," said Long.

"The INTerpath-001 trial shows that treatment built from the unique signature of a patient's own tumor, working alongside checkpoint inhibitor immunotherapy, can sharpen the immune system to find and destroy any remaining cancer cells. Just as email transformed how we communicate, individualized neoantigen therapy has the potential to transform how we treat cancer."

How does this new treatment work?

Abnormal proteins, called neoantigens, give every melanoma its own unique identity, like a fingerprint. The vaccine (also known as individualized neoantigen therapy) is created using mRNA technology.

"We analyze a sample of each patient's tumor to read its unique neoantigen fingerprint, then create a 'wanted poster' of the cancer. This is delivered as mRNA, so the body's own cells display the poster to the immune system, showing it exactly what to look out for and attack," said Long.

The vaccine helps the immune system to identify the individual patient's tumor cells. Meanwhile, pembrolizumab releases the brakes the tumor places on immune cells.

"Cancer can fool the immune system with a fake friendly handshake, so the immune system thinks the cancer cell is normal. Pembrolizumab blocks the handshake, allowing immune cells to recognize the cancer and attack it, but it is the same drug for everyone. The vaccine gives a patient's immune cells a personalized wanted poster of their cancer, so the combination works in more patients," said Long

The investigational mRNA-based individualized neoantigen therapy (also known as intismeran autogene, intismeran, V940, mRNA-4157, or personalized therapeutic cancer vaccine) is being jointly developed by MSD (trade name of Merck & Co) and Moderna, and is used in combination with MSD's anti-PD-1 checkpoint inhibitor immunotherapy pembrolizumab.

An international trial

The INTerpath-001 clinical trial was an international trial across 157 sites around the world. This included several Australian centers: Melanoma Institute Australia, Westmead Hospital NSW, One Clinical Research WA, Princess Alexandra Hospital QLD, Paula Fox Melanoma & Cancer Center VIC, and Peter MacCallum Cancer Center (Parkville Cancer Clinical Trials Unit) VIC.

Long AO was the global principal investigator of this international trial and chair of the trial steering committee.

"This is the first Phase III 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. That fingerprint is read by 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. Having succeeded in melanoma, this proof of concept could mark the beginning of a foundational shift in how we treat cancer, helping patients remain cancer-free for longer," said Long

Professor Matteo Carlino, medical oncologist and member of the MIA faculty, led the trial at Westmead Hospital. "It has been an incredible opportunity to be part of this Australian and international collaboration, contributing to the development of intismeran from its early phase of development through to this groundbreaking trial. Intismeran has the potential to revolutionize the management of melanoma, and also multiple other types of cancer," said Carlino

Professor Alex Menzies, medical oncologist and senior researcher, and MIA's medical oncology and clinical trials teams played a pivotal role in the trial's success.

"This trial demonstrates that the addition of a personalized mRNA-based vaccine to current standard immunotherapy treatment leads to a major improvement in recurrence-free survival for those with high-risk, resected melanoma. The hope for the near future is that it may not only improve outcomes for melanoma patients with advanced disease, but also those with other types of cancer where current immunotherapies are poorly effective," said Menzies

The 1,137 patients who volunteered for this trial have helped change the future of cancer treatment for others.

Melanoma leading the way for new cancer treatments

Melanoma is Australia's cancer. Australia has one of the highest melanoma rates in the world, with one person diagnosed every 30 minutes and one person dying every six hours from the disease. It is also the most common cancer in Australians ages 20 to 39.

Progress in melanoma treatment over the past decade has been extraordinary, driven by research led by Melanoma Institute Australia.

Fifteen years ago, survival after a stage IV advanced melanoma diagnosis, where the melanoma has spread to other parts of the body, was measured in months. Today, nearly 55% of patients with advanced melanoma are effectively cured.

First came BRAF-targeted drug therapies, followed by checkpoint inhibitor immunotherapies, which harness the body's own immune system to fight cancer. A recent groundbreaking advance was neoadjuvant immunotherapy, giving immunotherapy before surgery rather than after. Breakthroughs, such as immunotherapy, have transformed outcomes not only for melanoma, but also for cancers such as lung and kidney cancer.

What's next?

These results now enter a regulatory review process which may take several years, depending on the country. Until then, the treatment is not available. Patients with melanoma who want to know more should talk to their medical oncologist.

Key medical concepts

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OncologyDermatology Provided by Melanoma Institute Australia Who's behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →

Andrew Zinin

Master's in physics with research experience. Long-time science news enthusiast. Plays key role in Science X's editorial success. Full profile →

Citation: Melanoma vaccine reduces death or cancer recurrence by 42% (2026, October 23) retrieved 24 October 2026 from https://medicalxpress.com/news/2026-10-melanoma-vaccine-death-cancer-recurrence.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.