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A personalised cancer therapy trial has met its primary endpoint of recurrence-free survival in patients with completely resected high-risk melanoma, manufacturers Merck and Moderna have announced.
In a joint statement published on 19 August 2026, Merck and Moderna said that the phase III INTerpath-001 trial was aimed to evaluate the safety and efficacy of intismeran autogene (intismeran; V940 or mRNA-4157) in combination with pembrolizumab (Keytruda; Merck) compared with pembrolizumab alone in patients with high-risk (stage IIB-IV) resected cutaneous melanoma.
The topline results of the phase III trial have yet to be peer reviewed or published at a conference.
For the randomised, double-blind, placebo- and active-comparator-controlled global trial, researchers enrolled 1,137 patients who, following complete surgical resection, were randomised 2:1 to receive intismeran and pembrolizumab versus pembrolizumab alone for approximately one year until disease recurrence or unacceptable toxicity, or for a total treatment duration of up to approximately 56 weeks, whichever was sooner.
Intismeran autogene is a novel investigational mRNA-based individualised neoantigen therapy, which is being jointly developed by Merck and Moderna, while pembrolizumab (Keytruda) is Merck’s anti-PD-1 therapy.
“The trial met its primary endpoint of recurrence-free survival and a key secondary endpoint of distant metastasis-free survival,” the statement said.
“This represents the first positive phase III readout for an individualised neoantigen therapy and for an mRNA-based cancer therapy, as well as the first phase III study to demonstrate a clinically meaningful improvement over Keytruda alone, a standard-of-care immunotherapy, in the adjuvant setting for patients with resected melanoma.”
The statement added that the data “will be presented at an upcoming international medical meeting and shared with regulatory authorities”.
The trial’s initial findings build on phase II trial results, published in 2022, which suggested the treatment could cut cancer recurrence or death by 44%. Researchers in the phase III trial will continue to study other secondary endpoints, including overall survival.
According to Merck and Moderna’s statement, the INTerpath programme currently consists of nine phase II and phase III clinical trials across multiple tumour types and stages of disease, including melanoma, non-small cell lung cancer, bladder cancer and renal cell carcinoma.
Commenting on the trial results, Marco Gerlinger, professor of gastrointestinal cancer medicine and consultant medical oncologist at Barts Cancer Institute, St Bartholomew’s Hospital, said: “I think it is fair to call it a breakthrough in the development of new cancer immunotherapies as it is the first phase III study that shows that a vaccine can protect against recurrences of one of the deadliest cancer types.
“This is certainly good news for patients with melanoma, but the study has much wider implications. It provides proof of principle that personalised cancer vaccines work. This is important as they can be designed against many different cancer types. I am hopeful that we will see similar successes of this technology in a range of cancer types, such as colon cancer, where a large study has been performed.”
Yin Wu, a Wellcome Trust career development fellow at King’s College London, added: “This is the first phase III study to demonstrate improved recurrence-free survival and distant metastasis-free survival for a combination adjuvant treatment over anti-PD-1 adjuvant therapy in melanoma, which is significant in itself. How significant will depend on the details to be released later.”
Lennard Lee, consultant medical oncologist, associate professor at the University of Oxford and senior national clinical adviser on cancer vaccines, commented: “There is also a wider story here about what happened after the [COVID-19] pandemic. In 2020, enormous global investment accelerated mRNA technology, vaccine science and manufacturing, and it started in the UK. The question afterwards was whether that capability could be redirected towards other major diseases.
“In 2022, the UK made an early strategic decision to pursue that opportunity in cancer, launching a national cancer vaccine advance to accelerate clinical trials of mRNA cancer vaccines. It forms part of our ‘AI For Science Plan’, our ten-year cancer plan, and our modern industrial strategy.
“Since then, the UK has developed into one of the world’s leading environments for cancer vaccine trials.”
Dean Y. Li, president of Merck Research Laboratories, said: “We believe individualised neoantigen therapies have the potential to redefine how patients with completely resected stage IIB-IV melanoma are treated.
“Together with Moderna, we look forward to presenting data from INTerpath-001 at an international medical meeting and sharing with regulatory authorities.”
