Melanoma: an mRNA therapy made for each patient’s tumour reduced the risk of recurrence in a phase 3 trial

On 19 August 2026, Merck (known as MSD outside the US and Canada) and Moderna announced topline results from the phase 3 INTerpath-001 trial. It tested intismeran autogene (also known as mRNA-4157 or V940), an investigational messenger RNA therapy, given together with the immunotherapy pembrolizumab after complete surgical removal of high-risk melanoma (stages IIB–IV). According to the companies, it is the first positive phase 3 trial of an mRNA-based cancer therapy.

How it works

The therapy is made separately for each patient from a sample of their own tumour. The tumour’s specific mutations are identified, and the mRNA encodes up to 34 neoantigens, protein fragments altered by those mutations. Once given, they are presented to the immune system, with the aim of training it to recognise and attack cancer cells. Pembrolizumab, an anti-PD-1 immunotherapy, is already a standard treatment after surgery for some stages of melanoma.

What the trial showed

INTerpath-001 enrolled 1,137 patients, randomly assigned 2:1 to intismeran plus pembrolizumab or to pembrolizumab with placebo, for about one year. The trial is double-blind. At a pre-specified interim analysis, the combination produced statistically significant improvements in recurrence-free survival (the primary goal) and distant metastasis-free survival compared with pembrolizumab alone. The safety profile was consistent with earlier studies, with no new safety signals.

• The announcement does not yet include figures, such as how much the risk of recurrence fell. The data will be presented at the European Society for Medical Oncology (ESMO) congress in Madrid, 23–27 October 2026.
• Overall survival is still being followed.
• The result follows a phase 2b trial (KEYNOTE-942) of 157 patients, published in The Lancet in 2024. At five years, according to data presented at the 2026 ASCO meeting, the combination was linked to a 49% lower risk of recurrence or death than pembrolizumab alone.

What it means for patients now

Intismeran is an investigational therapy and is not approved; the companies will discuss the data with regulators. The exact size of the benefit, the effect on overall survival and whether the approach will work in other cancers, where further trials are under way (lung, kidney and bladder cancer), are still unknown. INTerpath-001 is no longer recruiting. If you or someone close to you has had surgery for melanoma, discuss the right treatment after surgery, and any clinical trials, with your oncologist.