Moderna and Merck report phase 3 success for personalised mRNA melanoma vaccine
A late-stage trial of mRNA-4157/V940 combined with pembrolizumab met its primary endpoint in advanced melanoma, according to data reported by Moderna and Merck.
Moderna and Merck have reported that their personalised mRNA cancer vaccine, mRNA-4157/V940, succeeded in a late-stage clinical trial in patients with advanced melanoma when combined with the checkpoint inhibitor pembrolizumab. The result, reported on 19 August 2026, marks a significant step for individualised neoantigen-targeting vaccine strategies in oncology.
The vaccine is designed around tumour-specific neoantigens identified from each patient's own tumour sequencing data. A personalised mRNA sequence encoding those neoantigens is then manufactured and administered alongside pembrolizumab, which blocks the PD-1 checkpoint pathway. The strategy is intended to train the immune system to recognise and attack residual tumour cells.
Full data from the trial have not yet been published in a peer-reviewed journal, and independent expert analysis of the complete dataset is awaited. Earlier phase 2 results, published in 2023, showed a reduction in recurrence or death compared with pembrolizumab alone in resected high-risk melanoma. The new phase 3 readout extends that signal into a larger, randomised cohort.
The development is relevant to oncologists following the hereditary and somatic genomics of melanoma, and to researchers working on neoantigen prediction, tumour mutational burden, and personalised immunotherapy design. Regulatory filings have not yet been announced. Stat News reported the result on 19 August 2026.
Plain-language version
For patients, families, and general readers. Educational only — not medical advice.
Scientists at the pharmaceutical companies Moderna and Merck have announced that a new type of personalised cancer treatment worked in a large clinical trial for a type of skin cancer called melanoma. The treatment is a vaccine made using a technology called mRNA — the same platform used in some COVID-19 vaccines — but instead of targeting a virus, it is designed to help the immune system recognise and fight a specific patient's cancer cells. Each vaccine is made individually, based on the genetic make-up of the patient's own tumour. In the trial, it was used alongside an existing cancer medicine called pembrolizumab. The companies say the combination reduced the chance of the cancer coming back or spreading compared with pembrolizumab alone. The full results have not yet been published in a scientific journal, so independent experts have not yet had the chance to review all the data. Researchers say results like these could, in future, help inform how doctors approach treatment for some cancers. This is an educational summary, not medical advice. If anything here raises questions for you, please speak with your GP or a clinical professional.
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Primary source Stat News · 2026-08-19STAT+: Moderna and Merck say mRNA cancer vaccine succeeded in late-stage melanoma trial
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