A new personalised mRNA vaccine, when combined with the immunotherapy drug Keytruda, halves the risk of melanoma recurring within five years, researchers at New York’s NYU Langone Perlmutter Cancer Center have announced. Among 107 patients who received the vaccine, known as intismeran, alongside Keytruda, nearly 69 percent remained cancer-free after five years, compared with 49 percent of those treated with Keytruda alone. “This means that adding intismeran to [Keytruda] reduced the risk for recurrence or death by 49 percent,” the centre said.
Most recurrences of melanoma, the deadliest form of skin cancer, occur within the first two to three years after treatment, but the disease can reappear even after a decade, according to the AIM at Melanoma Foundation. The new regimen therefore offers a significant improvement in long-term outcomes for patients.
How the personalised vaccine targets cancer cells
Intismeran — also known as V940 or mRNA-4157 and developed by the American biotech company Moderna — is an mRNA vaccine that works by training the immune system to recognise and attack cancer cells. Researchers analyse each patient’s tumour after surgical removal and create a bespoke vaccine tailored to the specific mutations, known as neoantigens, present in that individual’s cancer. The vaccine then instructs the body to produce protective T-cells that seek out and destroy cells displaying these abnormal proteins, making it harder for evasive cancer cells to hide.
Keytruda (pembrolizumab), made by Merck, is a separate immunotherapy that acts as an immune checkpoint inhibitor, making elusive cancer cells more visible to the immune system. While Keytruda is already a standard treatment for melanoma, it does not work for all patients because melanoma cells can become resistant to drugs, the researchers explained. The combination of the personalised vaccine and Keytruda appears to overcome this limitation, with the vaccine reducing the risk of cancer spreading to other parts of the body (distant metastasis) by 59 percent. Survival data from the Phase 2b trial, known as KEYNOTE-942, showed that 92.2 percent of patients receiving the combination were alive after five years, compared with 71.3 percent of those on Keytruda alone.
“Our findings also serve as encouragement to cancer researchers globally that mRNA vaccines like intismeran could work well in combination with immunotherapy for other cancers whose high rates of mutations have proven difficult to target,” said Dr. Janice Mehnert, associate director of clinical research at the cancer centre.
Future trials and UK involvement
Building on these results, a larger Phase 3 trial involving more than 1,000 patients is now underway for melanoma. The vaccine is also being tested against lung and other cancers to see if it can prevent recurrence in those disease types. In the UK, the NHS is directly involved in this final-stage testing. The Norfolk and Norwich University Hospitals NHS Foundation Trust is one of eight UK sites trialling the personalised mRNA vaccine, and University College London Hospitals (UCLH) has recruited its first patients for an international clinical trial. The Cancer Vaccine Launch Pad, an NHS programme, is fast‑tracking eligible patients into trials of new cancer vaccines.
Skin cancer is the most common form of cancer in the US, with an estimated 112,000 new melanoma cases and 8,500 deaths expected this year, according to the American Cancer Society. In the UK, melanoma is the fifth most common cancer, with around 19,392 new cases diagnosed annually and about 2,600 deaths each year. Incidence rates are projected to rise by 8 percent between 2024‑2026 and 2038‑2040, reaching around 26,500 new cases a year.
Keytruda is already available on the NHS for advanced melanoma following a draft recommendation from the National Institute for Health and Care Excellence (NICE) in 2015 and subsequent NICE guidance for adjuvant treatment of resected high-risk stage III melanoma. The US Food and Drug Administration has granted Breakthrough Therapy Designation to intismeran in combination with Keytruda for high‑risk melanoma, though no European Medicines Agency approval has been announced yet.
The findings from the KEYNOTE-942 trial were presented at the 2026 annual meeting of the American Society of Clinical Oncology and simultaneously published in the Journal of Clinical Oncology.