Intismeran mRNA vaccine cuts melanoma recurrence risk
- A personalised mRNA-based vaccine combined with an established immunotherapy drug cut the risk of skin cancer returning or causing death by 42% in a phase III clinical trial...
- The study found that the combination of intismeran and pembrolizumab reduced the risk of melanoma recurring or resulting in death by 42% compared to treatment with the immunotherapy...
- The experimental vaccine uses the same mRNA technology as certain COVID-19 jabs, but it is custom-made to target genetic mutations unique to an individual's tumour, as detailed by...
A personalised mRNA-based vaccine combined with an established immunotherapy drug cut the risk of skin cancer returning or causing death by 42% in a phase III clinical trial involving 1,137 patients, according to results reported by the BBC and other outlets on October 22, 2026. The trial tested the experimental vaccine, known as intismeran, alongside Merck’s Keytruda on adults who had their melanoma surgically removed but faced a high risk of recurrence.
Trial Data Shows 42% Reduction in Recurrence Risk
The study found that the combination of intismeran and pembrolizumab reduced the risk of melanoma recurring or resulting in death by 42% compared to treatment with the immunotherapy drug alone over a two-year period, as reported by The Guardian. Furthermore, the drug combination reduced the risk of the skin cancer spreading across the body by 38%. Data from the trial indicated that 82% of patients receiving the combination treatment were alive and recurrence-free after two years, compared with 70% of participants treated with Keytruda alone, according to Reuters and BBC reporting.
How the Personalised mRNA Treatment Targets Tumours
The experimental vaccine uses the same mRNA technology as certain COVID-19 jabs, but it is custom-made to target genetic mutations unique to an individual’s tumour, as detailed by ABC News and The Guardian. Medical teams take a biopsy of the patient’s tumour, compare its cells to healthy cells, rank the top 34 differences, and encode that fingerprint into an mRNA sequence. When injected, the vaccine acts like a wanted poster, training the patient’s immune system to recognise and attack those specific cancer cells if they return, while Keytruda removes the natural brakes cancer cells use to hide.
Market Reaction and Regulatory Filings Underway
Following leaks on an oncology website prior to the full presentation at the European Society for Medical Oncology conference in Madrid, shares in drugmakers Moderna and Merck fell on October 22, 2026, with CNBC reporting a drop of up to 25% for Moderna before closing down over 17%. Financial analysts noted that the sell-off reflected extremely high investor expectations rather than a failure of efficacy. Both companies stated they are engaging with authorities and could file for regulatory approval as soon as 2027, though widespread adoption will depend on manufacturing costs and the complex six-week genetic analysis required for each patient.
Long-Term Survival and Application Across Other Cancers
Independent experts cited by the BBC and Reuters described the results as an impressive proof of principle for personalised medicine, while noting that longer-term follow-up is necessary to establish whether the treatment improves overall survival across a broader population. Researchers are already testing the same bespoke mRNA approach against other tumour types, including non-small cell lung cancer, bladder cancer, and renal cell carcinoma. The trial will continue to monitor participants over time to track recurrence rates and assess how effectively the vaccine extends patient lives.
