Personalised mRNA cancer vaccine cuts melanoma recurrence risk by 42% in trial

A personalised mRNA cancer vaccine has reduced the relative risk of melanoma recurrence or death by 42% when combined with standard immunotherapy, according to results from an international phase III clinical trial involving 1,137 patients.

The findings were presented at the European Society for Medical Oncology (ESMO) Congress 2026.

The vaccine, intismeran autogene, remains investigational and is not yet available for routine clinical use.

The trial involved patients with high-risk melanoma whose tumours had been completely removed through surgery. It compared pembrolizumab alone with a combination of pembrolizumab and the personalised vaccine.

At two years, 82.2% of patients receiving the combination remained free from recurrence, compared with 70% of those receiving pembrolizumab alone. The combination also reduced the relative risk of distant metastasis or death by 38%.

“This is a very important development in cancer treatment. We have been talking about personalised cancer vaccines for several years, but we now have phase III evidence that this approach can improve outcomes over an established treatment,” Dr Vanita Noronha, professor and medical oncologist at Tata Memorial Hospital, Mumbai, told The Indian Express.

The vaccine uses genetic information from a patient's tumour to identify abnormal proteins called neoantigens. It then delivers mRNA instructions to help the immune system activate T cells that recognise and attack cancer cells carrying these targets.

Pembrolizumab works by blocking PD-1, an immune checkpoint that can restrain T-cell activity. The combination aims to direct and sustain the immune response against cancer cells that may remain after surgery.

The evidence applies to patients with high-risk stage IIB to stage IV cutaneous melanoma following complete surgical removal. Researchers cautioned that the findings cannot be extrapolated to other cancers or patients with active, unresectable disease.

Treatment-related adverse events were reported in 95.8% of patients receiving the combination, compared with 90% receiving pembrolizumab alone. Severe grade 3-5 treatment-related adverse events occurred in 14.2% and 13.4% of patients, respectively.

Dr Noronha said longer follow-up is needed to determine whether the improvement in recurrence-free outcomes translates into longer overall survival. Affordability, tumour sequencing and specialised manufacturing infrastructure will also be important for wider access in India.