Personalised cancer vaccine cuts skin cancer recurrence risk by 42%: What this means for patients

A personalised cancer vaccine that uses messenger RNA (mRNA) technology to train the immune system to recognise and attack an individual patient’s tumour has reduced the relative risk of melanoma (skin cancer) recurrence or death by 42% when added to standard immunotherapy.

The results from a large international phase III clinical trial, involving 1,137 patients with high-risk melanoma whose tumours had been completely removed through surgery, are being described as a breakthrough in cancer therapies. The vaccine, intismeran autogene, remains investigational and is not yet available for routine clinical use.

According to Melanoma Institute Australia, the trial compared pembrolizumab alone with pembrolizumab combined with intismeran. At two years, 82.2% of patients receiving the combination remained free from recurrence, compared with 70% receiving pembrolizumab alone — an absolute difference of 12.2 percentage points. The combination also reduced the relative risk of distant metastasis or death by 38%. The results were presented at the European Society for Medical Oncology (ESMO) Congress 2026.

“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,” says Dr Vanita Noronha, professor and medical oncologist at Tata Memorial Hospital, Mumbai.

How does the personalised vaccine work?

Unlike preventive vaccines, intismeran is designed for people who already have cancer, with the aim of reducing the risk of recurrence after treatment. Cancer cells accumulate genetic changes that can produce abnormal proteins called neoantigens. A sample of the patient’s tumour is analysed to identify suitable targets, and scientists design an mRNA vaccine carrying instructions for selected neoantigens. The vaccine helps the immune system activate T cells that can recognise and attack cancer cells carrying these targets.

The aim is to eliminate microscopic cancer cells that may remain after surgery, even when the visible tumour has been removed.

Pembrolizumab works differently. It blocks PD-1, an immune checkpoint that can restrain T-cell activity, helping immune cells mount an attack. “The vaccine helps direct the immune response towards the patient’s tumour, while pembrolizumab helps the immune system sustain that response,” Dr Noronha explains.

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Who could benefit?

The evidence relates to patients with high-risk stage IIB to stage IV cutaneous melanoma whose tumours have been completely removed surgically. The vaccine is being investigated as an adjuvant treatment — therapy given after primary treatment to reduce recurrence risk.

Dr Noronha cautions that the findings should not be extrapolated to patients with active, unresectable or metastatic melanoma, in whom measurable cancer remains. The vaccine is also not a replacement for pembrolizumab. The benefit demonstrated in the trial came from adding the personalised vaccine to existing immunotherapy, rather than using the vaccine alone.

The treatment remains subject to regulatory review, which could take several years depending on the country, according to Melanoma Institute Australia.

Could this work for cancers common in India?

Researchers are investigating personalised cancer vaccines in other cancers, including lung, kidney, bladder and pancreatic cancer. However, success in melanoma does not guarantee similar results elsewhere. “Researchers are investigating personalised mRNA cancer vaccines in several other cancer types, including non-small-cell lung cancer, kidney cancer, bladder cancer and pancreatic cancer. However, success in melanoma does not guarantee similar results in other cancers. Melanoma can carry a relatively high number of mutations, some of which produce neoantigens that the immune system can recognise. Other cancers may have fewer suitable targets or biological mechanisms that suppress immune responses, making treatment more challenging,” Dr Noronha says.

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“For lung cancer, breast cancer and pancreatic cancer, we will need disease-specific clinical trial results before drawing conclusions about efficacy,” she adds.

She also stresses that therapeutic cancer vaccines should not be confused with preventive vaccines. Human papillomavirus (HPV) vaccination can prevent many HPV-related cervical cancers, while hepatitis B vaccination reduces the risk of liver cancer associated with chronic hepatitis B infection. Intismeran, by contrast, is designed for an individual who already has cancer and aims to lower the risk of its return.

What are the limitations?

Although the phase III results are encouraging, questions remain about how long the benefit will last and whether the treatment ultimately helps patients live longer. Dr Noronha says overall survival data from INTerpath-001 remain immature and longer follow-up is needed to establish whether the improvement in recurrence-free outcomes translates into longer lives.

The combination also has side effects. According to the figures provided by Dr Noronha, treatment-related adverse events were reported in 95.8% of patients receiving intismeran with pembrolizumab, compared with 90% receiving pembrolizumab alone. Severe grade 3–5 treatment-related adverse events occurred in 14.2% and 13.4% of patients, respectively. The most common reported adverse events with the combination were fever (52.2%), injection-site pain (51%) and fatigue (38.5%). Pembrolizumab can also cause immune-related complications, some of which can be serious.

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Each vaccine must also be designed for an individual patient, requiring tumour tissue, genetic sequencing, specialised manufacturing facilities and time for production.

What about India?

Dr Noronha believes affordability, access to tumour sequencing and manufacturing infrastructure will be critical considerations before such treatments can be delivered at scale. “I would not describe this as a cure or suggest that it will eliminate the risk of recurrence for every patient. It is an additional treatment that has demonstrated a meaningful benefit in a defined group of patients,” she says.

For now, the trial provides evidence that tailoring treatment to the genetic characteristics of an individual’s tumour may help reduce the risk of melanoma returning. Whether the approach can improve long-term survival, extend to other cancers and become affordable enough for wider use will depend on further research and regulatory decisions.