A personalised cancer vaccine has posted a strong result in melanoma, with a new trial finding it cut the risk of recurrence or death by 49 percent after surgery.
The study, led by New York University researchers at the Perlmutter Cancer Center, tested the vaccine intismeran in combination with pembrolizumab, sold as Keytruda, in 107 patients after melanoma surgery. Researchers compared those results with a randomly selected group of 50 melanoma patients who received pembrolizumab alone after surgery, which is a current standard of care.
Results from the phase 2b trial, formally known as KEYNOTE-942, were presented at the 2026 annual meeting of the American Society of Clinical Oncology on June 1 in Chicago and published at the same time in the Journal of Clinical Oncology.
After five years of follow-up, 68.8 percent of patients who received the combination therapy remained cancer free, compared with 49.1 percent in the pembrolizumab-only group.
An NYU media release said: “This means that adding intismeran to pembrolizumab reduced the risk for recurrence or death by 49 percent. The combination therapy also reduced the risk of distant metastasis, the spread of cancer to another part of the body, by 59 percent.”
The release also said: “Overall survival, meaning no death from cancer or any other cause, was 92.2 percent for the vaccine with immunotherapy group, while for the immunotherapy-alone group it was 71.3 percent.”
“Our study offers strong evidence to melanoma patients that intismeran vaccine therapy, when used in combination with immunotherapy, can demonstrably reduce their risk of having their cancer return and improve clinical outcomes,” said study senior investigator Janice Mehnert, a professor in the Department of Medicine at NYU Grossman School of Medicine.
“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 Mehnert, director of the melanoma medical oncology program and a director of clinical research at Perlmutter Cancer Center.
Intismeran is a personalised immunotherapy strategy built using information from a patient’s individual tumour. In this study, researchers analysed tumour cells for 34 neoantigens specific to each melanoma and created a personalised vaccine for each patient.
The vaccine is based on messenger RNA, which provides cells with instructions for making proteins. Researchers said mRNA cancer vaccines are designed to teach the immune system to recognise cancer cells as different from normal cells.
The study results highlight the role of T cells, which can attack viruses and cancers. Pembrolizumab is an immunotherapy that blocks the PD-1 protein receptor, with the aim of making cancer cells more visible to immune cells again.
Researchers have looked at adding vaccines because pembrolizumab and other PD-1 inhibitors do not work for all patients, and melanoma cells can become resistant to immunotherapy.
For the KEYNOTE-942 trial, patients were enrolled at cancer centres in Australia and the United States from 2019 to 2021. All were men and women who had surgery to remove their melanoma tumours.
Seven patients in each treatment group died during follow-up, most from cancer. Side effects were considered manageable and included fatigue, pain at injection sites and chills.
Dr Mehnert said a phase 3 multicentre trial is already underway to test intismeran as a first-line therapy in combination with pembrolizumab for melanoma. The vaccine is also being tested to see if it can prevent recurrence in lung and other cancers.
Funding support for the study came from Moderna, the manufacturer of intismeran, and Merck, the manufacturer of pembrolizumab.
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