Personalized mRNA vaccine slashes melanoma recurrence in landmark trial

A new personalized vaccine given in combination with a drug has reported positive late-stage trial results, showing the treatment significantly reduced the risk of recurrence and metastasis in patients with high-risk melanoma.

The Phase III study involved more than 1,100 patients with stage IIB to IV melanoma who had undergone surgery to remove their tumors. Participants were randomized to receive either the immunotherapy drug Keytruda alone or Keytruda alongside the customized vaccine, known as Intismeran, for about one year.

According to the drug companies developing the vaccine, Moderna and Merck, the combination therapy met both its primary target of extending the time patients remained cancer-free and its secondary goal of preventing the disease from spreading to other organs. Full detailed results and overall survival data have not yet been released and will be presented at an upcoming medical meeting.

The vaccine is created using the same mRNA technology deployed in some COVID-19 shots. It works by surgically removing a small piece of a patient's tumor, sequencing its DNA to identify specific mutations, and then programming the immune system to recognize and destroy any remaining cancer cells. This makes it a highly individualized treatment – a first for a positive late-stage trial in solid tumors.

"This is the first time we've seen clinically significant, statistically significant improvements over checkpoints like Keytruda in this population, and it's the first time we've done that with an individualized treatment," said Moderna President Stephen Hoge. Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy, called the result an "auspicious start" that signals a new phase in immunotherapy.

The announcement sent Moderna's shares soaring, adding nearly $40 billion to its market value, while Merck also climbed on the prospect of expanding its cancer portfolio as Keytruda nears patent expiration. Analysts project the melanoma treatment could generate around $3 billion in annual sales by 2035.

Despite the optimism, experts urged caution. The findings are interim and have not yet been peer-reviewed, and the therapy would still require regulatory approval before reaching patients.

In the UK, NHS England's National Clinical Director for Cancer, Professor Peter Johnson, called the development "exciting" and noted that the health service is preparing to bring such treatments to patients. Dr. Lennard Lee of the University of Oxford added that while the news is good for melanoma patients, the study has wider implications, providing "proof of principle that personalized cancer vaccines work."

Moderna and Merck are already in talks with regulators and, given the vaccine's breakthrough therapy designation, it could potentially become available as early as next year. The companies are also testing similar personalized approaches against lung, bladder and kidney cancers.

(Cover: Conceptual diagram of mRNA cancer vaccine. /CFP)