‘Breakthrough’ mRNA cancer vaccine cuts melanoma recurrence in major trial

US drugmakers Merck and Moderna said Wednesday that a personalised cancer treatment significantly reduced the risk of melanoma recurrence in a late-stage clinical trial, with experts hailing the results as a potential “breakthrough”.

The announcement sent Moderna shares soaring 145% to $154, while Merck stock gained more than 12% to $152.

The treatment, intismeran autogene, uses messenger RNA (mRNA) technology similar to that employed in Covid-19 vaccines. Researchers have spent years exploring mRNA-based cancer therapies, but the trial marks the first time a personalised mRNA treatment has produced positive results in a large, late-stage study.

“Today marks an extraordinary milestone for Moderna, for mRNA science and, most importantly, for patients with cancer,” Moderna CEO Stephane Bancel said.

The approximately one-year trial involved 1,137 patients who had undergone surgery to remove their melanoma. About two-thirds received intismeran autogene alongside pembrolizumab, an established cancer treatment, while the remaining patients received pembrolizumab alone.

The companies said they will present detailed findings at an upcoming international medical conference and begin seeking regulatory approval.

‘Proof of principle’

Lennard Lee, an oncologist and assistant professor at the University of Oxford who was not involved in the study, described the results as “very encouraging” and said the full data would be eagerly awaited.

Marco Gerlinger, a professor at London’s Barts Cancer Institute, said the findings were significant not only for melanoma patients but also because they offered “proof of principle that personalised cancer vaccines work”.

“I think it is fair to call it a breakthrough in the development of new cancer immunotherapies,” Gerlinger said, while cautioning that the companies’ initial announcement provided limited details.

The treatment is personalised for each patient. Doctors analyse a sample of the tumour to identify its unique mutations, creating a genetic “fingerprint” that guides the mRNA-based therapy.

The mRNA delivers temporary molecular instructions to cells, prompting them to produce targets that activate the immune system against cancer cells.

Although mRNA technology was developed decades ago, it gained widespread attention during the Covid-19 pandemic after Moderna and Pfizer used it to develop vaccines that proved highly effective at preventing severe disease.

Melanoma is among the deadliest forms of skin cancer, with more than 330,000 new cases reported worldwide in 2022.

Moderna said it and Merck are also testing intismeran in combination with pembrolizumab and other cancer therapies, as well as as a standalone treatment, across several cancers including melanoma, lung, bladder and kidney cancers.