New experimental vaccine may help prevent melanoma from returning

Pharmaceutical companies Moderna and Merck have released new data on an experimental cancer vaccine that, combined with the established immunotherapy drug Keytruda, has shown encouraging results in treating high-risk melanoma patients.

The trial

The phase three clinical trial involved 1,137 patients who had already undergone surgical removal of melanoma. Some received the personalized vaccine, called Intismeran, together with Keytruda for about a year, while the rest were treated with Keytruda alone. The companies say the combined treatment extended the time before the disease returned, though full trial data have not yet been made public.

Earlier findings

In June, results from a smaller study of 157 patients were published, showing that over a five-year period the combined therapy cut the risk of melanoma recurrence by roughly half. Side effects were mostly mild to moderate, though for some patients they led to treatment being paused or discontinued.

How the vaccine works

Unlike traditional vaccines against infectious diseases, this vaccine is created individually for each patient using genetic information taken from their own tumor. Its goal is to train the immune system to recognize and attack abnormal proteins characteristic of cancer cells.

Moderna CEO Stéphane Bancel said that for years, the idea of an mRNA therapy tailored to an individual patient's cancer remained an aspiration, calling the phase three results a significant moment in cancer research.

The companies plan to present full trial data at an upcoming medical conference and submit them to regulators. The study will continue to determine whether the new therapy can also extend patients' overall survival.