First-of-its-kind mRNA cancer vaccine passes major test

A personalized cancer vaccine from Moderna and Merck succeeded in preventing melanoma from returning or spreading in a late-stage study of high-risk patients, marking the first successful late-stage trial for a personalized mRNA cancer therapy.

Cancer treatment gets personal

The new mRNA cancer vaccine, called intismeran, is built specifically for each individual patient after they undergo surgery to remove a high-risk melanoma tumor.

• Doctors send a blood sample and tumor biopsy for genetic analysis, then scientists identify mutations on the cancer cells likely to alert the immune system.
• Those targets are encoded into mRNA and manufactured into a personalized vaccine, a process that takes about six weeks.
• While the vaccine is being made, patients recover from surgery and begin treatment with Merck’s cancer immunotherapy Keytruda.

So, does it work?...Short answer: yes, to the unspecified satisfaction of researchers. After following 1,000+ patients who received either the mRNA vaccine and Keytruda or just immunotherapy alone for ~1 year, they found the vaccine combo met the trial’s main goal of extending time before melanoma returned (compared to just Keytruda), while also meeting a secondary goal of preventing cancer from spreading to other organs.

There are still some unknowns. Moderna and Merck haven’t released specifics on how long patients receiving the combination went without their cancer progressing, or how long they lived on average, with more details expected later this year.

Earlier results found adding the mRNA vaccine reduced the risk of melanoma recurrence or death by 49% compared with Keytruda alone.

Investors were ecstatic with the results. Moderna shares nearly tripled in trading yesterday (+177%), while Merck’s stock hit an all-time high (+12.6%) following news of the partners’ mRNA cancer vaccine breakthrough. Moderna CEO Stéphane Bancel says the companies hope to have the novel melanoma treatment on the market by 2027.