Moderna, Merck Cancer Vaccine Succeeds in Trial

Merck and Moderna said Wednesday that their personalized mRNA cancer vaccine, given alongside Merck's immunotherapy Keytruda, met its main goal in its first-ever late-stage trial in melanoma patients.

The combination significantly extended the time patients lived without their melanoma returning, compared with Keytruda alone, and also cut the risk of the cancer spreading to distant parts of the body, the companies said.

Investors moved fast. CNN reported Moderna shares up 60% in premarket trading, at $103.60, with Merck up 7.5%; CNBC, reporting earlier in the premarket session, had Moderna up more than 10% and Merck up more than 1%.

The Trial

The phase three study enrolled 1,137 high-risk patients with stage IIB-IV melanoma whose detectable cancer had been completely removed by surgery, according to CNN. CNBC put the enrollment at more than 1,100 patients with higher-risk or advanced melanoma.

Patients were randomized to receive up to nine doses of Keytruda plus the personalized vaccine — called Intismeran — or Keytruda alone, over roughly one year. The companies said no new safety signals emerged.

The vaccine is built to order: it is based on an analysis of the mutations found in each patient's own tumor, rather than a single one-size-fits-all shot.