What were the key efficacy results of Moderna and Merck's melanoma vaccine trial?

The late-stage trial of Intismeran—a combination of Moderna's personalized mRNA vaccine and Merck's Keytruda—met both its primary endpoint of reducing cancer recurrence and its secondary endpoint of preventing cancer spread in high-risk, surgically removed stage IIB-IV melanoma patients; interim results showed no new safety signals, and earlier mid-stage data from January indicated a 49% reduction in risk of recurrence or death after five years.

How does the Intismeran treatment work and who was included in the trial?

Intismeran combines Merck's immunotherapy Keytruda with a made-to-order mRNA vaccine from Moderna, tailored to mutations identified in each patient's own tumor; the trial enrolled 1,137 high-risk melanoma patients with stage IIB–IV disease that had been surgically removed, who were randomized to receive up to nine doses of Keytruda plus the personalized vaccine or Keytruda alone for about one year.