Merck and Moderna said their Phase 3 INTerpath-001 trial met its primary endpoint of recurrence-free survival in melanoma patients, sending Merck shares up roughly 10% in premarket trading on Wednesday.

Merck & Co., Inc. (MRK) reached $143.52 in premarket trading, a new 52-week high and above its previous peak of $137.98. Moderna also rallied sharply, surging more than 90% in premarket trading to $118.61.

The trial tested Intismeran autogene, Merck and Moderna’s personalized mRNA cancer vaccine, in combination with Keytruda. The study met its primary endpoint of recurrence-free survival and its secondary endpoint of distant metastasis-free survival in patients with completely resected Stage IIB-IV melanoma.

The Phase 3 trial enrolled 1,137 high-risk patients whose melanoma had been surgically removed. Participants received up to nine doses of Keytruda plus the personalized vaccine, or Keytruda alone, for about one year. The companies said no new safety signals were reported.

The result marks the first positive late-stage trial outcome for an mRNA cancer vaccine and the first study to show a treatment performed better than Keytruda alone in this patient group. That makes the readout important not just for the two companies, but for a newer cancer-vaccine category that has so far had limited late-stage clinical validation.

The latest data follow Phase 2b results released in January, when the combination was reported to reduce the risk of recurrence or death by 49% after five years compared with Keytruda alone. Together, the earlier and later-stage findings give investors and regulators a clearer view of how the regimen performed across different trial phases, even as the companies still need to work through the next development steps before any potential commercialization.

Merck’s R&D chief Dean Li told CNBC that the companies expect to begin regulatory discussions within the next few months. Moderna CEO Stephane Bancel said no pricing decision has been made yet, adding that the data had only become available “a couple days ago.” Bancel also said Intismeran does not use patients’ own cells, unlike some cell therapies, which could help the manufacturing process scale and potentially lower costs.

J.P. Morgan analysts said a launch of the vaccine in adjuvant melanoma will be important for Moderna’s return to profitability. Barclays analysts estimated the therapy could generate about $3 billion in melanoma sales by 2035.

The move also came after a series of positive analyst actions. On August 17, Daiwa upgraded MRK to Outperform from Neutral, citing pipeline progress, and Wells Fargo issued a Buy rating the same day.

William Blair analyst Myles Minter said the interim results put both companies in a strong position to pursue regulatory approval and suggested the data also read positively for ongoing studies in other cancer types. Additional Phase 3 studies in non-small cell lung cancer are still enrolling, making those programs another area for investors to watch as the companies expand beyond melanoma.

Broader markets were little changed on Wednesday, with the S&P 500 up 0.1% and the Nasdaq slightly lower, leaving Merck’s move driven by company-specific news.