Moderna (MRNA) and Merck (MRK) shares surged in premarket trading on Wednesday after the companies announced that their personalized mRNA cancer vaccine, Intismeran autogene, combined with Merck’s Keytruda immunotherapy, met primary and secondary endpoints in the Phase 3 INTerpath-001 trial for high-risk melanoma.
Moderna stock at one point doubled, rising more than 99% to $125.68 from Tuesday's close of $62.96, and was up over 87% at time of writing. Merck rose more than 7% before the open, hitting a new 52-week high of $143.52 in premarket trading, up around 10%.
The trial enrolled 1,137 patients with completely resected Stage IIB-IV melanoma. The combination reduced risk of recurrence and distant metastasis, marking the first positive late-stage result for an mRNA-based cancer vaccine and the first study to show a treatment worked better than Keytruda alone in this patient group.
No new safety signals emerged. Earlier Phase 2b data from January showed the combination reduced risk of recurrence or death by 49% after five years.
Merck R&D head Dean Li said regulatory discussions are expected within the next few months. Moderna CEO Stephane Bancel said no pricing decision has been made, and noted Intismeran does not use patients' own cells, potentially improving manufacturing scalability and lowering costs.
Analysts see major commercial potential. Barclays estimates the melanoma treatment could generate around $3 billion in annual sales by 2035. J.P. Morgan said the vaccine launch will be key to Moderna returning to profitability. Recent analyst upgrades from Daiwa and Wells Fargo also added fuel.
For Moderna, the results are especially important as it rebuilds after falling Covid-19 vaccine demand. The broader cancer pipeline includes trials in non-small cell lung, bladder, and renal cell carcinoma, which could validate the personalized mRNA platform beyond a single indication.
Despite the stock move, the broader market was little changed, with S&P 500 up 0.1% and Nasdaq fractionally negative, indicating the move was company-specific.
