mRNA Cancer Vaccine Boosts Survival in Landmark Melanoma Trial

Moderna’s experimental mRNA cancer vaccine intismeran, paired with Merck’s checkpoint inhibitor Keytruda, delivered a striking improvement in a late‑stage melanoma study, according to a joint press release.

mRNA cancer vaccine shows promise in melanoma trial

The trial enrolled 1,137 patients with stage 2‑4 melanoma who had undergone surgical resection. Participants received either the combination or Keytruda alone for roughly a year. Those given the intismeran‑Keytruda regimen experienced longer disease‑free intervals and fewer distant metastases. Earlier data presented at ASCO indicated a ↑ 49% reduction in recurrence risk and a ↑ 59% drop in the combined endpoint of distant spread or death.

“We are teaching the immune system to recognize each tumor’s unique mutation signature,” Moderna CEO Stéphane Bancel told TIME.

Intismeran is a personalized therapeutic vaccine: a patient’s tumor DNA is sequenced, mRNA encoding the mutations is synthesized, and the product is delivered to elicit a virus‑like immune response. The platform’s speed—producing a bespoke vaccine in weeks—could accelerate the shift toward truly individualized oncology. Merck’s pembrolizumab, approved for melanoma since 2014, serves as the backbone, ensuring every trial participant receives an established standard of care. The FDA permitted the combination because Keytruda mitigates ethical concerns about withholding effective therapy. Moderna is already testing intismeran as monotherapy in early‑stage lung cancer and expanding to kidney, pancreas and bladder tumors across nine ongoing studies. CEO Bancel envisions a future where a patient could receive a vaccine‑style shot at a local pharmacy, dramatically curbing metastasis risk. The company’s stock, battered after the pandemic-era surge and subsequent layoffs, may find new momentum if the melanoma results translate across cancer types. For broader context, see coverage by Reuters and Bloomberg.