Merck, Moderna mRNA cancer vaccine succeeds in Phase 3 trial

Merck ↗ 0.52% and Moderna ↘ 7.82% announced Wednesday that their personalized mRNA cancer vaccine succeeded in a Phase 3 clinical trial, marking the first late-stage positive readout for an individualized neoantigen therapy and for any mRNA-based cancer treatment.stocktitan+1

The INTerpath-001 trial showed that intismeran autogene, combined with Merck's immunotherapy Keytruda, delivered statistically significant improvements in recurrence-free survival and distant metastasis-free survival compared to Keytruda alone in patients with surgically removed high-risk melanoma.fiercebiotech+1

A Decade-Long Vision Realized

The 1,137-patient, randomized, double-blind trial enrolled patients with completely resected stage IIB-IV cutaneous melanoma who had not undergone prior systemic therapy. Patients received either intismeran plus Keytruda or Keytruda alone for approximately one year.stocktitan

Intismeran is customized for each patient, encoding mRNA instructions that help the immune system target up to 34 unique mutations found on an individual's tumor. The companies did not release specific hazard ratios or survival figures Wednesday, saying data will be presented at an upcoming international medical meeting.statnews+2

"For many years, the idea of creating an mRNA treatment designed specifically for an individual patient's cancer was aspirational. We are now helping turn that vision into a reality," Moderna CEO Stéphane Bancel said in the announcement.stocktitan

Path to Approval

The Phase 3 results build on earlier Phase 2b data presented at the 2026 ASCO Annual Meeting, which showed a 49% reduction in the risk of recurrence or death and a 59% reduction in the risk of distant metastasis or death at the five-year mark compared to Keytruda alone.stocktitan

Moderna previously sought accelerated approval for the vaccine in 2024 but was rebuffed by the FDA. Speaking to investors during a second-quarter earnings call last month, Moderna President Stephen Hoge said a positive interim readout "would obviously make the case for an accelerated review," according to Fierce Biotech.fiercebiotech

The companies said they plan to engage with regulators on filing submissions.stocktitan

Broader Implications

The trial will continue to evaluate overall survival, a key secondary endpoint. Merck and Moderna are also running a total of nine Phase 2 and Phase 3 trials of intismeran across multiple tumor types including non-small cell lung cancer, bladder cancer, and renal cell carcinoma.stocktitan

Professor Georgina Long, the study's principal investigator and medical director of Melanoma Institute Australia, called the results "a landmark moment for adjuvant melanoma treatment," adding that the combination "has the potential to establish a new treatment paradigm."stocktitan