Merck and Moderna will take the first successful mRNA cancer vaccine to regulators
Intismeran autogene, an mRNA therapy built from the mutations found in a single patient's tumour, met both the primary and key secondary endpoints of a Phase 3 melanoma trial, the first late-stage success for a cancer vaccine of its kind.
Merck and Moderna said in an August 19 release that the combination of intismeran and Keytruda delivered statistically significant and clinically meaningful improvements in recurrence-free survival and distant metastasis-free survival against Keytruda alone in patients with completely resected stage IIB to IV melanoma.
Merck, which operates as MSD outside the United States and Canada, said the companies will present the data at an international medical meeting and engage regulators on filing submissions.
The INTerpath-001 trial, according to the AJMC account of the results, randomized 1,137 patients who had not received prior systemic therapy on a 2:1 basis to intismeran 1 mg every three weeks for up to nine doses plus roughly one year of pembrolizumab, or to pembrolizumab alone.
Reuters reported that each vaccine targets up to 34 mutations unique to that patient's cancer, identified by sequencing the tumour after surgical removal.
Overall survival data, which would show whether the combination helps patients live longer, were not yet available, Reuters reported, and the extent of the benefit remains unclear pending detailed results.
The companies have not published in a peer-reviewed journal, NBC News reported.
Merck said no new safety signals emerged.
Five-year follow-up from the Phase 2b KEYNOTE-942 trial, presented at the 2026 ASCO Annual Meeting, showed a 49 percent reduction in the risk of recurrence or death and a 59 percent reduction in the risk of distant metastasis or death, Merck said.
"[The] results represent a landmark moment for adjuvant melanoma treatment," said Georgina Long, the study's principal investigator and medical director of Melanoma Institute Australia, in a statement carried by AJMC.
The Canadian Cancer Society expects around 11,300 melanoma diagnoses in Canada this year and an estimated 1,250 deaths, CBC News reported.
Melanoma Canada told the broadcaster that melanoma ranks among the most common cancers found in Canadians aged 15 to 29 and 30 to 49.
"We are still losing three people every day in Canada to melanoma," said Falyn Katz, CEO of Melanoma Canada, in comments to CBC News.
Keytruda on its own, in the adjuvant stage IIB and IIC melanoma indication, was expected to cost approximately $11,733 per patient per 28-day cycle, CADTH said in its 2022 reimbursement recommendation.
Three therapeutic cancer vaccines currently hold US Food and Drug Administration approval, according to the Journal of Integrative Medicine and Research. They are:
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Sipuleucel-T (Provenge) for castration-resistant prostate cancer
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BCG for early-stage bladder cancer
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Talimogene laherparepvec (T-VEC) for advanced melanoma that surgery cannot fully remove
Reuters reported that Merck and Moderna have large trials under way in non-small cell lung cancer, mid-stage trials in bladder and kidney cancers, and early-stage trials in pancreatic and stomach cancers, with readouts expected over the next year or two.
Roche and BioNTech are running mid-stage studies of a comparable therapy, autogene cevumeran, in colon and pancreatic cancer patients, CNN reported.
Each vaccine can take several months to produce once a cancer sample is collected, Seth Cheetham, an mRNA scientist at the University of Queensland, told Nature, describing the personalized nature of the vaccines as the biggest obstacle to widespread use.
Moderna president Stephen Hoge told Reuters the company can scale production to meet demand over the next few years.
Specialty drugs carrying annual treatment costs of at least $10,000 accounted for 33.9 percent of total eligible amounts across Canadian private plans in 2025, up from 32.7 percent in 2024, TELUS Health reported in its 2026 Drug Data Trends & National Benchmarks.
