News|Articles|August 19, 2026

Moderna, Merck mRNA Cancer Vaccine Succeeds in Late-Stage Trial

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Key Takeaways

INTerpath-001 met its primary (RFS) and key secondary (DMFS) endpoints in resected stage IIB–IV melanoma, representing a first positive Phase 3 signal for individualized mRNA cancer therapy.
Trial design randomized 1,137 systemic-therapy–naïve patients 2:1 to intismeran 1 mg q3w (≤9 doses) plus ~1 year pembrolizumab versus pembrolizumab alone.
Mechanistically, tumor sequencing informs a bespoke mRNA encoding up to 34 neoantigens, aiming to amplify tumor-specific T-cell immunity when combined with PD-1 blockade.
Phase 3 findings align with KEYNOTE‑942 5-year follow-up showing reduced recurrence/death (HR 0.51) and distant metastasis/death (HR 0.411) versus pembrolizumab monotherapy.
No new safety signals were observed at interim analysis, while overall survival and other secondary outcomes continue to mature ahead of medical meeting presentation and filings.

Intismeran autogene plus pembrolizumab significantly improved recurrence-free and distant metastasis-free survival compared with pembrolizumab alone in resected stage IIB-IV melanoma.

Merck and Moderna announced Wednesday that their personalized mRNA cancer therapy, intismeran autogene (intismeran; V940 or mRNA-4157), met both the primary and a key secondary end point of the phase 3 INTerpath-001 (NCT05933577) trial in patients with completely resected, high-risk melanoma—marking the first positive late-stage trial result for an mRNA-based cancer treatment and for an individualized neoantigen therapy.^1,2

“Today’s results represent a landmark moment for adjuvant melanoma treatment,” said Georgina Long, AO, BSc (Hons1, UM), PhD, MBBS (Hons), FRACP, FAHMS, FAA, FASCO, the study’s principal investigator and medical director of Melanoma Institute Australia and chair of Melanoma Medical Oncology & Translational Research at the University of Sydney, in a statement. “This is the first phase 3 study to show that intismeran, a treatment designed based on the unique mutational ‘fingerprint' of a patient's own tumor, given in combination with pembrolizumab can reduce the risk of recurrence or death in patients with completely resected stage IIB-IV melanoma compared to Keytruda alone. Intismeran in combination with pembrolizumab has the potential to establish a new treatment paradigm in the adjuvant melanoma setting, helping patients remain cancer-free for longer.”

At a pre-specified interim analysis, intismeran combined with pembrolizumab (Keytruda; Merk) as adjuvant therapy produced statistically significant and clinically meaningful improvements in recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) compared with pembrolizumab alone in patients with completely resected stage IIB, IIC, III, or IV cutaneous melanoma who had not received prior systemic therapy.¹ The trial enrolled 1137 patients, randomized 2:1 to receive intismeran (1 mg every 3 weeks for up to 9 doses) plus pembrolizumab or pembrolizumab alone for approximately 1 year following surgery. The study will continue to evaluate additional secondary end points, including overall survival, and no new safety signals were reported.

Building on Earlier Phase 2b Data

The result builds on 5-year follow-up data from the phase 2b KEYNOTE-942/mRNA-4157-P201 trial, presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, in which the combination cut the risk of recurrence or death by 49% (HR, 0.51; 95% CI, 0.294-0.887) and the risk of distant metastasis or death by 59% (HR, 0.411; 95% CI, 0.200-0.843) vs pembrolizumab alone. Intismeran is manufactured from a patient's own tumor sample to identify its unique mutational signature, then encodes up to 34 tumor-specific neoantigens into a synthetic mRNA designed to train the immune system to recognize and attack the cancer.

Merck and Moderna said full data will be presented at an upcoming international medical meeting alongside regulatory filing discussions.

“By intervening earlier in the course of disease, when many cancers are considered most treatable, the goal of adjuvant therapy given after surgery is to increase the possibility of cure for more patients,” said Dean Y. Li, MD, PhD, president, Merck Research Laboratories, in a statement. “These first Phase 3 findings for intimestrin in combination with Keytruda as adjuvant therapy reinforce the promise of a more personalized approach to cancer treatment. We believe individualized neoantigen therapies have the potential to redefine how patients with completely resected stage IIB-IV melanoma are treated. Together with Moderna, we look forward to presenting data from INTerpath-001 at an international medical meeting and sharing with regulatory authorities.”

Moderna's shares added roughly $40 billion in market capitalization on the news and touched multiyear highs; Merck climbed as much as 11%, and the Nasdaq Biotechnology Index hit a record.² The rally marks a reversal for Moderna, which has struggled to find a growth driver beyond its COVID-19 vaccine franchise and has faced skepticism toward mRNA technology from the Trump administration. Merck, meanwhile, is looking to diversify ahead of Keytruda's patent expiration later this decade.

“These phase 3 findings represent a pivotal moment for the field of cancer research,” said Stéphane Bancel, CEO of Moderna, in a statement.¹ “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. Together with Merck, we have started to demonstrate the transformative potential of this technology to address critical unmet needs in the adjuvant melanoma setting. We are deeply grateful to the patients, investigators and study teams whose contributions make this progress possible.”

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