# Merck and Moderna Cancer Vaccine Reduces Melanoma Recurrence by 42% in Phase 3 Trial

> A personalized mRNA cancer vaccine combined with immunotherapy significantly cut the risk of melanoma recurrence or death, marking the first positive Phase 3 trial for such a therapy.

By PrimaryBrief newsroom · Published 2026-10-23T00:17:15.951855Z
Canonical: https://primarybrief.com/article/merck-and-moderna-cancer-vaccine-reduces-melanoma-recurrence-by-42-in-phase-3-trial-50128d13

Merck and Moderna announced on October 22, 2026, that their personalized mRNA cancer vaccine, intismeran autogene (V940 or mRNA-4157), combined with Merck's immunotherapy Keytruda (pembrolizumab), cut the risk of melanoma recurrence or death by 42% in a Phase 3 clinical trial [1][5][7][9][16]. This outcome represents a significant advance, marking the first positive Phase 3 readout for an individualized neoantigen therapy and an mRNA-based cancer treatment, potentially ushering in a new era of personalized cancer care for patients with high-risk melanoma [8][16][21][22].

## Clinical Breakthrough

The INTerpath-001 trial, a Phase 3 study, involved 1,137 patients with completely resected stage IIB-IV melanoma [5][7][9][13][20]. The trial evaluated intismeran autogene alongside Keytruda against Keytruda alone [7][9][15]. After a median follow-up of 24.6 months, the combination therapy reduced the risk of recurrence-free survival (RFS) by 42% (HR 0.58; 95% CI, 0.45-0.75; p<0.001) [7][9]. The risk of distant metastasis or death also decreased by 38% (HR 0.62) with the combination treatment [1][7][9][20]. Two-year RFS rates showed 82.2% of patients receiving the combination remained cancer-free, compared to 70.0% for those on Keytruda alone [5][7][9][15]. Merck and Moderna highlighted this as the first successful Phase 3 trial of a personalized mRNA-based cancer therapy designed to help a patient's immune system recognize and attack cancer cells [22].

## Market Volatility

Despite the positive clinical trial results, Moderna's shares plunged between 17% and 25% on October 22, 2026 [1][2][4][5]. This market reaction was attributed to high investor expectations and a “sell-the-news” event [4]. The 42% reduction in recurrence or death risk was considered by some as being at the “low end” when compared to a 49% reduction observed in a previous Phase 2 study of the same combination therapy [4][10][19]. Trading in Moderna shares was briefly halted due to volatility [4]. Merck's shares also fell over 3% [5].

## Next Steps

Based on these detailed results, both companies plan to engage with regulatory authorities to seek approval for intismeran autogene in combination with Keytruda as an adjuvant treatment for melanoma [7][9]. Merck and Moderna are also progressing with nine Phase 2 and Phase 3 clinical trials, including three ongoing Phase 3 trials in non-small cell lung cancer, to explore the therapy's application in other tumor types like lung, bladder, and kidney cancer [3][6][9][14][18]. Moderna aims for regulatory approval as early as 2027 [3].

## What We Could Not Confirm

Specific timelines for regulatory approvals of intismeran autogene are not detailed in the available records, beyond Moderna's target of “as early as 2027” [3]. The precise challenges related to the

## Evidence cited
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13. A phase 3, randomized, double-blind, placebo- and active-comparator-controlled clinical study of Adjuvant V940 (mRNA-4157) plus Pembrolizumab versus adjuvant placebo plus Pembrolizumab in participants with high-risk stage II-IV Melanoma (INTerpath-001) (mdanderson.org) — https://www.mdanderson.org/clinical-trials/clinical-trials-detail?id=NCT05933577
14. (October 22 2026) Merck and Moderna Announce Detailed Positive Phase 3 INTerpath-001 Trial Results for V940 (mRNA-4157) in Combination With KEYTRUDA® (pembrolizumab) as Adjuvant Treatment for Patients With Completely Resected Stage IIB-IV Melanoma (natlawreview.com) — https://www.natlawreview.com/article/merck-and-moderna-announce-detailed-positive-phase-3-interpath-001-trial-results
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