Moderna and Merck reported that their investigational personalized cancer vaccine, intismeran autogene, combined with Merck’s Keytruda met the primary and a key secondary endpoint in a late-stage trial for patients with high-risk melanoma that had been surgically removed. The news sent Moderna shares sharply higher and lifted Merck as well.

Trial Results and Design

The Phase 3 INTerpath-001 study enrolled 1,137 patients with completely resected Stage IIB to IV cutaneous melanoma who had not received prior systemic therapy. Participants were randomized to receive the combination of intismeran autogene plus Keytruda or Keytruda alone for approximately one year.

At a pre-specified interim analysis, the combination produced statistically significant and clinically meaningful improvements in recurrence-free survival, the primary endpoint, and distant metastasis-free survival, a key secondary endpoint, compared with Keytruda monotherapy. No new safety signals were observed, and the safety profile remained consistent with earlier studies. The trial continues to evaluate overall survival and other secondary endpoints.

Intismeran autogene is an individualized mRNA neoantigen therapy. Tumor tissue is sequenced to identify mutations unique to each patient. An mRNA construct coding for as many as 34 neoantigens is then manufactured and administered to train the immune system to recognize and attack residual cancer cells. Keytruda, an anti-PD-1 immunotherapy, is intended to further enhance that immune response.

Building on Earlier Data

The Phase 3 outcome confirms signals seen in earlier research. Five-year follow-up from a Phase 2b study showed the same combination reduced the risk of recurrence or death by 49 percent and the risk of distant metastasis or death by 59 percent relative to Keytruda alone.

Company statements described the latest results as the first positive Phase 3 readout for any individualized neoantigen therapy and the first for an mRNA-based cancer treatment. It is also the first Phase 3 study to demonstrate a clinically meaningful improvement over Keytruda alone in the adjuvant melanoma setting.

Market Reaction and Broader Pipeline

Moderna shares more than doubled on the day of the announcement, with some reports citing gains exceeding 100 percent and intraday peaks near record levels. The move lifted the company’s market value substantially. Merck shares advanced roughly 7 to 11 percent in response.

Moderna has been working to expand beyond its earlier Covid-related franchise. The company and Merck currently have multiple Phase 2 and Phase 3 studies underway evaluating intismeran across melanoma, lung, bladder and kidney cancers. The partners said they plan to discuss the INTerpath-001 findings with regulators and will present the full dataset at a future medical meeting.

Moderna Chief Executive Stéphane Bancel described the outcome as a defining moment, stating the company is now focused on oncology. The firms aim to move the regimen toward potential commercial availability while continuing to gather longer-term survival data from the ongoing trial.

Detailed numerical results, including exact hazard ratios from the Phase 3 analysis, have not yet been released. Full presentation of the data is expected later, along with further regulatory discussions.