Moderna, Merck report positive melanoma trial

Moderna (MRNA) and Merck (MRK) announced that their personalized mRNA cancer vaccine, intismeran autogene, achieved positive results in a Phase 3 trial in high‑risk melanoma. The study focused on patients whose melanoma had been completely removed surgically but who remained at elevated risk of the disease returning. The vaccine is given in combination with pembrolizumab, also known as Keytruda, an established immunotherapy treatment. The goal is to help the immune system recognize tumor‑specific targets and reduce the chance that cancer comes back or spreads.

The randomized trial enrolled approximately 1,137 patients with resected stage IIB through stage IV melanoma. All participants had undergone surgery to remove their tumors before entering the study. They were then assigned to receive either pembrolizumab alone or the combination of pembrolizumab and intismeran. This design allowed direct comparison of outcomes between the standard treatment and the new combination regimen.

The companies reported that the combination of intismeran plus pembrolizumab met the trial’s primary endpoint of reducing cancer recurrence compared with pembrolizumab alone. This indicates that patients receiving the personalized mRNA vaccine alongside immunotherapy experienced a lower risk that their melanoma would return after surgery. Reducing recurrence is a central goal in the adjuvant treatment of high‑risk melanoma, where relapse rates can be significant.

A key secondary endpoint was also met: the combination lowered the risk of distant metastasis relative to pembrolizumab alone. Distant metastasis refers to the spread of cancer to organs or tissues away from the original tumor site and is associated with more advanced disease and poorer outcomes. Achieving improvement on both recurrence and distant metastasis measures suggests a broad impact of the regimen on disease control in this high‑risk population.

In reporting the Phase 3 results, Moderna (MRNA) and Merck (MRK) said there were no new safety signals observed with the intismeran and pembrolizumab combination. This means that, based on current information, the safety profile appeared consistent with what is already known from prior experience with the components. Safety will remain an important focus when full data are presented and evaluated by clinicians and regulators.

The companies plan to present detailed findings from the trial at an upcoming medical meeting, which is expected to provide more granular information on efficacy and safety outcomes. They have also begun discussions with regulators about potential next steps for the program. One report indicated that, subject to regulatory review and approval, the treatment could potentially become available as early as next year. The results position individualized mRNA vaccination as a potential new adjuvant option in resected high‑risk melanoma, pending full data disclosure and regulatory decisions.