The Moderna and Merck cancer vaccine has met the main goals of a large Phase 3 melanoma trial, marking a major milestone for personalized mRNA cancer treatment.

Moderna and Merck announced Wednesday that their experimental therapy, intismeran autogene, significantly improved both recurrence-free survival and distant metastasis-free survival when combined with Merck’s immunotherapy drug Keytruda. The comparison group received Keytruda alone.

The result is the first positive Phase 3 readout for an individualized neoantigen therapy and an mRNA-based cancer treatment, according to the companies.

Treatment Is Tailored to Each Patient’s Tumor

Unlike a traditional vaccine designed to prevent an infection, intismeran is created individually for each cancer patient.

Doctors analyze mutations found in a patient’s tumor and use that information to produce an mRNA treatment designed to teach the immune system to recognize and attack cancer cells carrying those mutations. Each treatment can encode as many as 34 tumor-specific neoantigens.

The experimental therapy was tested alongside Keytruda, which helps the immune system detect and fight tumor cells by blocking the PD-1 pathway.

The Phase 3 INTerpath-001 trial enrolled 1,137 patients with stage IIB through IV melanoma whose tumors had been completely removed by surgery. Participants received either the personalized treatment plus Keytruda or Keytruda alone for approximately one year.

Full Phase 3 Data Still to Come

The companies said the combination produced statistically significant and clinically meaningful improvements in both preventing cancer recurrence and preventing melanoma from spreading to distant parts of the body.

However, Moderna and Merck have not yet disclosed the detailed Phase 3 numbers. The study is also continuing to evaluate other outcomes, including overall survival. No new safety signals were identified in the interim analysis.

The companies plan to present the full findings at an upcoming international medical meeting and discuss regulatory submissions with health authorities.

Reuters reported that Moderna President Stephen Hoge said the treatment could potentially become available as early as 2027 if regulators approve it. Moderna shares surged as much as 160% following the announcement, while Merck rose 12% as investors reacted to the results.

Earlier Results Had Already Raised Expectations

The Phase 3 success builds on years of encouraging earlier research. USA Herald previously reported on early melanoma results from the Moderna-Merck partnership in 2022.

More recently, five-year Phase 2 data showed the combination reduced the risk of recurrence or death by 49% compared with Keytruda alone.

The new Phase 3 result provides much stronger evidence, but regulatory review will still be required before the Moderna and Merck cancer vaccine can become a routinely available treatment.

For patients with high-risk melanoma, the findings offer evidence that personalized mRNA technology may eventually become another tool for keeping cancer from returning after surgery.