mRNA cancer vaccine succeeded in Phase 3 melanoma trial, Moderna and Merck say

Promising design

Using the same platform Moderna used for its mRNA COVID-19 vaccine, intismeran delivers to healthy cells the mRNA code for those mutations. Healthy cells translate that mRNA code into protein fragments representing the cancer mutations, and then those fragments are presented to immune cells as antigens, a foreign substance to attack. As such, Moderna and Merck call their mRNA cancer vaccine a type of “neoantigen therapy.”

The term avoids both “mRNA” and “vaccine,” which draw hostility from Trump’s anti-vaccine Health Secretary Robert F. Kennedy Jr. In addition to his concerted efforts to undermine lifesaving vaccines, Kennedy has canceled hundreds of millions of dollars in federal grants for the development of mRNA vaccine technology.

In the companies’ announcement, Georgina Long, who led the trial, said the results were “a landmark moment” with the “potential to establish a new treatment paradigm.” Dean Li, president of Merck Research Laboratories, said the findings “reinforce the promise of a more personalized approach to cancer treatment.” Moderna CEO Stéphane Bancel, meanwhile, highlighted mRNA technology’s role, saying this is “a pivotal moment for the field of cancer research.”

“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,” Bancel said.

Despite the lack of details, outside experts are similarly hopeful and encouraged by the announcement. “This is the first positive Phase III trial of an individualized neoantigen therapy and an mRNA-based cancer treatment,” University of Oxford cancer expert Lennard Lee said in a statement. “That makes this an important moment for a field that scientists have been working towards for many years. Within six years of the pandemic, we have mRNA vaccines to treat cancer,” he said, also calling it “very encouraging” and “significant.”

Lee, however, highlighted that we don’t yet know the magnitude of the benefit, the detailed subgroup analyses, quality-of-life data, or mature overall-survival results. “Those details will allow the scientific and clinical community to understand precisely how large the benefit is, which patients benefit most, and ultimately where this treatment might sit within routine melanoma care,” he said.