mRNA’s potential

Previous data from the trial reported that 107 participants received the mRNA vaccine and Keytruda treatment, while the remaining 50 only received Keytruda. At the two-year follow-up, 24 of the 107 (22 percent) who got the experimental vaccine and Keytruda had recurrence or death, while 20 of 50 (40 percent) treated with just Keytruda had recurrence or death, indicating a 44 percent risk reduction. The companies did not report the breakdown of the two groups in the press release this week for the five-year follow-up, but said the risk reduction was 49 percent, which is also what the companies reported for the three-year follow-up.

As for side effects, the companies reported that little had changed from previous analyses; adverse events were similar between the two groups. The top side effects linked to the vaccine were fatigue, injection site pain, and chills.

The results “highlight the potential of a prolonged benefit” of the vaccine combined with Keytruda in patients with high-risk melanoma,” Kyle Holen, a senior vice president at Moderna, said.

They also “illustrate mRNA’s potential in cancer care,” he said, noting that the company has eight more Phase 2 and Phase 3 trials going for mRNA vaccines against a variety of other cancers, including lung, bladder, and kidney cancers.

Marjorie Green, a senior vice president at Merck, called the five-year follow-up data a “meaningful milestone” and “encouraging.”

“[W]e look forward to late-stage data from the INTerpath clinical development program with Moderna, across a range of tumor types where significant unmet needs remain,” she said.

While the top-line results appear positive, conclusions can’t be drawn until the full data from the trial are published. The vaccines are also being developed amid a political environment hostile to mRNA vaccines. Anti-vaccine Health Secretary Robert F. Kennedy Jr. has railed against mRNA COVID-19 vaccines, making false claims about their safety and efficacy. In August, Kennedy unilaterally canceled $500 million in grant funding for the development of mRNA-based vaccines against diseases that pose pandemic threats.