Here’s what Moderna’s latest mRNA cancer vaccine data actually show

October 22, 20262 min read Add Us On GoogleAdd SciAmThe Moderna-Merck mRNA cancer vaccine helps prevent cancer recurrence and death, the new results showModerna headquarters in Cambridge, Massachusetts Tada Images/ShutterstockData from Moderna and Merck’s phase 3 clinical trial for an mRNA-based skin cancer vaccine leaked on social media on Thursday, prompting the pharmaceutical companies to release an early look at the results of the trial.The results, which triggered Moderna’s stock to drop, are “really encouraging,” says Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy, a nonprofit. This kind of mRNA cancer vaccine was “fiction” 10 years ago, she says. “It was thought to be very difficult to do.”As Scientific American previously reported, the Moderna-Merck clinical trial includes two treatments: a personalized mRNA-vaccine called intismeran autogene, which works by instructing the body in how to identify and fight cancer, and pembrolizumab (sold as Keytruda), a drug designed to prevent cancer from “hiding” from our immune system, according to Merck.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.The clinical trial included 1,137 cancer patients with “high risk” melanoma, a type of skin cancer. Together, the mRNA vaccine and pembrolizumab reduced the risk of cancer recurrence or death by 42 percent in people, after a median period of about two years, compared to people on pembrolizumab alone. On top of that, the dual treatment reduced the risk of cancer spreading to other parts of the body or death by 38 percent over just pembrolizumab, according to Moderna and Merck.The findings don’t yet include overall survival, Knudsen notes. “Did people who got the vaccine live longer than people who didn't? And what was their quality of life?” she asks. Those results are coming. But the new findings are “really, really good milestones along the way,” she says.“From the beginning, we believed mRNA technology could make it possible to develop cancer treatments uniquely matched to each patient’s tumor, Moderna CEO Stéphane Bancel said in a statement. “These results reinforce our conviction that mRNA has the potential to fundamentally change how we treat cancer.”The results have been accepted for publication in the New England Journal of Medicine, Merck and Moderna said. Now, the companies are “engaging with regulatory authorities” to seek approval for their mRNA vaccine.Moderna and Merck did not immediately reply to requests for comment from Scientific American.Subscribe to Support Independent JournalismGreat science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber