SCIENCE Magazine, Oct 2025 By Phie Jacobs
The innovative messenger RNA (mRNA) vaccines that thwarted the ravages of COVID-19 may also help fight tumors in cancer patients, according to a new analysis of medical records and studies in mice.
People with cancer who coincidentally received the mRNA shots before starting drugs designed to unleash the immune system against tumors lived significantly longer than those who didn’t get vaccinated, a research team announced yesterday at the European Society for Medical Oncology Congress in Berlin. Laboratory experiments by the group suggest the vaccines rev up the immune system, making even stubborn tumors more susceptible to treatment.
The findings underscore the still-untapped potential of mRNA technology at a time when President Donald Trump’s administration has backed away from funding the area.
“I think this data is extraordinary,” says Ryan Sullivan, an oncologist and immunologist at Massachusetts General Hospital who wasn’t involved in the new research. Although the analysis of cancer patient data was retrospective, he notes that the observed association between COVID-19 vaccination and improved survival “is very strong.”
“I’m cautiously optimistic about these results,” says Mark Slifka, an immunologist at the Oregon Health & Science University. The research still needs to be confirmed with a prospective, randomized clinical trial—something Steven Lin, a radiation oncologist at the University of Texas MD Anderson Cancer Center and principal investigator on the work, says is already being planned.
The new findings build on results from the same group showing that, in mouse models, a generalized mRNA vaccine boosted the tumor-fighting effects of immunotherapy drugs called checkpoint inhibitors. Those results, published in July in Nature Biomedical Engineering, “really laid the groundwork” for the idea that an mRNA vaccine—even one not targeted toward any specific tumor protein—could bolster cancer immunotherapy, says Adam Grippin, a medical resident and immunotherapy researcher at MD Anderson who presented the group’s new data in Berlin on Sunday. “The next question we wanted to ask was, if this is true, what about the COVID vaccine?”
To find out, Grippin and colleagues analyzed the records of more than 1000 patients who were treated for advanced skin and lung cancer at MD Anderson between 2019 and ’23.
People who received a COVID-19 mRNA vaccine within 100 days of starting immunotherapy with checkpoint inhibitors lived significantly longer than those who received the same drugs but didn’t get the vaccine. For patients with advanced lung cancer, the median survival rate nearly doubled, rising from 20.6 months to 37.3.
Grippin says he and his colleagues “utilized as many statistical approaches as we could” to account for potential confounding factors, but the association between improved survival rates and COVID-19 vaccines persisted. Patients who received non-mRNA vaccines for influenza and pneumonia, for example, didn’t do better than the average immunotherapy patient.
The vaccines, which consist primarily of mRNA encoding the spike protein on the surface of the pandemic coronavirus SARS-CoV-2, are designed to prompt an immune response specific to the pathogen. But based on lab studies, Grippen and his colleagues think that in cancer patients, the mRNA vaccine acts “like a siren.” It triggers the release of immune signaling proteins known as cytokines, including type 1 interferon—the same protein responsible for many of the strong side effects people experience after getting immunized. The lab data suggest interferon, in turn, activates immune cells inside tumors and causes them to move into the lymph nodes, where they train other immune cells to travel back through the bloodstream and attack the tumors.
Tumors normally respond to this assault by expressing a protein called PD-L1, which is designed to suppress the immune system. But checkpoint inhibitors block immune cells from binding to these proteins. That thwarts the tumor’s attempts at evasion and helps “unleash the power of the immune system to kill cancer,” Grippin says.
The earlier mouse work suggests any mRNA-based vaccine could have a similar effect.
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