Pancreatic cancer is one of the deadliest types of cancer, with fewer than 13% of people diagnosed with it surviving for more than five years. It kills 88% of its patients, and its recurrence rate, after surgery, is nearly 90% within seven to nine months. U.S. mortality rates, meanwhile, are on the upswing.

But promising results from a small clinical trial for an mRNA pancreatic cancer vaccine are fueling new rays of hope.

“The latest data from the Phase I trial are encouraging,” said lead author Dr. Vinod Balachandran in a news release from Memorial Sloan Kettering (MSK), home to the Olayan Center for Cancer Vaccines (OCCV), the research hub behind the study. “They suggest this investigational therapeutic mRNA vaccine can mobilize anti-tumor T cells that may recognize pancreatic cancers as foreign, potentially years after vaccination.”

The trial, which had its results published earlier this month in the journal Nature, tested a therapeutic mRNA cancer vaccine called autogene cevumeran; it’s designed to treat, not prevent, cancer by delivering proteins found in cancer (neoantigens) as a way to train the immune system to recognize cancer cells as foreign.

A small group of 16 MSK patients, each of whom had had tumors removed, received personalized versions of the vaccine, based on the specifics of their tumor; they also received an immunotherapy drug called atezolizumab and a chemotherapy regimen called mFOLFIRINOX.

There were no reports of serious side effects—something that showed in early results and was noted in a 2023 Nature article.

Half of patients saw an immune response. Of those eight, just two had their cancer return during the three-year follow-up—compared with seven of the eight who did not respond to the vaccine. Researchers are not yet certain that the vaccine caused the delay in recurrence.

One participant died within two years.

In these latest findings, researchers could detect substantial vaccine-stimulated T cells (which are developed from stem cells in bone marrow as part of the immune system) up to nearly four years after treatment.

Those T cells retained their anti-cancer activity even after patients received post-vaccine chemotherapy—something that researchers thought could diminish the vaccine’s effects but did not.

The findings hold promise for treating a range of cancers with the same personalized mRNA approach.

“For patients with pancreatic cancer, our latest results continue to support the approach of using personalized mRNA vaccines to target neoantigens in each patient’s tumor,” Balachandran, also director of the OCCV, said. “If you can do this in pancreas cancer, theoretically you may be able to develop therapeutic vaccines for other cancer types.”

Genentech and BioNTech, sponsors of the trial, are behind a Phase II clinical trial that began in July to evaluate the vaccine in a larger patient group, enrolling approximately 260 patients at various sites around the world.

“Designing a cancer vaccine tailored to an individual is complex,” said Balachandran. “Because cancers arise from our own cells, it is much harder for the immune system to distinguish proteins in cancer cells as foreign compared with proteins in pathogens like viruses. But important advances in cancer biology, the development of novel biotechnologies, and genomic sequencing now make it possible to design investigational vaccines that may help the immune system to tell the difference.”