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An experimental vaccine targeting one of the most common genetic drivers of pancreatic cancer generated durable immune responses in people at high risk for the disease, offering an early glimpse of a strategy that could help prevent one of the deadliest cancers before it develops.
Researchers at the Johns Hopkins Kimmel Cancer Center and its Skip Viragh Center for Pancreatic Cancer say the study may be the first in humans to show that a vaccine targeting mutant KRAS can safely generate durable immune responses in people at increased risk for pancreatic cancer.
The findings were published in Cancer Discovery.
A Prevention Strategy for Pancreatic Cancer
Pancreatic ductal adenocarcinoma often develops slowly from precancerous pancreatic cysts and other precursor lesions, creating a window to intervene before cancer forms.
The experimental vaccine, known as mKRAS-VAX, targets the six most common KRAS mutations found in pancreatic cancer. These mutations are present in most pancreatic cancers and many precancerous pancreatic lesions.
The vaccine is designed to train the immune system to recognize and destroy cells carrying KRAS mutations before they develop into cancer.
Strong Immune Responses Seen in Most Participants
The study enrolled 20 people with an inherited predisposition to pancreatic cancer who also had a pancreatic abnormality detected through imaging. Participants received four doses of the vaccine over 13 weeks between April 2022 and February 2026.
Among the findings:
- 18 of 20 participants (90%) developed a significant immune response to the vaccine.
- Participants experienced a median 18.2-fold increase in mutant KRAS-specific T-cell responses.
- The vaccine generated both CD4-positive and CD8-positive T-cell responses.
- Vaccine-induced memory T cells remained detectable for up to two years after vaccination.
After a median follow-up of 16.5 months, none of the participants developed pancreatic cancer, and none developed a high-risk pancreatic lesion requiring surgical removal.
Vaccine Appeared Safe in Early Trial
All treatment-related side effects were mild to moderate.
The most common side effects included:
- Injection-site reactions
- Fatigue
- Chills
- Flu-like symptoms
All resolved without treatment.
An exploratory analysis of follow-up imaging showed that five participants had complete radiographic resolution of small pancreatic cysts, while three had partial regression; the remaining cysts remained stable.
However, the researchers emphasized that the study was designed to evaluate safety and immune responses, not whether the vaccine prevents pancreatic cancer. Its small size and relatively short follow-up limit conclusions about clinical effectiveness.
Researchers Call Findings an Important First Step
“This is just the beginning, but the findings suggest that the immune system is getting activated,” says Elizabeth Jaffee, M.D., deputy director of the Johns Hopkins Kimmel Cancer Center and co-senior author of the study. “We have more work to do, but this is a good start aimed at prevention, which no one had thought about doing before.”
The study builds on earlier research involving the same KRAS vaccine. In a previous study of patients who had undergone surgery for pancreatic cancer and were at high risk for recurrence, researchers found that participants who developed strong immune responses remained disease-free for at least five years.
“We thought if we can see an immune response in patients with cancer, the vaccine should work even better in people who are at higher risk because of a family history, gene alteration or cyst on the pancreas,” says Neeha Zaidi, M.D., associate professor of oncology and co-senior author of the study.
Michael Goggins, M.D., professor of pathology, medicine and oncology and co-senior author, said the findings establish an important proof of concept.
“The results of this study provide proof of concept that vaccination against mutant KRAS can generate durable immune responses in people at inherited risk for pancreatic cancer and support further clinical testing of the approach,” he says.
Jaffee added, “The ability to vaccinate people at risk early to try to prevent them from developing cancer in the future is an important opportunity.”
What Nurses Should Know
Although the vaccine remains investigational, the findings reflect growing interest in cancer interception, an emerging approach that aims to prevent cancer before it develops in people at elevated risk.
For oncology nurses, genetics nurses, nurse navigators, advanced practice providers, and other clinicians caring for people with hereditary cancer risk, the study highlights the expanding role of precision prevention and immunotherapy research.
Researchers have initiated a follow-up study involving patients with high-risk pancreatic cysts undergoing surgical removal. The trial will examine how vaccine-induced immune cells interact directly with precancerous pancreatic tissue.
