Could a KRAS vaccine stop pancreatic cancer before it starts?

Clinical takeaway: In a small phase 1 study of high-risk individuals with hereditary predisposition and pancreatic lesions, an investigational mutant KRAS vaccine was safe and elicited durable KRAS-specific T-cell responses in 90% of participants, supporting further evaluation as a pancreatic cancer interception strategy.

Pancreatic cancer remains one of the deadliest malignancies, and effective prevention strategies are lacking. These findings provide early proof of concept that immunologic interception of precancerous disease may be feasible in high-risk individuals.

Researchers from Johns Hopkins reported the first-in-human evaluation of mKRAS-VAX, an off-the-shelf peptide vaccine targeting the six most common KRAS mutations found in pancreatic cancer and its precursor lesions. Twenty participants with inherited pancreatic cancer risk and imaging-detected pancreatic abnormalities received four vaccine doses over 13 weeks.

The vaccine generated robust immune activity in 18 of 20 participants (90%), with a median 18-fold increase in mutant KRAS-specific T-cell responses. Both CD4+ and CD8+ T-cell responses were observed, and vaccine-induced memory T-cell populations remained detectable for up to two years, suggesting long-lasting immunity.

At a median follow-up of 16.5 months, no participant developed pancreatic cancer or a high-risk lesion requiring surgery. Treatment-related adverse events were mild to moderate, consisting primarily of injection-site reactions, fatigue, chills, and flu-like symptoms.

Exploratory imaging analyses also suggested possible biologic activity. Five participants experienced complete resolution of small pancreatic cysts and three had partial cyst regression. Overall, cyst reduction or resolution was observed in 37.5% of evaluable vaccinated participants compared with 6.8% in a similar unvaccinated cohort.

“This is just the beginning, but the findings suggest that the immune system is getting activated,” said co-senior author Elizabeth Jaffee, MD. Investigators emphasized that the trial was designed to assess safety and immune responses, not cancer prevention efficacy, and larger studies with longer follow-up are underway.

Source: Haldar SD, et al. (2026 July 16) Cancer Discov. First-in-human testing of a mutant KRAS vaccine for pancreatic cancer interception in high-risk cohorts