ROCHESTER, Minn. — An investigational vaccine helped the immune system recognize and respond to mutations that drive most pancreatic cancers, according to results from a randomized phase 2 clinical trial led by Mayo Clinic researchers. The findings, published in Nature Medicine, will help researchers design a larger phase 3 clinical trial.

Nearly every patient evaluated after receiving the vaccine developed an immune response against mutated KRAS, a gene that plays a major role in pancreatic cancer. Mayo Clinic researchers also found that patients with stronger immune responses tended to remain free of disease longer.

“Historically, pancreatic cancer has been very difficult to treat with immunotherapy,” says Ben George, M.B.B.S, M.D., a Mayo Clinic medical oncologist and lead author of the study. “What is encouraging is that we were able to generate a strong immune response against KRAS mutations in nearly every patient we evaluated. In an exploratory analysis, patients with greater immune responses to the vaccine appeared protected with longer disease-free survival times.”