A Phase I trial of a KRAS-mutant vaccine for pancreatic cancer interception cleared an early efficacy-and-safety milestone by inducing KRAS-specific T-cell responses in 90% of high-risk participants. Reported in Cancer Discovery, follow-up after a median of 16.5 months showed no pancreatic cancer cases developed in the study cohort. Some precancerous lesions shrank or stopped progressing, and the trial offers proof-of-concept for vaccination aimed at preventing pancreatic ductal adenocarcinoma in genetically predisposed or imaging-identified high-risk patients. The approach targets common KRAS mutations that drive most PDAC biology.