A first-in-human peptide vaccine targeting common mutant KRAS variants showed an early proof of concept for pancreatic cancer interception in high-risk patients. Researchers at Johns Hopkins Kimmel Cancer Center and the Skip Viragh Center for Pancreatic Cancer reported in Cancer Discovery that the mKRAS-VAX regimen was generally safe and stimulated mutant KRAS-specific T-cell responses in 18 of 20 participants (90%) who had hereditary PDAC predisposition and a radiographic pancreatic abnormality (NCT05013216). With a median follow-up of 16.5 months, none of the vaccinated participants developed pancreatic ductal adenocarcinoma. Longitudinal T-cell receptor sequencing demonstrated persistence of vaccine-induced mutant KRAS-specific clonotypes for up to two years, and adverse events were grade 1–2. The work frames vaccination as a strategy to train immune surveillance before detectable transformation. The study matters because prevention/interception in PDAC remains limited by late diagnosis and the difficulty of identifying which precancerous lesions will progress. By focusing on KRAS-driven biology present in most PDACs, the approach aims to translate immune activity into measurable clinical interruption endpoints. Investigators also emphasize that this is an early-stage signal meant to support advancement of mutant KRAS–targeted vaccination strategies for interception rather than treatment after cancer is established.