First-in-human testing of a mutant KRAS vaccine for pancreatic cancer interception in high-risk cohorts.

Pancreatic ductal adenocarcinoma (PDAC) arises from precursor lesions over a decade-plus, offering a window for interception in high-risk individuals, but current surveillance detects a minority of precursors. Mutant KRAS (mKRAS) is present in most PDACs and their precursors, making it an appealing target for immune-based interception. We conducted a phase I, first-in-human study of a peptide vaccine targeting six common KRAS mutations (mKRAS-VAX) in 20 individuals with hereditary PDAC predisposition and a radiographic pancreatic abnormality (NCT05013216) to assess safety, immunogenicity, and T cell persistence. Adverse events were grade 1-2. Vaccination elicited a significant mKRAS-specific T cell response in 18/20 participants (90%). Longitudinal TCR sequencing demonstrated persistence of vaccine-induced mKRAS-specific clonotypes for up to 2 years. Over a median follow-up of 16.5 months, no participants developed PDAC. These findings demonstrate that mKRAS-VAX is safe and generates durable T cell responses, which support the advancement of mKRAS-targeted vaccination for PDAC interception.