TARGETING pancreatic precursor lesions through a mutant KRAS vaccine generated durable immune responses for long-term cancer interception. Pancreatic ductal adenocarcinoma is typically diagnosed at advanced stages, resulting in an overall five-year survival rate of only thirteen percent. Because precursor lesions like pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasms evolve over more than a decade, intercepting malignant transformation represents a vital therapeutic window. Unlike established tumors that exhibit immunosuppressive microenvironments, pancreatic precancers provide a receptive setting for immune intervention. A phase 1 clinical trial evaluated an off-the-shelf mutant KRAS vaccine in twenty asymptomatic individuals with hereditary predisposition, including germline variants in ATM, BRCA1, BRCA2, CDKN2A, or APC, alongside baseline radiographic pancreatic abnormalities.
The synthetic peptide vaccine formulated with poly-ICLC adjuvant targeted six common driver mutations, specifically G12D, G12V, G12R, G12A, G12C, and G13D. Immune monitoring demonstrated that ninety percent of participants mounted a significant mutant KRAS-specific T-cell response, achieving a median 18.2-fold increase in interferon-gamma-secreting cells. Responses occurred across diverse HLA alleles, validating the feasibility of an HLA-agnostic intervention. Furthermore, fifty percent of participants mounted detectable T-cell activity against all six evaluated antigens. Functional profiling confirmed robust polyfunctional CD4+ and CD8+ memory T-cell responses with secretion of interferon-gamma, tumor necrosis factor-alpha, and interleukin-2. Longitudinal T-cell receptor sequencing showed that vaccine-induced memory clonotypes persisted in the peripheral repertoire for up to two years following vaccination.
At a median follow-up of 16.5 months, no participants developed pancreatic ductal adenocarcinoma or required surgical intervention. Post hoc radiographic evaluation demonstrated pancreatic cyst regression or complete resolution in 37.5% of vaccinated patients, compared with 6.8% in an unvaccinated surveillance cohort. The mutant KRAS vaccine exhibited an exceptional safety profile consisting exclusively of grade 1 and grade 2 adverse events, most commonly mild injection-site erythema, fatigue, chills, and self-limiting flu-like symptoms. These clinical findings establish proof-of-concept for targeted immunotherapy in oncology, demonstrating that interception vaccines can activate durable immune surveillance against high-risk premalignant lesions.
Reference
Haldar SD et al. First-in-human testing of a mutant KRAS vaccine for pancreatic cancer interception in high-risk cohorts. Cancer Discov. 2026.
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