Researchers at Johns Hopkins Kimmel Cancer Center and the Skip Viragh Center for Pancreatic Cancer report early results from a preventive strategy aimed at mutant KRAS, one of the most common genetic drivers of pancreatic ductal adenocarcinoma. The team describes an experimental peptide vaccine, mKRAS-VAX, designed to train the immune system to recognize and eliminate cells carrying frequent KRAS mutations before they can progress to cancer.

Pancreatic cancer often develops gradually over years from precursor lesions such as pancreatic cysts. Because KRAS mutations appear in most pancreatic cancers and many precancerous lesions, the investigators targeted these alterations with the goal of interrupting disease evolution at a high-risk stage.

The study focused on safety and immunogenicity in a phase 1, first-in-human trial. Twenty participants with hereditary predisposition to pancreatic cancer and pancreatic abnormalities detected through imaging received four vaccine doses over 13 weeks, between April 2022 and February 2026. Researchers used blood testing and follow-up assessments to track adverse events and measure KRAS-specific immune responses.

Immune monitoring showed that 18 of 20 participants (90%) developed a significant mutant KRAS-directed response. On average, participants demonstrated a median 18.2-fold increase in mutant KRAS-specific T-cell activity, indicating the vaccine successfully activated T cells capable of recognizing mutant KRAS antigens.

Further immunology analyses revealed both CD4-positive and CD8-positive T-cell responses, along with memory T-cell formation that persisted over time. Importantly, KRAS-specific T-cell clones remained detectable for as long as two years after vaccination, suggesting durability consistent with long-term immune surveillance.

After a median follow-up of 16.5 months, none of the participants developed pancreatic cancer or high-risk lesions requiring surgical removal. Treatment-related adverse events were reported as mild to moderate, with injection-site reactions and flu-like symptoms such as fatigue and chills being the most common effects.

Because the trial was not designed to prove prevention, the authors emphasize limitations: the sample size is small and the follow-up window relatively short for definitive clinical conclusions. They nonetheless interpret the results as proof of concept that KRAS-targeted vaccination can generate lasting immunity in people at elevated inherited risk.

The investigators also conducted exploratory imaging analyses for cyst dynamics in participants with follow-up scans. Complete radiographic resolution occurred in five participants with small cysts, partial regression was seen in three, and the remaining cysts remained stable.

The group previously reported that a KRAS vaccine tested in post-surgery patients at high risk of recurrence produced promising long-term disease-free outcomes when immune responses were robust. That earlier success motivated this prevention-focused trial, and the current study supports continued evaluation of the approach in larger cohorts.

Subject of Research: Preventive mutant KRAS-targeted cancer vaccination
Article Title: Phase 1 demonstration of durable immune responses with a mutant KRAS peptide vaccine in high-risk individuals
News Publication Date: July 16 (year not specified in provided text)
Web References: https://aacrjournals.org/cancerdiscovery
References: Nature Communications (2026) KRAS vaccine recurrence findings; Cancer Discovery phase 1 results (July 16)
Image Credits: Not provided

Keywords: KRAS, pancreatic cancer, vaccine, peptide vaccine, T-cell response, immunotherapy, prevention, hereditary risk, pancreatic cysts, Cancer Discovery

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