Researchers at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center have demonstrated that a mutant KRAS-targeted vaccine is safe and capable of inducing long-term immune responses in high-risk individuals. The phase 1 study, published in Cancer Discovery, marks a significant step toward using vaccination to intercept pancreatic cancer before it fully develops.
First-in-Human Feasibility for Pancreatic Cancer Interception
For individuals at high risk of developing pancreatic ductal adenocarcinoma (PDAC)—specifically those with hereditary predispositions or concerning pancreatic lesions—the current medical standard is often a waiting game of surveillance. If imaging detects a transformation toward cancer, the standard of care is surgical resection, a high-stakes procedure that carries significant risks.
A team led by Dr. Neeha Zaidi and Dr. Elizabeth Jaffee at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center recently tested a different strategy: intercepting the disease before it requires surgery. By developing a vaccine that targets the KRAS mutations responsible for more than 90% of PDAC cases, the team sought to activate the immune system in patients who have not yet developed cancer.
The research team reasoned that intercepting cancer development through noninvasive approaches could provide an effective strategy to prevent PDAC and improve survival in high-risk individuals.
Safety and Immune Response in the Phase 1 Trial
The phase 1 study enrolled 20 participants, all of whom carried high-risk factors, such as germline mutations in genes like ATM, BRCA1, BRCA2, APC, or CDKN2A. The vaccine, known as mKRAS-VAX, consists of synthetic long peptides targeting six common KRAS mutations (G12D, G12V, G12R, G12A, G12C, and G13D) paired with the adjuvant poly-ICLC.
All reported adverse events were grade 1 or 2, with common symptoms including injection site reactions, fatigue, and chills. Crucially, the vaccine stimulated KRAS-specific T-cell responses in 90% of the participants. These responses were not merely temporary; longitudinal sequencing showed that vaccine-induced T-cell clonotypes persisted for up to two years after the initial vaccination series.
Exploratory Findings on Pancreatic Cysts
Beyond safety and immunogenicity, the researchers monitored the physical status of pancreatic cysts in the participants. Over a median follow-up of 16.5 months, no vaccinated patients developed PDAC. In a post hoc exploratory analysis of 16 participants, researchers observed that 37.5% of the vaccinated cohort experienced either cyst resolution or a partial regression of at least 2 mm in the longest cyst axis.
While these findings provide a promising signal, they remain exploratory, and the primary goal of the study was to establish the feasibility of the vaccine platform itself.
The Path Toward Larger Interception Studies
Anirban Maitra, a professor at the Perlmutter Cancer Center, noted on social media that the study represents the first demonstration of the feasibility of a mutant KRAS-targeted vaccine in high-risk individuals rather than in patients with established cancer.
Despite these results, several questions remain regarding the long-term clinical impact of the vaccine. While the immune system was clearly activated, the researchers emphasize that this work is in its early stages. The team plans to use these results to support larger, more definitive studies to determine if such vaccinations can consistently prevent or delay the onset of pancreatic cancer in high-risk populations. For now, patients with hereditary predispositions or concerning imaging findings continue to rely on standard surveillance protocols while awaiting further data on the vaccine’s ability to fundamentally alter the disease’s progression.
Consult your healthcare provider regarding the latest clinical trial eligibility and surveillance options for pancreatic cancer.
Sources: Cancernetwork, Oncodaily.
