A small study showed preliminary evidence of activity in a peptide vaccine targeting KRAS mutations in pancreatic cancer.

I’ve written about an an mRNA-based pancreatic cancer vaccine that also targets KRAS, but this is a more traditional peptide vaccine, which can be used to target specific antigens on a cancer cell.

This post will examine this new study about the new peptide pancreatic cancer vaccine.

Pancreatic cancer

Before I discuss the vaccine, here are some facts about pancreatic cancer:

• An estimated 67,440 people (34,950 men and 32,490 women) will be diagnosed with pancreatic cancer in 2025.
• About 51,980 people (27,050 men and 24,930 women) will die of pancreatic cancer in 2025.
• Because early symptoms of pancreatic cancer may be missed, it is usually diagnosed in later stages, which leads to only a one-year survival after diagnosis.
• Treatment of pancreatic cancer usually requires surgery plus adjuvant therapies like chemotherapy and radiation therapy. Of course, the success rate of this strategy is lower with later-stage pancreatic cancer.
• According to the American Cancer Society, the five-year survival rate for all pancreatic cancer stages is around 13%.

Researchers are seeking vaccines that produce neoantigen-specific T-cells that target KRAS mutations on the surface of pancreatic cancer cells, helping to destroy the cancer cells. KRAS mutations are found in over 90% of pancreatic cancer cases, particularly in pancreatic ductal adenocarcinoma (PDAC), and play a crucial role in tumor development and treatment strategies.

Mutant (m)KRAS is an oncogenic driver in more than 90% of PDAC and a majority of associated precursor lesions. As an initiating genetic event, mKRAS is an attractive target for both precision immunotherapy in PDAC and immune-interception strategies in the precursor setting.

This peptide vaccine elicited KRAS-specific T-cell responses in patients with mutations associated with PDAC. 

The study researchers (discussed below) state that at least 10% of patients with PDAC have a hereditary predisposition for that cancer. Several studies have shown that increased hereditary PDAC risk is linked to pathogenic germline variants in cancer susceptibility genes. Although pancreas surveillance has been associated with PDAC downstaging and good long-term survival, outcomes remain poor for other patients, particularly those who drop out of surveillance.

The researchers also said that given that evolution from precursor lesions to PDAC occurs over a decade or longer, a window of opportunity exists to intercept cancer development with a vaccine in high-risk patients.

I need to make an important point — a cancer “vaccine” is a bit of a misnomer. These vaccines induce an immune response, but are not preventative like vaccines for pathogens – this new vaccine is an adjuvant to the treatment strategy for the cancer. It is a form of immunotheray.

This vaccine not only targets a current cancer but also could provide immunity to a cancer recurrence, so, in a sense, it is also preventative. It also could help prevent pancreatic cancer in individuals who are predisposed to the cancer.

Pancreatic cancer peptide vaccine paper

In a paper published on 16 July 2026 in Cancer Discovery, Neeha Zaidi, MD, of Johns Hopkins Medicine in Baltimore, and colleagues, 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 to assess safety, immunogenicity, and T cell persistence.”

Here are some of the key results:

• They found that the vaccine elicited KRAS-specific T-cell responses in 18 of 20 patients with mutations associated with pancreatic ductal adenocarcinoma.
• Vaccine-induced T-cells persisted for up to two years, and no patient developed pancreatic cancer during 16.5 months of follow-up.
• No patient developed grade ≥3 adverse events (AEs).

The researchers concluded:

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.

Summary

There is a lot of research on vaccines being used to treat cancer, and pancreatic cancer, which is difficult to treat, is one of the top priorities.

Although this study was quite small, it has a remarkable success rate of preventing cancer in individuals who had a high success rate.

This can be an important tool in fighting pancreatic cancer, one of the more dangerous cancers.

Citations

• Cancer Genome Atlas Research Network. Electronic address: andrew_aguirre@dfci.harvard.edu; Cancer Genome Atlas Research Network. Integrated Genomic Characterization of Pancreatic Ductal Adenocarcinoma. Cancer Cell. 2017 Aug 14;32(2):185-203.e13. doi: 10.1016/j.ccell.2017.07.007. PMID: 28810144; PMCID: PMC5964983.
• Haldar SD, Huff AL, Wang HH, Zhu Z, Berg M, Lu J, Sun N, Abou Diwan E, Sinan H, Thoburn CJ, Guo MZ, Yoshida T, Chu LC, Ferguson AK, Sidiropoulos DN, Kagohara LT, Ho WJ, Bever KM, Baretti M, Yarchoan M, Laheru DA, Nauroth JM, Thomas AM, Wang H, Azad NS, Goggins MG, Jaffee EM, Zaidi N. First-in-human testing of a mutant KRAS vaccine for pancreatic cancer interception in high-risk cohorts. Cancer Discov. 2026 Jul 16:10.1158/2159-8290.CD-25-2245. doi: 10.1158/2159-8290.CD-25-2245. Epub ahead of print. PMID: 42458705; PMCID: PMC13450700.

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