The study begins by highlighting the significant global burden of colorectal cancer (CRC) and the role of gut microbiota, particularly oncomicrobes, in CRC development. The researchers propose that vaccines targeting these oncomicrobes could offer a novel approach to cancer prevention and treatment. They conducted experiments using two mouse models: a preventive model targeting C. jejuni and a therapeutic model targeting ETBF. The vaccines were shown to elicit strong immune responses, reduce oncomicrobial colonization, and suppress tumorigenesis. The study also examined the impact of the vaccines on gut microbiota composition and found minimal disruption, suggesting that the vaccines could be safe and effective.
Key findings from the study include:

1. Oncomicrobial Vaccines Effectively Reduce Tumorigenesis in Preventive Models: The C. jejuni vaccine significantly reduced tumor incidence and accelerated the clearance of C. jejuni in mice, demonstrating its potential to prevent tumorigenesis without disrupting gut microbiota.
2. Therapeutic Vaccines Suppress Tumor Growth and Restore Gut Microbiota Balance: The ETBF vaccine effectively reduced ETBF colonization, decreased tumor numbers, and restored the abundance of non-toxic B. fragilis (NTBF), indicating a potential restoration of gut microbiota balance.
3. Vaccines Minimally Disrupt Gut Microbiota Composition: Both vaccines showed minimal impact on the overall gut microbiota, suggesting that they specifically target oncomicrobes without harming beneficial gut bacteria.
4. Robust Immune Responses Contribute to Tumor Suppression: The vaccines triggered strong immune responses, including increased antibody levels and T cell activation, which played a key role in suppressing tumor growth and reducing inflammation.
5. Vaccines Alter Intestinal Metabolome to Favor Antitumor Effects: The C. jejuni vaccine altered the intestinal metabolome, increasing antitumor metabolites and decreasing tumor-promoting metabolites, further supporting its potential to mitigate the impact of oncomicrobes on tumorigenesis.

The study demonstrates that oncomicrobial vaccines targeting C. jejuni and ETBF can effectively reduce the colonization of these cancer-promoting microbes, suppress tumor development, and mitigate inflammation in mouse models. Importantly, the vaccines did not significantly disrupt the gut microbiota, suggesting they could be safe for clinical use. These findings highlight the potential of oncomicrobial vaccines as a novel strategy for preventing and treating colorectal cancer, particularly in high-risk individuals. Further research is needed to translate these findings into effective human therapies, but the results are promising for the development of targeted cancer vaccines. The work entitled “ Oncomicrobial vaccines mitigate tumor progression via precisely targeting oncomicrobes in mice” was published on Protein & Cell (published on Jan. 7, 2025).