Engineered Bacteria Shows Promise in Targeted Cancer Therapy | PLOS Biology

The fight against cancer may have gained a surprising new ally: engineered probiotic bacteria. Scientists are exploring whether modified versions of Escherichia coli Nissle 1917 (EcN), a common gut bacterium, can be turned into targeted drug delivery systems, infiltrating tumors and releasing cancer-fighting medication directly at the source. Early research, published March 17th in PLOS Biology, demonstrates promising results in mouse models, though significant hurdles remain before this approach can be tested in humans.

Bacteria as Targeted Therapies: A Novel Approach

Cancer treatment is notoriously complex, often requiring aggressive therapies that impact the entire body. This can lead to debilitating side effects. The idea behind using bacteria like EcN is to exploit their natural ability to colonize certain environments – in this case, tumors – and deliver therapeutic payloads with pinpoint accuracy. Researchers at Shandong University in Qingdao, China, led by Tianyu Jiang, have been at the forefront of this perform. They focused on engineering EcN to produce Romidepsin (FK228), an FDA-approved drug used to treat certain types of lymphoma. The team’s work builds on the understanding that certain bacterial strains have a propensity to accumulate within solid tumors, a phenomenon scientists are increasingly leveraging for therapeutic purposes.

“By leveraging engineered EcN, we can design a bacteria-assisted, tumor-targeted therapy for the biosynthesis and targeted delivery of small-molecule anticancer agents,” the authors wrote in their publication. This isn’t simply about delivering an existing drug; it’s about creating a “living therapy” that both produces and delivers the medication.

How the Engineered Bacteria Work

The process involved significant genetic and genomic engineering. The researchers essentially rebuilt the biosynthetic pathway for Romidepsin within the EcN bacteria. This meant introducing the necessary genes and optimizing their expression to ensure the bacteria could actually manufacture the drug. The modified bacteria were then introduced into a mouse model of breast cancer, where they demonstrated an ability to accumulate within the tumors and release Romidepsin. The study showed that this combined approach – bacterial colonization and localized drug release – improved treatment outcomes compared to using the bacteria alone.

Importantly, the researchers observed a synergistic effect. The presence of the bacteria itself seemed to enhance the effectiveness of Romidepsin, suggesting a dual-action mechanism. As the authors explain, “Escherichia coli Nissle 1917’s tumor colonization synergizes with Romidepsin’s anticancer activity to form a dual-action cancer therapy.” This is a crucial finding, as it suggests that the bacteria aren’t just acting as passive delivery vehicles, but are actively contributing to the therapeutic effect.

Romidepsin and its Role in Cancer Treatment

Romidepsin, too known as FK228, is a histone deacetylase (HDAC) inhibitor. As explained by the National Center for Biotechnology Information, HDAC inhibitors work by altering gene expression in cancer cells, ultimately leading to cell death. It’s currently approved for the treatment of cutaneous T-cell lymphoma and peripheral T-cell lymphoma. However, like many chemotherapy drugs, Romidepsin can have significant side effects, including cardiotoxicity (damage to the heart). One of the potential benefits of this bacterial delivery system is the possibility of reducing systemic exposure to the drug, thereby minimizing these side effects. The study found that targeted synthesis reduced FK228’s cardiotoxicity and mortality in the mouse models.

Limitations and What the Study Doesn’t Tell Us

Although these findings are encouraging, it’s crucial to acknowledge the limitations of the study. The research was conducted in mice, and results may not directly translate to humans. The immune response to the engineered bacteria, potential long-term effects of bacterial colonization, and the optimal dosage and delivery methods all need to be carefully investigated. The study focused on a specific type of breast cancer in a mouse model. It remains to be seen whether this approach will be effective against other types of cancer.

The study also doesn’t address the practical challenges of scaling up production of the engineered bacteria and ensuring their stability and efficacy over time. As ScienceDaily reports, more research is needed before this can be tested in people.

What Comes Next: From Lab to Clinic

The next steps involve further preclinical studies to optimize the engineered bacteria and assess their safety and efficacy in larger animal models. Researchers will also need to develop strategies for controlling the bacteria’s growth and ensuring they can be safely removed from the body after treatment. Clinical trials in humans are likely several years away, but the initial results provide a strong rationale for pursuing this innovative approach. The authors emphasize that their mouse-model study establishes a solid foundation for engineering bacteria capable of producing small-molecule anticancer drugs and engaging in bacteria-assisted tumor-targeted therapy, paving the way for future advancements in this field.

The development of bacteria-based cancer therapies represents a paradigm shift in how we approach this devastating disease. While challenges remain, the potential benefits – targeted drug delivery, reduced side effects, and enhanced efficacy – are significant. This research offers a glimmer of hope for more effective and personalized cancer treatments in the future.