Our gut is home to trillions of microorganisms, collectively called the gut microbiota, which play a crucial role in digestion, immunity, and overall health. Excitingly, research is revealing that these tiny residents can also influence the effectiveness of cancer treatments—from immunotherapy to chemotherapy and beyond. Understanding this connection opens new possibilities for more personalized and effective cancer care.
Boosting Immunotherapy through Gut Microbes
Innovative therapies like CAR-T cell therapy, immune checkpoint inhibitors (ICIs), oncolytic viruses (OVs), and CpG-oligonucleotide immunotherapy have transformed cancer treatment in recent years. Studies show that the composition of gut microbiota can affect how well patients respond to these therapies.
For instance, certain bacteria—such as Ruminococcus, Faecalibacterium, and Akkermansia—are linked to better CAR-T outcomes, while broad-spectrum antibiotics may reduce therapy effectiveness. Similarly, gut microbes can enhance responses to ICIs by stimulating immune cells that attack tumors. OVs, which work by killing cancer cells and activating the immune system, also benefit from a healthy gut microbiota. Even CpG-based therapies are more effective when gut microbes activate immune pathways.
In short, a balanced gut microbiota can help “turn cold tumors into hot tumors,” making them more responsive to modern immunotherapies.
Gut Microbes and Traditional Treatments
Gut microbiota also affects chemotherapy and radiotherapy. Some microbes can influence drug metabolism, improving efficacy or reducing side effects. For example, bacteria like Enterococcus hirae and Barnesiella intestinihominis enhance the response to cyclophosphamide, a common chemotherapy drug, by activating immune cells.
On the other hand, disruptions in gut microbiota—often caused by antibiotics or radiation—can increase treatment toxicity, leading to issues like intestinal inflammation or mucositis. Promising strategies like fecal microbiota transplantation (FMT) and certain probiotics have shown potential to restore gut balance, reduce side effects, and improve overall outcomes.
Complementary Approaches: TCM and Probiotics
Traditional medicine can also benefit from gut microbes. Traditional Chinese Medicine (TCM) compounds, when processed by gut bacteria, can transform into more potent anti-cancer agents. Certain TCM herbs and formulas can also promote beneficial bacteria while suppressing harmful ones.
Similarly, probiotics, prebiotics, and synbiotics—foods or supplements that nourish or contain helpful bacteria—can support cancer treatment by strengthening gut immunity, reducing inflammation, and enhancing drug effectiveness. For example, in combination with chemotherapy or immunotherapy, synbiotics have been shown to reduce treatment-related side effects while boosting therapeutic benefits.
Emerging Strategies: Engineering the Microbiota
Beyond diet and probiotics, scientists are developing targeted microbiota interventions to fight cancer more precisely. These include:
- Engineered microbes, designed to deliver anti-cancer agents directly to tumors.
- Phage therapy, using viruses that selectively kill harmful bacteria.
- Nanomedicine and OMVs (outer membrane vesicles), which can deliver drugs or immune-stimulating molecules to tumors while sparing healthy microbes.
These cutting-edge approaches are still under study, but they demonstrate the incredible potential of harnessing gut microbes to improve therapy effectiveness and reduce toxicity.
Looking Ahead: Precision Medicine and Microbiota
The future of cancer treatment may increasingly involve personalized microbiota strategies. By analyzing an individual’s gut bacteria and metabolites, clinicians could tailor therapies to maximize efficacy and minimize side effects. Combining microbiota profiling with multi-omics analysis, AI, and big data could allow doctors to predict treatment response and guide interventions in a way that was unimaginable just a decade ago.
While challenges remain—including differences in individual microbiotas, safety considerations, and regulatory hurdles—the potential is enormous. Gut microbiota represents a promising frontier in precision oncology, offering hope for more effective, safer, and individualized cancer care.
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Text/Adaptation: Ifiyenia Anastasiou for Kapa3
