The gut microbiota influences the effectiveness and tolerance of cancer treatments

The gut microbiota, this complex ensemble of microorganisms inhabiting the digestive tract, plays a key role in the response to cancer treatments. Recent research shows that its composition can enhance or reduce the effectiveness of immunotherapies and chemotherapies, while also modulating side effects for patients.

In the context of immunotherapies, certain bacteria such as Bifidobacterium, Akkermansia muciniphila, or Faecalibacterium are associated with a better response to treatment. For example, predictive models based on the microbiota achieve remarkable accuracy, with values up to 88% for predicting the response to immune checkpoint inhibitors, thus surpassing traditional clinical markers. Furthermore, clinical trials have demonstrated that fecal microbiota transplantation from responder patients could restore the effectiveness of immunotherapy in resistant patients, paving the way for new therapeutic strategies.

For chemotherapy, the microbiota also exerts a major influence. Certain bacteria, such as Fusobacterium nucleatum, promote treatment resistance, while others, like Akkermansia muciniphila, enhance the effect of certain drugs. One study, for example, revealed that a probiotic mixture significantly reduced the severity of oral mucositis, a frequent and painful side effect, decreasing severe cases from 47% to 25%. Additionally, microbial signatures allow for predicting treatment response with greater accuracy than traditional clinical markers, as seen in urothelial cancer, where a microbiota-based model achieved 88% accuracy compared to 50% for conventional criteria.

The microbiota acts through several mechanisms. It modulates the immune system by activating cells such as T lymphocytes or by influencing inflammatory signaling pathways. It also participates in drug metabolism, with some microorganisms converting therapeutic molecules into active forms or, conversely, inactivating them. For example, bacteria like Bacteroides vulgatus synthesize nucleotides that diminish the effect of radiotherapy, while others, such as Lactobacillus, improve the response to certain chemotherapeutic agents.

Beyond effectiveness, the microbiota also helps anticipate treatment-related toxicities. Specific bacteria, such as Bacteroides plebeius or Bacteroides uniformis, have been identified as markers of increased risk of severe adverse effects during chemotherapy. These findings could help tailor treatments based on each patient’s microbial profile, thereby limiting complications.

Predictive models based on the microbiota therefore offer a promising approach for precision oncology. They not only allow for better selection of patients likely to respond to a treatment but also optimize therapeutic regimens and reduce side effects. However, their routine use still faces methodological challenges, such as the lack of standardization in analysis protocols or the need to validate these models on a large scale.

Variations in microbiota composition can also reflect disease progression. For example, an increase in Bacteroides is often associated with tumor progression, while a higher presence of Lactobacillus or Bifidobacterium appears linked to a better response to treatments. These observations highlight the potential of the microbiota as a non-invasive biomarker for patient monitoring.

Finally, the gut microbiota represents a serious avenue for developing new therapeutic strategies. Modulating its composition—whether through diet, probiotics, targeted antibiotics, or microbiota transplantation—could optimize treatment effectiveness while reducing toxicity. These approaches, still under development, could ultimately transform the management of cancer patients.

Bibliographie

Source de l’étude

DOI : https://doi.org/10.1007/s00520-026-10918-1

Titre : Clinical potential of the gut microbiome in oncology: a scoping review of treatment response, toxicity and biomarker development

Revue : Supportive Care in Cancer

Éditeur : Springer Science and Business Media LLC

Auteurs : João Daniel de Souza Menezes; Matheus Querino da Silva; Emerson Roberto dos Santos; Stela Regina Pedroso Vilela Torres de Carvalho; Mikaell Alexandre Gouvea Faria; Rita de Cássia Helú Mendonça Ribeiro; Júlio César André