Abstract:
The introduction of immune checkpoint inhibitors has constituted a major revolution
in the treatment of patients with cancer. In contrast with the traditional cytotoxic therapies that
directly kill tumor cells, this treatment modality enhances the ability of the host’s immune system
to recognize and target cancerous cells. While immune checkpoint inhibitors have been effective
across multiple cancer types, overcoming resistance remains a key area of ongoing research. The gut
microbiota and its role in cancer immunosurveillance have recently become a major field of study.
Gut microbiota has been shown to have direct and systemic effects on cancer pathogenesis and hosts
anti-tumor immune response. Many studies have also shown that the host microbiota profile plays
an essential role in the response to immunotherapy, especially immune checkpoint inhibitors. As
such, modulating this microbial environment has offered a potential path to overcome the resistance
to immune checkpoint inhibitors. In this review, we will talk about the role of microbiota in cancer
pathogenesis and immune-system activity. We will also discuss preclinical and clinical studies that
have increased our understanding about the roles and the mechanisms through which microbiota
influences the response to treatment with immune checkpoint inhibitors.
