Cancer immunotherapy refers to a set of approaches aiming at enhancing the immune system to fight cancer growth and spread. This variety of therapeutic approaches, especially those inhibiting immune checkpoints, have shown very promising results. Nevertheless, patients may respond differently to treatments and the efficacy of immunotherapy seems to be dependent on several factors that go beyond the molecular targeting of immune cells modulation. Here, we review how the activity of gut microbiota appears to be crucial in determining the effectiveness of some immunotherapeutic treatments, fostering or impeding the conditions under which treatments can work or not. Moreover, we discuss how these findings suggest not only extending the range of immunotherapeutic approaches but also reshaping our understanding of immunotherapy itself.
Keywords: ecology; fecal microbiota transplantation; gut microbiota; holobiont; immune checkpoint inhibitors; microbiota engineering cancer immunotherapy; microbiota manipulation; symbiosis; system therapeutics.