The presence of certain types of gut microbes in mice can boost the anti-tumor effects of cancer immunotherapy, according to two studies from independent research teams published today (November 5) in Science Express.

Cancer immunotherapies that block immune inhibitory pathways are now available as treatments for several tumor types, yet patients’ responses to these therapies vary. Aside from the presence of T cells within the tumor before the start of treatment, it has not been clear what other factors are linked to a response to these antibodies. The two studies published today, while not the first to suggest that gut microbes can influence the efficacy of cancer therapy, provide a definitive link between gut microbiome composition and cancer immunotherapy response and implicate the positive role of specific bacterial species.