Abstract
Despite the introduction of immune checkpoint inhibitors (ICIs) in the treatment of lung cancer, the number of deaths from lung cancer remains high, and further improvements in response rates are necessary. Recently, the gut microbiota has been reported to be involved in the therapeutic effects of ICIs; however, only a few studies have examined patients with lung cancer in this context. In the current study, we aimed to explore the association between the gut microbiota before therapy and the efficacy of ICIs in patients with advanced non-small cell lung cancer (NSCLC). The a-diversity of the intestinal microbiota in patients who responded to ICI treatment (responders) was significantly higher than that in those who did not respond to ICIs (non-responders). Additionally, the abundance of Bifidobacteriaceae was significantly higher in the responders than in the non-responders. Furthermore, patients with a high abundance of Bifidobacteriaceae had significantly longer overall survival than those with a low abundance. Counts of Levilactobacillus brevis were significantly higher in responders than in non-responders. Our findings suggest that a higher diversity of the gut microbiota and an abundance of Bifidobacterium and/or L. brevis are distinctive features of the microbiota in patients with NSCLC who respond to ICI treatment.