Enhancing cancer immunotherapy and antiangiogenic therapy by regulating gut microbes: Opportunities and challenges

As the largest microecosystem in the human body, gut microbes (GMs) and their metabolites play an important role in regulating human health. In recent years, immune checkpoint therapy (ICT) combined with antiangiogenic agents is an emerging combination therapy for cancer. There is growing evidence that GMs can affect the effectiveness of drugs to treat cancer. GMs not only regulate angiogenesis in the tumor microenvironment, but also influence the efficacy of immune checkpoint inhibitors. Many studies show that Bifidobacterium can upregulate the anticancer function of immune checkpoint blockers. In addition, GMs have been found to be involved in the formation of blood vessels and other developmental processes. Clinically, GMs are believed to play a key role in patients receiving antiangiogenic therapy and ICT. In this perspective, we provide an overview of the composition and function of the gut microbiome, and discuss the role of the GMs against the conditioning of angiogenic therapy and ICT. We also summarize new approaches and clinical translational trials using GMs for cancer therapy, and present opportunities and challenges for targeting GMs for cancer therapy in the future.