Can we harness the microbiota to enhance the efficacy of cancer immunotherapy?

There is currently much interest in defining how the microbiota shapes immune responses in the context of cancer. Various studies in both mice and humans have associated particular commensal species with better (or worse) outcomes in different cancer types and following treatment with cancer immunotherapies. However, the mechanisms involved remain ill-defined and even controversial. In this Viewpoint, Nature Reviews Immunology has invited six eminent scientists in the field to share their thoughts on the key questions and challenges for the field. In this Viewpoint, six leading experts consider the ways in which the microbiota can influence immune responses to cancer. Immunotherapies have been revolutionary in the treatment of cancer, but will we one day further increase their efficacy with microbiota-derived drugs? The contributors B. Brett Finlay is a professor in the Michael Smith Laboratories at the University of British Columbia. His research interests are focused on host–microorganism interactions, at the molecular level, and he has published more than 500 articles. He is a co-author of the books Let Them Eat Dirt and The Whole-Body Microbiome . Romina Goldszmid is an Earl Stadtman Investigator and Head of the Inflammatory Cell Dynamics Section in the Laboratory of Integrative Cancer Immunology, National Cancer Institute, National Institutes of Health (NIH). She received her PhD degree from the University of Buenos Aires, Argentina, and completed her postdoctoral training at the National Institute of Allergy and Infectious Diseases, NIH. She has a long-standing interest in understanding myeloid cell development, differentiation and function in the context of cancer and infections. Current work in her laboratory aims to dissect the myeloid cell repertoire within tumours, determine their contribution to therapy efficacy and unravel the mechanisms by which the microbiota regulates their function. Kenya Honda is a professor at Keio University School of Medicine and a team leader at the RIKEN Center for Integrative Medical Sciences, Japan. His laboratory has been aiming to elucidate and translate the mutualistic relationship between the gut microbiota and the host immune system using gnotobiotic animal models. Giorgio Trinchieri is an NIH Distinguished Investigator and Chief of the Laboratory of Integrative Cancer Immunology, Center for Cancer Research, National Cancer Institute, NIH. His research has focused for many years on the interplay between inflam