Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota

TLDR

Gut microbes influence the efficacy of antitumor T cell immunotherapies, which can produce dramatic tumor regressions in some patients but not others. Two mouse studies examined how gut microbiota affect CTLA‑4 blockade efficacy. Optimal responses to CTLA‑4 blockade require specific Bacteroides species, while Bifidobacterium species enhance anti‑PD‑L1 therapy efficacy. See Vétizou et al.

Abstract

Gut microbes affect immunotherapy The unleashing of antitumor T cell responses has ushered in a new era of cancer treatment. Although these therapies can cause dramatic tumor regressions in some patients, many patients inexplicably see no benefit. Mice have been used in two studies to investigate what might be happening. Specific members of the gut microbiota influence the efficacy of this type of immunotherapy (see the Perspective by Snyder et al. ). ). Vétizou et al. found that optimal responses to anticytotoxic T lymphocyte antigen blockade required specific Bacteroides spp. Similarly, Sivan et al. discovered that Bifidobacterium spp. enhanced the efficacy of antiprogrammed cell death ligand 1 therapy. Science , this issue, p. 1079 and p. 1084 ; see also p. 1031