CTLA4 and cancer: In addition, other studies support the role of Bifidobacterium, Bacteroides, Faecalibacterium and Akkermansia species in cancer therapy targeting the immune checkpoint blockade (CTLA-4, PD-1), showing a T cell-specific anti-tumor-induced response (Sivan et al., 2015; Vetizou et al., 2015; Gopalakrishnan et al., 2018; Routy et al., 2018).