CTLA4 and cancer: Three bacteria from the intestinal tract, Bifidobacterium pseudolongum, Lactobacillus johnsonii, and Olsenella from the intestinal tract significantly enhanced the efficacy of anti-CTLA4 and anti–PD-L1 immunotherapy in four different cancer mice when they were introduced into aseptic mice with ICIs, and the Bifidobacterium pseudolongum in the intestine contributes to regulating and enhancing the immunotherapeutic response by producing inosine (12).