CTLA4 and melanoma: For example, antibiotic treatment prominently abolishes responses to ICIs in a mouse model with melanoma.461 However, gavage with B. fragilis or Bifidobacterium to GF or antibiotic-treated mice reverses the compromised efficacy of anti-CTLA-4 mAb and anti-PD-L1 mAb, respectively.461,462 Moreover, the anti-tumor effect by supplementation with Bifidobacterium alone is comparable to anti-PD-L1 treatment.