PDCD1 and melanoma: In a similar study, Routy et al., uncovered the role of Akkermansia muciniphila in regulating the response of melanoma patients to anti-PD-1 treatment (49).Oral supplementation with A. muciniphila after fecal material transplantation (FMT) with feces from non-responders significantly restored the efficacy of PD-1 blockade (49).