Major gut microbial taxa and their predominant influence on systemic immunity and response to immunotherapy

Gut Taxa	Immune effect/Treatment response	Study type	Cancer type	Reference
Predominately positive influence
Firmicutes
Faecalibacterium prauznitzii	Boosts effector T-cells and dampens T-regs [38].	Humans	Melanoma	Gopalakrishnan et al. (2018)
Faecalibacterium spp.	Increases efficacy of anti-CTLA-4 immunotherapy [44].	Humans	Multiple myeloma	Chaput et al. (2017)
Eubacterium limosum Clostridiales spp. Ruminococcaceae spp. Phasolarctobacterium spp.	Boost CD8+ T-cells and enhance anti-PD-1 responses [33].	Cell line	Colorectal AdenocarcinomaCell line (MC38)	Tanoue et al. (2019)
Fusobacteria
Fusobacterium ulcerans Fusobacterium varium	Boost CD8+ T-cells and enhance anti-PD-1 responses [33].	Cell line	MC38	Tanoue et al. (2019)
Verrucomicrobia
Akkermansia muciniphilia	Increase in memory T-cells and decrease in T-regs in the TME [39].	Humans	Epithelial tumors	Routy et al. (2018)
Akkermansia muciniphilia	Increases mucus layer of the gut to prevent lipopolysaccharides absorption [39, 41].	Humans; review	Epithelial tumors	Routy et al. (2018); Routy et al. (2018)
Mixed influence
Bacteroidetes
Bacteroides fragilis	Increases efficacy of anti-CTLA-4 immunotherapy [42].	Human/Animal/Cell line	Epithelial tumors	Vetizou et al. (2015)
	Promotion of T-regs through polysaccharide-A [40].	Humans	N/A	Telesford et al. (2015)
	Higher IL-12 levels in transplant recipients [47].	Animal/Cell line	Cervical cancer	Uribe-Herranz et al. (2018)
Bacteroides thetaiotaomicron	Increases efficacy of anti-CTLA-4 and anti-PD-1 immunotherapy [Vetizou et al. showed in anti-CTLA–4 alone; Frankel et al. showed in dual setting] [42, 45].	Humans	Melanoma	Frankel et al. (2017)
Bacteroides spp.	Inferior response of anti-CTLA-4 immunotherapy [44].	Humans	Multiple myeloma	Chaput et al. (2017)
Actinobacteria
Bifidobacterium longum	Increases CD8+ T-cells [43, 46].	Animal/Cell line	Melanoma	Sivan et al. (2015)
Bifidobacterium longum		Humans	Melanoma	Matson et al. (2018)
Bifidobacterium bifidum	Induces naïve T-cell differentiation into T-regs and increases IL-10.Increases the integrity of epithelial barrier [41].	Review	N/A	Routy et al. (2018)
Predominately negative influence
Proteobacteria
Enterobacteriaceae	Inferior response and survival [41].	Review	N/A	Routy et al. (2018)