Table 1.

Roles of bacteria in regulating the response to cancer therapies

Bacterial species	Cancer type	Therapy	Mechanism	Ref.
Streptococci	Different types	Tumor cell killing	Unknown	[59]
Mycobacterium bovis	Human bladder	Reduction of tumor progression	Unknown	[60]
Lactobacillus casei	Human bladder	Decrease of recurrence	Unknown	[61]
B. thetaiotaomicron and B. fragilis	Mouse sarcoma, melanoma, colon	Response to anti-CTLA-4	Th1 induction, DC maturation (IL-12 production)	[63]
Bifidobacterium	Mouse melanoma	Response to anti-PD-L1	DC activation, stimulation of CD8+ T cell effector functions	[65]
A. muciniphila	Human NSCLC, RCC, UC	Response to anti-PD-1/PD-L1	DC activation, increased CD4+ TCM tumor infiltration	[66]
Bifidobacterium longum, Collinsella aerofaciens, and Enterococcus faecium	Human melanoma	Response to anti-PD-1	Cancer immune response	[68]
Faecalibacterium, Ruminococcaceae	Human melanoma	Response to anti-PD-1	Increased CD8+ T cell tumor infiltration	[69]
Bacteroides thetaiotaomicron, Escherichia coli, Anaerotruncus colihominis	Human melanoma	Response to anti-PD-1	Increased levels of Treg cells and MDSCs	[69]
B. caccae, B. thetaiotaomicron, B. vulgatus, B. massiliensis, P. distasonis, E. coli	Normal mouse colon	No therapy	Increase the proportion of Foxp3+ Treg cells among the CD4+ T cells	[70]
Commensal microbiota	Mouse lymphoma	Oxaliplatin	ROS-mediated cytotoxicity	[62]
Lactobacillus johnsonii, Lactobacillus murinus, Enterococcus hirae	Mouse melanoma, sarcoma	Cyclophosphamide	Induction of Th1, Th17-IFN-γ+, CD3+ T cell tumor infiltration	[93]
E. hirae, B. intestinihominis	Mouse sarcoma	Cyclophosphamide	Induction of Th1, CD8+ T cell tumor infiltration	[95]
Gammaproteobacteria	Mouse colon cancer	Gemcitabine	Intratumor gemcitabine deamination	[96]

NSCLC: non-small cell lung carcinoma; RCC: renal cell carcinoma; UC: urothelial carcinoma; TCM: T central memory; MDSCs: myeloid-derived suppressor cells; ROS: reactive oxygen species; DC: dendritic cell