Table 2.

CircRNAs in the regulation of PD-1/PD-L1 pathways

CircRNA	Cancer	Functions	Sponge miRNA	Targets	PD-1/PD-L1	Reference
Hsa_circ_0000190	NSCLC	Indicates poor survival and prognosis	N/S	N/S	Increases PD-L1	[114]
CircFGFR1		Indicates poor prognosis and survival	miR-381-3p	CXCR4	Resistance to anti-PD-1 immunotherapy	[115]
Circ-CPA4		Indicates poor prognosis, inactives CD8 + T cells	let-7	N/S	Increases PD-L1	[118]
Circ_0000284		Induces cell migration, invasion and proliferation	miR-377	N/S	Increases PD-L1	[120]
Hsa_circ_0020397	CRC	Induces cell viability and invasion, inhibits cell apoptosis	miR-138	TERT	Increases PD-L1	[121]
CDR1-AS	CRC	Related to poor prognosis	Independent on miR-7	CMTM4, CMTM6	Increases PD-L1	[122]
Circ_0020710	Mel	Induces cell proliferation, migration, invasion; inhibits cytotoxic lymphocyte exhaustion	miR-370-3p	CXCL12/CXCR4/CXCR7	Immune suppressive	[123]
Circ-UBAP2	PAAD	Inhibits antigen presentation; induces immune escape	miR-494	CXCR4 and ZEB1	Increases CTLA-4 and PD-1	[124]

Mel Melanoma, NSCLC Non-small-cell lung cancer, PAAD Pancreatic adenocarcinoma