Blocking the PD-1/PD-L1 pathway in glioma: a potential new treatment strategy

Table 1 Summary of different assays for PD-L1 in the studies

Author (year)	Sample size	WHO grade	Assay	Material	Tissue samples	Antibody	Staining patterns	Cut-off^a	Rate (%)^b
Wintterle et al. (2003)	10	III + IV	IHC	Frozen sections	Full slides	5H1	NM	Presence of PD-L1 staining	100
Wilmotte et al. (2005)	54	II–IV	IHC	Frozen sections	Full slides	MIH1	Membranous/cytoplasm	Presence of PD-L1 staining	85.2
Yao et al. (2009)	48	I–IV	IHC	Frozen sections	Full slides	MIH1 (Ebioscience)	Membranous/cytoplasm	NM	NM
Yao et al. (2009)	48	I–IV	WB	Fresh tissues	Full slides	Anti-PD-L1 (R&D Systems)	NM	NM	75.0
Avril et al. (2010)	20	IV	IHC	PE	NM	Anti-PD-L1 (Clinisciences)	NM	>25%	45.0
Liu et al. (2013)	17	III + IV	IFC	Frozen sections	NM	Anti-human PD-L1 (558065; BD PharMingen)	NM	Presence of PD-L1 staining	76.5
Berghoff et al. (2014)	135	IV	IHC	PE	Full slides	5H1	Membranous	>5%	34.8
Berghoff et al. (2014)	135	IV	IHC	PE	Full slides	5H1	Diffuse/fibrillary	Presence of PD-L1 staining	82.9
Nduom et al. (2015)	99	IV	IHC	PE	Tissue microarray	EPR1161(2) (Abcam)	Membranous	≥1%	60.6
Zeng et al. (2016)	229	I–IV	IHC	PE	Tissue microarrays	Rabbit anti-PD-L1	Membranous/cytoplasm	>5%	51.1
Garber et al. (2016)	345	I–IV	IHC	PE	Full slides	SP142 (Spring Biosciences)	Membrane	>5%	6.1
Pooled data	957								44.7

Abbreviations: IHC immunohistochemistry, IFC immunofluorescence histochemistry, WB western blot, PE paraffin-embedded specimens, NM not mentioned
^aCut-off value to determine positivity
^bThe rates of patients with glioblastomas with any PD-L1 protein expression on tumor cells

ISSN: 1756-8722