TABLE 3.

Review of previous studies of PD-L1 or PD-L2 expression in adenoid cystic carcinoma

Author, year citation	Tumors studied	Positive PD-L1 expression (no. positive/total)	Positive PD-L2 expression (no. positive/total)	CD8 expression
Mosconi et al. (2019)12	36 ACCs	Greater than 1% expression by IHC:	Greater than 10% expression by IHC:	Intratumoral:
	−10 parotid			Low: 19/36
	−9 sublingual	ACC tumor PD-L1: 0/36	ACC tumor PD-L2: 36/36	High: 17/36
	−5 submandibular	ACC stroma PD-L1; 0/36	ACC stroma PD-L1; 29/36	Intrastromal:
	−4 palate			Low: 22/36
	−4 tongue			High: 14/36
	−4 jugal mucosa (primary and recurrences)
Nakano et al. (2019)13	11 ACCs (out of 30 head and neck salivary gland tumors)	Greater than 1% expression by IHC:	Positive by in situ hybridization	ACC:
				Low: 11/11
		ACC tumor PD-L1: 0/11	ACC tumor PD-L2: 5/11	High: 0/11
		Non-ACC tumor PD-L1: 11/19	Non-ACC tumor PD-L2: 6/17	Non-ACC: Low: 9/19 High: 10/19
Sridliaran et al. (2016)14	28 ACCs (from 21 patients) (mixture of primary and metastatic tumors to the lung—primary site unspecified; 7 patients had both primary and metastatic tumor sample)	Greater than 5% expression by IHC:	Greater than 10% expression by IHC:	High: 42%
		ACC tumor PD-L1: 0/28	ACC tumor PD-L2:
			−9/15 of primary
			−8/11 of metastatic
Mukaigawa et al. (2016)15	53 ACCs (out of 219 salivary gland tumors of oral cavity )	Greater than 5% expression by IHC:	Not studied	Unspecified
		ACC tumor PD-L1: 1/53
		ACC TIMC PD-L1 : 0/53
Tapias et al. (2019)16	14 ACCs (out of 23 primary tracheal tumors)	Greater than 1% expression by IHC: ACC tumor: 0/14	Not studied	Low: 14/14
				High: 0/14
Harada et al. (2018)17	25 ACCs (out of 47 malignant salivary gland tumors)	Greater than 5% expression by IHC: PD-L1 tumor: 11/25 ACC	Not studied	Unspecified

ACC, adenoid cystic carcinomas; IHC, immunohistochemistry; PD-L, programmed cell death ligand; TIMC, tumor-infiltrating mononuclear cell.