Table 1.

The list of representative PD-L1 inhibitors belonging to various classes and their PD-L1 blockade characteristics. IC₅₀ values were determined with the HTRF assay and EC₅₀ values were determined with the ICB assay. %RLU_max indicates the maximal activation of Jurkat T cells in the ICB assay, calculated as the % of the activation achieved for therapeutic anti-PD-L1 antibody (atezolizumab or durvalumab). When available, the data on the in vitro PD-L1 dimerization in the presence of the molecule, and the species specificity (human PD-L1, hPD-L1, and mouse PD-L1, mPD-L1) are indicated. “√”, particular activity confirmed experimentally; “No”, the compound was confirmed not to possess a particular activity; “n.d.”, no data on a particular activity.

Class	Name	HTRF IC50 [nM]		ICB Assay			PD-L1 Dimerization	Target Specificity
		Other	Ours	EC50 [nM]	%RLUmax	Ref.		hPD-L1	mPD-L1
Small molecules	BMS-202	18 [3]	96 [22]	no act.			√	√	No
	BMS-1166	1.4 [4]	3.89 [18]	1574	47	(Figure A1)	√	√	No
	2k		14.9 [12]	6632	87	[12]	√	√	No
	8j		<1 [18]	1026	87	[18]	√	√	No
	A20	17 [20]		430	55	[20]	n.d.	√	n.d.
	CH20	8.5 [19]		5600	93	[19]	n.d.	√	n.d.
	L7	1.8 [13]		375	75	[13]	n.d.	√	n.d.
	C13	4.23 [23]		104	100	[23]	n.d.	√	n.d.
	2b		3 [22]	763	93	[22]	√	√	No
	comp. A	0.4 [21]		18.9	86.3	[21]	√	√	No
Macrocyclic peptides	p57	9 [10]		566	91	[25]	No	√	No
	p71	7 [10]		293	89	[25]	No	√	No
	p99	153 [10]		6300	83	[25]	No	√	No
	p101	120 [10]	27.75 [24]	7500	85	[24]	No	√	No
Antibodies	atezolizumab			0.14	100	[18]	No	√	√
	durvalumab		0.1 (Figure A2)	0.23	100	[24]	No	√	No
	nivolumab	0.2 [21]		1.27	100	[25]	-	-	-
	MIH1							√	No
	MIH5							No	√
	hPD-1							√	√