TABLE 2.

Properties of anti-CD4 Adnectins

Adnectin	Origin library	Cell-cell fusion EC50 (nM)	Replicating virus EC50 (nM)	Affinity at 37°C (nM)a	Cell-binding EC50 (nM)b	Melting temp (°C)c	Monomers (%)d
2886_C08	WS1	105	48	12	7.9	49.5	97
4945_C06	WS1	21	7.8	1.3	2.2	63.0	97
4945_G05	WS1	36	11	4.0	4.4	51.3	93
4945_G06	WS1	7.1	4.9	2.0	2.3	55.8	98
6940_B01	WS1	6.9	8.5 ± 2.5f	3.9 ± 0.7f	2.1	77.7	96
3517_G01	NP1	12g	6g	0.3	0.7	NDe	96
4911_E03	NP1	0.7g	>400g	<0.01h	0.4	58.4	99
4911_A07	NP1	1.6g	>5,500g	<0.01h	1.0	46.5	86
4910_A08	NP1	0.7g	255	<0.01h	1.2	55.7	97
Ibalizumab	None	0.2	0.2 ± 0.1f	0.3 ± 0.1f	0.1	ND	95

^aAffinity (equilibrium dissociation constant) measurements made by Biacore SPR.

^bBinding to CD4-expressing human PBMCs was determined by FACS; no binding to CD8⁺/CD4⁻ PBMCs was detected for any Adnectin at concentrations up to 1 μM.

^cDifferential scanning calorimetry (DSC) was used to determine the temperature at which the protein unfolds.

^dSize exclusion chromatography was used to determine the percent monomers.

^eND, not determined.

^fn = 1 for most measurements made during screening; for the activity and affinity of the final lead Adnectin (6940_B01) and ibalizumab, the average of at least three independent measurements ± 1 standard deviation is reported.

^gInhibition curves do not surpass 80%.

^hOff-rates were too slow to measure as they were out of the range of the instrument.