Table 2.

Binding affinities of rhumAbs to immobilized recombinant rat, cynomolgus monkey, and human FcRn proteins at pH 6.0.

	Mean KD ( ± SD) (μM)
Species of FcRn	rhumAb1	rhumAb2
Rat	0.9 ± 0.04**	< 0.3*
Cynomolgus monkey	3.7 ± 0.1	< 0.3*
Human	4.3 ± 0.1	< 0.6*

K_D = dissociation equilibrium constant.

Notes: Mean and standard deviation (SD) were calculated based on 4 independent experimental runs. The binding data of rhumAb1 to immobilized rat FcRn was obtained by kinetics analysis using a bivalent binding model in the Biacore T200 evaluation software. The averaged k_a1 and k_d1 values for rhumAb1 are (9.9 ± 0.6)×10⁴ 1/Ms, and (8.6 ± 0.8)×10⁻² 1/s. The binding data of rhumAb1 to immobilized cynomolgus monkey and human FcRn proteins were obtained by steady-state equilibrium analysis using Biacore T200 evaluation software.

*The lower limit of K_D value was the estimated concentration of rhumAb2 that reached at (or is slightly higher than) the theoretical Rmax level of rhumAb1, assuming rhumAb2 and rhumAb1 have the same FcRn binding activities.

^**KD1 of rhumAb1 to immobilized rat FcRn was reported.