Table 1.

Binding kinetics of trastuzumab and trastuzumab-Flexmab to recombinant HER2.

	kon (1/Ms)	koff (1/s)	Kd, M
Trastuzumab	2.24 × 105	4.81 × 10−4	2.15 × 10−9
Trastuzumab-Flexmab	3.22 × 105	1.21 × 10−4	3.75 × 10−10

Kinetic measurements were carried out using BIAcore T100 biosensor. The equilibrium dissociation constants, K_d, were calculated as the ratio of the two rate constants, k_off/k_on.