Figure 4

Affinity and association rate of tozorakimab for IL-33^red measured using KinExA. (a) The affinity (K_D) of tozorakimab for IL-33^red (residues 112–270) was obtained after a 1:1 binding model was fitted to two KinExA datasets simultaneously; the black solid line and filled squares are the data from IL-33^red titrated into 5 pM fixed [IgG] (■) and the grey solid line and filled diamonds are from a 0.20 pM fixed [IgG] data titration (◆). (b) Error curve indicating the extent (grey shaded rectangle) of 95% CIs around the affinity value (indicated by dashed line) from the fit to the data in panel a. (c) Fitting error plot of the 95% CIs of the active receptor CBP parameter that arise from the fit in panel a. (d) The association rate constant for the tozorakimab Fab fragment binding IL-33^red (residues 112–270) measured using KinExA. (e) Error plot of the 95% CI around the association rate (k_a) estimate from the fit in panel d. CBP, constant-binding partner; CI, confidence interval; Fab, antigen-binding fragment; IgG, immunoglobulin G; KinExA, kinetic exclusion assays; IL, interleukin; red, reduced.