Fig. 5: Fc-MST-HN inhibits FcRn-mediated recycling of IgG in vitro and reduces IgG tracer levels in cynomolgus monkeys more efficiently than IgG1-MST-HN.

a Absolute amounts of recycled anti-biotin IgG1-WT and anti-biotin IgG1-IHH in experiments using HEK-FcRn-GFP cells as measured by ELISA. b Relative amount of recycled anti-biotin IgG1-WT. Cells were preloaded with the inhibitors at different concentrations, washed extensively, and then loaded with a fixed concentration of anti-biotin IgG1-WT, again washed extensively, and incubated under culture conditions. Recycled amounts of anti-biotin IgG1-WT were quantified by ELISA the next day. Data represent aggregated data presented as mean values from four independent experiments in (a) and three in (b). Data in (b) are normalized to medium control (in two experiments) or point of least inhibition. Error bars indicate standard deviations. c Cynomolgus monkeys were assigned to groups of two animals per group and injected with 1 mg/kg anti-mouse CD70-hIgG1 tracer antibody 5 min prior to infusion of PBS or equimolar amounts per kg of Fc-MST-HN or anti-HEL IgG1-MST-HN. Tracer antibody levels were plotted as percentage relative to predose (mean ± SEM). Statistical analysis in (a) was performed using a two-tailed Mann–Whitney test and a two-way ANOVA (Sidak’s multiple-comparisons test) in (b). Statistical analysis in (c) was performed using a two-sided Walt test on the logarithm of the relative tracer antibody levels using a longitudinal model with treatment group, time post-infusion and their interaction as fixed effects, and a heterogeneous first-order autoregressive covariance structure. The model was run with restricted maximum likelihood and the Kenward–Roger approximation; for the denominator, degrees of freedom were applied. Closed testing procedure was applied to control the type 1 error rate at 5%, no multiple testing correction was needed. Statistically significant differences are indicated by asterisks *<0.05, **<0.01. ns not significant.