SAR443809 specifically inhibits AP without inhibiting CP or LP. SAR443809 and its corresponding IgG isotype control were tested in a series of assays to assess their ability to inhibit the different complement pathways. A dose-dilution series of SAR443809 (●) or IgG control antibody (○) were tested in the commercial Wieslab EIA assays for (A) AP, (C) CP, and (D) LP, in which the inhibition of MAC deposition upon pathway specific activation was assessed per manufacturer’s protocol. (B) Antibodies were also tested in AP hemolysis assay. Rabbit erythrocytes were incubated with 10% NHS containing Mg²⁺-EGTA in the presence of varying concentrations of either SAR443809 (●) or the isotype control (○). The extent of hemolysis was quantified using the absorbance of the released hemoglobin in the supernatant. The data reported here is a mean of 3 independent experiments ± standard deviation, for all 4 data sets.