Crovalimab Approved Naked monospecific

Recycling antibody: Designed to have pH-dependent binding to target. mAb will release bound target in lysosome, then mAb will recycle via FcRn-mediated pathway. A series of rabbit anti-C5 antibodies were generated by immunizing rabbits with human C5 protein. The screening process was designed to identify antibodies with pH-dependent antigen-binding capabilities. To accomplish this, we screened for antibodies with different binding affinities at pH 7.4 compared to pH 5.8 using ELISA and Biacore analysis. As a result, several antibodies which preferentially bind to C5 at pH7.4, but weakly at pH 5.8 were obtained. Among them, CFA0305 was chosen as a lead antibody to be further optimized based on its pH-dependent C5-binding property. After humanization of CFA0305, comprehensive mutagenesis on the antibody variable region was performed to identify mutations that improve the antigen-binding property, and combination of effective mutations gave the antibody high affinity with pH-dependent binding property (Fig. 1b). Some of histidine residues present in SKY59 were found to be important for the pH-dependent interaction.Various mutations were further applied to the variable regions of the antibody to improve pharmacokinetics (PK) and physicochemical properties, and to minimize the likelihood of immunogenicity in human. The constant region of the antibody was converted to a modified human IgG1/κ without effector functions, and engineered (M428L/N434A) to have enhanced affinity to FcRn at an acidic pH to extend the plasma half-life of the antibody. This final humanized and optimized antibody was named SKY59. ACT-Fc is applied to crovalimab