In vivo PK/PD assessment of invisibilized IgG cleaving protease for chronic treatment of autoimmune diseases

Abstract

Abstract Pathogenic autoantibodies are key effectors of inflammation, promoting complement cascade activation, immune cell response, and the consequent tissue damage in autoimmune disease and transplant rejection. Proteases that cleave IgG antibodies present a novel therapeutic opportunity to treat autoimmune diseases and antibody mediated transplant rejection. Using our IMPACT platform leveraging machine learning, we engineered IgG proteases with reduced immunogenicity for acute and chronic treatment of antibody-mediated diseases. In addition, the invisibilized protease was fused to a Fc to extend its half-life. To evaluate these IgG proteases in vivowe developed a pharmacokinetics and pharmacodynamics (PK/PD) model. C57BL6 mice were dosed with intravenous immunoglobulin (IVIg) at different time points after protease treatment. Protease and IgG levels were quantified by MSD 15 minutes before and two hours after IVIg injection, respectively. IgG cleavage was detected at early time points which correlated with higher systemic drug levels. Additionally, the Fc-fused protease was detected at later time points with increased systemic enzymatic activity, as compared to the enzyme domain only. Finally, we evaluated the potential of the Fc-protease to cleave antigen bound IgG at the tissue level in a mouse anti–glomerular basement membrane (GBM) induced nephritis model. In summary, our in vivo studies established a PK/PD relationship between exposure and cleaved IgG while showing the benefit of fusing the protease domain to a Fc.