S-1117

S-1117 is a novel engineered Fc-fused pan-immunoglobulin G (IgG) protease developed by Seismic Therapeutic. It is designed to target and degrade IgG autoantibodies that play a central role in the pathogenesis of various chronic and acute autoantibody-mediated diseases, including myasthenia gravis, chronic inflammatory demyelinating polyneuropathy (CIDP), and immune thrombocytopenia (ITP)[3][4][5][9]. The molecule consists of a pan-IgG protease fused to an effector function-silent human IgG1 Fc domain, optimized for stability, manufacturability, reduced immunogenicity, and suitability for chronic subcutaneous administration[1][9]. S-1117 acts by cleaving both soluble and membrane-bound forms of IgG—including the B cell receptor (BCR) on memory B cells—resulting in rapid and sustained reduction of all IgG subclasses. This leads to decreased levels of pathogenic antibodies and immune complexes as well as reduced antibody-dependent cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC)[4][5][6][10]. Preclinical studies have demonstrated superior efficacy compared to benchmark therapies such as FcRn inhibitors in animal models[6][8]. The drug is being developed for both prophylactic and therapeutic use with potential for convenient self-administered subcutaneous dosing every 4–6 weeks[5].

Other names

Pan-IgG protease-Seismic Therapeutics