OPC-X + OPC-Z

OPC-X and OPC-Z are novel, once-weekly oral selective immunoproteasome (IP) inhibitors developed by Otsuka Pharmaceutical for the treatment of autoimmune diseases, including lupus nephritis [1112]. In preclinical studies, both compounds demonstrated high selectivity for the immunoproteasome over the constitutive proteasome (CP), offering a significantly wider safety margin compared to non-selective proteasome inhibitors like bortezomib and the selective IP inhibitor zetomipzomib [1112]. In animal models, once-weekly oral administration of OPC-X or OPC-Z achieved robust suppression of autoimmune responses, including reductions in anti-dsDNA antibody titers, proteinuria, and circulating plasma cells, without causing thrombocytopenia [1112].