Eculizumab in the treatment of complement system disorders including paroxysmal nocturnal hemoglobinuria

The main function of the complement system is to provide humoral defence against foreign pathogens. It contributes to immune response and is a crucial component of innate immunity that provides immediate non-specific immune defence. Inherited or acquired deficiencies of the complement system associated with excessive activation or other impairments of complement activity have varied clinical manifestations. Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal blood disorder that clinically manifests with anemia, thrombosis, chest and abdominal pain, chronic kidney disease and bone marrow failure. The complement-mediated hemolysis due to the lack of membrane-bound complement-regulatory proteins CD55 and CD59 is a central underlying mechanism of the disease and mortality associated with PNH. The severity of clinical symptoms determines the type of treatment which may include allogeneic hematopoietic stem cell transplantation and pathogenetic treatment through the inhibition of the complement system. Eculizumab, a humanized monoclonal anti-C5 antibody, has become the first complement inhibitor to show effectiveness in treating any of complement-mediated hemolytic anemias and now serves as a standard of treatment for patients with PNH. Brisk development of biotechnological methods for the production of new drugs in Russia has enabled the initiation of drug discovery efforts and the creation of the world's first biosimilar of Eculizumab.