[C5: eculizumab].

Eculizumab is a recombinant humanized monoclonal antibody that specifically binds to a C5 terminal complement and inhibits the cleavage of C5 to C5a and C5b through complement activation. Eculizumab has been used clinically for paroxysmal nocturnal hemoglobinuria. Clinical studies have been initiated for neurological disorders, such as, optic neuromyelitis and myasthenia gravis, mediated by the complement system. In addition, eculizumab is expected to be useful for the treatment of intractable neurological diseases.