C5 and autoimmune polyendocrinopathy: However, complement modulators are not commonly used in the treatment of APS, though there have been reports of therapeutic use of the monoclonal anti-C5 antibody eculizumab with occasional successes in cases of catastrophic antiphospholipid syndrome (CAPS) [[114], [115], [116], [117]] effectively preventing re-thrombosis in some patients [[118], [119], [120]].