Complement inhibition therapy in patients with atypical hemolytic uremic syndrome and secondary microangiopathies

Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) caused by uncontrolled complement activation and leading to thrombocytopenia, microangiopathic hemolysis and acute kidney injury. Eculizumab, a humanized monoclonal antibody that inhibits the cleavage of complement protein C5, effectively reverses laboratory evidence of TMA and improves kidney function in most patients with aHUS. Hereditary aHUS should be differentiated from the secondary HUS associated with drugs, autoimmune diseases (e.g. antiphospholipid syndrome), malignancies, infections, solid organ transplantation. Case reports and retrospective studies suggest that eculizumab may be effective in a proportion of patients with secondary TMA, although its efficacy and regimens of administration should be evaluated in additional studies.