Anti-C5 monoclonal antibodies are designed to prevent the cleavage of C5. A murine monoclonal antibody to human C5, m5G1.1-mAb, was humanized (h5G1.1-mAb) by grafting the antibody's antigen-binding CDR regions onto human antibody-derived framework and constant domains. This antibody is being made available by Alexion Pharmaceuticals, and will be used under their IND.