C5AR1 and meningococcal infection: Treatment with Soliris® has caused serious meningococcal infections and failed in rheumatoid arthritis trials; 2) The previously FDA approved PMX-53, a C5aR antagonist, was discontinued in 2012 due to off-target side-effects [26–28]; 3) Avacopan (CCX-168) is a C5aR antagonist that is currently in phase III clinical studies for ANCA associated vasculitis [29]; 4) DF2593A is a C5aR negative allosteric modulator in preclinical studies against inflammatory neuropathic pain [30].