More effective glucocorticoid-sparing therapies are needed for the treatment of giant cell arteritis (GCA). Studies found that complement signaling pathways involving complement factor 5 and its receptor (C5aR1) were overexpressed, and that a C5aR1 antagonist, avacopan, reduced the need for glucocorticoids and improved renal recovery. This led researchers to investigate the association of anti-C5aR1 antibodies with GCA and its outcomes.