Based on results from the open-label use of the IL-6R antagonist tocilizumab (TCZ, Actemra; Roche) for the treatment of GCA [17–25] and data generated in TCZ trials for rheumatoid arthritis (RA) [26–29], a phase III randomized, double-blind, and placebo-controlled trial of TCZ for GCA has been initiated. This evidence concerns the gene IL6R and rheumatoid arthritis.