Treatment of Giant Cell Arteritis (GCA).

Giant cell arteritis (GCA) is the most frequent primary large-vessel vasculitis in individuals older than 50. Glucocorticoids (GCs) are considered the cornerstone of treatment. GC therapy is usually tapered over months according to clinical symptoms and inflammatory marker levels. Considering the high rate of GC-related adverse events in these older individuals, immunosuppressive treatments and biologic agents have been proposed as add-on therapies. Methotrexate was considered an alternative option, but its clinical impact was limited. Other immunosuppressants failed to demonstrate a significant favourable benefit/risk ratio. The approval of tocilizumab, an anti-interleukin 6 (IL-6) receptor inhibitor brought significant improvement. Indeed, tocilizumab had a noticeable effect on cumulative GCs' dose and relapse prevention. After the improvement in pathophysiological knowledge, other targeted therapies have been proposed, with anti-IL-12/23, anti-IL-17, anti-IL-1, anti-cytotoxic T-lymphocyte antigen 4, Janus kinase inhibitors or anti-granulocyte/macrophage colony stimulating factor therapies. These therapies are currently under evaluation. Interestingly, mavrilimumab, ustekinumab and, to a lesser extent, abatacept have shown promising results in phase 2 randomised controlled trials. Despite this recent progress, the value, specific condition and optimal application of each treatment remain undecided. In this review, we discuss the scientific rationale for each treatment and the therapeutic strategy.