A recent study of tocilizumab highlights the potential for a promising new treatment for giant cell arteritis.
Giant cell arteritis (GCA) is the most common form of vasculitis (inflammation of the blood vessels) affecting the elderly. Although it doesn’t usually affect life expectancy in patients, it can lead to other serious conditions, such as optic neuropathy and cause blindness. The current mainstay treatment for giant cell arteritis is long-term glucocorticoids, such as prednisone, but it can have serious adverse effects and until recently, past studies haven’t demonstrated any potential glucocorticoid-sparing alternatives.
A New Alternative to Glucocorticoids?
Tocilizumab is a biologic agent that works by targeting interleukin-6 (IL-6), which is correlated with giant cell arteritis disease activity. A recent article published in JAMA Neurology describes a study demonstrating the potential for tocilizumab treatment in giant cell arteritis. In this randomized controlled study conducted by Stone and colleagues, patients were assigned to one of four treatment groups: 26-week prednisone taper plus placebo, 52-week prednisone taper plus placebo, 26-week prednisone taper plus 162 mg of subcutaneous tocilizumab every other week and 26-week prednisone taper plus 162 mg subcutaneous tocilizumab weekly.
Tocilizumab Was Effective for Treating Giant Cell Arteritis
The study’s primary outcome was the rate of sustained glucocorticoid-free remission by week 52, which was met by significantly more patients in the tocilizumab groups than placebo groups. The potential side effects of tocilizumab include infections, thrombocytopenia, neutropenia, hyperlipidemia, and transaminitis but the frequency of serious side effects in the study was lower in tocilizumab groups than placebo groups. The study’s finding demonstrated the superiority of a glucocorticoid taper with tocilizumab versus a glucocorticoid taper alone to maintain a glucocorticoid-free remission at 52 weeks. As a result, the US Food and Drug Administration approved tocilizumab therapy in giant cell arteritis.
Despite the promising results from the study, there are still questions to be answered regarding tocilizumab therapy in giant cell arteritis. Both the long-term efficacy and safety of tocilizumab remains unknown and how to determine which patients are optimal candidates for tocilizumab is another question.
A potential long-term safety concern from reports in patients using tocilizumab to treat rheumatoid arthritis is the risk of lower gastrointestinal perforation. Although Stone and colleagues did not report gastrointestinal perforation in their study, the rate of this adverse event can’t be estimated given that tocilizumab hasn’t been in use long-term. Further, many giant cell arteritis patients are maintained on low-dose glucocorticoid therapy but it’s unclear how tocilizumab therapy compares to low-dose glucocorticoids since it wasn’t evaluated in the study.
At present, there are too many unknown variables to be able to recommend tocilizumab as first-line therapy or be used alone to treat giant cell arteritis. The best candidates for tocilizumab may be those who experience adverse effects to glucocorticoids or those who develop giant cell arteritis flares and cannot lower their glucocorticoid dose to an acceptable range. Nonetheless, these are promising results that give way to future studies to explore tocilizumab therapy as a treatment option in giant cell arteritis.
Written by Maggie Leung, PharmD
Reference: Tamaki, H., & Hajj-Ali, R. A. (2017). Tocilizumab for Giant Cell Arteritis—A New Giant Step in an Old Disease. JAMA Neurology. doi:10.1001/jamaneurol.2017.3811
