Tocilizumab in Giant Cell Arteritis

Giant cell arteritis is a granulomatous immune-mediated vasculitis of medium and large vessels. It most commonly affects white females over the age of 50 and is the most common primary vasculitis in the United States. Treatment of this disease has classically been with high-dose corticosteroids, but this therapy has been associated with severe morbidity and mortality. Tocilizumab, a humanized monoclonal antibody targeting the interleukin-6 receptor, has been used with great efficacy and safety in rheumatoid arthritis and systemic-onset juvenile idiopathic arthritis. As interleukin-6 has been shown to be a key cytokine in giant cell arteritis, the use of an inhibiting agent has been explored. In the 15 case reports/series that were reviewed, most patients were given tocilizumab due to refractory giant cell arteritis and/or intolerance to glucocorticoid therapy, and most experienced remission of symptoms. At this time, there are only 2 randomized control trials to evaluate the efficacy and safety of tocilizumab use in giant cell arteritis. The phase II trial by Villiger et al and the GiACTA trial both showed that tocilizumab greatly increased the rate of sustained remission in giant cell arteritis over the course of 1 year. The most common adverse events were similar to those seen with use in rheumatoid arthritis: infections, neutropenia, and increases in lipids and liver function test enzymes. Based on the results of numerous case studies and the 2 randomized control trials, tocilizumab is the first agent to be approved by the Food and Drug Administration for treatment of giant cell arteritis.