A phase 3 clinical trial has confirmed that regular treatment with tocilizumab, an inhibitor of interleukin-6, successfully reduced both symptoms of and the need for high-dose steroid treatment for giant cell arteritis, the most common form of blood-vessel inflammation. Results of the trial are being published in the New England Journal of Medicine and were the basis for the Food and Drug Administration’s approval of tocilizumab to treat giant cell arteritis in May.
“Giant cell arteritis affects around 250,000 individuals in the U.S. alone, targeting people over the age of 50, and is three times more likely in women,” says John Stone, MD, MPH, of the Massachusetts General Hospital (MGH) Rheumatology Unit, lead and corresponding author of the NEJM report. “This trial is the first to demonstrate beyond any doubt that an alternative to chronic, unending steroid treatment exists. One of the most surprising findings was just how poorly the traditional, steroid-only regimens worked. These results are likely to have an immediate, sustained impact on the lives of hundreds of thousands of patients across the world.”
Primarily affecting arteries in the head, neck and eyes – as well as the aorta and its primary branches – giant cell arteritis, also called temporal arteritis, is an important cause of irreversible blindness. Symptoms include headache, pain in the scalp or other areas, and changes in vision, which can be sudden. Blindness, which affects up to 20 percent of giant cell arteritis patients, can result from inflammation of the arteries supplying the optic nerve and the retina. Giant cell arteritis patients are also at increased risk for stroke and aortic aneurysms.
Until now the only effective treatment has been doses of steroids – primarily prednisone – which can be gradually decreased or tapered over several months, so long as symptoms continue to be suppressed. However, most patients require high doses for effective treatment, and the side effects can be serious – ranging from weight gain, body fat redistribution and osteoporosis to mood alterations, hypertension, glucose intolerance and increased infection risk.
Tocilizumab is a monoclonal antibody that targets the receptor for the inflammatory cytokine IL-6. Subcutaneous administration of tocilizumab has been FDA approved for treatment of rheumatoid arthritis, and intravenous administration is approved for several other forms of arthritis. For giant cell arteritis, previous studies, including a phase 2 clinical trial, indicated that intravenous tocilizumab allowed a reduction in the steroid doses required to reduce symptoms and maintain remission.