Giant cell arteritis (GCA) is an autoimmune condition that causes the inflammation of large and medium sized blood vessels. An alternative name for this condition is “Temporal Arteritis” as the blood vessels in the temple area of the head (sides of the forehead) are commonly affected. The “giant” cells are abnormal large cells that develop in the wall of the inflamed arteries. GCA is very rare in people younger than 50 years, and is more common in women and people of northern European descent. The cause of GCA is not known. The most common symptoms of GCA include headache, with severe pain and tenderness over the temples and the scalp, prominent blood vessels at the temples, and pain in the jaw or tongue when talking or chewing. Visual loss occurs in up to 20% of patients, and this may be related to late recognition.
Tocilizumab is a disease modifying drug that acts by blocking specific proteins that signal the inflammatory processes affecting blood vessels in GCA. It is currently licensed for the treatment of GCA in adults as a subcutaneous (under the skin) injection, but reactions at the place of injection include redness, itching and pain. It is anticipated that these reactions would be avoided if the drug was given as an intravenous infusion.
Mepolizumab is a medicinal product currently in development as an add-on for the treatment of hypereosinophilic syndrome (HES). HES is a rare group of inflammatory disorders characterised by an overproduction of eosinophils (a type of disease-fighting white blood cell). When eosinophils infiltrate certain tissues, they can cause inflammation and organ damage which, over time, can impact patients’ day-to-day ability to function. Although any organ system can be involved in HES, the heart, central nervous system, skin, and respiratory tract are the most commonly affected.