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.
Mepolizumab is given by injection and works by blocking the activity of human interleukin-5 (IL-5), an immune protein that is responsible for the production and survival of eosinophils. By blocking the activity of IL-5, the production and survival of the eosinophils is reduced. Using mepolizumab in addition to the standard of care may improve outcomes and reduce symptoms in patients with HES.
Anifrolumab is a drug designed to specifically block type I IFN signalling by binding to part of the type I IFN receptor and therefore preventing activity of all IFNs that are involved in the inflammatory pathway. If licensed, anifrolumab will offer an add-on treatment option for patients with moderately to severely active SLE.