Anifrolumab is a medication being studied for its effectiveness and safety in treating idiopathic inflammatory myopathies, specifically polymyositis and dermatomyositis. It is administered as a subcutaneous injection and is added to the standard care treatment. The goal of the trial is to see if anifrolumab can provide a moderate improvement in disease activity over a period of 52 weeks.

Polymyositis – Polymyositis is an inflammatory disease that causes muscle weakness, primarily affecting the muscles closest to the trunk of the body. It progresses gradually, leading to increasing difficulty in performing tasks such as climbing stairs, lifting objects, or rising from a seated position. The condition can also affect muscles involved in swallowing and breathing. Over time, the inflammation can cause muscle tissue to break down, resulting in muscle atrophy. The exact cause of polymyositis is unknown, but it is believed to involve an autoimmune response where the body’s immune system attacks its own muscle fibers.

Dermatomyositis – Dermatomyositis is a rare inflammatory disease characterized by muscle weakness and a distinctive skin rash. The rash often appears as a violet or dusky red discoloration, typically on the face, eyelids, knuckles, elbows, knees, chest, and back. Muscle weakness usually affects the muscles closest to the trunk, similar to polymyositis, and can progress over weeks or months. This weakness can make everyday activities challenging, such as lifting objects or climbing stairs. The cause of dermatomyositis is not fully understood, but it is thought to involve an autoimmune reaction.