Etanercept - In ankylosing spondylitis

Etanercept is a dimeric fusion protein based on the p75 tumor necrosis factor (TNF) receptor. It binds to TNFalpha and blocks its biological activity. Subcutaneous etanercept is effective in the treatment of rheumatoid arthritis, psoriatic arthritis, and polyarticular-course juvenile rheumatoid arthritis. More recently, etanercept has shown efficacy in the treatment of adults with ankylosing spondylitis. In randomized, double-blind, placebo-controlled trials, subcutaneous etanercept 25mg twice weekly for 6-24 weeks significantly reduced disease activity in patients with active ankylosing spondylitis. In the largest trial, etanercept produced a response rate of 57% compared with 22% for placebo after 24 weeks (response was determined via the validated ASAS 20 response criteria developed by the Assessments in Ankylosing Spondylitis [ASAS] Working Group). Etanercept therapy significantly improved health-related quality of life in patients with ankylosing spondylitis compared with placebo. The greatest improvements in a 16-week study were seen in the domains of physical functioning, physical role, bodily pain, vitality, and social functioning. Etanercept was generally well tolerated, with few serious adverse events or treatment withdrawals. The most common adverse events were injection-site reactions and minor upper respiratory tract infections.