Etanercept (Enbrel®, co-marketed by Amgen and Wyeth) is a recombinant human soluble tumor necrosis factor-alpha (TNFα) receptor. It is a small protein (p75, i.e., its molecular weight is 75 kDa) that binds TNFα and decreases its role in inflammatory diseases such as rheumatoid arthritis, Crohn's disease, psoriasis, psoriatic arthritis, and ankylosing spondylitis. It was released soon after infliximab, a monoclonal antibody with anti-TNFα activity, but etanercept is generally tolerated better and does not seem to cause reactivation of tuberculosis.
