What is/are Etanercept?
Etanercept (trade name Enbrel) is a biopharmaceutical that treats autoimmune diseases by interfering with tumor necrosis factor (TNF; a soluble inflammatory cytokine) by acting as a TNF inhibitor. It has U.S. F.D.A. approval to treat rheumatoid, juvenile rheumatoid and psoriatic arthritis, plaque psoriasis and ankylosing spondylitis. TNF-alpha is the "master regulator" of the inflammatory (immune) response in many organ systems. Autoimmune diseases are caused by an overactive immune response. Etanercept has the potential to treat these diseases by inhibiting TNF-alpha.
Etanercept is a fusion protein produced by recombinant DNA. It fuses the TNF receptor to the constant end of the IgG1 antibody. First, the developers isolated the DNA sequence that codes the human gene for soluble TNF receptor 2, which is a receptor that binds to tumor necrosis factor-alpha. Second, they isolated the DNA sequence that codes the human gene for the Fc end of immunoglobulin G1 (IgG1). Third, they linked the DNA for TNF receptor 2 to the DNA for IgG1 Fc. Finally, they expressed the linked DNA to produce a protein that links the protein for TNF receptor 2 to the protein for IgG1 Fc.
The prototypic fusion protein was first synthesized and shown to be highly active and unusually stable as a modality for blockade of TNF in vivo in the early 1990s by Bruce A. Beutler, an academic researcher then at the University of Texas Southwestern Medical Center at Dallas, and his colleagues. These investigators also patented the protein, selling all rights to its use to Immunex, a biotechnology company that was acquired by Amgen in 2002.
It is a large molecule, with a molecular weight of 150 kDa., that binds to TNFα and decreases its role in disorders involving excess inflammation in humans and other animals, including autoimmune diseases such as ankylosing spondylitis, juvenile rheumatoid arthritis, psoriasis, psoriatic arthritis, rheumatoid arthritis, and, potentially, in a variety of other disorders mediated by excess TNFα.
In North America, etanercept is co-marketed by Amgen and Pfizer under the trade name Enbrel in two separate formulations, one in powder form, the other as a pre-mixed liquid. Wyeth is the sole marketer of Enbrel outside North America excluding Japan where Takeda Pharmaceuticals markets the drug.
Etanercept is an example of a protein-based drug created using the tools of biotechnology and conceived through an understanding afforded by modern cell biology.
Etanercept was developed by researchers at Immunex, and was released for commercial use in late 1998, soon after the release of infliximab (Remicade) – the first chimeric monoclonal antibody against TNFα to be marketed for clinical use.
Etanercept is a dimeric molecule, and this dimeric structure is necessary for its proper therapeutic activity. During its development at Immunex Corporation an earlier monomeric version did not have sufficient biologic activity.
Mode of action
It reduces the effect of naturally present TNF, and hence is a TNF inhibitor, functioning as a decoy receptor that binds to TNF.
Tumor necrosis factor-alpha (TNFα) is a cytokine produced by lymphocytes and macrophages, two types of white blood cells. It mediates the immune response by increasing the transport of white blood cells to sites of inflammation, and through additional molecular mechanisms which initiate and amplify inflammation. Inhibition of its action by etanercept reduces the inflammatory response which is especially useful for treating autoimmune diseases.
There are two types of TNF receptors: those found embedded in white blood cells that respond to TNF by releasing other cytokines, and soluble TNF receptors which are used to deactivate TNF and blunt the immune response. In addition, TNF receptors are found on the surface of virtually all nucleated cells (red blood cells, which are not nucleated, do not contain TNF receptors on their surface). Etanercept mimics the inhibitory effects of naturally occurring soluble TNF receptors, the difference being that etanercept, because it is a fusion protein rather than a simple TNF receptor, has a greatly extended half-life in the bloodstream, and therefore a more profound and long-lasting biologic effect than a naturally occurring soluble TNF receptor.
Etanercept is made from the combination of two naturally occurring soluble human 75-kilodalton TNF receptors linked to an Fc portion of an IgG1. The effect is an artificially engineered dimeric fusion protein.
This article uses material from the Wikipedia article Etanercept, which is released under the Creative Commons Attribution-Share-Alike License 3.0.