Etanercept (trade name Enbrel) is a drug that treats autoimmune diseases by interfering with the tumor necrosis factor (TNF, a part of the immune system) by acting as a TNF inhibitor. Pfizer describes in a SEC filing that the drug is used to treat rheumatoid, juvenile rheumatoid and psoriatic arthritis, plaque psoriasis and ankylosing spondylitis. Sales reached record $3.3 billion in 2010.
Etanercept is a fusion protein produced through expression of recombinant DNA. That is, it is a product of a DNA "construct" engineered to link the human gene for soluble TNF receptor 2 to the gene for the Fc component of human immunoglobulin G1 (IgG1). Expression of the construct produces a continuous protein "fusing" TNF receptor 2 to IgG1. Production of Etanercept is accomplished by the large-scale culturing of cells that have been "cloned" to express this recombinant DNA construct.
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.
This therapeutic potential is based on the fact that TNF-alpha is the "master regulator" of the inflammatory response in many organ systems.
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 of 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.
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