Tumor necrosis factor alpha (TNFα) is the "master regulator" of the inflammatory (immune) response in many organ systems.

Second, they isolated the DNA sequence that codes the human gene for the Fc end of immunoglobulin G1 (IgG1).

[20] 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.

[21][22] These investigators also patented the protein,[23] selling all rights to its use to Immunex, a Seattle biotechnology company that was acquired by Amgen in 2002.

Writing for Science-Based Medicine, Steven Novella said that it was "unethical for physicians to practice outside of their area of competence and expertise".

[40] Tumor necrosis factor-alpha (TNFα) is a cytokine produced by lymphocytes and macrophages, two types of white blood cells.

Inhibition of its action by etanercept reduces the inflammatory response, which is especially useful for treating autoimmune diseases.

[41] Etanercept is made from the combination of two naturally occurring soluble human 75-kilodalton TNF receptors linked to an Fc portion of an IgG1.

[46] The fusion protein was developed by Bruce A. Beutler, an academic researcher then at the University of Texas Southwestern Medical Center at Dallas, and colleagues, who patented it and licensed the rights in 1995 to Immunex.

[47] Another patent on such fusion protein technology from Brian Seed at Massachusetts General Hospital was licensed to Immmunex in 1997.

[51][52] In 2013, a survey by the International Federation of Health Plans (IFHP) found that the average US cost for etanercept was $2,225 per month, or $26,700 per year.

[57] In April 2013, the Indian pharma major Cipla made an announcement about launching the first biosimilar of Etanercept in India under the brand name Etacept for the treatment of rheumatic disorders.