Etanercept - TNF inhibitor for the treatment of inflammatory autoimmune diseases

Etanercept is a biotechnologically produced fusion protein, which is used as a so-called TNF inhibitor in inflammatory rheumatic diseases. It acts specifically against tumour necrosis factor alpha (TNF-α) - a key inflammatory mediator in the immune system.

Etanercept consists of the extracellular domain of the human TNF receptor type II, which is coupled to the Fc fragment of a human IgG1 antibody. This creates a stable, soluble protein that binds circulating TNF-α and thus blocks its pro-inflammatory effect.

Application areas

Etanercept is authorised in the EU and Germany for the following indications:

• Rheumatoid arthritis (usually in combination with methotrexate)

• Juvenile idiopathic arthritis

• Psoriatic arthritis

• Plaque psoriasis (psoriasis vulgaris)

• Morbus Bechterew (ankylosing spondylitis)

• Non-radiographic axial spondyloarthritis

It is primarily used when conventional basic therapy (e.g. methotrexate) is not sufficiently effective.

Application and dosage

Etanercept is injected subcutaneously (under the skin) - typically once or twice a week. The dosage depends on age, body weight and disease. Trade names include Enbrel® or Benepali®.

Side effects and risks

The most common side effects include:

• Reactions at the injection site (redness, itching, swelling)

• Respiratory tract infections

• Headache, nausea, skin rashes

Less common, but to be taken seriously:

• Severe infections (e.g. tuberculosis, fungal infections)

• Reactivation of latent infections

• Autoimmune reactions, neurological side effects

• Rare cases of malignancies (e.g. lymphomas)

Therefore, screening for tuberculosis, hepatitis B/C and other chronic infections is required before starting therapy.

Special features and differentiation

Compared to other TNF inhibitors such as adalimumab or adalimumab, Infliximab, etanercept is a soluble TNF receptor fusion, not an antibody. As a result, its efficacy profile differs slightly, for example in certain tissue diseases or susceptibility to infection.

Etanercept has a relatively short half-life, which allows better controllability of the therapy.

Importance in biologics therapy

Etanercept is one of the very first approved biologics and has revolutionised the treatment of chronic inflammatory diseases. It is exemplary for the use of recombinant fusion proteins in immunomodulation and is constantly being developed further - for example through biosimilars and new formulations.

Literature references:

• Smolen, J. S. et al. (2017). ""Treating rheumatoid arthritis to target: recommendations of an international task force."" Annals of the Rheumatic Diseases

• European Medicines Agency (EMA): ""Etanercept - Product Information.""

• Tracey, D. et al. (2008). ""Tumour necrosis factor antagonist mechanisms of action: a comprehensive review."" Pharmacology & Therapeutics