## **Core Concept**
Tumor Necrosis Factor (TNF) blockers are a class of drugs used to treat autoimmune diseases such as rheumatoid arthritis, psoriasis, and Crohn's disease. They work by inhibiting the action of TNF-alpha, a pro-inflammatory cytokine involved in systemic inflammation. TNF blockers are crucial in managing conditions where TNF-alpha plays a pivotal role in disease pathogenesis.

## **Why the Correct Answer is Right**
The correct answer, , is not a TNF blocker. To understand why, let's examine what each option represents:
- A. Etanercept: A fusion protein that acts as a decoy receptor for TNF-alpha.
- B. Infliximab: A chimeric monoclonal antibody that binds to TNF-alpha.
- C. Adalimumab: A fully human monoclonal antibody that targets TNF-alpha.
- D. : This option needs to be identified as not belonging to the TNF blocker class.

Given that , which is actually Tocilizumab, is a monoclonal antibody that targets the interleukin-6 receptor (IL-6R), not TNF-alpha. Therefore, it is used for treating conditions like rheumatoid arthritis but through a different mechanism than TNF blockers.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Etanercept is indeed a TNF blocker. It is a decoy receptor that binds to TNF-alpha, preventing it from interacting with cell surface TNF receptors.
- **Option B:** Infliximab is a TNF blocker. It directly binds to TNF-alpha, preventing its interaction with TNF receptors on cell surfaces.
- **Option C:** Adalimumab is also a TNF blocker. It works similarly to infliximab by directly binding to TNF-alpha.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while TNF blockers have revolutionized the treatment of autoimmune diseases, they increase the risk of infections, particularly reactivation of latent tuberculosis. Therefore, screening for TB is recommended before initiating TNF blocker therapy.

## **Correct Answer:** . Tocilizumab