TNF Blockade
🔥 TNF: A Pivotal Cytokine Mediator
- 🧬 Tumour Necrosis Factor (TNF) is a master regulator of inflammation, central to many immune-mediated diseases.
- Exists in both soluble and transmembrane forms.
- Binds to TNFR1 and TNFR2 → driving inflammation, apoptosis, and cell survival pathways.
💉 TNF Blockade: A Revolutionary Therapy
- First modern biological therapy introduced at the turn of the 21st century.
- Now licensed for both adults and children across several immune-mediated diseases:
- 🤲 Rheumatoid arthritis
- 🦴 Ankylosing spondylitis
- 🧩 Psoriatic arthritis
- 👶 Juvenile idiopathic arthritis
- 🩸 Psoriasis
- 🌿 Crohn’s disease
- 🧻 Ulcerative colitis
- 👁 Uveitis
- 💥 Hidradenitis suppurativa
💊 Licensed Anti-TNF Agents
- Currently 5 licensed anti-TNF drugs:
- 🧬 Fully human monoclonal antibodies (e.g., adalimumab, golimumab)
- 🧪 Chimeric monoclonal antibody (infliximab)
- ⚗️ Certolizumab – PEGylated Fab fragment, produced in E. coli
- 🔗 Etanercept – soluble receptor (also blocks lymphotoxin-α3)
🤲 Impact on Rheumatoid Arthritis
- 📈 Licensed in early 2000s → transformed management.
- Marked improvements in pain, stiffness, fatigue → reduced disability and need for surgery.
- Registry data: ↑ risk of serious infection, but no increase in malignancy overall.
- 💡 Teaching pearl: Anti-TNFs often combined with methotrexate for durability and to reduce antibody formation against biologics.
⚠️ Unexpected Complications
- 🧫 Tuberculosis (TB) reactivation:
- Disruption of granulomas → extrapulmonary/miliary TB.
- Now standard: TB screening (IGRA or Mantoux + CXR) before therapy.
- Etanercept less likely to reactivate TB compared to infliximab/adalimumab.
- ⬆️ Susceptibility to intracellular pathogens: listeria, salmonella, fungi.
🌿 Crohn’s Disease & Ulcerative Colitis
- Highly effective in severe Crohn’s (esp. fistulising or perianal disease).
- ~50% achieve remission & mucosal healing within 2 years.
- Etanercept ❌ ineffective in Crohn’s → reflects granulomatous nature of disease.
- Effective in ulcerative colitis too.
🩸 Psoriasis & Psoriatic Arthritis
- Clear benefit in moderate-severe psoriasis: infliximab → >80% achieve PASI 75 improvement.
- Also effective in psoriatic arthritis & ankylosing spondylitis → ↓ joint inflammation and improved spinal mobility.
🚫 Limitations of TNF Blockade
- Not effective in all conditions → can worsen:
- 🧠 Multiple sclerosis
- ❤️ Congestive heart failure
- Trials in these diseases stopped due to adverse outcomes.
💥 Adverse Effects of TNF Blockade
- In addition to infections, rare but important side effects include:
- 🩸 Neutropenia
- 🩻 Vasculitis
- 🩺 Paradoxical psoriasis (new onset)
- 🌙 Drug-induced lupus (including renal & CNS disease)
💡 Clinical pearl: Anti-TNF agents have redefined outcomes in chronic inflammatory diseases, but require pre-treatment screening (TB, hepatitis B/C, HIV) and ongoing vigilance for infections and autoimmune complications.
