Understanding Biologics: How They Treat Immune-Mediated Diseases

Biologics are genetically engineered proteins that target specific immune pathways. Unlike conventional immunosuppressants, they offer precision targeting with potentially fewer off-target effects.

Major Classes and Mechanisms

• Monoclonal Antibodies (mAbs): Bind and neutralize specific cytokines or receptors.
  • Anti-TNF: infliximab, adalimumab, etanercept, certolizumab, golimumab
  • Anti-IL-17: secukinumab, ixekizumab, brodalumab
  • Anti-IL-23: guselkumab, risankizumab, tildrakizumab
  • Anti-IL-12/23: ustekinumab
  • Anti-IL-6: tocilizumab, sarilumab
  • Anti-IgE: omalizumab
  • Anti-IL-4/13: dupilumab
• Receptor Fusion Proteins: Soluble receptors acting as decoys.
  • CTLA-4-Ig: abatacept (blocks T-cell co-stimulation)
  • TNF receptor: etanercept
• B-Cell Depleting Agents: Anti-CD20 (rituximab, ocrelizumab, ofatumumab) → reduce autoantibody production.
• T-Cell Modulators: Abatacept (see above); alefacept (withdrawn).
• Interferons: IFN-β (multiple sclerosis); IFN-α (hepatitis, some cancers).
• Complement Inhibitors: Eculizumab (C5), ravulizumab (PNH, aHUS, gMG).

Clinical Impact

• Transformed management of RA, PsA, AS, IBD, psoriasis, asthma, CSU, MS, and more.
• Higher remission rates, structural damage prevention, improved quality of life.
• Risks: infections (TB reactivation), malignancy surveillance, infusion/injection reactions, cost.

Future Directions

Bispecific antibodies, oral small molecules (JAK inhibitors), biosimilars, and personalized biomarker-guided therapy.