Dupilumab, an IL-4/IL-13 receptor alpha antagonist, is approved for severe eosinophilic asthma and atopic dermatitis. Which specific cytokine signaling pathway does it target and why does blocking this single receptor affect both IL-4 and IL-13?

• A Dupilumab blocks JAK1/JAK2 kinases downstream of both IL-4R and IL-13R, providing dual pathway inhibition
• B Dupilumab is a monoclonal antibody against the IL-4 receptor alpha chain (IL-4Rα), which is a shared subunit of both the Type I IL-4 receptor complex (IL-4Rα/γc) and the Type II receptor complex (IL-4Rα/IL-13Rα1); blocking IL-4Rα simultaneously abolishes signaling by both IL-4 (through Type I and II) and IL-13 (through Type II only) ✓
• C Dupilumab binds both IL-4 and IL-13 directly (bispecific design), neutralizing both cytokines in the extracellular space before they reach their respective receptors
• D Dupilumab blocks TSLP (thymic stromal lymphopoietin) receptor which is upstream of both IL-4 and IL-13 production from ILC2 cells

Explanation

IL-4 signals through two receptor complexes: Type I (IL-4Rα + common gamma chain, γc) expressed on hematopoietic cells including lymphocytes, and Type II (IL-4Rα + IL-13Rα1) expressed on non-hematopoietic cells including airway epithelium and smooth muscle. IL-13 signals ONLY through the Type II receptor complex (IL-4Rα + IL-13Rα1). Critically, the IL-4Rα subunit is shared between both receptor types. Dupilumab is a fully human IgG4 antibody that binds the IL-4Rα chain, sterically preventing its assembly into either receptor complex. This single-target blockade simultaneously abolishes IL-4 signaling (through both Type I and Type II) and IL-13 signaling (through Type II), explaining its dual cytokine blockade property and clinical efficacy across type 2 inflammatory diseases (asthma, atopic dermatitis, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis).

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.