Psoriasis — SCE Dermatology MCQ

Correct answer: A — Dual IL-17A and IL-17F inhibitor

The correct answer is A, dual IL-17A and IL-17F inhibitor. Bimekizumab is a humanised monoclonal antibody engineered to simultaneously neutralise both IL-17A and IL-17F, cytokines that act synergistically to drive keratinocyte hyperproliferation and neutrophil recruitment in plaque psoriasis. Blocking IL-17F in addition to IL-17A produces more complete suppression of downstream inflammatory signalling than IL-17A blockade alone, which translates into higher and faster PASI 90/100 response rates in trials. NICE has recommended bimekizumab (TA723) for moderate to severe plaque psoriasis in adults where standard systemic therapy is inadequate or not tolerated, reflecting this distinct dual-cytokine mechanism. Why the other options are wrong: E. IL-12/23 inhibitor: This describes ustekinumab, which targets the shared p40 subunit of IL-12 and IL-23, not the IL-17 pathway that bimekizumab blocks. D. IL-23 inhibitor: This describes agents such as risankizumab, guselkumab and tildrakizumab, which selectively target the p19 subunit of IL-23 upstream of Th17 cell differentiation, distinct from bimekizumab's direct IL-17A/F blockade. C. TNF-alpha inhibitor: This describes adalimumab, etanercept and infliximab, which act on a different upstream inflammatory cytokine and are not IL-17 pathway agents. B. IL-17A inhibitor: This describes secukinumab and ixekizumab, which block IL-17A only; bimekizumab is distinguished precisely by its additional neutralisation of IL-17F, which these agents do not target. Key point: Bimekizumab is unique among licensed psoriasis biologics for simultaneously and specifically inhibiting both IL-17A and IL-17F, unlike secukinumab or ixekizumab which target IL-17A alone.

Reference: NICE Technology Appraisal Guidance TA723: Bimekizumab for treating moderate to severe plaque psoriasis (2021), https://www.nice.org.uk/guidance/ta723