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First-Line Biologic PsA Skin — SCE Rheumatology MCQ

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ModerateSpondyloarthropathyFirst-Line Biologic PsA SkinSCE Rheumatology

A 55-year-old man has active psoriatic arthritis with oligoarthritis and dactylitis of two fingers despite six months of methotrexate 25 mg weekly. He also has extensive plaque psoriasis affecting the scalp and genital area with a high dermatology impact score. He has no inflammatory bowel disease, no uveitis and no cardiovascular or thromboembolic risk factors, and he meets criteria for escalation to a biologic DMARD. Which therapeutic mechanism should be prioritised on the basis of his dominant disease domain?

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Correct answer: E — IL-17 or IL-23 pathway inhibition

IL-17 or IL-23 pathway inhibition is preferred. He has active peripheral PsA with dactylitis after an adequate methotrexate trial, so a biologic is indicated, and his extensive high-impact-site psoriasis is the dominant domain. EULAR 2023 and UK (BSR-based) domain-led pathways direct choice towards IL-23p40, IL-23p19, IL-17A or IL-17A/F inhibitors when relevant skin psoriasis is present, reflecting their higher PASI 90/100 response rates. TNF inhibition is effective for peripheral arthritis and dactylitis and would be favoured if uveitis or inflammatory bowel disease dominated, but skin clearance is generally lower. JAK inhibition is positioned mainly after biologic failure. Apremilast (PDE4) suits mild disease only, and abatacept has weak cutaneous efficacy.

Reference: EULAR recommendations for the management of psoriatic arthritis with pharmacological therapies: 2023 update, Annals of the Rheumatic Diseases 2024 — recommendation on relevant skin psoriasis orienting bDMARD choice to IL-23/IL-17 inhibition: https://pubmed.ncbi.nlm.nih.gov/38499325/