Alopecia Areata — SCE Dermatology MCQ

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ModerateHair DisordersAlopecia AreataSCE Dermatology

A 28-year-old man with alopecia totalis (complete scalp hair loss and loss of eyebrows and eyelashes) has been offered treatment with Baricitinib. What is the mechanism of action of this drug?

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Correct answer: E — Janus kinase (JAK) 1/2 inhibitor

Baricitinib is an oral JAK1/JAK2 inhibitor that has been licensed for severe alopecia areata (NICE TA875). JAK inhibitors block the JAK-STAT signalling pathway that is critical for the IFN-gamma-driven immune attack on the hair follicle in alopecia areata. By inhibiting JAK1/2, Baricitinib reduces the expression of MHC class I and II molecules on hair follicle cells, restoring immune privilege. Ritlecitinib (JAK3/TEC inhibitor) is also licensed for alopecia areata. Side effects include infection risk, hyperlipidaemia, and VTE (black box warning).

Reference: NICE TA875 2023 Baricitinib for alopecia areata