Apremilast for moderate hidradenitis suppurativa: no significant change in lesional skin inflammatory biomarkers

Background Treatment with apremilast has recently demonstrated clinically meaningful improvement in moderate hidradenitis suppurativa (HS). Objective To evaluate the change in expression of inflammatory markers in lesional skin of HS patients receiving apremilast 30 mg twice daily (n = 15) for 16 weeks compared with placebo (n = 5). Methods At baseline, 5‐mm punch biopsies were obtained from an index lesion (HSL) and non‐lesional (HSN) skin in the same anatomical area. Subsequent HSL samples were taken as close as possible to the previously biopsied site at week 4 and week 16. After sampling, biopsies were split; one half was processed for in vivo mRNA analysis using real‐time quantitative PCR; the other half was cultured for ex vivo protein analysis using a proximity extension assay (Olink). Linear mixed effects models were calculated to compare the levels of inflammatory markers in HSL skin between apremilast and placebo over time. Results At baseline, 17 proteins with a fold change >2 in HSL vs. HSN skin were identified in 20 patients. The top five were IL‐17A (5), S100A12, CST5, IL‐12/23p40, CD6 (1) with fold changes ranging from 6.6 to 1638, respectively (FDR