The Association of Interleukin‐36 Staining Intensity and Response to Biologic Therapy in Patients With Psoriasis: A Retrospective Immunohistochemical and Chart Review Pilot Study

ABSTRACT Background There are limited surrogate biomarkers to identify the active inflammatory pathway in psoriasis to direct treatment with targeted biologic therapies. We investigated the association of interleukin (IL)‐36 epidermal expression, a diagnostic marker of psoriasis, with response to biologic therapy in patients with psoriasis. Methods Retrospective immunohistochemical and chart review pilot study. Results Patients with psoriasis with low (scores 0–2) vs. high (scores 3–4) IL‐36 expression did not have significantly different response rates to tumor necrosis factor α (TNFα), IL‐17, and IL‐12/23 or IL‐23 inhibitors; and similarly, mean IL‐36 expression scores did not significantly differ among responders vs. non‐responders to each treatment mechanism. However, in patients with psoriasis treated with IL‐12/23 or IL‐23 inhibitors, there was a marked absolute difference in response rates in those with high vs. low IL‐36 (84% vs. 50%, p = 0.12) and in mean IL‐36 scores in responders vs. non‐responders (3.35 vs. 2.57, p = 0.19). Conclusions Patients with psoriasis with high IL‐36 expression were more likely to respond to IL‐12/23 and IL‐23 inhibition than those with low IL‐36, though these findings were not statistically significant. Additional studies with larger sample sizes are needed to validate and expand upon these findings.