Oral Janus kinase/SYK inhibition (ASN002) suppresses inflammation and improves epidermal barrier markers in patients with atopic dermatitis

Background: Moderate-to-severe atopic dermatitis (AD) has been associated with significant disease burden and systemic abnormalities and often requires systemic treatments. Currently, safe and effective oral systemic treatments for moderate-to-severe AD are not yet available. ASN002 is an oral inhibitor of the Janus kinase/spleen tyrosine kinase signaling pathways, targeting several cytokine axes (T_H2/T_H22/T_H17/T_H1) and epidermal differentiation. Objective: We sought to evaluate the effect of ASN002 on the cellular and molecular biomarker profile of patients with moderate-to-severe AD and to correlate changes in biomarkers to improvements in clinical severity measures and pruritus. Methods: Thirty-six patients with moderate-to-severe AD were randomized to groups with dose escalation of ASN002 (20, 40, and 80 mg) and a placebo group. Skin biopsy specimens were performed at baseline, day 15, and day 29. Gene expression studies were conducted by using microarray and quantitative RT-PCR, and cellular infiltrates and protein expression were studied by using immunohistochemistry. Results: ASN002 reversed the lesional skin transcriptome toward a nonlesional phenotype. It also rapidly and significantly suppressed key inflammatory pathways implicated in AD pathogenesis, including T_H2 (IL4 receptor [IL4R], IL13, CCL13/monocyte chemoattractant protein 4, CCL17/thymus and activation-regulated chemokine, CCL18/pulmonary and activation-regulated chemokine, CCL22/macrophage-derived chemokine, and CCL26/eotaxin-3), T_H17/T_H22 (lipocalins, PI3/elafin, CCL20, S100A7/S100A8/S100A9, and IL36G/IL36RN), and T_H1 (IFNG, CXCL9/CXCL11, and MX1) axes and barrier-related measures (filaggrin [FLG] and CLDN23). Significant improvements in AD gene signatures were observed predominantly in the 40- and 80-mg groups. Smaller and largely nonsignificant molecular changes were seen in the 20-mg and placebo groups. Conclusion: The Janus kinase/spleen tyrosine kinase inhibitor ASN002 significantly suppressed key AD inflammatory pathways, corresponding to clinical response. ASN002 might be an effective novel therapeutic agent for moderate-to-severe AD.