Interleukin-17RA blockade by brodalumab decreases inflammatory pathways in hidradenitis suppurativa skin and serum

Abstract

Background: Hidradenitis suppurativa (HS) is an inflammatory skin disease with dysregulation of the interleukin (IL)-17 axis. Recently, we reported the clinical benefit of brodalumab, a human anti-IL-17 receptor A (IL-17RA) monoclonal antibody, in moderate-to-severe HS.

Objectives: To characterize the molecular response to brodalumab in HS skin and serum, and to identify biomarkers of treatment response.

Methods: Ten participants, who received brodalumab 210 mg /1·5 mL subcutaneously at weeks 0, 1, 2, 4 and every 2 weeks thereafter, were included in this molecular profiling study (NCT03960268). RNA sequencing and immunohistochemistry of nonlesional, perilesional and lesional HS skin biopsies, and Olink high-throughput proteomics of serum at baseline, weeks 4 and 12 were assessed.

Results: At week 12, brodalumab led to a decrease of overall inflammation, and improvement of psoriasis-, keratinocyte- and neutrophil-related pathways. Despite perilesional and lesional skin exhibiting no differentially expressed genes at baseline, treatment response was best assessed in perilesional skin. In serum, brodalumab treatment decreased pathways involved in neutrophil inflammation. Patients with higher baseline expression of neutrophil-associated lipocalin-2 (LCN2) in the skin or IL-17A in the serum demonstrated greater decreases of HS-related inflammatory cytokines as measured in skin biopsies at week 12.

Conclusions: IL-17RA inhibition by brodalumab decreases several pathogenic inflammatory axes in HS. Perilesional skin provides a valid and robust assessment of treatment response. Expression of LCN2 in skin or IL-17A in serum may be used as biomarkers to stratify patients that may have a superior molecular response to brodalumab.

Figure 1:. Perilesional hidradenitis suppurativa (HS) skin shares overlapping transcriptomic profile with lesional skin at baseline but exhibits more changes with treatment response

A) Correlation of differentially expressed genes (DEGs) as defined by fold change ≥ |1.5| and false discovery rate ≤ 0.05. Red circles indicate upregulated DEGs while blue circles indicate downregulated DEGs in baseline (BL) lesional (LS) and perilesional (PL) skin relative to nonlesional (NL) skin. r is Pearson correlation. Grey circles indicate genes that are not differentially expressed. Volcano plot of differentially expressed genes in B) lesional versus perilesional skin C) perilesional versus nonlesional skin and D) lesional versus nonlesional skin at baseline. Modulation of DEGs by brodalumab at week 12 in E) perilesional and F) lesional versus baseline nonlesional skin.

Figure 2:. Decreased inflammatory pathways in hidradenitis suppurativa (HS) perilesional and lesional skin following treatment with brodalumab.

A) Decrease of overall inflammatory pathways, known psoriasis pathways and pathways involved in keratinocyte proliferation at week 4 and week 12 following treatment B) Decrease of neutrophil-associated pathways following treatment with brodalumab. W=week, BL=baseline, NL=nonlesional PL= perilesional LS=lesional skin. The size of the bubble diameter is proportional to the gene-set variation analysis (GSVA) score and the bubble color intensity indicates significance (p value) while red and blue indicates up or down regulation respectively.

Figure 3:. Treatment response is best observed in perilesional skin at week 12.

Means of percentage improvement at A) week 12 between perilesional and lesional skin, and B) improvement in perilesional skin between week 4 and week 12. N (%) = number of genes in the hidradenitis suppurativa transcriptome shared with pathway (percentage of total gene in pathway). Stars denote significance with * p ≤ 0.05 ** p ≤ 0.01 *** p ≤ 0.001.

Figure 4:. Histological analysis demonstrates decreased inflammatory infiltration in hidradenitis suppurativa (HS) lesional and perilesional skin following treatment with brodalumab

A) Hematoxylin and Eosin (H&E) stain demonstrates a mild reduction in epidermal thickness in lesional skin. There is also comparable reduction of B) CD3⁺ infiltration, and C) CD11c⁺ infiltration in both perilesional and lesional skin. Scale bar = 100 μM. D) Quantification of total inflammatory infiltration across the patient cohort (n=10 patients). Dashed line represents infiltrate quantification of nonlesional skin at baseline. Error bars show standard error of mean (SEM), with two-way ANOVA analysis. Stars denote significance with * p ≤ 0.05 ** p ≤ 0.01 *** p ≤ 0.001.

Figure 5:. Assessment of pathways modulated in serum by brodalumab treatment

Enrichment analysis of all proteins downregulated with treatment at week 4 and 12 based on PANTHER-Slim Gene Ontology biological processes. Stars denote significance with * p ≤ 0.1 ** p ≤ 0.05 *** p ≤ 0.01 **** p ≤ 0.001

Figure 6:. Correlation of biomarkers with molecular disease activity at week 12.

A) Expression of baseline LCN2 expression in lesional skin correlated with changes in inflammatory markers at week 12 in perilesional skin. B) expression of IL-17A in serum correlate with a decrease of inflammatory markers at week (W) 12 in perilesional skin. r is Spearman correlation. X axis is log2(Expression).