Early intervention with secukinumab prevents epigenetic scar development in new-onset psoriasis: STEPIn mechanistic substudy results.

Abstract

Psoriasis is a common chronic inflammatory skin disease characterized by recurrent flares at previously affected locations. Although biologics targeting IL-17 or IL-23 effectively suppress active disease, they rarely result in long-term remission, suggesting that clinically resolved skin retains molecular changes predisposing to relapse. The STEPIn main study indicated that early intervention with secukinumab, an anti-IL-17A monoclonal antibody, may modify the course of psoriasis. This mechanistic substudy sought to define cellular and molecular changes in psoriatic skin lesions during treatment. Psoriatic skin was sampled at baseline and at up to 52 weeks of secukinumab treatment in new-onset (≤1 year) and long-standing (≥5 years) cohorts. Biopsy samples were evaluated histologically by immune profiling, global gene expression, and genome-wide DNA CpG methylation analyses. Treatment with secukinumab resulted in marked molecular differences between new-onset and long-standing psoriasis despite similar clinical improvement. Gene expression normalized faster in new-onset disease but ultimately resolved in both cohorts. In contrast, disease-associated CpG methylation detected at baseline persisted despite treatment, but only in long-standing psoriasis. Baseline methylation differences were enriched for AP-1 transcription factor binding sites in long-standing disease and persistent methylation changes mapped to genes enriched for small GTPase pathways. Notably, AP-1 components were found to amplify IL-17A and TNF-α responses in keratinocytes, and a subset of these persistent methylation sites overlapped with accessible chromatin regions in psoriatic keratinocytes. Early secukinumab intervention may prevent formation of an epigenetic scar that persists in long-standing psoriasis even after clinical resolution. NCT03020199.