Atopic dermatitis: pathomechanisms and lessons learned from novel systemic therapeutic options.

Atopic dermatitis (AD) is a chronic, heterogenous, inflammatory skin disorder associated with a high skin-related health burden, typically starting in childhood and often persisting into adulthood. AD is characterized by a wide range of clinical phenotypes, reflecting multiple underlying pathophysiological mechanisms and interactions between genetics, immune system dysregulation and environmental factors. In this review, we describe the diverse cellular and molecular mechanisms involved in AD, including the critical role of T-cell-driven inflammation, primarily via T helper (Th) 2- and Th17-derived cytokines, many of which are mediated by the Janus kinase (JAK) signaling pathway. These local inflammatory processes interact with sensory neuronal pathways, contributing to the clinical manifestations of AD, including itch, pain and sleep disturbance. The recent elucidation of the molecular pathways involved in AD has allowed treatment strategies to evolve from broad-acting systemic immunosuppressive therapies to more targeted agents, including JAK inhibitors and cytokine-specific biologic agents. Evidence from the clinical development of these targeted therapies has reinforced and expanded our understanding of the pathophysiological mechanisms underlying AD and holds promise for individualized treatment strategies tailored to specific AD subtypes.

Baricitinib improves symptoms in patients with moderate-to-severe atopic dermatitis and inadequate response to topical corticosteroids: patient-reported outcomes from two randomized monotherapy phase III trials.

BACKGROUND: Itch, skin pain, and sleep disturbance are burdensome symptoms in atopic dermatitis (AD) that negatively influence a patient's quality of life (QoL). OBJECTIVE: To evaluate the impact of baricitinib on patient-reported outcomes (PROs) in adult patients with moderate-to-severe AD, and explore the association between improvement in key signs and symptoms of AD with improvements in QoL and patient's assessment of disease severity. METHODS: Data were analyzed from two phase III monotherapy trials (BREEZE-AD1/BREEZE-AD2) in which patients were randomized 2:1:1:1 to once-daily placebo, baricitinib 1-mg, 2-mg, or 4-mg for 16 weeks and assessed using PRO measures. RESULTS: At week 16, baricitinib 4-mg and 2-mg significantly reduced itch severity (Itch Numeric Rating Scale (NRS) (BREEZE-AD1: percent change from baseline -36.6% and -29.4% vs. placebo (-12.0%), p≤.001 and p≤.05; BREEZE-AD2: -47.2% and -46.9% vs. placebo (-16.6%), p≤.001). Baricitinib significantly reduced SCORing AD (SCORAD) pruritus (4-mg in BREEZE-AD1 and 2-mg in BREEZE-AD2) and Patient Oriented Eczema Measure (POEM) itch (both doses). Improvements in skin pain severity and sleep disturbance were also observed. Improvements in AD symptoms showed higher correlations with patients' assessment of AD severity and QoL than improvements in skin inflammation. CONCLUSIONS: Baricitinib significantly improved symptoms in patients with moderate-to-severe AD. CLINICALTRIALS.GOV IDENTIFIERS: NCT03334396 (BREEZE-AD1) and NCT03334422 (BREEZE-AD2).