Baseline Body Surface Area and Itch Severity Define Response to Baricitinib in Patients with Moderate-to-Severe Atopic Dermatitis at Week 16

Abstract

Introduction: Atopic dermatitis (AD) is a chronic, inflammatory skin disease characterized by heterogeneous clinical phenotypes and high symptom burden, especially through itch. Baricitinib (BARI), an oral Janus Kinase 1/2 inhibitor, is approved in Europe, Japan, and other countries, for treatment of adults with moderate-to-severe AD who are candidates for systemic therapy. This post hoc analysis of a Phase 3 topical corticosteroid (TCS) combination therapy trial (BREEZE-AD7) aims to characterize patients who might benefit most from BARI.

Method: Classification and regression tree (CART) analysis was used to identify baseline predictors for patients treated with BARI 4-mg, who achieved ≥ 75% improvement in Eczema Area and Severity Index (EASI75), or EASI75 or Itch Numerical Rating Scale (NRS) ≥ 4-point improvement at week 16 (responders), versus non-responders. Subgroup efficacy analyses were performed based on identified predictor variables, combined with Itch NRS < 7/ ≥ 7. Missing data were imputed as non-responder.

Results: Baseline body surface area (BSA) was identified by CART as strongest variable predicting response to BARI at week 16, with a cut-off around 40% (BSA ≤ 40%). When combining BSA with itch severity, highest response rates were achieved by BARI patients with BSA ≤ 40%/Itch NRS ≥ 7 at baseline. In this subgroup, 69% and 58% of patients treated with BARI 4-mg achieved EASI75 and Itch NRS ≥ 4-point response at week 16, respectively. While these response rates were 65% and 50% for BARI 4-mg patients with baseline BSA ≤ 40%/Itch NRS < 7, they were 33% and 11% in BSA > 40%/Itch NRS < 7, and 32% and 49% in BSA > 40%/Itch NRS ≥ 7 subgroups, respectively.

Conclusion: Using a machine learning approach, patients with moderate-to-severe AD and a BSA affecting 10-40% and Itch NRS ≥ 7 were characterized as likely to benefit most from BARI 4-mg TCS combination therapy. This was confirmed by subgroup analyses, which showed that these patients are most likely to show favorable response rates in improving AD signs and symptoms, specifically itch, after 16 weeks of treatment.

Keywords: Atopic dermatitis; Classification and regression tree analysis; Severe itch.