Background

GBR 830 is a humanized mAb against OX40, a costimulatory receptor on activated T cells. OX40 inhibition might have a therapeutic role in T cell–mediated diseases, including atopic dermatitis (AD).

Objective

This exploratory phase 2a study investigated the safety, efficacy, and tissue effects of GBR 830 in patients with AD.

Methods

Patients with moderate-to-severe AD (affected body surface area, ≥10%; Eczema Area and Severity Index score, ≥12; and inadequate response to topical treatments) were randomized 3:1 to 10 mg/kg intravenous GBR 830 or placebo on day 1 (baseline) and day 29. Biopsy specimens were collected (n = 40) at days 1, 29, and 71. Primary end points included treatment-emergent adverse events (TEAEs) and changes from baseline in biomarkers (epidermal hyperplasia/cytokines) at days 29 and 71.

Results

GBR 830 was well tolerated, with equal TEAE distribution (GBR 830, 63.0% [29/46]; placebo, 63.0% [10/16]). One serious TEAE in the GBR 830 group was deemed unrelated to study drug. At day 71, the proportion of intent-to-treat subjects achieving 50% or greater improvement in Eczema Area and Severity Index score was greater with GBR 830 (76.9% [20/26]) versus placebo (37.5% [3/8]). GBR 830 induced significant progressive reductions in T H 1 (IFN-γ/CXCL10), T H 2 (IL-31/CCL11/CCL17), and T H 17/T H 22 (IL-23p19/IL-8/S100A12) mRNA expression in lesional skin. Significant progressive reductions until day 71 in the drug group were seen in OX40 + T cells and OX40L + dendritic cells ( P < .001). Hyperplasia measures (thickness/keratin 16/Ki67) showed greater reductions with GBR 830 ( P < .001).

Conclusions

Two doses of GBR 830 administered 4 weeks apart were well tolerated and induced significant progressive tissue and clinical changes until day 71 (42 days after the last dose), highlighting the potential of OX40 targeting in patients with AD.