WAYNE, Pennsylvania, United States — October 27, 2026
Aclaris Therapeutics, Inc., a clinical-stage biopharmaceutical company developing novel treatments for immuno-inflammatory diseases, announced positive primary analysis results from two Phase 1b proof-of-concept trials evaluating ATI-052, an investigational bispecific antibody targeting thymic stromal lymphopoietin (TSLP) and interleukin-4 receptor alpha (IL-4Rα), in atopic dermatitis (AD) and asthma. Both studies met their primary objectives and demonstrated rapid clinical responses across diverse patient populations, alongside favorable safety and tolerability findings. In the atopic dermatitis trial, ATI-052 was associated with improvements in eczema severity and itching, while the asthma trial showed reductions in airway inflammation and improvements in lung function following a single dose. Pharmacodynamic analyses also indicated broad changes in inflammatory pathways, supporting the potential benefits of simultaneously targeting TSLP and IL-4Rα. No conjunctivitis was observed in either trial, and no Grade 3 or 4 treatment-emergent adverse events were reported. Aclaris plans to prioritize further development of ATI-052 in eosinophilic esophagitis (EoE), with a Phase 2b study targeted for initiation in early 2027.
Phase 1b Atopic Dermatitis Trial Shows Improvements in Eczema Severity and Itching
The randomized, double-blind, placebo-controlled Phase 1b trial evaluated ATI-052 in 14 patients with severe atopic dermatitis. Participants received five weekly doses of 480 mg of ATI-052 or placebo, with the primary analysis conducted on Day 57. In the prespecified per-protocol analysis, patients receiving ATI-052 experienced a 58% mean reduction in Eczema Area and Severity Index (EASI) scores from baseline, compared with a 13% reduction in the placebo group, representing a 45-percentage-point placebo-adjusted difference. The company also reported a 78% placebo-adjusted EASI-50 result at Day 57, indicating a higher proportion of patients achieving at least a 50% improvement in eczema severity relative to placebo. Itching improved rapidly, with benefits emerging during the first week and continuing through Week 10 among patients with available follow-up data. At Day 57, the ATI-052 group showed a 38% absolute mean improvement in Peak Pruritus Numerical Rating Scale scores, compared with a 5% worsening in the placebo group. Some patients with available follow-up data maintained improvements through Week 16, although longer-term durability remains under evaluation. The findings are preliminary and require confirmation in larger clinical studies.
Asthma Trial Demonstrates Reduced Airway Inflammation and Improved Lung Function
The Phase 1b asthma study enrolled 16 patients with mild-to-moderate asthma and baseline fractional exhaled nitric oxide (FeNO) levels of at least 35 parts per billion. Participants received a single 480 mg dose of ATI-052 or placebo, with assessments continuing through Day 29. At Day 15, patients receiving ATI-052 experienced a 59% mean absolute reduction in FeNO, compared with a 15% reduction in the placebo group. The company also reported that 58% of ATI-052-treated patients achieved FeNO normalization, defined as a level of 25 parts per billion or lower, by Day 15. Improvements were also observed in forced expiratory volume in one second (FEV1), a measure of lung function. At Day 15, the treatment group demonstrated a placebo-adjusted mean improvement of approximately 200 milliliters in FEV1. In a post hoc subgroup of participants with baseline FEV1 below 80% of predicted and demonstrated reversibility, the mean improvement from baseline was 350 milliliters, compared with a 140-milliliter decline in the placebo group. These results suggest that ATI-052 may rapidly influence airway inflammation and respiratory function. However, the study was small and early-stage, and larger trials will be needed to determine the consistency, clinical significance and durability of these responses.
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ATI-052 Safety Profile and Dual-Target Mechanism Support Further Development
ATI-052 was generally well tolerated across both Phase 1b studies. Treatment-emergent adverse events were predominantly Grade 1, with no Grade 3 or 4 events and no adverse events leading to study discontinuation. Injection-site reactions were infrequent, generally mild and transient, and no cases of conjunctivitis were observed. ATI-052 is an investigational humanized bispecific antibody designed to inhibit TSLP, an upstream regulator of inflammatory responses, while blocking IL-4 and IL-13 signaling through their shared receptor, IL-4Rα. The combined mechanism is intended to address multiple pathways involved in allergic and inflammatory diseases. In the atopic dermatitis trial, pharmacodynamic analyses indicated that 95% normalization of the lesional skin proteome was observed at Week 8, with immune protein expression resembling that of non-lesional skin. The company also reported changes across several inflammatory pathways, including Th1, Th2 and Th17/Th22-associated pathways, as well as fibrosis, tissue remodeling and itch-related molecular pathways. Despite these encouraging early findings, ATI-052 remains investigational and has not been established as safe or effective for any indication. Aclaris intends to prioritize a Phase 2b program in eosinophilic esophagitis, where the company believes the development opportunity aligns with its strategy and capital priorities. The company expects to initiate the study in early 2027 and provide further updates regarding potential development in additional indications.
Source:Aclaris Therapeutics, Press release
