Aclaris Therapeutics, Inc. announced positive primary analysis results from Phase 1b proof-of-concept trials for its anti-TSLP/IL-4Rα bispecific antibody ATI-052 in atopic dermatitis (AD) and asthma. The company stated that the trials demonstrated strong proof-of-concept with rapid and broad responses to ATI-052 and a favorable safety profile.
In the randomized, double-blind, placebo-controlled Phase 1b trial for AD, 14 patients with severe AD received five weekly doses of 480 mg of ATI-052 or placebo. At day 57, patients treated with ATI-052 experienced a 45% placebo-adjusted mean improvement in the Eczema Area and Severity Index (EASI) score. The absolute mean improvement was 58% in the ATI-052 arm compared to 13% in the placebo arm. Additionally, 78% of patients treated with ATI-052 achieved a placebo-adjusted EASI-50 response at day 57. Improvement in itch, measured by the Peak Pruritus Numerical Rating Scale (PP-NRS), was observed in the first week and continued through week 10, with a 43% placebo-adjusted mean improvement at day 57.
Regarding pharmacodynamics, patients treated with ATI-052 experienced a 95% overall improvement in the difference between lesional and non-lesional skin proteome at day 57. The company noted that ATI-052 broadly downregulated inflammatory pathways, including Th1, Th2, and Th17/Th22, as well as itch-associated molecular pathways.
In the randomized, double-blind, placebo-controlled Phase 1b trial for asthma, 16 patients with mild-to-moderate asthma received a single 480 mg dose of ATI-052 or placebo. At day 15, patients that received ATI-052 experienced a 59% mean reduction from baseline in fractional exhaled nitric oxide (FeNO), representing an absolute reduction of 45 parts per billion, compared to a 15% reduction in the placebo arm. A 40% mean reduction in FeNO was observed at day 29. Furthermore, patients treated with ATI-052 experienced a 200 mL placebo-adjusted and absolute mean improvement in forced expiratory volume in one second (FEV1) at day 15.
Safety analysis indicated that ATI-052 was well tolerated across both trials. Treatment-emergent adverse events were predominantly Grade 1, with no Grade 3 or 4 events observed and no adverse events leading to study discontinuation. The company stated that no conjunctivitis was observed.
Aclaris intends to prioritize the clinical development of ATI-052 initially in eosinophilic esophagitis (EoE) and expects to initiate a Phase 2b trial in EoE in early 2027. The company also announced that its cash, cash equivalents, and marketable securities were approximately $204.6 million as of September 30, 2026.
