Aclaris Therapeutics, Inc. filed a Form 8-K on October 27, 2026, disclosing primary analysis results from Phase 1b proof-of-concept trials of its anti-TSLP/IL-4Ra bispecific antibody ATI-052 in atopic dermatitis and asthma, along with a preliminary cash position as of September 30, 2026.

Key Highlights

  • AD trial EASI improvement: Patients treated with ATI-052 experienced a 45% placebo-adjusted mean improvement in EASI score from baseline at day 57, according to the filing.
  • Itch reduction: At day 57, patients that received ATI-052 experienced a 43% placebo-adjusted mean improvement in Peak Pruritus Numerical Rating Scale, with a 5% mean worsening observed in the placebo arm.
  • Asthma FeNO reduction: At day 15, patients that received ATI-052 experienced a 59% mean reduction from baseline in FeNO, representing a mean absolute reduction of 45 parts per billion.
  • FEV1 improvement: At day 15, patients that received ATI-052 experienced a 200 mL placebo-adjusted and absolute mean improvement in FEV1.
  • Preliminary cash position: The company estimates cash, cash equivalents and marketable securities were approximately $204.6 million as of September 30, 2026, though this figure has not been audited, reviewed, or compiled by its independent registered public accounting firm.
  • Trial sizes: The AD trial enrolled 14 patients randomized 3:1; the asthma trial enrolled 16 patients randomized 3:1.

ATI-052 Phase 1b Trial Data: Atopic Dermatitis and Asthma Findings

According to the filing, Aclaris Therapeutics (NASDAQ:ACRS) announced primary analysis results from two randomized, double-blind, placebo-controlled Phase 1b proof-of-concept trials evaluating ATI-052, an anti-TSLP/IL-4Ra bispecific antibody. The atopic dermatitis trial evaluated safety and tolerability in 14 patients with severe AD, with patients receiving five weekly doses of 480 mg of ATI-052 or placebo from weeks 0 through 4, and endpoints assessed at day 57. The filing noted that four patients were excluded from the prespecified per-protocol analysis before unblinding, resulting in a per-protocol population of nine patients in the ATI-052 arm and one patient in the placebo arm.

In the AD trial, the filing reported that 78% of per-protocol patients in the ATI-052 arm had severe disease at baseline, defined by a score of 4 on the Validated Investigator's Global Assessment. The filing also disclosed pharmacodynamic findings, stating that at day 57, patients treated with ATI-052 experienced a 95% overall improvement in the difference between lesional and non-lesional skin proteome, and that ATI-052 "broadly downregulated inflammatory pathways, with modulation across multiple inflammatory mediators in AD, including Th1, Th2 and Th17/Th22." Endogenous serum biomarkers including CCL17, IL-5, and blood eosinophils were also reported as reduced.

The asthma trial evaluated a single 480 mg dose of ATI-052 in 16 patients with mild-to-moderate asthma and baseline FeNO of at least 35 parts per billion, with endpoints assessed through day 29. The analysis population consisted of 12 patients in the ATI-052 arm and four in the placebo arm. The filing further noted that a post-hoc subgroup analysis of patients with baseline pre-bronchodilator FEV1 of less than 80% predicted and qualifying reversibility showed a 350 mL mean improvement from baseline in FEV1 at day 15 for ATI-052-treated patients, compared with a 140 mL mean decrease in the placebo arm. The company also disclosed a preliminary, unaudited cash estimate and stated that actual figures may differ after completion of comprehensive accounting procedures.

What Was Disclosed

Aclaris Therapeutics filed an 8-K on October 27, 2026, reporting primary Phase 1b POC trial results for ATI-052 in atopic dermatitis and asthma, and disclosing a preliminary unaudited cash, cash equivalents and marketable securities estimate of approximately $204.6 million as of September 30, 2026.