Data Readout

Aclaris heads toward H2 2026 Phase 2 readout for TSLP drug bosakitug in eczema

The trial has finished enrolling and completed dosing, setting up a placebo-controlled EASI readout that will test whether bosakitug can compete with dupilumab-class biologics in moderate-to-severe eczema.

By AppliedXLJuly 13, 2026Trial NCT07011706

Executive Summary

Aclaris Therapeutics is closing in on a placebo-controlled Phase 2 readout for its anti-TSLP antibody in moderate-to-severe eczema, with enrollment now finished and the trial in a stable holding pattern ahead of results.
The readout will show how much the drug lowers a validated eczema severity score against placebo in patients who already failed topical treatment, the same type of result regulators and rivals use to judge biologics in this disease.
The trial is the only Phase 2 program targeting this specific pathway in this indication, placing it in mechanistically uncrowded territory even as multiple approved biologics and oral therapies already treat the same patients through different mechanisms.
The enrollment increase and status change are routine markers of a trial finishing on schedule, not signs of distress, which keeps the sponsor's second-half timing guidance intact.

The catalyst

Aclaris has guided to a second-half-2026 topline readout for bosakitug (ATI-045) in three separate disclosures dated August 2025, November 2025, and February 2026, all pointing to the same July 1 to December 31, 2026 window. The trial, registered as NCT07011706, is a randomized, double-blind, placebo-controlled Phase 2 study designed to evaluate the anti-TSLP monoclonal antibody in patients with moderate-to-severe atopic dermatitis who have had an inadequate response to topical treatment. The registered primary endpoint is percent change in Eczema Area and Severity Index, or EASI, a standard clinical measure of eczema severity, against placebo. Aclaris+1

Probability of Success

Endpoint Met34%

Completes81%

Clinical Significance9%

Regulatory26%

Trial status

The trial moved from Recruiting to Active, not recruiting on March 25, 2026, and enrollment closed at 110 patients, above the study's original 96-patient anticipated enrollment. The primary completion date sits at August 1, 2026, inside the sponsor's guided H2 2026 window, and the count of protocol amendments has stayed low since the trial's June 2025 registration. Aclaris' August 2025 disclosure described the trial as evaluating bosakitug in approximately 90 patients with dosing then ongoing, meaning the eventual 110-patient close represents completed enrollment rather than a stalled or shrinking program. NCT07011706+1

The endpoint bar

The trial carries one primary endpoint, percent change in EASI, plus seven secondary endpoints covering body surface area, Investigator Global Assessment treatment success, Peak Pruritus Numerical Rating Scale improvement, and anti-drug antibody incidence. A randomized, double-blind, placebo-controlled design with EASI percent change as the primary measure is a design capable of producing a decision-grade signal on efficacy, though the trial is not registrational and its 110-patient enrollment sizes it as hypothesis-testing for dose and mechanism rather than confirmatory for approval. NCT07011706

Competitive position

No other industry-sponsored trial pairs the TSLP target with moderate-to-severe atopic dermatitis at Phase 2, making bosakitug the only asset in that specific mechanism-indication cell. The broader TSLP field is concentrated in respiratory disease: AstraZeneca's tezepelumab and Sanofi's lunsekimig, the two largest TSLP programs by enrollment, are both being tested in asthma and COPD rather than eczema. Within atopic dermatitis itself, the competitive field is built on different mechanisms entirely, including Regeneron's IL-4Rα antibody dupilumab and multiple IL-13 and JAK-targeted programs, none of which share bosakitug's target. Since no resolved trial has tested TSLP blockade in this indication before, the bar for an informative result is a percent EASI reduction against placebo that reads in the range clinicians associate with the approved biologics and oral therapies already used in this disease.

Sponsor track record

Aclaris has completed 28 of 32 trials across its portfolio, with 4 terminated, and the sponsor is credited with an 80% completion rate specifically in inflammatory skin disease across 10 trials. That track record, combined with the trial's on-schedule move to Active, not recruiting and an enrollment close above target, points to execution as the least uncertain part of this catalyst; the open variable is the clinical result itself. Aclaris

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