Aclaris Therapeutics Initiates Phase 1b Proof-of-Concept Trial in Atopic Dermatitis (AD) with Its Novel Bispecific Antibody ATI-052

Rhea-AI Summary

Aclaris Therapeutics (NASDAQ: ACRS) has initiated a randomized (3:1), blinded, placebo-controlled Phase 1b proof-of-concept trial in atopic dermatitis (AD) for ATI-052, a bispecific anti-TSLP/IL-4Rα antibody. The company cited positive Phase 1a interim results showing a strong safety and tolerability profile, extended pharmacokinetics, and concentration-dependent pharmacodynamics at low dose. The Phase 1b AD trial will assess safety, EASI, IGA response, PP-NRS, PK, and PD using lesional and non-lesional skin tape strips. Aclaris expects to start a second Phase 1b POC trial in asthma in Q1 2026 and to report topline results from both POC trials in H2 2026.

Positive

• Phase 1b AD trial is randomized (3:1) and placebo-controlled
• Phase 1a interim showed strong safety and tolerability
• Phase 1a reported extended pharmacokinetics for ATI-052
• Phase 1a showed concentration-dependent pharmacodynamics at low dose
• Second Phase 1b asthma trial planned for Q1 2026
• Topline results for both POC trials expected H2 2026

Negative

• ATI-052 remains early-stage with Phase 1b POC trials ongoing
• No Phase 1b efficacy topline data available before H2 2026

News Market Reaction

+0.76%

1 alert

+0.76% News Effect

On the day this news was published, ACRS gained 0.76%, reflecting a mild positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Trial phase: Phase 1b Randomization ratio: 3:1 Top line timing: Second half of 2026 +1 more

4 metrics

Trial phase Phase 1b Proof-of-concept trial in atopic dermatitis for ATI-052

Randomization ratio 3:1 ATI-052 vs placebo in Phase 1b AD trial

Top line timing Second half of 2026 Expected top line results from both Phase 1b POC trials

Asthma Phase 1b start First quarter of 2026 Planned initiation of ATI-052 POC trial in asthma

Market Reality Check

Price: $3.38 Vol: Volume 489,683 is 0.42x t...

low vol

$3.38 Last Close

Volume Volume 489,683 is 0.42x the 20-day average of 1,163,642, indicating muted pre-news activity. low

Technical Shares at $2.64 are trading above the 200-day MA of $1.90, but sit 24.03% below the $3.475 52-week high and above the $1.05 52-week low.

Peers on Argus

ACRS was down 1.49% pre-announcement. Several biotech peers were also negative (...

ACRS was down 1.49% pre-announcement. Several biotech peers were also negative (e.g., PRQR -15.71%, SLN -5.48%, IPHA -4.86%, TLSA -4.67%, IMMP -0.67%), suggesting broader weakness, though the momentum scanner did not flag a coordinated sector move.

Historical Context

5 past events · Latest: Jan 06 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Jan 06	Clinical data update	Positive	+0.0%	Positive Phase 1a ATI-052 safety, PK and PD data in healthy adults.
Dec 19	Index inclusion	Positive	-2.2%	Inclusion in Nasdaq Biotechnology Index following eligibility criteria satisfaction.
Nov 25	Conference participation	Neutral	-0.7%	Management participation in Piper Sandler healthcare conference fireside chat.
Nov 06	Earnings and update	Neutral	+0.4%	Q3 2025 results with ATI-2138 Phase 2a data and cash runway into H2 2028.
Oct 29	Conference schedule	Neutral	-2.1%	Planned participation in three November healthcare conferences by leadership.

Pattern Detected

Recent positive or index-related news (ATI-052 Phase 1a data, NBI inclusion) has not produced sustained upside, with flat or negative next-day moves.

Recent Company History

Over the last few months, Aclaris has advanced multiple immuno‑inflammatory programs and maintained a solid balance sheet. On Jan 6, 2026, positive Phase 1a data for ATI-052 supported moving into Phase 1b in AD and asthma. Earlier, the company was added to the Nasdaq Biotechnology Index on Dec 19, 2025. Q3 2025 results highlighted $167.2M in cash and a runway into H2 2028. Today’s Phase 1b initiation follows through on those ATI-052 development plans.

Market Pulse Summary

This announcement advances ATI-052 from earlier Phase 1a results into a Phase 1b proof-of-concept tr...

Analysis

This announcement advances ATI-052 from earlier Phase 1a results into a Phase 1b proof-of-concept trial in moderate-to-severe atopic dermatitis, with an additional Phase 1b study in asthma planned for the first quarter of 2026. It follows recent ATI-052 data reported on Jan 6, 2026 and Q3 2025 disclosures of a runway into H2 2028. Key metrics to watch are safety, early efficacy (EASI, IGA, PP‑NRS), and timing of top line results in the second half of 2026.

Key Terms

bispecific antibody, tslp, il-4rα, eczema area and severity index, +4 more

8 terms

bispecific antibody medical

"its novel bispecific antibody ATI-052, the Company’s potential best-in-class"

A bispecific antibody is a specially designed protein that can attach to two different targets at the same time. Think of it as a custom-made connector that brings two things together—such as a disease cell and an immune system component—helping the body fight illnesses more effectively. For investors, understanding bispecific antibodies is important because they represent innovative therapies that could lead to new treatments and potentially lucrative market opportunities.

tslp medical

"investigational bispecific anti-TSLP/IL-4Rα antibody"

TSLP (thymic stromal lymphopoietin) is an immune-system signaling protein that acts like an alarm, triggering inflammation in conditions such as asthma and allergic disease. Investors watch TSLP because drugs that block its action can reduce symptoms and prevent flares; successful clinical trials or approvals for TSLP-targeting therapies can materially change a biotech company's prospects, market value, and potential market size for respiratory and allergic treatments.

il-4rα medical

"investigational bispecific anti-TSLP/IL-4Rα antibody"

IL-4Rα is a protein on the surface of certain immune cells that acts like a docking station for chemical messengers (interleukins) that drive allergic and inflammatory responses. Investors watch it because drugs that block or modify this receptor can calm overactive immunity in conditions such as asthma or eczema, so successful trial results or approvals can directly affect a drug’s commercial potential and a biotech’s valuation.

eczema area and severity index medical

"Eczema Area and Severity Index (EASI), validated Investigator Global Assessment"

A standardized clinical score that measures how much skin is affected by eczema and how severe the lesions are, combining area and intensity into one number much like a report card for a skin condition. Investors care because changes in this score are often used as a primary measure of a treatment’s effectiveness in clinical trials, influencing regulatory approval chances, market potential, and the perceived value of companies developing eczema therapies.

investigator global assessment medical

"validated Investigator Global Assessment (IGA) response, and Peak Pruritus"

A clinician’s overall rating of a patient’s disease severity or improvement in a medical study, recorded on a standard numerical or descriptive scale. It serves as a key measure of whether a treatment appears to work; for investors, strong or weak results on this score can sway trial outcomes, regulatory approval chances and a drug’s commercial prospects, like a referee’s score influencing the final result of a contest.

peak pruritus numerical rating scale medical

"and Peak Pruritus Numerical Rating Scale (PP-NRS)), pharmacokinetic parameters"

A 0-to-10 scale used in clinical studies where individuals rate the worst level of itching they experienced over a specified period, with 0 meaning no itch and 10 the worst imaginable. Investors watch changes on this scale because it’s a primary measure of whether a treatment actually relieves severe itch; meaningful drops can signal clinical benefit, influence regulatory decisions, and affect a drug’s commercial prospects—think of it as the medical equivalent of a customer satisfaction score for relief.

pharmacokinetics medical

"extended pharmacokinetics, and concentration-dependent pharmacodynamics even"

Pharmacokinetics is the study of how a substance, such as a drug or chemical, moves through and is processed by the body over time. It tracks how it is absorbed, distributed, broken down, and eventually eliminated. For investors, understanding pharmacokinetics helps gauge the effectiveness, safety, and potential risks of new medications or treatments, which can influence a company’s success and valuation in the healthcare industry.

pharmacodynamics medical

"extended pharmacokinetics, and concentration-dependent pharmacodynamics even"

Pharmacodynamics is how a drug actually affects the body — the strength, type and duration of its effects and the relationship between dose and response. Think of it like how turning a thermostat changes room temperature: it shows what the drug does and how much is needed to get the desired effect. Investors care because these properties drive clinical success, dosing convenience, safety profile and competitive advantage, all of which influence commercial potential and regulatory approval.

AI-generated analysis. Not financial advice.

WAYNE, Pa., Jan. 12, 2026 (GLOBE NEWSWIRE) -- Aclaris Therapeutics, Inc. (NASDAQ: ACRS), a clinical-stage biopharmaceutical company focused on developing novel product candidates for immuno-inflammatory diseases, today announced that it has initiated a placebo-controlled Phase 1b proof-of-concept (POC) trial in atopic dermatitis (AD) for ATI-052, the Company’s potential best-in-class investigational bispecific anti-TSLP/IL-4Rα antibody.

“We are experiencing strong momentum in the ATI-052 clinical development program including the recent positive Phase 1a interim results which demonstrated a strong safety and tolerability profile, extended pharmacokinetics, and concentration-dependent pharmacodynamics even at the lowest dose,” said Dr. Jesse Hall, Chief Medical Officer of Aclaris. “Further to this, we are excited to announce the initiation of the first POC Phase 1b trial in people living with atopic dermatitis. We expect to initiate the second Phase 1b POC trial in asthma this quarter as well. We intend to provide top line results from both trials in the second half of the year.”

This randomized (3:1), blinded, placebo-controlled Phase 1b POC trial will evaluate the safety and tolerability of ATI-052 compared to placebo in patients with moderate-to-severe AD. Other endpoints that will be assessed include AD clinical efficacy assessments (Eczema Area and Severity Index (EASI), validated Investigator Global Assessment (IGA) response, and Peak Pruritus Numerical Rating Scale (PP-NRS)), pharmacokinetic parameters, and pharmacodynamic endpoints measured by assays including lesional and non-lesional skin tape strips.

Aclaris also expects to initiate a Phase 1b POC trial in asthma in the first quarter of 2026. Top line results from both POC trials are expected in the second half of 2026.

About ATI-052

ATI-052 is an investigational humanized anti-TSLP and anti-IL-4Rα bispecific antibody that simultaneously inhibits thymic stromal lymphopoietin (TSLP) and interleukin-4 receptor (IL-4Ra) with high affinity and potency. By targeting TSLP, which sits at the top of the inflammatory cascade, it inhibits a broad range of inflammation; by targeting IL-4Rα, it blocks both downstream IL-4 and IL-13, which are key cytokines involved in Th2-mediated inflammation and allergic diseases. ATI-052 exhibits potential best-in-class potency and utilizes the same TSLP antigen-binding fragment (Fab) region as bosakitug (ATI-045), retaining the dissociation kinetics, long residence time, and high potency advantages over comparator antibodies, but is engineered to bind more tightly to the neonatal Fc receptor (FcRn) to extend its half-life. ATI-052 has the potential to treat a variety of atopic, immunologic and respiratory diseases. Aclaris has the exclusive worldwide rights to ATI-052, excluding Greater China.

About Aclaris Therapeutics, Inc.

Aclaris Therapeutics, Inc. is a clinical-stage biopharmaceutical company developing a pipeline of novel product candidates to address the needs of patients with immuno-inflammatory diseases who lack satisfactory treatment options. The company has a multi-stage portfolio of product candidates powered by a robust R&D engine. For additional information, please visit www.aclaristx.com and follow Aclaris on X (formerly Twitter) at @AclarisTx and on LinkedIn.
        
Cautionary Note Regarding Forward-Looking Statements

Any statements contained in this press release that do not describe historical facts may constitute forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “anticipate,” “believe,” “expect,” “intend,” “may,” “plan,” “potential,” “will,” and similar expressions, and are based on Aclaris’ current beliefs and expectations. These forward-looking statements include expectations regarding its development plans for ATI-052, including the timing to initiate its Phase 1b trial of ATI-052 in asthma and the timing to report results from its Phase 1b trials of ATI-052 in AD and asthma, the potential for ATI-052 to be a best-in-class anti-TSLP/IL-4Rα bispecific monoclonal antibody, and the therapeutic potential for ATI-052 including in other atopic, immunologic and respiratory diseases. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements. Risks and uncertainties that may cause actual results to differ materially include uncertainties inherent in the conduct of clinical trials, potential changes to interim, topline and preliminary data as more subject data become available, Aclaris’ reliance on third parties over which it may not always have full control, Aclaris’ ability to enter into strategic partnerships on commercially reasonable terms, the uncertainty regarding the macroeconomic environment and other risks and uncertainties that are described in the Risk Factors section of Aclaris’ Annual Report on Form 10-K for the year ended December 31, 2024, and other filings Aclaris makes with the U.S. Securities and Exchange Commission from time to time. These documents are available under the “SEC Filings” page of the “Investors” section of Aclaris’ website at www.aclaristx.com. Any forward-looking statements speak only as of the date of this press release and are based on information available to Aclaris as of the date of this release, and Aclaris assumes no obligation to, and does not intend to, update any forward-looking statements, whether as a result of new information, future events or otherwise.

Aclaris Therapeutics Contact:

Will Roberts
Senior Vice President
Corporate Communications and Investor Relations
(484) 329-2125
wroberts@aclaristx.com

FAQ

What trial did Aclaris (ACRS) initiate for ATI-052 in January 2026?

Aclaris initiated a randomized (3:1), blinded, placebo-controlled Phase 1b proof-of-concept trial in moderate-to-severe atopic dermatitis.

What did Aclaris report from the ATI-052 Phase 1a interim results?

The Phase 1a interim results showed strong safety and tolerability, extended pharmacokinetics, and concentration-dependent pharmacodynamics at the lowest dose.

What endpoints will the ATI-052 Phase 1b AD trial assess for ACRS?

Endpoints include safety, EASI, IGA response, PP-NRS, pharmacokinetics, and pharmacodynamics via skin tape strips.

When will Aclaris (ACRS) start the ATI-052 Phase 1b asthma trial?

Aclaris expects to initiate the second Phase 1b proof-of-concept trial in asthma in Q1 2026.

When does Aclaris expect topline results for the ATI-052 POC trials?

Topline results from both Phase 1b proof-of-concept trials are expected in H2 2026.