Aclaris Therapeutics (ACRS) has upcoming FDA regulatory milestones for ATI-045. The table below outlines estimated target dates and event types for these pending regulatory actions.
This section highlights FDA-related milestones and regulatory updates for drugs developed by Aclaris Therapeutics (ACRS).
Over the past two years, Aclaris Therapeutics has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
ATI-052, ATI-2138, and ATI-045. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
Select a button below to view the list of FDA events for that drug.
ATI-052 FDA Regulatory Timeline and Events
ATI-052 is a drug developed by Aclaris Therapeutics for the following indication: bispecific anti-TSLP/IL-4R monoclonal antibody.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ATI-052
- Announced Date:
- April 28, 2026
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc provided a clinical update on its biologic and oral inhibitor compounds including positive full top line results from the first-in-human Phase 1a single (SAD) and multiple ascending dose (MAD) trial of its anti-TSLP/IL-4Rα bispecific antibody ATI-052 and the selection of lichen planus (LP) as the lead indication for its selective ITK/JAK3 inhibitor ATI-2138.
AI Summary
Aclaris reported positive full top-line Phase 1a SAD/MAD results for ATI-052, its anti-TSLP/IL‑4Rα bispecific antibody. The data exceeded the company’s target profile, showing an estimated half-life of about 45 days that could enable dosing intervals up to three months. ATI-052 produced complete and sustained inhibition of TSLP-induced and IL-4–induced CCL17 (TARC), suggesting potential to raise the efficacy ceiling in Th2-driven diseases. Phase 1b proof-of-concept trials in atopic dermatitis and asthma are enrolling, with top-line results expected in the second half of 2026. Aclaris intends to start a Phase 2b program in Q4 2026, initially targeting asthma.
Aclaris also selected lichen planus as the lead indication for ATI-2138, its selective ITK/JAK3 oral inhibitor. ATI-2138 is designed to deeply suppress pathogenic T cells by inhibiting T-cell receptor signaling and effector cytokine activation, with the goal of addressing both root inflammation and symptoms in a disease with few effective options.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- February 24, 2026
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc. announced that it has initiated a placebo-controlled Phase 1b proof-of-concept (POC) trial of ATI-052, the Company's potential best-in-class investigational bispecific anti-TSLP/IL-4Rα antibody, in asthma.
AI Summary
Aclaris Therapeutics has started a placebo-controlled Phase 1b proof-of-concept trial of ATI-052 in people with asthma. ATI-052 is an investigational bispecific antibody that targets two key inflammatory pathways, TSLP and IL-4Rα. The company describes it as a potential best-in-class therapy designed to block multiple drivers of type 2 inflammation that contribute to asthma symptoms.
The Phase 1b study will assess safety, tolerability, and early signs of effectiveness versus placebo in an effort to show proof of concept. Top-line results from this asthma trial, along with results from Aclaris’s ongoing Phase 1b POC trial in atopic dermatitis, are expected in the second half of 2026. ATI-052 remains investigational and is not yet approved for use.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- January 12, 2026
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc 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..
AI Summary
Aclaris Therapeutics has begun a placebo‑controlled Phase 1b proof‑of‑concept trial of ATI‑052 in people with moderate‑to‑severe atopic dermatitis (AD). ATI‑052 is an investigational bispecific antibody that targets TSLP and IL‑4Rα and is being developed as a potential best‑in‑class therapy. The company reported positive Phase 1a interim data showing a favorable safety and tolerability profile, extended pharmacokinetics, and dose‑dependent pharmacodynamics.
The randomized (3:1), blinded Phase 1b will compare ATI‑052 to placebo and focus on safety and tolerability. Key efficacy measures include Eczema Area and Severity Index (EASI), Investigator Global Assessment (IGA) responses, and Peak Pruritus Numerical Rating Scale (PP‑NRS). The trial will also assess pharmacokinetics and pharmacodynamics using assays such as lesional and non‑lesional skin tape strips. Aclaris plans a separate Phase 1b POC trial in asthma and expects topline results from both AD and asthma trials in the second half of 2026.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- January 6, 2026
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc. announced positive interim results from the first-in-human Phase 1a single (SAD) and multiple ascending dose (MAD) trial of its anti-TSLP/IL-4Rα bispecific antibody ATI-052.
AI Summary
Aclaris reported positive interim results from the first-in-human Phase 1a single (SAD) and multiple ascending dose (MAD) trial of ATI-052, its anti-TSLP/IL-4Rα bispecific antibody. The randomized, placebo-controlled study tested single doses (30–720 mg) and multiple weekly doses (240, 480 mg). ATI-052 was well tolerated up to 720 mg, with mostly Grade 1 treatment-emergent adverse events. There were no drug-related Grade 3 events, no serious adverse events, and no study discontinuations. The most common side effect was mild, self-resolving injection site redness; no conjunctivitis was seen.
Pharmacokinetics showed dose-proportional increases in Cmax and AUC and an effective half-life of at least 26 days. Pharmacodynamics showed strong target engagement and near-complete target occupancy at low doses. At 30 mg ATI-052 inhibited IL-4 and TSLP-stimulated CCL17/TARC; 120 mg gave sustained inhibition through week 1 and near-complete TSLP inhibition for ≥3 weeks; 360 mg maintained effects through week 3 and near-complete TSLP inhibition for ≥6 weeks. These findings support potential dosing every three months.
Aclaris expects to start Phase 1b proof-of-concept trials in atopic dermatitis and asthma in Q1 2026 and is planning a Phase 2b AD trial for the second half of 2026. Management hosted a conference call to discuss the update.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- June 23, 2025
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc. announced that it has initiated a placebo-controlled Phase 1a/1b program for ATI-052, the Company's potential best-in-class investigational bispecific anti-TSLP/IL-4R antibody.
AI Summary
Aclaris Therapeutics, Inc. has initiated a placebo-controlled Phase 1a/1b clinical trial for its investigational bispecific antibody, ATI-052. This potential best-in-class therapy is designed to block both thymic stromal lymphopoietin (TSLP) and interleukin-4 receptor (IL-4R), targeting key drivers of Th2-mediated inflammation and allergic diseases.
The early phase study is divided into two parts. The Phase 1a portion involves single and multiple ascending dose testing in healthy volunteers to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ATI-052. The company expects to complete this initial stage by the end of 2025, with early results anticipated in early 2026. The subsequent Phase 1b trial will provide proof-of-concept data in up to two conditions, further assessing the drug’s potential to offer improved treatment options in immune-mediated diseases.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- April 22, 2025
- Target Action Date:
- Q2 2025
- Estimated Target Date Range:
- April 1, 2025 - June 30, 2025
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc. announced that Initiation of Upcoming Phase 1a/1b Clinical Trial Expected in the Second Quarter of 2025 -
AI Summary
Aclaris Therapeutics, Inc. has received FDA clearance for its Investigational New Drug (IND) application, allowing the company to launch a Phase 1a/1b clinical trial for ATI-052. This investigational treatment is a bispecific antibody designed to block both the TSLP ligand and the IL-4 receptor, which are involved in key inflammatory pathways. The randomized, blinded, placebo-controlled trial will assess both single and multiple ascending doses of ATI-052, followed by a proof-of-concept study in an undisclosed immuno-inflammatory indication.
Aclaris plans to start the clinical trial in the second quarter of 2025. The company emphasizes that this study is an important milestone, as it may help determine the safety, proper dosage, and potential effectiveness of ATI-052 in treating a range of immune-mediated diseases. This move highlights the ongoing efforts to develop novel immunotherapies and improve treatment options for patients.
Read Announcement- Drug:
- ATI-052
- Announced Date:
- April 22, 2025
- Indication:
- bispecific anti-TSLP/IL-4R monoclonal antibody.
Announcement
Aclaris Therapeutics, Inc. announced that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for a Phase 1a/1b clinical trial of ATI-052, a potential best-in-class bispecific anti-TSLP/IL-4R monoclonal antibody.
AI Summary
Aclaris Therapeutics, Inc. announced that the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for a Phase 1a/1b clinical trial of ATI-052. This potential best-in-class bispecific monoclonal antibody targets both the TSLP ligand and the IL-4 receptor, blocking two key components in the inflammatory process. The trial, which is randomized, blinded, and placebo-controlled, will assess single and multiple ascending doses, followed by a proof-of-concept study in an undisclosed indication. ATI-052’s dual mechanism of action may offer improved effectiveness compared to traditional treatments, marking a significant step forward in the treatment of immuno-inflammatory diseases. The trial is expected to begin in the second quarter of 2025, highlighting the company’s commitment to advancing innovative therapies in the field of immunotherapy.
Read Announcement
ATI-2138 FDA Regulatory Timeline and Events
ATI-2138 is a drug developed by Aclaris Therapeutics for the following indication: For the Treatment of Moderate to Severe Atopic Dermatitis.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ATI-2138
- Announced Date:
- March 27, 2026
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. provided additional results from its Phase 2a trial of ATI-2138, a potent and selective investigational oral covalent inhibitor of ITK and Janus kinase 3 (JAK3), presented in an electronic poster at the 2026 American Academy of Dermatology (AAD) Annual Meeting in Denver, CO.
AI Summary
Aclaris Therapeutics, Inc. presented additional results from its Phase 2a trial of ATI-2138 in an electronic poster at the 2026 American Academy of Dermatology Annual Meeting in Denver. Participants with atopic dermatitis who received ATI-2138 showed meaningful improvements in key clinical measures, including overall disease severity, itch, and quality of life. Notably, at the end of treatment (week 12) patients taking a low dose of ATI-2138 (10 mg twice daily) experienced a 77% improvement in the Eczema Area and Severity Index (EASI), which measures the extent and severity of atopic dermatitis.
ATI-2138 is an investigational, oral, covalent inhibitor that selectively targets ITK and JAK3, enzymes involved in immune signaling. These Phase 2a results are an early indication of clinical activity and support further evaluation of ATI-2138 in larger, controlled studies to confirm benefits and assess safety over longer periods.
Read Announcement- Drug:
- ATI-2138
- Announced Date:
- January 27, 2026
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. announced recent positive preclinical results from its potent and selective ITK/JAK3 inhibitor ATI-2138 in a murine model of severe alopecia areata (AA).
AI Summary
Aclaris Therapeutics reported positive preclinical results for ATI-2138, a potent and selective dual ITK/JAK3 inhibitor, in a murine reversal model of alopecia universalis, the most severe form of alopecia areata. ATI-2138 produced rapid, near-complete, and sustained hair regrowth and outperformed ritlecitinib in the study.
In older, hard-to-treat mice, the 300 ppm ATI-2138 group showed mean hair regrowth of 37% at week 2 and 87% at week 4, compared with 25% and 48% for 300 ppm ritlecitinib. By week 6 the ATI-2138 group reached 93% regrowth versus 78% for ritlecitinib; control animals showed no improvement.
ATI-2138 blocks T cell receptor signaling (ITK) and JAK3-mediated IL-2Rγc cytokine signaling, modulating T cell activity and inflammatory pathways. It is highly selective over other JAKs and is being pursued for inflammatory and autoimmune alopecias, with a Phase 2b trial expected in the first half of 2026.
Read Announcement- Drug:
- ATI-2138
- Announced Date:
- September 9, 2025
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. announced that a late-breaking abstract on its open-label Phase 2a trial of ATI-2138, a potent and selective investigational oral covalent inhibitor of interleukin-2-inducible T cell kinase (ITK) and Janus kinase 3 (JAK3), was selected for oral presentation at the 2025 European Academy of Dermatology and Venereology (EADV) Congress, being held September 17-20, 2025, in Paris, France.
AI Summary
Aclaris Therapeutics announced that a late-breaking abstract on its open-label Phase 2a trial of ATI-2138 was selected for oral presentation at the 2025 European Academy of Dermatology and Venereology (EADV) Congress, to be held September 17–20, 2025, in Paris, France.
The presentation will report additional molecular and clinical data from patients with moderate-to-severe atopic dermatitis treated with ATI-2138, a potent, selective oral covalent inhibitor of interleukin-2-inducible T cell kinase (ITK) and Janus kinase 3 (JAK3).
Presentation details:
Title: “Molecular and Clinical Effects of oral ATI-2138, an ITK/JAK3 inhibitor, in Moderate-to-Severe Atopic Dermatitis: Sub-study of a Phase 2a Open-Label, Single-Arm Trial”
Abstract ID: LBA-323
Session: D2T01.3A (Paris Nord)
Date & Time: Thursday, September 18, 2025, 14:15–14:30 CEST
Presenter: Jessica Beaziz-Tordjman, M.D., Icahn School of Medicine at Mount Sinai
Read Announcement- Drug:
- ATI-2138
- Announced Date:
- July 29, 2025
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. announced positive top-line results from its open-label, single-arm Phase 2a trial of ATI-2138, a potent and selective investigational oral covalent inhibitor of interleukin-2-inducible T cell kinase (ITK) and Janus kinase 3 (JAK3), in 14 patients with moderate-to-severe atopic dermatitis (AD).
AI Summary
Aclaris Therapeutics reported positive top-line results from its open-label, single-arm Phase 2a trial of ATI-2138, an oral inhibitor of ITK and JAK3, in 14 patients with moderate-to-severe atopic dermatitis. Over 12 weeks at 10 mg twice daily, the drug showed a favorable tolerability profile with no severe or serious adverse events and only mild, transient side effects.
Patients experienced clinically meaningful skin improvements. By week 12, the mean Eczema Area and Severity Index (EASI) score improved by 60.5%, and 62.5% of patients had at least a four-point reduction in worst itch (PP-NRS). Improvements appeared as early as week 1 and were sustained through week 12, matching outcomes seen with approved therapies.
Pharmacodynamic analyses confirmed strong ITK target occupancy and downregulation of key inflammatory markers (Th2, Th17, Th1, TCR) and fibrosis-related signals. Aclaris plans to explore higher doses in atopic dermatitis and to study ATI-2138 in alopecia areata and other immune-mediated diseases.
Read Announcement- Drug:
- ATI-2138
- Announced Date:
- February 12, 2025
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. announced the availability of a new publication describing the unique properties of Aclaris Therapeutics' ATI-2138, a novel investigational covalent inhibitor of interleukin-2-inducible T cell kinase (ITK) and Janus kinase 3 (JAK3) in development for the treatment of autoimmune and inflammatory diseases.
AI Summary
Aclaris Therapeutics, Inc. has released a new publication in The Journal of Pharmacology and Experimental Therapeutics that highlights the unique properties of its investigational drug, ATI-2138. This novel compound is a covalent inhibitor that targets interleukin-2-inducible T cell kinase (ITK) and Janus kinase 3 (JAK3), two enzymes involved in key immune cell functions. The publication details how ATI-2138 effectively and selectively blocks the activity of these enzymes, leading to the inhibition of Th1, Th2, and Th17 cells, which play significant roles in many autoimmune and inflammatory diseases. Preclinical data in animal models have shown promising results, supporting ongoing Phase 2a clinical trials in atopic dermatitis. The findings also underline ATI-2138’s potential safety, tolerability, and pharmacological profile, making it a promising candidate for future treatments of conditions such as allergic and autoimmune diseases.
Read Announcement- Drug:
- ATI-2138
- Announced Date:
- September 17, 2024
- Indication:
- For the Treatment of Moderate to Severe Atopic Dermatitis
Announcement
Aclaris Therapeutics, Inc. announced that the first patient has been dosed in Aclaris' Phase 2a clinical trial of ATI-2138, an investigational oral covalent inhibitor of interleukin-2-inducible T cell kinase (ITK) and Janus kinase (JAK) 3, for the treatment of moderate to severe atopic dermatitis (AD).
AI Summary
Aclaris Therapeutics, Inc. has begun dosing the first patient in its Phase 2a clinical trial for ATI-2138, a new investigational drug aimed at treating moderate to severe atopic dermatitis. ATI-2138 is an oral covalent inhibitor that targets both interleukin-2-inducible T cell kinase (ITK) and Janus kinase (JAK) 3. This dual-action mechanism is designed to interfere with T cell signaling, offering a unique treatment approach for patients with this condition.
The open-label study will assess the drug’s safety, tolerability, pharmacokinetics, efficacy, and pharmacodynamics over a 12-week period. Approximately 15 patients in the United States are expected to participate. Early data regarding the drug’s potential to improve symptoms, measured using several Eczema Area and Severity Index (EASI) responses and related endpoints, is anticipated in the first half of 2025.
Read Announcement
ATI-045 FDA Regulatory Timeline and Events
ATI-045 is a drug developed by Aclaris Therapeutics for the following indication: In Atopic Dermatitis (AD).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- ATI-045
- Announced Date:
- March 18, 2026
- Target Action Date:
- Q4 2026
- Estimated Target Date Range:
- October 1, 2026 - December 31, 2026
- Indication:
- In Atopic Dermatitis (AD)
Announcement
Aclaris Therapeutics, Inc. announced that the Top line results are expected in the fourth quarter of 2026.
AI Summary
Aclaris Therapeutics announced that top-line results for Bosakitug (ATI-045) are expected in the fourth quarter of 2026. Bosakitug is an investigational treatment being developed for atopic dermatitis and is designed to interfere with thymic stromal lymphopoietin (TSLP), a signaling protein involved in allergic inflammation. The company plans to report initial trial outcomes that will show the main safety and efficacy measures used to judge whether the drug meets its goals.
These top-line data are an early but important milestone that will shape Aclaris’s next steps, including further studies and potential regulatory planning. Timing is forward-looking and subject to change. Investors, patients, and clinicians will watch the Q4 2026 update to learn whether Bosakitug shows promise as a new option for people with moderate-to-severe atopic dermatitis.
Read Announcement- Drug:
- ATI-045
- Announced Date:
- March 18, 2026
- Indication:
- In Atopic Dermatitis (AD)
Announcement
Aclaris Therapeutics, Inc. announced that it has completed patient enrollment in its randomized, double-blind, placebo-controlled Phase 2 trial of bosakitug (ATI-045) in patients with moderate-to-severe atopic dermatitis (AD).
AI Summary
Aclaris Therapeutics announced it has completed patient enrollment in a randomized, double-blind, placebo-controlled Phase 2 trial of bosakitug (ATI-045) in patients with moderate-to-severe atopic dermatitis (AD). The study will compare bosakitug to placebo to evaluate its safety and effectiveness at reducing skin inflammation and symptoms in this patient group.
Bosakitug (ATI-045) is designed to block thymic stromal lymphopoietin (TSLP), a signaling protein that helps trigger and sustain the allergic and inflammatory responses seen in atopic dermatitis. By targeting TSLP, the treatment aims to reduce itching, redness, and flares associated with moderate-to-severe AD.
With enrollment finished, Aclaris will complete follow-up and data collection. The company expects to report top-line results in the fourth quarter of 2026, after analyzing safety and efficacy outcomes from the trial.
Read Announcement- Drug:
- ATI-045
- Announced Date:
- June 2, 2025
- Indication:
- In Atopic Dermatitis (AD)
Announcement
Aclaris Therapeutics, Inc. announced that it has initiated a randomized, double-blind, placebo-controlled Phase 2 trial of bosakitug (ATI-045) in patients with moderate-to-severe atopic dermatitis (AD).
AI Summary
Aclaris Therapeutics recently announced the start of a Phase 2 clinical trial for bosakitug (ATI-045), an investigational monoclonal antibody, in patients with moderate-to-severe atopic dermatitis (AD). The trial is randomized, double-blind, and placebo-controlled, aiming to evaluate both the efficacy and safety of bosakitug. This study builds on promising early results from a previous Phase 2a trial, where significant improvements were observed in measures such as the Eczema Area and Severity Index (EASI) and Investigator Global Assessment (IGA) scores. Approximately 90 patients will be enrolled, and the primary endpoint will focus on the percent change from baseline in EASI at week 24. Top line results from the trial are expected in the second half of 2026, potentially positioning bosakitug as a best-in-class treatment option for AD.
Read Announcement- Drug:
- ATI-045
- Announced Date:
- February 27, 2025
- Indication:
- In Atopic Dermatitis (AD)
Announcement
Aclaris Therapeutics, Inc. provided a corporate update.
AI Summary
Aclaris Therapeutics, Inc. provided a corporate update highlighting its transformative progress in 2024. The company reported strong financial results along with multiple clinical catalysts expected in 2025. In partnership with Chia Tai Tianqing Pharmaceutical Group, phase 2 data for bosakitug is anticipated in the first half of 2025 from trials in severe asthma and chronic rhinosinusitis with nasal polyps. This upcoming data is seen as crucial for guiding future development in respiratory diseases. Additionally, Aclaris plans to start enrollment in a phase 2b trial for bosakitug in patients with atopic dermatitis during the same period, and expects top-line data from a phase 2a trial of ATI-2138 for atopic dermatitis. The update also detailed recent licensing achievements, a successful $80 million private placement, and leadership changes, with Dr. Neal Walker named CEO, reinforcing the company’s commitment to innovation in immuno-inflammatory treatments.
Read Announcement
