A Phase 2 interventional study of ATI-450 and Placebo oral tablet in Hidradenitis Suppurativa, sponsored by Aclaris Therapeutics, Inc.. Completed at 20 sites in United States. Open to participants aged 18 Years to 70 Years. Per ClinicalTrials.gov, last updated 2026-01-07.
Sponsored by Aclaris Therapeutics, Inc. · Phase 2, Interventional, and Treatment
This is a Phase 2a study to investigate the efficacy, safety, tolerability, pharmacokinetics, and pharmacodynamics of ATI-450 vs placebo in patients with moderate to severe Hidradenitis Suppurativa (HS).
284 studies on the registry are indexed under Hidradenitis Suppurativa; 87 are open to participants now.
This study's enrollment of 95 is above the median of 45 across 199 interventional studies indexed under Hidradenitis Suppurativa.
Browse Hidradenitis Suppurativa studies →Aclaris Therapeutics, Inc. is the lead sponsor of 33 studies on the registry; none are open to participants now.
Of its 25 completed or terminated interventional studies of FDA-regulated products, 22 (88%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ATI-450 50 milligrams (mg) oral tablet twice daily (BID)
Drug: ATI-450
Placebo oral tablet BID
Drug: Placebo oral tablet
Oral, small molecule MK2 inhibitor
Also known as: Zunsemetinib
Placebo tablet manufactured to match ATI-450 in appearance
Also known as: Placebo
Change From Baseline in Abscess and Inflammatory Nodule (AN) Count at Week 12
AN count was the sum of number of abscess and inflammatory nodules across anatomical regions. The least square (LS) mean change from baseline in the count at Week 12 was estimated from the Mixed Model Repeated Measures (MMRM) model.
Time frame: Baseline, Week 12
Percentage of Participants Achieving Hidradenitis Suppurativa Clinical Response (HiSCR50) at Week 12
HiSCR50 Achiever was defined as a participant having a ≥50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase in the number of abscesses, and no increase in the number of draining fistula counts from baseline. A participant was considered an achiever only if all 3 criteria mentioned above were fulfilled. Model-based estimates and 90% confidence intervals (CIs) were produced. Firth's penalized likelihood logistic regression model with fixed effects for treatment and baseline count of inflammatory abscesses and nodules was used.
Time frame: Week 12
Change From Baseline in International Hidradenitis Suppurativa Severity Score System (IHS-4) at Week 12
The IHS-4 is a validated tool used to access the HS severity and is calculated based on the clinical signs of HS: inflammatory nodules, abscesses and draining tunnels (fistulas and sinuses). The IHS-4 score = (number of nodules multiplied by 1) + (number of abscesses multiplied by 2) + (number of draining tunnels \[fistulas/sinuses\] multiplied by 4). Mild HS is a score of 3 or less, moderate HS is a score of 4-10, and severe HS is a score of 11 or higher. A decrease in score means less severity.
Time frame: Baseline, Week 12
Percentage of Participants Achieving NRS30
NRS30 Achiever was defined as participants achieving at least a 30% reduction from baseline in Patient's Global Assessment of Skin Pain (PGA-SP) and at least 1 unit reduction from baseline in PGA-SP at Week 12 among participants with baseline PGA-SP ≥3. Model-based estimates and 90% CIs were produced. Firth's penalized likelihood logistic regression model with fixed effects for treatment and baseline PGA-SP was used.
Time frame: Week 12
Change From Baseline in Hidradenitis Suppurativa-Physician Global Assessment (HSPGA) at Week 12
In the HS-PGA scale, the Investigators rated the counts of nodules (inflammatory and non-inflammatory) abscesses and fistulas (both draining and nondraining) and assigned a participant to 1 of 6 categories ranging from clear (0) to very severe (5). A decrease in score means a better outcome.
Time frame: Baseline, Week 12
Change From Baseline in Dermatology Life Quality Index (DLQI) at Week 12
The DLQI is a 10-item validated questionnaire used to assess the impact of HS disease symptoms and treatment on quality of life (QoL). It consists of questions including a single "yes/no" question and questions with possible responses of "not at all," "a little," "a lot," or "very much." These questions evaluate the impact of skin diseases on different aspects of a participant's QoL over the prior week, including symptoms and feelings, daily activities, leisure, work or school, personal relationships, and the side effects of treatment. Each question was scored using a 4-point scale ranging from 0 to 3 based on a participant's response: not at all/not relevant (0), a little (1), a lot (2) and very much (3). The total score of the DLQI ranged from 0 to 30 and was calculated by adding up the scores from each question. The higher the score, the greater the impact on a participant's QoL.
Time frame: Baseline, Week 12
Number of Participants With Treatment-emergent Adverse Events (TEAEs)
TEAEs are defined as AEs with an onset date on or after the date of first administration of study drug and before the date of last administration of study drug + 30 days. A summary of non-serious AEs and serious AEs, regardless of causality is located in Reported AEs section.
Time frame: Baseline through Day 115
ATI-450 and Metabolite (CDD-2164) Concentrations
Time frame: 2 hours postdose on Days 1, 8, and 85
| Milestone | ATI-450 | Placebo |
|---|---|---|
| Started | 48 | 47 |
| Received at least 1 dose of study drug | 48 | 47 |
| Completed | 25 | 32 |
| Not completed | 23 | 15 |
| Withdrew: Adverse event | 6 | 3 |
| Withdrew: Lack of efficacy | 1 | 0 |
| Withdrew: Lost to follow-up | 8 | 6 |
| Withdrew: Protocol violation | 1 | 1 |
| Withdrew: Withdrawal by subject | 6 | 5 |
| Withdrew: Other than specified | 1 | 0 |
AN count was the sum of number of abscess and inflammatory nodules across anatomical regions. The least square (LS) mean change from baseline in the count at Week 12 was estimated from the Mixed Model Repeated Measures (MMRM) model.
| AN count | ATI-450 | Placebo |
|---|---|---|
| Change From Baseline in Abscess and Inflammatory Nodule (AN) Count at Week 12 | -2.93 (-3.99 to -1.87) | -5.94 (-7.01 to -4.87) |
HiSCR50 Achiever was defined as a participant having a ≥50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase in the number of abscesses, and no increase in the number of draining fistula counts from baseline. A participant was considered an achiever only if all 3 criteria mentioned above were fulfilled. Model-based estimates and 90% confidence intervals (CIs) were produced. Firth's penalized likelihood logistic regression model with fixed effects for treatment and baseline count of inflammatory abscesses and nodules was used.
| percentage of participants | ATI-450 | Placebo |
|---|---|---|
| Percentage of Participants Achieving Hidradenitis Suppurativa Clinical Response (HiSCR50) at Week 12 | 31.5 (21.6 to 43.4) | 51.4 (39.5 to 63.2) |
The IHS-4 is a validated tool used to access the HS severity and is calculated based on the clinical signs of HS: inflammatory nodules, abscesses and draining tunnels (fistulas and sinuses). The IHS-4 score = (number of nodules multiplied by 1) + (number of abscesses multiplied by 2) + (number of draining tunnels \[fistulas/sinuses\] multiplied by 4). Mild HS is a score of 3 or less, moderate HS is a score of 4-10, and severe HS is a score of 11 or higher. A decrease in score means less severity.
| units on a scale | ATI-450 | Placebo |
|---|---|---|
| Change From Baseline in International Hidradenitis Suppurativa Severity Score System (IHS-4) at Week 12 | -4.01 (-6.31 to -1.71) | -11.86 (-14.18 to -9.53) |
NRS30 Achiever was defined as participants achieving at least a 30% reduction from baseline in Patient's Global Assessment of Skin Pain (PGA-SP) and at least 1 unit reduction from baseline in PGA-SP at Week 12 among participants with baseline PGA-SP ≥3. Model-based estimates and 90% CIs were produced. Firth's penalized likelihood logistic regression model with fixed effects for treatment and baseline PGA-SP was used.
| percentage of participants | ATI-450 | Placebo |
|---|---|---|
| Percentage of Participants Achieving NRS30 | 43.7 (30.9 to 57.3) | 57.5 (44.0 to 69.9) |
In the HS-PGA scale, the Investigators rated the counts of nodules (inflammatory and non-inflammatory) abscesses and fistulas (both draining and nondraining) and assigned a participant to 1 of 6 categories ranging from clear (0) to very severe (5). A decrease in score means a better outcome.
| units on a scale | ATI-450 | Placebo |
|---|---|---|
| Change From Baseline in Hidradenitis Suppurativa-Physician Global Assessment (HSPGA) at Week 12 | -0.31 (-0.48 to -0.14) | -0.73 (-0.90 to -0.55) |
The DLQI is a 10-item validated questionnaire used to assess the impact of HS disease symptoms and treatment on quality of life (QoL). It consists of questions including a single "yes/no" question and questions with possible responses of "not at all," "a little," "a lot," or "very much." These questions evaluate the impact of skin diseases on different aspects of a participant's QoL over the prior week, including symptoms and feelings, daily activities, leisure, work or school, personal relationships, and the side effects of treatment. Each question was scored using a 4-point scale ranging from 0 to 3 based on a participant's response: not at all/not relevant (0), a little (1), a lot (2) and very much (3). The total score of the DLQI ranged from 0 to 30 and was calculated by adding up the scores from each question. The higher the score, the greater the impact on a participant's QoL.
| units on a scale | ATI-450 | Placebo |
|---|---|---|
| Change From Baseline in Dermatology Life Quality Index (DLQI) at Week 12 | -3.27 (-4.66 to -1.89) | -4.08 (-5.48 to -2.68) |
TEAEs are defined as AEs with an onset date on or after the date of first administration of study drug and before the date of last administration of study drug + 30 days. A summary of non-serious AEs and serious AEs, regardless of causality is located in Reported AEs section.
| Participants | ATI-450 | Placebo |
|---|---|---|
| Number of Participants With Treatment-emergent Adverse Events (TEAEs) | 35 | 26 |
| Nanograms per milliliter (ng/ml) | ATI-450 | Placebo |
|---|---|---|
| ATI-450 Day 1 | 144.995 ± 62.7707 | 0.623 ± 1.2728 |
| ATI-450 Day 8 | 207.571 ± 98.0314 | 0.504 ± 1.2063 |
| ATI-450 Day 85 | 232.110 ± 116.3028 | 0.250 ± 0.000 |
| CDD-2164 Day 1 | 49.741 ± 26.7662 | 0.364 ± 0.3932 |
| CDD-2164 Day 8 | 63.632 ± 32.1682 | 0.277 ± 0.1231 |
| CDD-2164 Day 85 | 70.698 ± 34.0962 | 0.250 ± 0.000 |
Collected over Baseline through Day 115. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| ATI-450 | 0/48 (0%) | 0/48 (0%) | 23/48 (47.9%) |
| Placebo | 0/47 (0%) | 1/47 (2.1%) | 13/47 (27.7%) |
| Event | ATI-450 | Placebo |
|---|---|---|
| HidradenitisSkin and subcutaneous tissue disorders | 0/48 | 1/47 |
| Event | ATI-450 | Placebo |
|---|---|---|
| DizzinessNervous system disorders | 8/48 | 0/47 |
| DiarrhoeaGastrointestinal disorders | 6/48 | 4/47 |
| HeadacheNervous system disorders | 6/48 | 2/47 |
| NasopharyngitisInfections and infestations | 1/48 | 5/47 |
| AcneSkin and subcutaneous tissue disorders | 5/48 | 0/47 |
| Blood creatine phosphokinase increasedInvestigations | 4/48 | 0/47 |
| NauseaGastrointestinal disorders | 2/48 | 3/47 |
| COVID-19Infections and infestations | 1/48 | 3/47 |
| Mouth ulcerationGastrointestinal disorders | 3/48 | 0/47 |
| FatigueGeneral disorders | 3/48 | 0/47 |
Full analysis set (FAS) population included all participants who have been randomized and administered at least 1 dose of study drug.
| Age, Continuous(years) | ATI-450 | Placebo | Total |
|---|---|---|---|
| Mean | 35.1 ± 9.87 | 36.6 ± 9.32 | 35.9 ± 9.58 |
| Sex: Female, Male(Participants) | ATI-450 | Placebo | Total |
|---|---|---|---|
| Female | 39 | 40 | 79 |
| Male | 9 | 7 | 16 |
| Ethnicity (NIH/OMB)(Participants) | ATI-450 | Placebo | Total |
|---|---|---|---|
| Hispanic or Latino | 10 | 8 | 18 |
| Not Hispanic or Latino | 38 | 39 | 77 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | ATI-450 | Placebo | Total |
|---|---|---|---|
| American Indian or Alaska Native | 1 | 0 | 1 |
| Asian | 0 | 0 | 0 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 18 | 20 | 38 |
| White | 28 | 27 | 55 |
| More than one race | 0 | 0 | 0 |
| Unknown or Not Reported | 1 | 0 | 1 |
PDFs hosted by the registry, ClinicalTrials.gov.
Ran from Dec 2021 to primary completion in Dec 2022, 11 months.
Results were first posted in Jan 2026, 3 years after primary completion. A results delay was requested in Dec 2023.
Of 44 industry-sponsored phase 2 interventional studies under Hidradenitis Suppurativa, half reached primary completion within 15 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 20. This study's 11 months is below that.
Counting every sponsor, half of 54 studies reached it within 15 months; a quarter within 11 and three quarters within 24.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Dec 2025. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Zunsemetinib