NCT05905783

Hidradenitis Suppurativa Study of Izokibep

Terminated Phase 3 Results posted Last updated 15 October 2025

What this trial tests

Phase 3 trial testing Placebo in Hidradenitis Suppurativa in 258 participants. Terminated before completion.

Timeline

22 June 2023

Primary endpoint
24 July 2024

27 January 2025

Quick facts

Lead sponsor	ACELYRIN Inc.
Phase	Phase 3
Status	Terminated
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	double
Primary purpose	treatment
Enrollment	258
Start date	22 June 2023
Primary completion	24 July 2024
Estimated completion	27 January 2025
Sites	98 locations across France, Japan, Germany, Hungary, Poland, Canada, United States, Spain

Drugs / interventions tested

• Placebo
• Izokibep — full drug profile →

Conditions studied

• Hidradenitis Suppurativa — all drugs for Hidradenitis Suppurativa →

Sponsor

ACELYRIN Inc. — full company profile →

Who can join

18 and older, any sex, with Hidradenitis Suppurativa. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Percentage of Participants Achieving Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) at Week 12 Primary · Week 12

The percentage of participants achieving HiSCR75 was defined as meeting all 3 criteria below: * (\[abscess and inflammatory nodule (AN) count at baseline - AN count at current visit\] / AN count at baseline) × 100% ≥ 75% * Abscess count at baseline ≥ abscess count at the current visit * Draining fistula count at baseline ≥ draining fistula count at the current visit. HiSCR75 was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	20.3	13.1 – 27.6
Izokibep 160 mg QW	32.6	24.3 – 40.9

Percentage of Participants Achieving HiSCR90 at Week 12 Secondary · Week 12

The percentage of participants achieving HiSCR90 was defined as meeting all 3 criteria below: * (\[AN count at baseline - AN count at current visit\] / AN count at baseline) × 100% ≥ 90% * Abscess count at baseline ≥ abscess count at the current visit * Draining fistula count at baseline ≥ draining fistula count at the current visit. HiSCR90 was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	9.2	3.8 – 14.5
Izokibep 160 mg QW	24.3	16.7 – 31.9

Percentage of Participants Achieving HiSCR100 at Week 12 Secondary · Week 12

The percentage of participants achieving HiSCR100 was defined as meeting all 3 criteria below: * (\[AN count at baseline - AN count at current visit\] / AN count at baseline) × 100% = 100% * Abscess count at baseline ≥ abscess count at the current visit * Draining fistula count at baseline ≥ draining fistula count at the current visit. HiSCR100 was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	7.3	2.5 – 12.2
Izokibep 160 mg QW	21.4	14.2 – 28.7

Percentage of Participants Achieving HiSCR50 at Week 12 Secondary · Week 12

The percentage of participants achieving HiSCR50 was defined as meeting all 3 criteria below: * \[(AN count at baseline - AN count at current visit) / AN count at baseline\] × 100% ≥ 50% * Abscess count at baseline ≥ abscess count at the current visit * Draining fistula count at baseline ≥ draining fistula count at the current visit. HiSCR50 was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	36.5	27.8 – 45.2
Izokibep 160 mg QW	47.9	39.0 – 56.8

Percentage of Participants Who Experienced One or More (≥ 1) Disease Flare at Week 12 Secondary · Up to Week 12

HS flares were defined as ≥ 25% increase in AN count with a minimum increase of 2 AN relative to baseline, i.e. participants must meet all the following criteria: * (AN count at current visit- AN count at baseline) / AN count at baseline ×100% ≥ 25% * AN count at current visit- AN count at baseline ≥ 2. Participants who received antibiotic therapy that could affect HS were imputed as non-response (NRI). Other participants with missing data were imputed with multiple imputation.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	31.1	22.9 – 39.3
Izokibep 160 mg QW	28.3	20.5 – 36.2

Change From Baseline in Dermatology Life Quality Index (DLQI) Secondary · Baseline and Week 12

DLQI included 10 items arranged in 6 categories: symptoms and feelings, daily activity, leisure, work or study, interpersonal relationships, and treatment. The total score could range from 0 (no impact to life quality) to 30 (maximum impact).

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	-2.71	± 0.519
Izokibep 160 mg QW	-4.87	± 0.536

Percentage of Participants With Baseline Hurley Stage II Who Achieved AN Count of 0, 1, or 2 at Week 12 Secondary · Week 12

Calculated as observed values of 0, 1, or 2 for AN count (abscess count + inflammatory nodule count). AN count of 0, 1, or 2 was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	25.0	15.2 – 34.8
Izokibep 160 mg QW	49.5	38.1 – 61.0

Percentage of Participants With Baseline NRS ≥ 4 Achieving at Least 3-point Reduction at Week 12 in Numeric Rating Scale (NRS) Patient Global Assessment of Skin Pain at Its Worst Secondary · Week 12

NRS in Patient Global Assessment of Skin Pain ranged from 0 (no skin pain) to 10 (skin pain bad as you can imagine). The skin pain score at each visit was calculated using average of daily scores among the 7 days up to and including the day of visit, with a minimum of 4 days (consecutive or non-consecutive) with scores required. Reduction in NRS was evaluated using nonresponse imputation (NRI) and multiple imputation (MI) methods.

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	17.2	8.4 – 25.9
Izokibep 160 mg QW	33.5	22.1 – 44.8

Number of Participants With Treatment-emergent Adverse Events (TEAEs), Serious AEs (SAEs) and Adverse Event of Special Interest (AESIs) in Period 1 Secondary · Up to Week 16

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study drug, whether or not considered related to the study drug. An SAE is defined as any untoward medical occurrence that, at any dose, meets one or more of the criteria listed: results in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, or is an important medical event. The following events of special interest were monitored

TEAEs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	76
Izokibep 160 mg QW	107

SAEs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	5
Izokibep 160 mg QW	1

AESIs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	3
Izokibep 160 mg QW	0

Number of Participants With TEAEs, SAEs and AESIs in Period 2 Secondary · From Week 16 to follow-up, Week 59

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study drug, whether or not considered related to the study drug. An SAE is defined as any untoward medical occurrence that, at any dose, meets one or more of the criteria listed: results in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, or is an important medical event. The following events of special interest were monitored

TEAEs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	87
Izokibep 160 mg QW	66

SAEs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	3
Izokibep 160 mg QW	4

AESIs

Group	Value	95% CI
Placebo-Izokibep 160 mg QW	5
Izokibep 160 mg QW	1

Adverse events — posted to ClinicalTrials.gov

Time frame: From Screening (Day -28) to Follow-up (Week 59), up to approximately 63 weeks. Reporting threshold: 5%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

Placebo QW - Izokibep 160 mg QW: Period 1

Serious: 5/129 (4%)

Deaths: 0/129

Izokibep 160 mg QW: Period 1

Serious: 1/129 (1%)

Deaths: 0/129

Placebo QW - Izokibep 160 mg QW: Period 2

Serious: 3/109 (3%)

Deaths: 0/109

Izokibep 160 mg QW: Period 2

Serious: 4/100 (4%)

Deaths: 0/100

Serious adverse events (13 terms)

Reaction	System	Placebo QW - Izokibep 160 …	Izokibep 160 mg QW: Period 1	Placebo QW - Izokibep 160 …	Izokibep 160 mg QW: Period 2
Pelvic fracture	Injury, poisoning and procedural complications	—	—	—	—
Post procedural complication	Injury, poisoning and procedural complications	—	—	—	—
Abdominal pain lower	Gastrointestinal disorders	—	—	—	—
Hepatic enzyme increased	Investigations	—	—	—	—
Urinary retention	Renal and urinary disorders	—	—	—	—
Hidradenitis	Skin and subcutaneous tissue disorders	—	—	—	—
Vasculitis	Vascular disorders	—	—	—	—
Intervertebral disc protrusion	Musculoskeletal and connective tissue disorders	—	—	—	—
Spinal stenosis	Musculoskeletal and connective tissue disorders	—	—	—	—
Adenocarcinoma of colon	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—
Transitional cell carcinoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—
Eye disorder	Eye disorders	—	—	—	—
Cellulitis	Infections and infestations	—	—	—	—

Other adverse events (6 terms — click to expand)

Reaction	System	Placebo QW - Izokibep 160 …	Izokibep 160 mg QW: Period 1	Placebo QW - Izokibep 160 …	Izokibep 160 mg QW: Period 2
Injection site reaction	General disorders	—	—	—	—
Headache	Nervous system disorders	—	—	—	—
Nasopharyngitis	Infections and infestations	—	—	—	—
Fatigue	General disorders	—	—	—	—
Upper respiratory tract infection	Infections and infestations	—	—	—	—
Diarrhoea	Gastrointestinal disorders	—	—	—	—

Most-reported serious reactions: Pelvic fracture, Post procedural complication, Abdominal pain lower, Hepatic enzyme increased, Urinary retention, Hidradenitis, Vasculitis, Intervertebral disc protrusion.

Data from ClinicalTrials.gov NCT05905783 adverse events section.

Sponsor's own description

Izokibep is a small protein molecule that acts as a selective, potent inhibitor of interleukin 17A, to which it binds with high affinity. This study investigates izokibep in participants with active Hidradenitis Suppurativa (HS), including tumor necrosis factor-alpha inhibitor (TNFi) naïve participants, and those who had an inadequate response or intolerance to TNFi, or for whom TNFi is contraindicated.

Publications & conference data

4 peer-reviewed publications reference this trial (live from Europe PMC):

1. IL-17 Inhibition: A Valid Therapeutic Strategy in the Management of Hidradenitis Suppurativa.
   Malvaso D, Calabrese L, Chiricozzi A, Antonelli F, et al · · 2023 · cited 19× · PMID 37896210 · DOI 10.3390/pharmaceutics15102450
2. Interleukin-17 Inhibitors in the Treatment of Hidradenitis Suppurativa.
   Pinto Salgueiro G, Yilmaz O, Nogueira M, Torres T. · · 2025 · cited 8× · PMID 39604776 · DOI 10.1007/s40259-024-00687-w
3. An anti-sortilin affibody-peptide fusion inhibits sortilin-mediated progranulin degradation.
   Ek M, Nilvebrant J, Nygren PÅ, Ståhl S, et al · · 2024 · cited 3× · PMID 39185427 · DOI 10.3389/fimmu.2024.1437886
4. Abstracts of the 10th Annual Symposium on Hidradenitis Suppurativa Advances 2025 : Nashville, Tennessee | October 31-November 2, 2025.
   · 2026 · PMID 41348395 · DOI 10.1007/s13555-025-01579-9