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CompletedNCT05355805Updated Jun 3, 2025Results posted

Hidradenitis Suppurativa Phase 2b Study of Izokibep

A Phase 2 interventional study of Izokibep and Placebo to izokibep in Hidradenitis Suppurativa, sponsored by ACELYRIN Inc.. Completed at 44 sites in 6 countries. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2025-06-03.

Sponsored by ACELYRIN Inc. · Phase 2, Interventional, and Treatment

Phase
Phase 2
Study type
Interventional
Enrollment
205
Allocation
Randomized
Ages
18 Years to 75 Years
Sex
All
01

Study summary

Izokibep is a potent and selective inhibitor of interleukin 17A (IL-17A) that is being developed for treatment of hidradenitis suppurativa (HS).

This study will evaluate the efficacy, safety, and immunogenicity of izokibep administered subcutaneously (SC) in adult subjects with moderate to severe HS.

02

Conditions studied

  • Hidradenitis Suppurativa

Keywords

  • hidradenitis suppurativa
  • Izokibep
03

In context

Hidradenitis Suppurativa

277 studies on the registry are indexed under Hidradenitis Suppurativa; 87 are open to participants now.

This study's enrollment of 205 is above the median of 45 across 195 interventional studies indexed under Hidradenitis Suppurativa.

Browse Hidradenitis Suppurativa studies →

Lead sponsor

ACELYRIN Inc. is the lead sponsor of 7 studies on the registry; none are open to participants now.

Of its 5 completed or terminated interventional studies of FDA-regulated products, 3 (60%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 75 Years
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

General

  • Subject has provided signed informed consent including consenting to comply with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
  • 18 years to 75 years of age

Type of Subject and Disease Characteristics

  • Diagnosis of hidradenitis suppurativa (HS) for ≥ 1 year prior to first dose of study drug.
  • Hidradenitis suppurativa lesions present in ≥ 2 distinct anatomic areas, one of which is Hurley Stage II or III.
  • A total abscess and inflammatory nodule (AN) count of ≥ 5 at screening and Day 1 prior to enrollment/randomization.
  • Subject must have had an inadequate response to oral antibiotics OR exhibited recurrence after discontinuation to, OR demonstrated intolerance to, OR have a contraindication to oral antibiotics for treatment of their HS.
  • Must agree to use daily over-the-counter topical antiseptics.
  • Subject must be willing to complete a daily skin pain diary for at least 3 days prior to Day 1 visit.

Exclusion criteria

Exclusion Criteria:

Medical Conditions

  • Draining fistula count of > 20.
  • Outpatient surgery ≤ 8 weeks prior or inpatient surgery ≤ 12 weeks prior to enrollment/randomization.
  • Other active skin disease or condition that could interfere with study assessments.
  • Chronic pain not associated with HS.
  • Uncontrolled, clinically significant system disease.
  • History of demyelinating disease or neurological symptoms suggestive of demyelinating disease.
  • Malignancy within 5 years.
  • The subject is at risk of self-harm or harm to others.
  • Active infection or history of certain infections.
  • Tuberculosis or fungal infection seen on available chest x-ray taken ≤ 3 months of screening or at screening (Exception: documented evidence of completed treatment and clinically resolved).
  • Known history of human immunodeficiency virus (HIV).

Other protocol defined inclusion/exclusion criteria may apply.

05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Participant, Investigator)
Enrollment
205 participants (actual)

Study arms

  • Experimental
    Part A (Open-label) izokibep every week

    Participants will receive izokibep every week from Day 1 through Week 31

    Drug: Izokibep

  • Experimental
    Part B (Double-blind) izokibep every week

    Participants will receive izokibep every week for 31 weeks.

    Drug: Izokibep

  • Experimental
    Part B (Double-blind) izokibep every other week

    Participants will receive izokibep every other week for 30 weeks.

    Drug: Izokibep

  • Placebo comparator
    Part B (Double-blind) placebo every week

    Participants will receive placebo every week up to Week 15, then izokibep from Week 16 to Week 31.

    Drug: Placebo to izokibep

  • Placebo comparator
    Part B (Double-blind) placebo every other week

    Participants will receive placebo every other week up to Week 14, then izokibep from Week 16 to Week 30.

    Drug: Placebo to izokibep

Interventions

  • DrugIzokibep

    Biologic: IL-17A inhibitor Form: Solution for injection Route of administration: Subcutaneous (SC)

  • DrugPlacebo to izokibep

    Form: Solution for injection Route of administration: Subcutaneous (SC)

06

What researchers measure

Primary outcomes

  1. Part A: Number of Participants Who Achieved Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) at Week 12

    HiSCR75 was defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

    Time frame: Part A: Baseline to Week 12

  2. Part B: Number of Participants Who Achieved HiSCR75 at Week 16

    HiSCR75 was defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

    Time frame: Part B: Baseline to Week 16

Secondary outcomes

  1. Part A: Number of Participants With Treatment-emergent Adverse Events (TEAEs)

    An adverse event (AE) referred to any untoward medical occurrence in a clinical study participant, regardless of a causal relationship with the study treatment. TEAEs included any event occurring after the participant received the study treatment. Clinically significant changes in vital signs, electrocardiograms, and laboratory tests recorded after treatment administration were documented as TEAEs. Serious TEAEs (SAEs) were untoward medical occurrences after the first dose, irrespective of a causal link to the study treatment, that led to death, were life-threatening, required hospitalization or its prolongation, caused significant disability, resulted in congenital anomalies, or were considered other medically important events.

    Time frame: Part A: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks

  2. Part A: Number of Participants Testing Positive for Anti-drug Antibodies (ADAs)

    Blood samples were collected at different time points throughout the study.

    Time frame: Baseline, Week 16, Week 32, Week 39

  3. Part B: Number of Participants Who Achieved HiSCR90 at Week 16

    HiSCR90 was defined as at least a 90% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count

    Time frame: Part B: Baseline to Week 16

  4. Part B: Number of Participants Who Achieved HiSCR100 at Week 16

    HiSCR100 was defined as at least a 100% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

    Time frame: Part B: Baseline to Week 16

  5. Part B: Number of Participants Who Achieved HiSCR50 at Week 16

    HiSCR50 was defined as at least a 50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count

    Time frame: Part B: Baseline to Week 16

  6. Part B: Percentage of Participants Who Experienced ≥ 1 Disease Flare Through 16 Weeks of Treatment

    A flare was defined as ≥ 25% increase in AN count with a minimum increase of 2 AN relative to baseline. Missing data of abscess and inflammatory nodules counts at scheduled visits are imputed assuming monotone missingness pattern. Predictors in the regression model for missing values at Week 4 are Baseline Hurley stage, baseline abscess count, baseline inflammatory nodule count, baseline draining fistula count, sex, race, age, body mass index (BMI) and prior Biologic/JAK inhibitor use for HS. Predictors in the regression model for missing values after Week 4 are all of these variables, plus counts of abscess, inflammatory nodule, and draining fistula at prior scheduled assessment. Missing flare values in both the placebo and izokibep groups are imputed using observed data from the placebo group only.

    Time frame: Part B: Day 1 through to Week 16

  7. Part B: Number of Participants With Hurley Stage II at Baseline Who Achieved AN Count of 0, 1, or 2

    The percentage of participants with baseline Hurley Stage II who achieved AN count of 0, 1, or 2 at Week 16. Hurley stages: Stage 1 - solitary or multiple, isolated abscess formation without scarring or sinus tracts Stage 2 - recurrent abscesses, single or multiple widely separated lesions, with sinus tract formation Stage 3 - diffuse or broad involvement, with multiple interconnected sinus tracts and abscesses.

    Time frame: Part B: Week 16

  8. Part B: Number of Participants Who Achieved at Least a 3-Point Reduction From Baseline in Numeric Rating Scale (NRS) in Patient Global Assessment of Skin Pain at Its Worst at Week 16 Among Participants With Baseline NRS ≥ 4

    The Patient Global Assessment of Skin Pain is a NRS that consists of scores from 0 to 10 with 0 indicating "no skin pain" and 10 indicating "pain as bad as you can imagine".

    Time frame: Part B: Baseline to Week 16

  9. Part B: Number of Participants With TEAEs of Special Interest

    Adverse events of special interest were adverse events in the following categories: candida infection, inflammatory bowel disease, suicidal ideation, malignancies, major cardiovascular and cerebrovascular events, tuberculosis, infections, cytopenias and hypersensitivity reactions.

    Time frame: Part B: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks

  10. Part B: Number of Participants With TEAEs

    An AE referred to any untoward medical occurrence in a clinical study participant, regardless of a causal relationship with the study treatment. TEAEs included any event occurring after the participant received the study treatment. Clinically significant changes in vital signs, electrocardiograms, and laboratory tests recorded after treatment administration were documented as TEAEs. SAEs were untoward medical occurrences after the first dose, irrespective of a causal link to the study treatment, that led to death, were life-threatening, required hospitalization or its prolongation, caused significant disability, resulted in congenital anomalies, or were considered other medically important events.

    Time frame: Part B: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks

  11. Part B: Number of Participants Testing Positive for ADAs

    Blood samples were collected at different time points throughout the study.

    Time frame: Up to 39 weeks

07

Results

Posted Sep 25, 2024

Participant flow

Participants were recruited at different centers in the United States, Canada, Germany, Hungary, Poland, and Spain, and participated from May 2022 to February 2024.

Participant flow — Overall Study
MilestonePart A Izokibep 160 mg QW (Open-label)Part B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Started30595759
Switched to izokibep 160 mg qw02400
Switched to izokibep 160 mg q2w02600
Completed17343140
Not completed13252619
Withdrew: Lost to follow-up611106
Withdrew: Decision by sponsor0010
Withdrew: Withdrawal by subject7141513

Outcome measures

PrimaryPart A: Number of Participants Who Achieved Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) at Week 12

HiSCR75 was defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

Time frame:
Part A: Baseline to Week 12
Reported as:
Count of participants · Participants
Part A: Number of Participants Who Achieved Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) at Week 12
ParticipantsPart A Izokibep 160 mg QW
Part A: Number of Participants Who Achieved Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) at Week 1212
PrimaryPart B: Number of Participants Who Achieved HiSCR75 at Week 16

HiSCR75 was defined as at least a 75% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

Time frame:
Part B: Baseline to Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants Who Achieved HiSCR75 at Week 16
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants Who Achieved HiSCR75 at Week 16162119
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.3055 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 8.27
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.6192 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 4.19
SecondaryPart A: Number of Participants With Treatment-emergent Adverse Events (TEAEs)

An adverse event (AE) referred to any untoward medical occurrence in a clinical study participant, regardless of a causal relationship with the study treatment. TEAEs included any event occurring after the participant received the study treatment. Clinically significant changes in vital signs, electrocardiograms, and laboratory tests recorded after treatment administration were documented as TEAEs. Serious TEAEs (SAEs) were untoward medical occurrences after the first dose, irrespective of a causal link to the study treatment, that led to death, were life-threatening, required hospitalization or its prolongation, caused significant disability, resulted in congenital anomalies, or were considered other medically important events.

Time frame:
Part A: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks
Reported as:
Count of participants · Participants
Part A: Number of Participants With Treatment-emergent Adverse Events (TEAEs)
ParticipantsPart A Izokibep 160 mg QW
Any TEAE26
Serious TEAE2
SecondaryPart A: Number of Participants Testing Positive for Anti-drug Antibodies (ADAs)

Blood samples were collected at different time points throughout the study.

Time frame:
Baseline, Week 16, Week 32, Week 39
Reported as:
Count of participants · Participants
Part A: Number of Participants Testing Positive for Anti-drug Antibodies (ADAs)
ParticipantsPart A Izokibep 160 mg QW
Baseline12
Week 1611
Week 3215
Week 3917
SecondaryPart B: Number of Participants Who Achieved HiSCR90 at Week 16

HiSCR90 was defined as at least a 90% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count

Time frame:
Part B: Baseline to Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants Who Achieved HiSCR90 at Week 16
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants Who Achieved HiSCR90 at Week 1691512
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.1606 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 10.14
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.5116 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 4.79
SecondaryPart B: Number of Participants Who Achieved HiSCR100 at Week 16

HiSCR100 was defined as at least a 100% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count.

Time frame:
Part B: Baseline to Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants Who Achieved HiSCR100 at Week 16
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants Who Achieved HiSCR100 at Week 1671511
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.0514 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 13.67
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.3322 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 6.56
SecondaryPart B: Number of Participants Who Achieved HiSCR50 at Week 16

HiSCR50 was defined as at least a 50% reduction from baseline in the total abscess and inflammatory nodule count, with no increase from baseline in abscess or draining fistula count

Time frame:
Part B: Baseline to Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants Who Achieved HiSCR50 at Week 16
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants Who Achieved HiSCR50 at Week 16222626
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.3258 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 8.63
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.4068 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 7.28
SecondaryPart B: Percentage of Participants Who Experienced ≥ 1 Disease Flare Through 16 Weeks of Treatment

A flare was defined as ≥ 25% increase in AN count with a minimum increase of 2 AN relative to baseline. Missing data of abscess and inflammatory nodules counts at scheduled visits are imputed assuming monotone missingness pattern. Predictors in the regression model for missing values at Week 4 are Baseline Hurley stage, baseline abscess count, baseline inflammatory nodule count, baseline draining fistula count, sex, race, age, body mass index (BMI) and prior Biologic/JAK inhibitor use for HS. Predictors in the regression model for missing values after Week 4 are all of these variables, plus counts of abscess, inflammatory nodule, and draining fistula at prior scheduled assessment. Missing flare values in both the placebo and izokibep groups are imputed using observed data from the placebo group only.

Time frame:
Part B: Day 1 through to Week 16
Reported as:
Number · Percentage of participants
Part B: Percentage of Participants Who Experienced ≥ 1 Disease Flare Through 16 Weeks of Treatment
Percentage of participantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Percentage of Participants Who Experienced ≥ 1 Disease Flare Through 16 Weeks of Treatment22.32 (11.7 to 32.9)18.29 (8.43 to 28.1)14.93 (5.72 to 24.1)
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.3329 (The estimated risk difference divided by the standard error will be used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): -7.40
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.5882 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 4.06
SecondaryPart B: Number of Participants With Hurley Stage II at Baseline Who Achieved AN Count of 0, 1, or 2

The percentage of participants with baseline Hurley Stage II who achieved AN count of 0, 1, or 2 at Week 16. Hurley stages: Stage 1 - solitary or multiple, isolated abscess formation without scarring or sinus tracts Stage 2 - recurrent abscesses, single or multiple widely separated lesions, with sinus tract formation Stage 3 - diffuse or broad involvement, with multiple interconnected sinus tracts and abscesses.

Time frame:
Part B: Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants With Hurley Stage II at Baseline Who Achieved AN Count of 0, 1, or 2
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants With Hurley Stage II at Baseline Who Achieved AN Count of 0, 1, or 2151814
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.5422 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 7.31
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.6569 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): -5.23
SecondaryPart B: Number of Participants Who Achieved at Least a 3-Point Reduction From Baseline in Numeric Rating Scale (NRS) in Patient Global Assessment of Skin Pain at Its Worst at Week 16 Among Participants With Baseline NRS ≥ 4

The Patient Global Assessment of Skin Pain is a NRS that consists of scores from 0 to 10 with 0 indicating "no skin pain" and 10 indicating "pain as bad as you can imagine".

Time frame:
Part B: Baseline to Week 16
Reported as:
Count of participants · Participants
Part B: Number of Participants Who Achieved at Least a 3-Point Reduction From Baseline in Numeric Rating Scale (NRS) in Patient Global Assessment of Skin Pain at Its Worst at Week 16 Among Participants With Baseline NRS ≥ 4
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Part B: Number of Participants Who Achieved at Least a 3-Point Reduction From Baseline in Numeric Rating Scale (NRS) in Patient Global Assessment of Skin Pain at Its Worst at Week 16 Among Participants With Baseline NRS ≥ 4459
Statistical analysis
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg QW · Cochran-Mantel-Haenszel · p = 0.4031 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 7.48
  • Part B Placebo QW/Q2W Then Izokibep QW/Q2W vs Part B Izokibep 160 mg Q2W · Cochran-Mantel-Haenszel · p = 0.0327 (The estimated risk difference divided by the standard error was used as the test statistic and a p-value calculated assuming that the test statistic follows a standard normal distribution under the null hypothesis.) · Risk difference (rd): 21.27
SecondaryPart B: Number of Participants With TEAEs of Special Interest

Adverse events of special interest were adverse events in the following categories: candida infection, inflammatory bowel disease, suicidal ideation, malignancies, major cardiovascular and cerebrovascular events, tuberculosis, infections, cytopenias and hypersensitivity reactions.

Time frame:
Part B: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks
Reported as:
Count of participants · Participants
Part B: Number of Participants With TEAEs of Special Interest
ParticipantsPart B Placebo QW/Q2W (Up to Week 16)Part B Izokibep 160 mg Q2W (Up to Week 16)Part B Izokibep 160 mg QW (Up to Week 16)Part B Placebo/Izokibep 160 mg QW (Week 16 to 31)Part B Placebo/Izokibep 160 mg Q2W (Week 16 to 30)Part B: Izokibep 160 mg QW (Week 16 to 31)Part B: Izokibep 160 mg Q2W (Week 16 to 30)
Part B: Number of Participants With TEAEs of Special Interest4211202
SecondaryPart B: Number of Participants With TEAEs

An AE referred to any untoward medical occurrence in a clinical study participant, regardless of a causal relationship with the study treatment. TEAEs included any event occurring after the participant received the study treatment. Clinically significant changes in vital signs, electrocardiograms, and laboratory tests recorded after treatment administration were documented as TEAEs. SAEs were untoward medical occurrences after the first dose, irrespective of a causal link to the study treatment, that led to death, were life-threatening, required hospitalization or its prolongation, caused significant disability, resulted in congenital anomalies, or were considered other medically important events.

Time frame:
Part B: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks
Reported as:
Count of participants · Participants
Part B: Number of Participants With TEAEs
ParticipantsPart B Placebo QW/Q2W (Up to Week 16)Part B Izokibep 160 mg QW (Up to Week 16)Part B Izokibep 160 mg Q2W (Up to Week 16)Part B Placebo/Izokibep 160 mg QW (Week 16 to 31)Part B Placebo/Izokibep 160 mg Q2W (Week 16 to 30)Part B: Izokibep 160 mg QW (Week 16 to 31)Part B: Izokibep 160 mg Q2W (Week 16 to 30)
Any TEAE40494817162725
Serious TEAE2212110
SecondaryPart B: Number of Participants Testing Positive for ADAs

Blood samples were collected at different time points throughout the study.

Time frame:
Up to 39 weeks
Reported as:
Count of participants · Participants
Part B: Number of Participants Testing Positive for ADAs
ParticipantsPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2W
Baseline272936
Week 16212939
Week 32133512
Week 39173215

Adverse events

Collected over Part A: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks. Part B: Screening (Day -28) to Follow-up (Week 45), for a total of 49 weeks.. Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Part A Izokibep 160 mg QW0/30 (0%)2/30 (6.7%)25/30 (83.3%)
Part B Placebo QW/Q2W (Up to Week 16)0/59 (0%)2/59 (3.4%)25/59 (42.4%)
Part B Izokibep 160 mg QW - (Up to Week 16)0/57 (0%)2/57 (3.5%)43/57 (75.4%)
Part B Izokibep 160 mg Q2W (Up to Week 16)0/59 (0%)1/59 (1.7%)34/59 (57.6%)
Part B Placebo/Izokibep 160 mg Q2W (Week 16 to 30)0/26 (0%)1/26 (3.8%)10/26 (38.5%)
Part B Placebo/Izokibep 160 mg QW (Week 16 to 31)0/24 (0%)2/24 (8.3%)14/24 (58.3%)
Part B: Izokibep 160 mg Q2W (Week 16 to 30)0/53 (0%)0/53 (0%)9/53 (17%)
Part B: Izokibep 160 mg QW (Week 16 to 31)0/43 (0%)1/43 (2.3%)13/43 (30.2%)
Most frequent serious events
Showing 10 of 12
Most frequent serious events
EventPart A Izokibep 160 mg QWPart B Placebo QW/Q2W (Up to Week 16)Part B Izokibep 160 mg QW - (Up to Week 16)Part B Izokibep 160 mg Q2W (Up to Week 16)Part B Placebo/Izokibep 160 mg Q2W (Week 16 to 30)Part B Placebo/Izokibep 160 mg QW (Week 16 to 31)Part B: Izokibep 160 mg Q2W (Week 16 to 30)Part B: Izokibep 160 mg QW (Week 16 to 31)
ArthritisMusculoskeletal and connective tissue disorders0/300/591/570/590/261/240/530/43
Still's diseaseMusculoskeletal and connective tissue disorders0/300/590/570/590/261/240/530/43
COVID-19 pneumoniaInfections and infestations0/300/590/570/591/260/240/530/43
SepsisInfections and infestations1/301/590/570/590/260/240/530/43
Colonic abscessInfections and infestations1/300/590/570/590/260/240/530/43
Crohn's diseaseGastrointestinal disorders1/300/590/570/590/260/240/530/43
Drug-induced liver injuryHepatobiliary disorders0/300/590/571/590/260/240/531/43
Multiple sclerosisNervous system disorders0/300/590/570/590/260/240/531/43
Epstein-Barr virus infectionInfections and infestations0/300/591/570/590/260/240/530/43
Cutaneous vasculitisSkin and subcutaneous tissue disorders0/300/591/570/590/260/240/530/43
Most frequent other events
Showing 10 of 21
Most frequent other events
EventPart A Izokibep 160 mg QWPart B Placebo QW/Q2W (Up to Week 16)Part B Izokibep 160 mg QW - (Up to Week 16)Part B Izokibep 160 mg Q2W (Up to Week 16)Part B Placebo/Izokibep 160 mg Q2W (Week 16 to 30)Part B Placebo/Izokibep 160 mg QW (Week 16 to 31)Part B: Izokibep 160 mg Q2W (Week 16 to 30)Part B: Izokibep 160 mg QW (Week 16 to 31)
Injection site erythemaGeneral disorders12/300/5931/5723/597/2612/245/533/43
Injection site pruritusGeneral disorders8/300/5916/577/595/265/242/532/43
Injection site swellingGeneral disorders6/300/599/575/592/263/243/530/43
Injection site warmthGeneral disorders5/300/591/570/590/260/240/530/43
NasopharyngitisInfections and infestations0/305/599/575/591/260/241/534/43
HeadacheNervous system disorders0/308/598/576/590/261/240/535/43
Injection site reactionGeneral disorders4/300/591/571/590/260/241/530/43
Injection site painGeneral disorders3/301/593/573/592/263/241/531/43
Upper respiratory tract infectionInfections and infestations0/306/595/572/590/261/244/532/43
MigraineNervous system disorders0/300/591/570/591/262/240/530/43

Baseline characteristics

Full Analysis Set (FAS), Part A: all participants who received at lease one dose of study drug in Part A. FAS, Part B: all participants randomized in Part B.

Age, Categorical
Age, Categorical(Participants)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A — <=18 years0———0
Part A — Between 18 and 65 years30———30
Part A — >=65 years0———0
Part B — <=18 years—0000
Part B — Between 18 and 65 years—585658172
Part B — >=65 years—1113
Age, Continuous
Age, Continuous(years)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A38.3 ± 9.68———38.3 ± 9.68
Part B—37.2 ± 11.4535.3 ± 11.6640.3 ± 10.0437.6 ± 11.2
Sex: Female, Male
Sex: Female, Male(Participants)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A — Female21———21
Part A — Male9———9
Part B — Female—403936115
Part B — Male—19182360
Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A — Hispanic or Latino4———4
Part A — Not Hispanic or Latino26———26
Part A — Unknown or Not Reported0———0
Part B — Hispanic or Latino—911727
Part B — Not Hispanic or Latino—504652148
Part B — Unknown or Not Reported—0000
Race (NIH/OMB)
Race (NIH/OMB)(Participants)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A — American Indian or Alaska Native0———0
Part A — Asian0———0
Part A — Native Hawaiian or Other Pacific Islander0———0
Part A — Black or African American14———14
Part A — White16———16
Part A — More than one race0———0
Part A — Unknown or Not Reported0———0
Part B — American Indian or Alaska Native—0101
Part B — Asian—1304
Part B — Native Hawaiian or Other Pacific Islander—0000
Part B — Black or African American—97622
Part B — White—474551143
Part B — More than one race—2125
Part B — Unknown or Not Reported—0000
Abscess Count
Abscess Count(Abcesses)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A1.7 ± 2.18———1.7 ± 2.18
Part B—1.8 ± 2.101.9 ± 3.571.9 ± 4.861.9 ± 3.67
Inflammatory Nodule Count
Inflammatory Nodule Count(Nodules)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A8.8 ± 7.20———8.8 ± 7.20
Part B—7.5 ± 5.1010.0 ± 8.457.9 ± 4.218.5 ± 6.22
Draining Fistula Count
Draining Fistula Count(Fistulas)Part A Izokibep 160 mg QWPart B Placebo QW/Q2W Then Izokibep QW/Q2WPart B Izokibep 160 mg QWPart B Izokibep 160 mg Q2WTotal
Part A1.7 ± 2.35———1.7 ± 2.35
Part B—3.5 ± 5.183.0 ± 3.972.6 ± 3.383.1 ± 4.24

1 further baseline measures are reported on the registry.

08

Study locations

44 sites
  • Clinical Research Site
    Birmingham, Alabama 35233-3110, United States
  • Clinical Research Site
    Encino, California 91436-2428, United States
  • Clinical Research Site
    Fountain Valley, California 92708-3701, United States
  • Clinical Research Site
    Los Angeles, California 90033, United States
  • Clinical Research Site
    Los Angeles, California 90045-3606, United States
  • Clinical Research Site
    Ocala, Florida 34470, United States
  • Clinical Research Site
    Tampa, Florida 33624-2038, United States
  • Clinical Research Site
    Sandy Springs, Georgia 30328, United States
  • Clinical Research Site
    Savannah, Georgia 31406, United States
  • Clinical Research Site
    Rolling Meadows, Illinois 60008-3811, United States
  • Clinical Research Site
    Indianapolis, Indiana 46250, United States
  • Clinical Research Site
    Plainfield, Indiana 46168, United States
  • Clinical Research Site
    Murray, Kentucky 42071-2515, United States
  • Clinical Research Site
    Baton Rouge, Louisiana 70808, United States
  • Clinical Research Site
    New York, New York 10028-3001, United States
  • Clinical Research Site
    Mason, Ohio 45040-4520, United States
  • Clinical Research Site
    Portland, Oregon 97223, United States
  • Clinical Research Site
    Philadelphia, Pennsylvania 19103-4708, United States
  • Clinical Research Site
    Pittsburgh, Pennsylvania 15213-3403, United States
  • Clinical Research Site
    Webster, Texas 77598, United States
  • Clinical Research Site
    London, Ontario N6A 2C2, Canada
  • Clinical Research Site
    Markham, Ontario L3P 1X2, Canada
  • Clinical Research Site
    Waterloo, Ontario N2J 1C4, Canada
  • Clinical Research Site
    Québec, Quebec G1N 4V3, Canada
  • Clinical Research Site
    Saskatoon, Saskatchewan S7K 2C1, Canada
  • Clinical Research Site
    Bad Bentheim, NI 48455, Germany
  • Clinical Research Site
    Bochum, Northwest 44791, Germany
  • Clinical Research Site
    Kiel, SH 24105, Germany
  • Clinical Research Site
    Kiel, SH 24148, Germany
  • Clinical Research Site
    Schwerin, 19055, Germany
  • Clinical Research Site
    Budapest, BU 1036, Hungary
  • Clinical Research Site
    Debrecen, HB 4032, Hungary
  • Clinical Research Site
    Wrocław, DS 50-566, Poland
  • Clinical Research Site
    Wrocław, DS 51-318, Poland
  • Clinical Research Site
    Krakow, MA 30-510, Poland
  • Clinical Research Site
    Kraków, MA 31-147, Poland
  • Clinical Research Site
    Bialystok, PD 15-453, Poland
  • Clinical Research Site
    Katowice, SL 40-615, Poland
  • Clinical Research Site
    Lublin, 20-573, Poland
  • Clinical Research Site
    Szczecin, 70-332, Poland
  • Clinical Research Site
    Palma De Mallorca, PM 07120, Spain
  • Clinical Research Site
    Pontevedra, PO 36001, Spain
  • Clinical Research Site
    Manises, V 46940, Spain
  • Clinical Research Site
    Barcelona, 8036, Spain
09

References and documents

Study documents

  • Study protocol · Dec 13, 2023
  • Statistical analysis plan · Apr 4, 2024

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: Undecided

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Jun 3, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT05355805
Lead sponsor
ACELYRIN Inc.
Responsible party
Sponsor
First posted
May 2, 2022
Start date
May 5, 2022
Primary completion
Aug 2, 2023
Completion
Feb 21, 2024
Results posted
Sep 25, 2024
Last update
Jun 3, 2025

Study contacts

Donald Betah, MD
study director · ACELYRIN Inc.

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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