Trial Outcomes & Findings for A Study to Assess the Pharmacokinetics, Safety, and Efficacy of Two Doses of Bimekizumab in Adolescent Study Participants With Moderate to Severe Plaque Psoriasis (NCT NCT04718896)

Last Updated: 2026-05-18

Results Overview

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 0. PK-PPS = Pharmacokinetic per-protocol set, IMP = investigational medicinal product.

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

41 participants

Primary outcome timeframe

Baseline (Week 0)

Results posted on

2026-05-18

Participant Flow

The study started to enroll participants in April 2021 and concluded in March 2025.

The Participant Flow refers to the Randomized Set (RS).

Participant milestones

Participant milestones
Measure	BKZ Dose A (320/160 mg) Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Initial Treatment Period: Weeks 0-20 STARTED	20	21
Initial Treatment Period: Weeks 0-20 COMPLETED	19	21
Initial Treatment Period: Weeks 0-20 NOT COMPLETED	1	0
Open-Label Extension: Weeks 20-104 STARTED	19	20
Open-Label Extension: Weeks 20-104 COMPLETED	17	19
Open-Label Extension: Weeks 20-104 NOT COMPLETED	2	1

Reasons for withdrawal

Reasons for withdrawal
Measure	BKZ Dose A (320/160 mg) Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Initial Treatment Period: Weeks 0-20 Lack of Efficacy	1	0
Open-Label Extension: Weeks 20-104 Lack of Efficacy	0	1
Open-Label Extension: Weeks 20-104 Consent withdrawn by participant (not due to AE)	1	0
Open-Label Extension: Weeks 20-104 The patient left to study in the USA	1	0

Baseline Characteristics

A Study to Assess the Pharmacokinetics, Safety, and Efficacy of Two Doses of Bimekizumab in Adolescent Study Participants With Moderate to Severe Plaque Psoriasis

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=21 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.	Total n=41 Participants Total of all reporting groups
Age, Continuous	15.1 years STANDARD_DEVIATION 1.9 • n=11 Participants	14.6 years STANDARD_DEVIATION 2.0 • n=9 Participants	14.8 years STANDARD_DEVIATION 1.9 • n=20 Participants
Age, Customized 12 - <18 years	20 Participants n=11 Participants	21 Participants n=9 Participants	41 Participants n=20 Participants
Sex: Female, Male Female	11 Participants n=11 Participants	13 Participants n=9 Participants	24 Participants n=20 Participants
Sex: Female, Male Male	9 Participants n=11 Participants	8 Participants n=9 Participants	17 Participants n=20 Participants
Race/Ethnicity, Customized Black	1 Participants n=11 Participants	0 Participants n=9 Participants	1 Participants n=20 Participants
Race/Ethnicity, Customized White	19 Participants n=11 Participants	21 Participants n=9 Participants	40 Participants n=20 Participants
Race/Ethnicity, Customized Hispanic or Latino	0 Participants n=11 Participants	1 Participants n=9 Participants	1 Participants n=20 Participants
Race/Ethnicity, Customized Not Hispanic or Latino	20 Participants n=11 Participants	20 Participants n=9 Participants	40 Participants n=20 Participants

PRIMARY outcome

Timeframe: Baseline (Week 0)

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=19 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=20 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 0	NA microgram per milliliter (µg/mL) Geometric Coefficient of Variation NA Geometric mean and coefficient of variation (CV) could not be calculated at Baseline (Week 0), as the blood sample was collected prior to the first dose of BKZ (i.e., pre-dose), and the measured BKZ concentration was below the limit of quantification (BLQ; \<0.25 µg/mL).	NA microgram per milliliter (µg/mL) Geometric Coefficient of Variation NA Geometric mean and CV could not be calculated at Baseline (Week 0), as the blood sample was collected prior to the first dose of BKZ (i.e., pre-dose), and the measured BKZ concentration was below the limit of quantification (BLQ; \<0.25 µg/mL).

PRIMARY outcome

Timeframe: Week 1

Blood samples were collected to determine the bimekizumab plasma concentration at Week 1.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=20 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 1	21.145 µg/mL Geometric Coefficient of Variation 33.510	3.811 µg/mL Geometric Coefficient of Variation 30.424

PRIMARY outcome

Timeframe: Week 4

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 4.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=19 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 4	11.718 µg/mL Geometric Coefficient of Variation 35.259	1.986 µg/mL Geometric Coefficient of Variation 22.888

PRIMARY outcome

Timeframe: Week 8

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 8.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=19 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 8	16.344 µg/mL Geometric Coefficient of Variation 39.386	2.562 µg/mL Geometric Coefficient of Variation 91.934

PRIMARY outcome

Timeframe: Week 12

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 12.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=19 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=20 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 12	19.312 µg/mL Geometric Coefficient of Variation 38.235	2.600 µg/mL Geometric Coefficient of Variation 89.916

PRIMARY outcome

Timeframe: Week 16

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 16.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=19 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=20 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 16	20.163 µg/mL Geometric Coefficient of Variation 41.323	2.560 µg/mL Geometric Coefficient of Variation 99.017

PRIMARY outcome

Timeframe: Week 20

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 20.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=19 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=19 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 20	21.579 µg/mL Geometric Coefficient of Variation 38.806	2.689 µg/mL Geometric Coefficient of Variation 99.146

PRIMARY outcome

Timeframe: Week 40

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. Open-label set (OLS) consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 40.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=18 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=19 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 40	20.404 µg/mL Geometric Coefficient of Variation 48.700	3.354 µg/mL Geometric Coefficient of Variation 115.576

PRIMARY outcome

Timeframe: Week 64

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. OLS consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 64.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=18 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=19 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 64	23.177 µg/mL Geometric Coefficient of Variation 42.505	3.339 µg/mL Geometric Coefficient of Variation 106.934

PRIMARY outcome

Timeframe: Week 88

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. OLS consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 88.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=17 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=17 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 88	20.342 µg/mL Geometric Coefficient of Variation 42.584	2.928 µg/mL Geometric Coefficient of Variation 107.926

PRIMARY outcome

Timeframe: Week 112

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. OLS consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 112.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=17 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=17 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 112	18.770 µg/mL Geometric Coefficient of Variation 50.422	3.017 µg/mL Geometric Coefficient of Variation 109.444

PRIMARY outcome

Timeframe: Week 124

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. OLS consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 124.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=15 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=18 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Week 124	17.495 µg/mL Geometric Coefficient of Variation 40.714	3.104 µg/mL Geometric Coefficient of Variation 107.492

PRIMARY outcome

Timeframe: Week 140 (SFU)

Population: PK-PPS consisted of all randomized participants who received at least 1 dose of IMP and provided at least 1 quantifiable plasma concentration post-dose without important protocol deviations that would affect concentration. OLS consisted of all study participants who received at least 1 dose of study medication at or after Week 20 in OLE Period (including Week 20 dose). Here, number of participants analyzed signifies participants who were evaluable for this outcome measure.

Blood samples were collected prior to the scheduled dose to determine the bimekizumab plasma concentration at Week 140 (SFU).

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=17 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=17 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Plasma Concentration of Bimekizumab at Safety Follow up (SFU)	0.762 µg/mL Geometric Coefficient of Variation 166.309	NA µg/mL Geometric Coefficient of Variation NA Geometric mean and CV could not be calculated as the SFU visit occurred approximately 20 weeks after the final BKZ dose and based on the t 1/2 of BKZ, more than one-third of the samples collected at this visit had measured BKZ concentrations below the limit of quantification (BLQ; \<0.25 µg/mL).

SECONDARY outcome

Timeframe: From day of first dose (Week 0) through 20 weeks after final dose of IMP (up to Week 140)]

Population: The Safety Set (SS) consisted of all participants that received at least 1 dose of the IMP.

An adverse event (AE) is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of IMP, whether or not considered related to the IMP. Treatment-emergent AEs are defined as those AEs that started date on or following the first dose of IMP through the final dose of IMP +20 weeks. The last dose was given 4 weeks prior end of extension period.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=21 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Percentage of Participants With Treatment-emergent Adverse Events (TEAEs)	85.0 percentage of participants	81.0 percentage of participants

SECONDARY outcome

Timeframe: From day of first dose (Week 0) through 20 weeks after final dose of IMP (up to Week 140)

Population: The Safety Set consisted of all participants that received at least 1 dose of the IMP.

An serious adverse event (SAE) must meet 1 or more of the following criteria: Results in death; Is life-threatening; Requires inpatient hospitalization or prolongation of existing hospitalization; Results in persistent disability/incapacity; Is a congenital anomaly/birth defect; Important medical event that, based upon appropriate medical judgment, may jeopardize the patient or subject and may require medical or surgical intervention to prevent 1 of the other outcomes listed in the definition of serious. Treatment-emergent AEs are defined as those AEs that started date on or following the first dose of IMP through the final dose of IMP +20 weeks. The data was rounded to one decimal place. The last dose was given 4 weeks prior end of extension period.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=21 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Percentage of Participants With Serious Treatment-emergent Adverse Events	10.0 percentage of participants	14.3 percentage of participants

SECONDARY outcome

Timeframe: From day of first dose (Week 0) through 20 weeks after final dose of IMP (up to Week 140)

Population: The Safety Set consisted of all participants that received at least 1 dose of the IMP.

An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of IMP, whether or not considered related to the IMP. Treatment-emergent AEs are defined as those AEs that started date on or following the first dose of IMP through the final dose of IMP +20 weeks. This measure considers any TEAE leading to permanent discontinuation of IMP regardless of reason. The last dose was given 4 weeks prior end of extension period.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=21 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Percentage of Participants With Treatment-emergent Adverse Events (TEAEs) Leading to Discontinuation of Investigational Medicinal Product (IMP)	5.0 percentage of participants	0 percentage of participants

SECONDARY outcome

Timeframe: From day of first dose (Week 0) through 20 weeks after final dose of IMP (up to Week 140)

Population: The Safety Set consisted of all participants that received at least 1 dose of the IMP.

An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of IMP, whether or not considered related to the IMP. Treatment-emergent AEs are defined as those AEs that started date on or following the first dose of IMP through the final dose of IMP +20 weeks. This measure considers any TEAEs leading to withdrawal from the study. The last dose was given 4 weeks prior end of extension period.

Outcome measures

Outcome measures
Measure	BKZ Dose A (320/160 mg) n=20 Participants Participants received bimekizumab dose A subcutaneously (SC) based on baseline body weight during the 20-weeks initial treatment period (ITP); participants greater than or equal to (\>=) 65 kilogram (kg) received 320 milligram (mg) every 4 weeks (Q4W), and participants less than (\<) 65 kg received 160 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an investigator' s global assessment (IGA) response less than equal to (≤) 2 continued bimekizumab treatment at the same dose (BKZ Dose A) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65 kg boundary at 2 consecutive weight assessments.	BKZ Dose B (64/32 mg) n=21 Participants Participants received bimekizumab dose B SC based on baseline body weight during the 20-weeks ITP; participants \>= 65 kg received 64 mg Q4W, and participants \< 65 kg received 32 mg Q4W. Participants who completed the initial treatment period, tolerated the treatment, and achieved an IGA response ≤ 2 continued bimekizumab treatment at the same dose (BKZ Dose B) in the open label extension (OLE) Period (104 weeks). A participant's weight-categorized dose was changed during the OLE Period after assessment of weight change by the Investigator at a scheduled clinic visit and if the participant's weight crossed the 65kg boundary at 2 consecutive weight assessments.
Percentage of Participants With Treatment-emergent Adverse Events (TEAEs) Leading to Withdrawal From the Study	0 percentage of participants	0 percentage of participants

SECONDARY outcome

Timeframe: From day of first dose (Week 0) through 20 weeks after final dose of IMP (up to Week 140)

Population: The Safety Set consisted of all participants that received at least 1 dose of the IMP.

Selected safety topics of interest (including infection \[serious, opportunistic, fungal, and tuberculosis (TB)\], inflammatory bowel disease \[IBD\], and injection site reactions) with onset occurring from day of first dose through 20 weeks after final dose of IMP adjusted by duration of participant exposure to IMP. The exposure-adjusted incidence rate (EAIR) is defined as the number of participants (n) with a specific AE adjusted for the exposure and was scaled to 100 participant-years. The last dose was given 4 weeks prior end of extension period.