A Study to Evaluate the Efficacy and Safety of Bimekizumab in Adult Korean Study Participants With Moderate to Severe Plaque Psoriasis

The Investigator's Global Assessment measures the overall psoriasis severity following a 5-point scale (0-4), where scale 0= Clear, no signs of psoriasis; post-inflammatory hyperpigmentation may be present, scale 1= Almost clear, no thickening; normal to pink coloration; no to minimal focal scaling, scale 2= Mild, just detectable to mild thickening, pink to light red coloration and predominately fine scaling, scale 3= Moderate, clearly distinguishable to moderate thickening; dull to bright red; moderate scaling and scale 4= Severe, severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. IGA 0/1 response was defined as clear \[0\] or almost clear \[1\] with at least a two-category improvement from Baseline.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PASI90 response assessments are based on a 90% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (Non responder imputation (NRI)).

The PHQ-9 is a multipurpose instrument for screening, diagnosing, monitoring, and measuring the severity of depression. The PHQ-9 score ranges from 0 to 27 with higher scores indicating a worse state. A score of 5 to 9 is considered to be minimal symptoms of depression. A score of 10 to 14 is considered minor depression, dysthymia, or mild major depression. A score of 15 to 19 is considered to indicate moderately severe major depression, and a score ≥20 is considered to be severe major depression. Change from Baseline is derived as post-Baseline score minus Baseline score, where a positive change indicates worsening and a negative change indicates improvement.

Time frame: Baseline, Week 16

Population: The Safety Set consisted of all study participants that received at least 1 dose of the IMP. Study participants with missing data at Week 16 were imputed using LOCF.

The Investigator's Global Assessment measures the overall psoriasis severity following a 5-point scale (0-4), where scale 0= Clear, no signs of psoriasis; post-inflammatory hyperpigmentation may be present, scale 1= Almost clear, no thickening; normal to pink coloration; no to minimal focal scaling, scale 2= Mild, just detectable to mild thickening, pink to light red coloration and predominately fine scaling, scale 3= Moderate, clearly distinguishable to moderate thickening; dull to bright red; moderate scaling and scale 4= Severe, severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. IGA 0 response (Clear) is defined as clear \[0\] with at least a two-category improvement from Baseline.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PSD (P-SIM) was designed for use as a daily diary to collect data about the experience of participants with moderate to severe psoriasis related to the severity of signs, symptoms or impacts, at their worst during the past 24 hours, on a 0-10 point numeric rating scale (NRS) where 0 (no symptoms/impact) and 10 (very severe symptoms/worst impact). It consists of 14 items measuring: redness, scaling, cracking, lesions, thickening, itch, pain, burning, dryness, irritation, sensitivity, fatigue, embarrassment and choice of clothing. A weekly score for each item (including itch) is obtained as an average of daily values for the considered item over the 7 days preceding the visit (weekly score range: 0 (no itch)-10 (very severe itch)). Itch response was defined as a reduction from baseline to Week 16 of at least 4 points on the PSD itch weekly score.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. The denominator when calculating the percentage of participants with a response to the PSD itch item is the number of participants with a baseline itch score \>=4 and the numerator is the number of participants with a PSD response for itch at Week 16. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PSD (P-SIM) was designed for use as a daily diary to collect data about the experience of participants with moderate to severe psoriasis related to the severity of signs, symptoms or impacts, at their worst during the past 24 hours, on a 0-10 point NRS where 0 (no symptoms/impact) and 10 (very severe symptoms/worst impact). It consists of 14 items measuring: redness, scaling, cracking, lesions, thickening, itch, pain, burning, dryness, irritation, sensitivity, fatigue, embarrassment and choice of clothing. A weekly score for each item (including pain) is obtained as an average of daily values for the considered item over the 7 days preceding the visit (weekly score range: 0 (no pain)-10 (very severe pain)). Pain response was defined as a reduction from baseline to Week 16 of at least 4 points on the PSD pain weekly score.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. The denominator when calculating the percentage of participants with a response to the PSD pain item is the number of participants with a baseline pain score \>=4 and the numerator is the number of participants with a PSD response for pain at Week 16. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PSD (P-SIM) was designed for use as a daily diary to collect data about the experience of participants with moderate to severe psoriasis related to the severity of signs, symptoms or impacts, at their worst during the past 24 hours, on a 0-10 point numeric rating scale (NRS) where 0 (no symptoms/impact) and 10 (very severe symptoms/worst impact). It consists of 14 items measuring: redness, scaling, cracking, lesions, thickening, itch, pain, burning, dryness, irritation, sensitivity, fatigue, embarrassment and choice of clothing. A weekly score for each item (including scaling) is obtained as an average of daily values for the considered item over the 7 days preceding the visit (weekly score range: 0 (no scaling)-10 (very severe scaling)). Scaling response was defined as a reduction from baseline to Week 16 of at least 4 points on the PSD scaling weekly score.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. The denominator when calculating the percentage of participants with a response to the PSD scaling item is the number of participants with a baseline scaling score \>=4 and the numerator is the number of participants with a PSD response for scaling at Week 16. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PASI100 response assessments are based on a 100% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

The PASI75 response assessments are based on at least 75% improvement in the PASI score from Baseline. This is a scoring system that averages the redness, thickness, and scaliness of the psoriatic lesions (on a 0-4 scale), and weights the resulting score by the area of skin involved. Body divided into 4 areas: head, arms, trunk to groin, and legs to top of buttocks. Assignment of an average score for the redness, thickness, and scaling for each of the 4 body areas with a score of 0 (clear) to 4 (very marked). Determining the percentage of skin covered with PSO for each of the body areas and converting to a 0 to 6 scale. Final PASI= average redness, thickness, and scaliness of the psoriatic skin lesions, multiplied by the involved psoriasis area score of the respective section, and weighted by the percentage of the person's affected skin for the respective section. The minimum possible PASI score is 0= no disease, the maximum score is 72= maximal disease.

Time frame: Week 4

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP) prior to their Week 4 PASI assessment or who had missing data at Week 4 are counted as non-responders (NRI).

The DLQI is a skin disease-specific questionnaire aimed at the evaluation of how symptoms and treatment affect study participants' health related quality of life (QOL). This instrument asks study participants about symptoms and feelings, daily activities, leisure, work and school, personal relationships, and treatment. It has been shown to be valid and reproducible in study participants with PSO. The DLQI total score ranges from 0 to 30, with higher scores indicating lower health related QOL. A 4-point change in the DLQI total score has been reported to be meaningful for the study participant (within-participant minimal important difference); while a DLQI total score of 0 or 1 indicates no impact of the skin disease on participant's life.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

Participants with scalp involvement at Baseline were defined as those with a scalp IGA score \>0 at Baseline. Scalp lesions were assessed in terms of clinical signs of redness, thickness, and scaliness using a 5-point scale (0=Clear, 1=Almost Clear, 2=Mild, 3=Moderate, 4= Severe). Scalp IGA response 0/1 at Week 16 was defined as clear (0) or almost clear (1) with at least a 2-category improvement from Baseline to Week 16.

Time frame: Week 16

Population: Randomized Set consisted of all randomized study participants. Here, Number of Participants analyzed reflect those with a scalp IGA Baseline score \>=2. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are counted as non-responders (NRI).

An adverse event is any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of IMP, whether or not considered related to the IMP. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of IMP. TEAEs were defined as those AEs that have a start date on or following the first dose of IMP through the end of the time at risk.

Time frame: From Baseline to End of Safety Follow-Up (up to Week 32)

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

An adverse event is any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of IMP, whether or not considered related to the IMP. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of IMP. TEAEs were defined as those AEs that have a start date on or following the first dose of investigational medicinal product (IMP) through the end of the time at risk.

Time frame: From Baseline to End of Safety Follow-Up (SFU) (up to Week 32)

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

A serious adverse event (SAE) is any untoward medical occurrence that at any dose: 1) Results in death 2) Is life-threatening 3) Requires in participant hospitalisation or prolongation of existing hospitalisation 4) Resulted in persistent disability/incapacity 5) Is a congenital anomaly or birth defect 6) Other important medical events which based on medical or scientific judgement may jeopardise the participants, or may require medical or surgical intervention to prevent any of the above.

Time frame: From Baseline to End of Safety Follow-Up (up to Week 32)

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

The Total BSA affected by PSO was entered as a percentage from 0 to 100.

Time frame: Baseline, Week 16

Population: Randomized Set consisted of all randomized study participants. Study participants with an intercurrent event (discontinuation of IMP prior to Week 16) or who had missing data at Week 16 are imputed using last observation carried forward (LOCF).