TEAEs were events that had a start date on or after the first administration of study treatment in PS0018 until the last received dose of investigational medicinal product (IMP) +140 days [which covered the 20-week Safety Follow-Up (SFU) Visit]. The number of TEAEs adjusted by duration of exposure to study treatment was scaled such that it provides an incidence rate per 100 patient-years. If a participant had multiple events, the time of exposure was calculated to the first occurrence of the adverse event (AE) being considered. If a participant had no events, the total time at risk was used.

The Safety Set consisted of all participants who received at least 1 dose of the study medication in PS0018.

Plasma concentration of Bimekizumab was expressed in micrograms per milliliter (μg/mL). Values Below Limit of Quantification (BLQ) were replaced by value of Lower Limit of Quantification (LLOQ) divided by 2 (=0.075 μg/mL) in calculations of Means and Coefficient of Variations (CVs). Means and CVs were only calculated if at least 2/3 of the concentrations were quantified at the respective timepoint.

The Pharmacokinetics Per-Protocol Set consisted of all enrolled participants who received at least 1 dose of the study medication and provided at least 1 quantifiable plasma concentration postdose in PS0018. Here, 'number analyzed' signifies participants who were evaluable at specified time points.

For a given visit / time point, an Anti-BKZ status of positive was concluded for any participant with an anti-drug antibody (ADA) level that was above cut point (ACP) and CP at that visit/ time point. A participant was classified as overall positive if at least one PS0018 measurement is ACP and CP (this included participants who had negative results at PS0016 Baseline). Percentages were based on the number of participants with a non-missing measurement, from samples that did not contain BKZ concentration levels above the drug tolerance, at the visit. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Safety Set consisted of all participants who received at least 1 dose of the study medication in PS0018.

For a given visit / time point, an Anti-BKZ status of positive was concluded for any participant with an anti-drug antibody (ADA) level that was above cut point (ACP) and CP at that visit/ time point. A participant was classified as overall positive if at least one PS0018 measurement is ACP and CP (this included participants who had negative results at PS0016 Baseline). Percentages were based on the number of participants with a non-missing measurement, from samples that did not contain BKZ concentration levels above the drug tolerance, at the visit. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Safety Set consisted of all participants who received at least 1 dose of the study medication in PS0018. The number of participants analyzed reflects participants with a non-missing measurement.

The PASI quantifies the severity and extent of the disease and weighs these with the percentage of body surface area (BSA) involvement. The degree of involvement is estimated across 4 body areas; head, upper limbs, trunk, and lower limbs and then transferred into a grade. The Investigator assessed the average redness, thickness, and scaliness of lesions in each body area (each on a 5 - point scale); 0 = none, 1 = slight, 2 = moderate, 3 = marked, and 4 = very marked. The PASI score ranges from 0 to 72 with a higher score indicating increased disease severity. The PASI50 responses were based on at least 50% improvement in the PASI score at the Baseline of PS0016. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and had a valid efficacy measurement for PASI at Baseline of PS0018.

The PASI quantifies the severity and extent of the disease and weighs these with the percentage of body surface area (BSA) involvement. The degree of involvement is estimated across 4 body areas; head, upper limbs, trunk, and lower limbs and then transferred into a grade. The Investigator assessed the average redness, thickness, and scaliness of lesions in each body area (each on a 5 - point scale); 0 = none, 1 = slight, 2 = moderate, 3 = marked, and 4 = very marked. The PASI score ranges from 0 to 72 with a higher score indicating increased disease severity. The PASI75 responses were based on at least 75% improvement in the PASI score at the Baseline of PS0016. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and had a valid efficacy measurement for PASI at Baseline of PS0018.

The PASI quantifies the severity and extent of the disease and weighs these with the percentage of body surface area (BSA) involvement. The degree of involvement is estimated across 4 body areas; head, upper limbs, trunk, and lower limbs and then transferred into a grade. The Investigator assessed the average redness, thickness, and scaliness of lesions in each body area (each on a 5 - point scale); 0 = none, 1 = slight, 2 = moderate, 3 = marked, and 4 = very marked. The PASI score ranges from 0 to 72 with a higher score indicating increased disease severity. The PASI90 responses were based on at least 90% improvement in the PASI score at the Baseline of PS0016. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and had a valid efficacy measurement for PASI at Baseline of PS0018.

The PASI quantifies the severity and extent of the disease and weighs these with the percentage of body surface area (BSA) involvement. The degree of involvement is estimated across 4 body areas; head, upper limbs, trunk, and lower limbs and then transferred into a grade. The Investigator assessed the average redness, thickness, and scaliness of lesions in each body area (each on a 5 - point scale); 0 = none, 1 = slight, 2 = moderate, 3 = marked, and 4 = very marked. The PASI score ranges from 0 to 72 with a higher score indicating increased disease severity. The PASI100 responses were based on 100% improvement in the PASI score at the Baseline of PS0016. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and had a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0=Clear to 4=Severe. The response was defined as clear [0] or almost clear [1] with at least 2 category improvement from PS0016 Baseline. Clear was defined as no signs of PSO; post-inflammatory hyperpigmentation may be present. Almost clear was defined as no thickening; normal to pink coloration; no to minimal focal scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

The total PASI score ranges from 0 to 72 with a reduction from PS0016 Baseline indicating improvement. Missing data was imputed using Last observation carried forward (LOCF) at all visits. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A negative percentage change from PS0016 baseline indicated improvement in Total PASI score. The total PASI score ranges from 0 to 72 with a reduction from PS0016 Baseline indicating improvement. Missing data was imputed using Last Observation Carried Forward (LOCF) at all visits. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Moderate IGA was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Clear IGA was defined as no signs of PSO; post-inflammatory hyperpigmentation may be present. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Moderate IGA was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Almost clear was defined as no thickening; normal to pink coloration; no to minimal focal scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Moderate IGA was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Mild was defined as just detectable to mild thickening; pink to light red coloration; predominately fine scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Moderate IGA was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Moderate IGA was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Severe was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Severe IGA was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Clear was defined as no signs of PSO; post-inflammatory hyperpigmentation may be present. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Severe IGA was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Almost clear was defined as no thickening; normal to pink coloration; no to minimal focal scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Severe IGA was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Mild was defined as just detectable to mild thickening; pink to light red coloration; predominately fine scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Severe IGA was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Moderate was defined as clearly distinguishable to moderate thickening; dull to bright red, clearly distinguishable to moderate thickening; moderate scaling. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

A static IGA for Psoriasis (PSO) was used to assess disease severity in all study participants during the study. IGA is a 5 point scale ranging from 0 = Clear to 4 = Severe. Severe IGA was defined as severe thickening with hard edges; bright to deep dark red coloration; severe/coarse scaling covering almost all or all lesions. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

The BSA palm method was used for the evaluation of BSA as follows: Body surface area estimation used the palm (study participant's flat hand and thumb together, fingers included) as representing around 1% of the total BSA. Missing data was imputed using Last Observation Carried forward (LOCF) at all visits. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

The percentage BSA (0 to 100%) affected by PSO was listed by PS0016 randomized treatment, by study participant and visit including the percentage change from PS0016 Baseline. The BSA palm method was used for the evaluation of BSA as follows: Body surface area estimation used the palm (study participant's flat hand and thumb together, fingers included) as representing around 1% of the total BSA. Missing data was imputed using Last observation carried forward (LOCF) at all visits. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

HADS-A score is the sum of the 7 individual scores in the anxiety domain and ranges from 0 to 21 with higher scores indicating worse state. A score below 8 was considered normal whereas a score of 15 and above was considered severe. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

HADS-D score is the sum of the 7 individual scores in the depression domain and ranges from 0 to 21 with higher scores indicating worse state. A score below 8 was considered normal whereas a score of 15 and above was considered severe. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018.

HADS-A score is the sum of the 7 individual scores in the anxiety domain and ranges from 0 to 21 with higher scores indicating worse state. A score below 8 was considered normal. Percentages were based on the number of participants with a non-missing measurement at the visit. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018. Here, 'number analyzed' signifies participants who were evaluable at specified time points.

HADS-D score is the sum of the 7 individual scores in the depression domain and ranges from 0 to 21 with higher scores indicating worse state. A score below 8 was considered normal. Percentages were based on the number of participants with a non-missing measurement at the visit. Baseline was defined as the last available value prior to the first injection of study medication in the PS0016 study.

The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the study medication and have a valid efficacy measurement for PASI at Baseline of PS0018. Here, 'number analyzed' signifies participants who were evaluable at specified time points.