A Study to Evaluate the Long-Term Safety and Efficacy of Bimekizumab in Subjects With Psoriatic Arthritis

An adverse event (AE) is any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product, which does not necessarily have a causal relationship with this treatment. An AE could therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product. TEAEs were defined as events with onset date on or after the start date of study medication in PA0009.

Time frame: From Entry Visit of PA0009 until Safety Follow-Up Visit (up to Week 120)

Population: The Safety Set (SS) consisted of all study participants who had given informed consent for PA0009 and had received at least one dose of study medication in PA0009.

A serious adverse event (SAE) was any untoward medical occurrence that at any dose resulted in death, life-threatening, significant or persistent disability/incapacity, congenital anomaly/birth defect, important medical event, initial inpatient hospitalization or prolongation of hospitalization.

Time frame: From Entry Visit of PA0009 until Safety Follow-Up Visit (up to Week 120)

Population: The SS consisted of all study participants who had given informed consent for PA0009 and had received at least one dose of study medication in PA0009.

The MASES is an index that measures the severity (ie, intensity and extent) of enthesitis through the assessment of 13 entheses (bilateral costochondral 1, costochondral 7, anterior superior iliac spine, posterior iliac spine, iliac crest and proximal insertion of the Achilles tendon sites, and the fifth lumbar vertebral body spinous process). Each item was scored as 0 = not tender or 1 = tender and then were summed for a possible score of 0 to 13, with higher scores indicating worse enthesitis. If 7 or more items were available, MASES was calculated by dividing the summed score with the number of assessments and multiplying the result by 13. If less than 7 items were available, MASES was treated as missing.

Time frame: Baseline of PA0008, Week 48

Population: Subset of study participants in the FAS with Enthesitis at PA0008 Baseline (MASES\>0).

Presence of dactylitis was assessed using the LDI basic which evaluated for a greater than or equal to (\>=) 10% difference in the circumference of the digit compared to the opposite digit and was then multiplied by the tenderness score, using a simple grading system (0=absent, 1=present). The results from each digit with dactylitis were summed to produce a final score. For the final score, the minimum value for LDI is zero and there is no maximum value. A low score indicates less dactylitis symptoms. A score of zero is considered dactylitis free. Observed values have been reported in this outcome measure.

Time frame: Baseline of PA0008, Week 48

Population: Subset of study participants in the FAS with Dactylitis at PA0008 Baseline (LDI\>0).

An adverse event (AE) is any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product, which does not necessarily have a causal relationship with this treatment. An AE could therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product.

Time frame: From Entry Visit of PA0009 until Safety Follow-Up Visit (up to Week 120)

Population: The SS consisted of all study participants who had given informed consent for PA0009 and had received at least one dose of study medication in PA0009.

The ACR20 response rate was based on 20% or greater improvement relative to Baseline of PA0008 in the following measures: Tender Joint Count (TJC) based on 78 joints, Swollen Joint Count (SJC) based on 76 joints; 3 of the 5 remaining core set measures: Disease activity as assessed by Patient's Global Assessment of Disease Activity (PGADA), Disease activity as assessed by Physician's Global Assessment of Disease Activity (PhGADA), Pain as assessed by Patient's Assessment of Arthritis Pain (PtAAP), Physical function as assessed by Health Assessment Questionnaire - Disability Index (HAQ-DI), Acute phase response as assessed by high sensitivity C-reactive protein (hs CRP). Participants for whom ACR could not be derived due to missing data were counted as non-responders as per NRI analysis.

Time frame: Baseline of PA0008, Week 48

Population: The Full Analysis Set (FAS) consisted of all enrolled participants who received at least 1 dose of study medication in PA0009 and had a valid measurement for at least 1 efficacy variable after PA0009 entry visit.

The ACR50 response rate was based on 50% or greater improvement relative to Baseline of PA0008 in the following measures: TJC based on 78 joints, SJC based on 76 joints; 3 of the 5 remaining core set measures: Disease activity as assessed by PGADA, Disease activity as assessed by PhGADA, Pain as assessed by PtAAP, Physical function as assessed by HAQ-DI, Acute phase response as assessed by hs CRP. Participants for whom ACR could not be derived due to missing data were counted as non-responders as per NRI analysis.

Time frame: Baseline of PA0008, Week 48

Population: The FAS consisted of all enrolled participants who received at least 1 dose of study medication in PA0009 and had a valid measurement for at least 1 efficacy variable after PA0009 entry visit.

The ACR70 response rate was based on 70% or greater improvement relative to Baseline of PA0008 in the following measures: TJC based on 78 joints, SJC based on 76 joints; 3 of the 5 remaining core set measures: Disease activity as assessed by PGADA, Disease activity as assessed by PhGADA, Pain as assessed by PtAAP, Physical function as assessed by HAQ-DI, Acute phase response as assessed by hs CRP. Participants for whom ACR could not be derived due to missing data were counted as non-responders as per NRI analysis.

Time frame: Baseline of PA0008, Week 48

Population: The FAS consisted of all enrolled participants who received at least 1 dose of study medication in PA0009 and had a valid measurement for at least 1 efficacy variable after PA0009 entry visit.

The PASI75 response assessments are based on at least 75% improvement in the PASI score from Baseline of PA0008. 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 percentage of skin covered with psoriasis (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. For the Final score, minimum possible PASI value is 0= no disease, maximum value is 72= maximal disease. Missing PASI responses were imputed using least observation carried forward (LOCF) for any visits where the corresponding BSA has not increased compared to the preceding visit.

Time frame: Baseline of PA0008, Week 48

Population: Subset of study participants in FAS with body surface area (BSA) affected by psoriasis of \>=3% at PA0008 Baseline.

The PASI90 response assessments are based on at least 90% improvement in the PASI score from Baseline of PA0008. 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 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. For the final score, minimum possible PASI value is 0= no disease, maximum value is 72= maximal disease. Missing PASI responses were imputed using LOCF for any visits where the corresponding BSA has not increased compared to the preceding visit.

Time frame: Baseline of PA0008, Week 48

Population: Subset of study participants in FAS with BSA affected by psoriasis of \>=3% at PA0008 Baseline.