A Study to Evaluate the Long Term Safety and Efficacy of Bimekizumab in Subjects With Ankylosing Spondylitis

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) Is a congenital anomaly or birth defect 5) Is an infection that requires treatment with parenteral antibiotics 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 Entry Visit (Visit 1) until Safety Follow Up (up to Week 224)

Population: The Safety Set consisted of all participants in the enrolled set who received at least one dose of study medication in AS0009.

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. Treatment emergent adverse events were defined as those events with onset date on or after the first administration of study medication in AS0009 and on or before 140 days after the final study medication administration.

Time frame: From Entry Visit (Visit 1) until Safety Follow Up (up to Week 224)

Population: The Safety Set consisted of all participants in the enrolled set who received at least one dose of study medication in AS0009.

BASDAI is a validated self-reported instrument, which consisted of 6 questions to measure the disease activity of ankylosing spondylitis (AS) from the participant's perspective. It measured the severity of fatigue, spinal and peripheral joint pain and swelling, enthesitis, and morning stiffness (both severity and duration). Each question was rated using a numerical rating scale from 0 (none) to 10 (very severe), higher score=high disease activity. The BASDAI score was calculated by computing the mean of questions 5 and 6 and adding it to the sum of questions 1 to 4. This score was then divided by 5. The total BASDAI score was ranged from 0=none to 10= very severe, where higher score indicated high disease activity. A negative value indicated improvement and a positive value indicated worsening.

Time frame: Baseline of AS0008, Week 48 (AS0009)

Population: The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the IMP and had a valid measurement for at least 1 efficacy variable at AS0009 study entry.

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. Treatment emergent adverse events were defined as those events with onset date on or after the first administration of study medication in AS0009 and on or before 140 days after the final study medication administration.

Time frame: From Entry Visit (Visit 1) until Safety Follow Up (up to Week 224)

Population: The Safety Set consisted of all participants in the enrolled set who received at least one dose of study medication in AS0009.

The ASAS20 response was defined as relative improvements of at least 20% and absolute improvement of at least 1 unit on a 0 to 10 NRS, where 0 is not active and 10 is very active in at least 3 of the 4 domains: PGADA (score ranged from 0 (not active) to 10 (very active), Pain assessment (total spinal pain NRS score) (assessed on a scale of 0 (no pain) to 10 (severe pain)), Function (BASFI) (score ranged from 0 (easy) to 10 (impossible)), Inflammation (mean of BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) (score ranged from 0 (none) to 10 (very severe) and no worsening at all in the remaining domain. Participants for whom ASAS could not be derived due to missing data were counted as non-responders.

Time frame: Baseline of AS0008, Week 48 (AS0009)

Population: The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the IMP and had a valid measurement for at least 1 efficacy variable at AS0009 study entry. Both Non-responder imputation and observed case analysis (imputation methods) have been reported in this outcome measure. Here, Number analyzed signifies those participants evaluable at specified categories.

The ASAS40 response was defined as relative improvements of at least 40% and absolute improvement of at least 2 units on a 0 to 10 Numeric Rating Scale (NRS), where 0 is not active and 10 is very active in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PGADA) (score ranged from 0 (not active) to 10 (very active), Pain assessment (total spinal pain NRS score) (assessed on a scale of 0 (no pain) to 10 (severe pain)), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)) (score ranged from 0 (easy) to 10 (impossible)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) (score ranged from 0 (none) to 10 (very severe) and no worsening at all in the remaining domain. Participants for whom ASAS could not be derived due to missing data were counted as non-responders.

Time frame: Baseline of AS0008, Week 48 (AS0009)

Population: The Full Analysis Set consisted of all enrolled participants who received at least 1 dose of the IMP and had a valid measurement for at least 1 efficacy variable at AS0009 study entry. Both Non-responder imputation and observed case analysis (imputation methods) have been reported in this outcome measure. Here, Number analyzed signifies those participants evaluable at specified categories.