ASAS40 response was defined as improvement of ≥ 40% relative to Baseline and absolute improvement of ≥ 20 units (on a scale from 0 to 100) in ≥ 3 of the following 4 domains with no deterioration (defined as a net worsening of > 0 units on a scale from 0 to 100) in the potential remaining domain:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none/0 hours) to 10 (very severe/2 hours or more duration).

Full analysis set. Participants with missing data at Week 12 were counted as non-responders (non-responder imputation).

ASAS20 response was defined as improvement of ≥ 20% relative to Baseline and absolute improvement of ≥ 10 units (on a scale from 0 to 100) in ≥ 3 of the following 4 domains with no deterioration (defined as a change for the worse of ≥ 20% and net worsening of ≥ 10 units) in the potential remaining domain:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none/0 hours) to 10 (very severe/2 hours or more duration).

Full analysis set; Non-responder imputation performed.

The Bath Ankylosing Spondylitis (AS) Disease Activity Index assesses disease activity by asking the participant to answer 6 questions (each on a 10 cm VAS) pertaining to symptoms experienced for the past week. For 5 questions (level of fatigue/tiredness, level of AS neck, back or hip pain, level of pain/swelling in joints, other than neck, back or hips, level of discomfort from any areas tender to touch or pressure, and level of morning stiffness), the response is from 0 (none) to 10 (very severe); for Question 6 (duration of morning stiffness), the response is from 0 (0 hours) to 10 (≥ 2 hours). The overall BASDAI score ranges from 0 to 10 cm. Lower scores indicate less disease activity. BASDAI50 is a 50% improvement from Baseline in BASDAI score.

Full analysis set; Non-responder imputation performed.

The Medical Outcome Study Short Form 36-Item Health Survey, Version 2 (SF-36) is a self-administered instrument that measures the impact of disease on overall quality of life. The SF-36 consists of 36 questions in 8 domains (limitations in physical functioning due to health problems; limitations in usual role because of physical health problems; bodily pain; general health perceptions; vitality; limitations in social functioning because of physical or emotional problems; limitations in usual role due to emotional problems; and general mental health). Two component scores can be summarized: physical and mental; domains 1-4 comprise the physical component summary of the SF-36. A transformed summary score is calculated ranging from 0 to 100 where higher scores indicate a higher level of functioning. A positive change from Baseline score indicates an improvement.

Full analysis set with available data

ASAS partial remission is an absolute score of < 20 units on a 0 to 100 scale for each of the four following domains:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none/0 hours) to 10 (very severe/2 hours or more duration).

Full analysis set; Non-responder imputation performed.

Adverse events were collected at designated study visits for all participants who received at least 1 dose of study drug. The number of participants experiencing any adverse event (serious and non-serious) is summarized.

All participants who received at least 1 dose of study drug. For the double-blind phase of the study, adverse events are reported through Week 12.

Blood was collected for analysis at designated study visits; hematology and chemistry results were provided by a central laboratory. The number of participants with an abnormal laboratory result (higher then upper normal limit or lower than lower normal limit) meeting Common Toxicity Criteria (CTC) of Grade 3 or higher is summarized.

All participants who received at least 1 dose of study drug. Results for the double-blind phase phase of the study are reported through Week 12.

ASAS5/6 response is a 20% improvement in five out of the following six domains:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none) to 10 (very severe/2 hours or more duration).
• Spinal mobility, measured from the lateral lumbar flexion score of the Bath AS Metrology Index (BASMI) on a scale from 0 (best mobility) to 10 (worst mobility);
• C-reactive protein level (lower levels indicate less inflammation).

Full analysis set; Non-responder imputation performed.

Health Assessment Questionnaire modified for spondyloarthropathies (HAQ-S) is a self-reported measure to assess the physical function and health-related quality of life. The Disability Index (DI) of HAQ-S is calculated as the mean of the following 8 category scores (range: 0 [without any difficulty] to 3 [unable to do]): Dressing and Grooming, Rising, Eating, Walking, Hygiene, Reach, Grip, and Activities. Five additional items in the functional status measure were included in the HAQ-S, including carrying heavy packages, sitting for long periods, able to work at a flat topped table, and (if the participant had a driver's license or a car) able to look in the rear view mirror and able to turn head to drive in reverse. The overall score ranges from 0 (no disability) to 3 (three very severe, high-dependency disability). Negative mean changes from Baseline in the overall score indicate improvement.

Full analysis set; participants with non-missing Baseline and at least one non-missing post-baseline values were included. Last observation carried forward was used.

C-reactive protein (CRP) is considered an efficacy variable for the axial spondyloarthritis indication. It is a general marker of inflammation that is sensitive to acute changes in inflammatory response. Higher levels indicate more inflammation.

Full analysis set; participants with non-missing Baseline and at least one non-missing post-baseline value were included. Last observation carried forward was used.

Six consecutive sacroiliac (SI) joint image coronal slices representing the largest proportion of the synovial compartment of the SI joints were assessed for edema, intensity and depth of edema using SPARCC scoring.

Each SI joint (left and right) was divided into quadrants for a total of 8 SI scoring locations. Each quadrant was scored for the presence (1) or absence (0) of edema; the maximum score is 8 per slice and maximum score for 6 SI joint slices is 48.

Intensity of edema: A score of 1 was assigned for each SI joint (left and right) if an intense signal was seen in any quadrant of that joint for each slice. The maximum score is 2 per slice and 12 for 6 slices.

A lesion was graded as deep (score of 1) if there was homogeneous and unequivocal increase in signal extending over a depth of at least 1 cm from the articular surface of the SI joint in any quadrant. The maximum score per slice is 2 and for 6 slices 12.

The total maximum score for all SI joints across 6 slices is 72.

Full analysis set; participants with non-missing Baseline and non-missing post-baseline value were included.

Six discovertebral units (DVU) representing the 6 most abnormal DVUs, and 3 consecutive sagittal slices at each DVU representing the most abnormal slices for that DVU were selected for scoring. Each DVU was divided into 4 quadrants and scored for the presence (1) or absence (0) of edema. The maximum score is 12 per DVU. The maximum score is 72 for 6 DVUs.

If edema was present in at least 1 quadrant of a DVU slice, it was scored for intensity and depth of the edema representing that slice:

A score of 1 was assigned if an intense signal was seen in any quadrant on a DVU slice. The maximum score for intensity per slice is 1, per DVU is 3 and for 6 DVUs is 18.

A lesion was graded as deep (score of 1) if there was homogeneous and unequivocal increase in signal extending over a depth of at least 1 cm from the surface of the endplate in any quadrant. The maximum score per slice is 1, for a DVU is 3 and for 6 DVUs is 18.

The total maximum SPARCC score for all 6 DVUs is 108.

Full analysis set; participants with non-missing Baseline and non-missing post-baseline value were included.

ASAS20 response was defined as improvement of ≥ 20% relative to Baseline and absolute improvement of ≥ 10 units (on a scale from 0 to 100) in ≥ 3 of the following 4 domains with no deterioration (defined as a change for the worse of ≥ 20% and net worsening of ≥ 10 units) in the potential remaining domain:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none/0 hours) to 10 (very severe/2 hours or more duration).

Full analysis set participants with available data at each time point (as indicated by N)

ASAS40 response was defined as improvement of ≥ 40% relative to Baseline and absolute improvement of ≥ 20 units (on a scale from 0 to 100) in ≥ 3 of the following 4 domains with no deterioration (defined as a net worsening of > 0 units on a scale of 0 to 100) in the potential remaining domain:

• Patient's Global Assessment of disease activity, measured on a visual analog scale (VAS) from 0 (none) to 100 (severe);
• Pain, measured by the total back pain VAS from 0 (no pain) to 100 (most severe);
• Function, measured by the Bath Ankylosing Spondylitis Functional Index (BASFI) which consists of 10 items assessing participants' ability to perform activities on a VAS ranging from 0 (easy) to 100 (impossible);
• Inflammation, measured by the mean of the 2 morning stiffness-related Bath AS Disease Activity Index (BASDAI) VAS scores (items 5 [level of stiffness] and 6 [duration of stiffness]) each on a scale from 0 (none/0 hours) to 10 (very severe/2 hours or more duration).

Full analysis set participants with available data at each time point (indicated by N)

The Bath Ankylosing Spondylitis (AS) Disease Activity Index assesses disease activity by asking the participant to answer 6 questions (each on a 10 cm VAS) pertaining to symptoms experienced for the past week. For 5 questions (level of fatigue/tiredness, level of AS neck, back or hip pain, level of pain/swelling in joints, other than neck, back or hips, level of discomfort from any areas tender to touch or pressure, and level of morning stiffness), the response is from 0 (none) to 10 (very severe); for Question 6 (duration of morning stiffness), the response is from 0 (0 hours) to 10 (≥ 2 hours). The overall BASDAI score ranges from 0 to 10 cm. Lower scores indicate less disease activity. BASDAI50 is a 50% improvement from Baseline in BASDAI score.

Full analysis set participants with available data at each time point (indicated by N)