A Study Investigating the Efficacy and Safety of BGB-45035 Versus Placebo in Adults With Moderate to Severe Active Rheumatoid Arthritis

The ACR20 is defined as at least 20% improvement in the ACR core set values as defined below. Participants must meet 3 conditions for improvement from Baseline:

1. ≥ 20% improvement in 68-tender joint count;
2. ≥ 20% improvement in 66-swollen joint count; and
3. ≥ 20% improvement in at least 3 of the 5 following parameters:

• Physician global assessment of disease activity
• Patient global assessment of disease activity
• Patient assessment of pain
• Health Assessment Questionnaire - Disability Index (HAQ-DI)
• High-sensitivity C-reactive protein (hsCRP).

The ACR50 is defined as at least 50% improvement in the ACR core set values as defined below. Participants must meet 3 conditions for improvement from Baseline:

1. ≥ 50% improvement in 68-tender joint count;
2. ≥ 50% improvement in 66-swollen joint count; and
3. ≥ 50% improvement in at least 3 of the 5 following parameters:

• Physician global assessment of disease activity
• Patient global assessment of disease activity
• Patient assessment of pain
• Health Assessment Questionnaire - Disability Index (HAQ-DI)
• High-sensitivity C-reactive protein (hsCRP).

The ACR70 is defined as at least 70% improvement in the ACR core set values as defined below. Participants must meet 3 conditions for improvement from Baseline:

1. ≥ 70% improvement in 68-tender joint count;
2. ≥ 70% improvement in 66-swollen joint count; and
3. ≥ 70% improvement in at least 3 of the 5 following parameters:

• Physician global assessment of disease activity
• Patient global assessment of disease activity
• Patient assessment of pain
• Health Assessment Questionnaire - Disability Index (HAQ-DI)
• High-sensitivity C-reactive protein (hsCRP).

The TJC 68 is an assessment of tenderness or pain in 68 joints. Sixty-eight joints will be assessed for tenderness/pain by an independent, blinded assessor. The response to pressure/motion on each joint is assessed using the following scale: Present/Absent/Not Done/Not Applicable. A lower score indicates there is less pain or tenderness present, while a higher score indicates more pain or tenderness is present.

The SJC 66 is an assessment of swelling in 66 joints. Sixty-six joints will be assessed for swelling by an independent, blinded assessor. The swelling present in each joint is assessed using the following scale: Present/Absent/Not Done/Not Applicable. A lower score indicates there is less swelling present, while a higher score indicates more swelling is present.

The PhGADA_VAS is a single item that asks the physician to assess the participant's current disease activity on a 0- to 100-mm visual analog scale (VAS), with anchors of 0 = "no disease activity" and 100 = "extremely active disease."

The simplified disease activity index (SDAI) is a composite measure that sums the total number of:

• 28 tender joint counts,
• 28 swollen joint counts,
• Patient's Global Assessment of Disease Activity measured on a VAS from 0 to 10 where 0= lowest disease activity and 10 = highest;
• Physician's Global Assessment of Disease Activity measured on a VAS from 0 to 10, where 0 = lowest disease activity and 10 = highest, and
• C-reactive protein (CRP) in mg/dL. The SDAI score ranges from 0 to approximately 86 where lower scores indicate less disease activity.

The Clinical Disease Activity Index (CDAI) is a composite index that is calculated as the sum of the:

• 28 tender joint count (TJC),
• 28 swollen joint count (SJC),
• Patient's Global Assessment of Disease Activity measured on a VAS from 0 to 10 where 0 = lowest disease activity and 10 = highest;
• Physician's Global Assessment of Disease Activity (measured on a VAS from 0 to 10 where 0 = lowest disease activity and 10 = highest).

The CDAI score ranges from 0 to 76 where lower scores indicate less disease activity.

The PaGADA_VAS is a single item that asks the patient to rate the current severity of their disease activity on a 0- to 100-mm VAS, with anchors of 0 = "no disease activity" and 100 = "extremely active disease."

The Participants's global assessment of arthritis pain (VAS) is a single item that asks the patient to rate the current severity of their pain in relation to their RA on a 0- to 100-mm VAS, with anchors of "no pain" and "worst possible pain."

The HAQ-DI is a patient-reported questionnaire that is commonly used in RA to measure disease-associated disability (assessment of physical function). Participants answer 24 questions using a scale from 0 to 3 to score difficulty when performing daily activities over the past week (0 = without any difficulty, 1 = with some difficulty, 2 = with much difficulty, and 3 = unable to do). Scores on each task are averaged to provide an overall score ranging from 0 to 3, where zero represents no disability and three represents very severe, high-dependency disability.

Number of participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs), including findings from laboratory tests