Study to Assess Safety and Effectiveness of Branebrutinib Treatment in Participants With Active Systemic Lupus Erythematosus or Primary Sjögren's Syndrome, or Branebrutinib Treatment Followed by Open-label Abatacept Treatment in Study Participants With Active Rheumatoid Arthritis

mCLASI response is defined as a decrease of ≥ 50% from baseline mCLASI activity score, in participants with a baseline mCLASI activity score ≥ 10, at Week 24. Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

To be considered as meeting the second criterion, the CS (prednisone or equivalent) dose had to remain stable and ≤ 10 mg from Week 16 until Week 24.

The modified CLASI (mCLASI) is defined as the activity portions of CLASI that describe skin erythema and scale/hypertrophy and inflammation of the scalp. The percentage of patients who entered the study with a positive mCLASI activity score (≥ 10) and who achieved a ≥ 50% decrease from baseline at Week 24 is considered to likely represent a clinically meaningful improvement. The scores are calculated by simple addition based on the extent of the symptoms.

mCLASI: Modified Cutaneous Lupus Erythematosus Disease Area and Severity Index

Composite response is defined as the percent of participants with at least 3 of the following at Week 24:

• Decrease of ≥ 1 point or 15% from baseline in the ESSPRI Total Score
• Decrease of ≥ 3 points from baseline in ESSDAI score
• Decrease of ≥ 25% from baseline in ocular staining score, or if normal score at baseline no change to abnormal
• Increase of ≥ 25% from baseline in stimulated salivary flow
• Improvement in one or more serological markers (rheumatoid factor (RF), immunoglobulin G protein (IgG), complement C3 or C4, cryoglobulin).

ACR50 response is defined as both improvement of 50% in the number of tender and swollen joints and a 50% improvement in 3 of the following 5 criteria:

• Subject global assessment (SGA)
• Physician global assessment (PGA)
• Functional ability measure
• Pain visual analog scale (VAS)
• Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).

Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

The SLEDAI-2K is a global index providing a total score of overall disease activity ranging from 0 to 105, with higher scores representing more active disease. The SLEDAI index includes 24 items divided into 9 organ systems: neurological, musculoskeletal, renal, mucocutaneous, general, heart, respiratory, vascular, and hematological. Each item is scored based on the severity of the symptom or finding, with higher scores indicating more severe disease activity. The weighted scores for each item range from 0 to 8. To calculate the SLEDAI-2K score, the scores for each of the 24 items are added together.

Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

BILAG-based composite lupus assessment (BICLA) response is defined as:

• At least one gradation of improvement in baseline BILAG scores in all body systems with moderate or severe disease activity at entry
• No new BILAG A or more than one new BILAG B scores
• No worsening of total SLEDAI score from baseline
• No significant deterioration (< 10%) in PGA and
• No treatment failure (initiation of nonprotocol treatment).

BILAG scores: A (severe disease), B (moderate), C (mild), or D (no activity). Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

The Disease Activity Score-28-C-Reactive Protein (DAS28CRP) is a composite outcome assessment that measures: 1) How many joints in the hands, wrists, elbows, shoulders, and knees are swollen and/or tender over a total of 28, 2) CRP in the blood to measure the degree of inflammation, and 3) SGA of disease activity.

DAS28-CRP scores range from 1.0 to 9.4, where lower scores indicate less disease activity. The results are combined to produce the DAS28-CRP score, which correlates with the extent of disease activity:

< 2.6: Disease remission 2.6 - 3.2: Low disease activity 3.2 - 5.1: Moderate disease activity > 5.1: High disease activity

A negative change from baseline in DAS28-CRP indicates an improvement. Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

The Disease Activity Score Erythrocyte Sedimentation Rate - DAS28ESR is a composite outcome assessment that measures:

• How many joints in the hands, wrists, elbows, shoulders, and knees are swollen and/or tender over a total of 28
• ESR in the blood to measure the degree of inflammation
• SGA of disease activity

DAS28-ESR scores range from 1.0 to 9.4, where lower scores indicate less disease activity. The results are combined to produce the DAS28-ESR score, which correlates with the extent of disease activity:

< 2.6: Disease remission 2.6 - 3.2: Low disease activity 3.2 - 5.1: Moderate disease activity > 5.1: High disease activity

A negative change from baseline in DAS28-ESR indicates an improvement. Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

The Simplified Disease Activity Index (SDAI) is the sum of the tender joint score (range 0 to 28), the swollen joint score (range 0 to 28), the subject global assessment (SGA) of disease activity (range 0 to 10 in increments of 0.5), the PGA of disease activity (range 0 to 10 in increments of 0.5), and C-reactive protein (CRP) test result. Baseline values are defined as the last nonmissing value prior to the first dose of study treatment. A SDAI score ranges from 0 (disease remission) to 86 (high disease activity).

The Clinical Disease Activity Index (CDAI) is the sum of the tender joint score (range 0 to 28), the swollen joint score (range 0 to 28), the SGA of disease activity (range 0 to 10 in increments of 0.5), and the PGA of disease activity (range 0 to 10 in increments of 0.5). Baseline values are defined as the last nonmissing value prior to the first dose of study treatment. A CDAI score ranges from 0 to 76.

The interpretation of CDAI is as follows:

0.0 - 2.8: Disease remission 2.9 - 10.0: Low disease activity (LDA) 10.1 - 22.0: Moderate disease activity 22.1 - 76.0: High disease activity

ACR20 defined as both improvement of 20% in the number of tender and swollen joints and a 20% improvement in 3 of the following 5 criteria:

• Subject global assessment (SGA)
• Physician global assessment (PGA)
• Functional ability measure
• Pain visual analog scale (VAS)
• Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).

Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.

ACR70 is defined as both improvement of 70% in the number of tender and swollen joints and a 70% improvement in 3 of the following 5 criteria:

• Subject global assessment (SGA)
• Physician global assessment (PGA)
• Functional ability measure
• Pain visual analog scale (VAS)
• Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).

Baseline values are defined as the last nonmissing value prior to the first dose of study treatment.