Mean Change From Baseline in High-Sensitivity C-Reactive Protein (hsCRP) at Day 28;Proportion of Participants Achieving American College of Rheumatology-50 (ACR50) Response;Proportion of Participants Achieving American College of Rheumatology-70 (ACR70) Response;Mean Change From Baseline in High-Sensitivity C-Reactive Protein (hsCRP) at Day 84;Mean Change From Baseline in Disease Activity Score Based on a 28 Joint Count High-Sensitivity C-Reactive Protein (DAS28-hsCRP) at Day 28 and 84;Proportion of Participants With Disease Activity Score- High Sensitivity C-Reactive Protein (DAS28-hsCRP) Value Less Than (<) 3.2;Proportion of Participants With Disease Activity Score- High Sensitivity C-Reactive Protein (DAS28-hsCRP) Value Less Than (<) 2.6;Change From Baseline in Erythrocyte Sedimentation Rate (ESR) at Day 28 and 84;Change From Baseline in Anti-cyclic Citrullinated Peptide (Anti-CCP) Antibody Levels at Day 28 and 84;Change From Baseline in Rheumatoid Factor (RF) at Day 28 and 84;Change From Baseline in Global Assessment of Disease Activity Based on Visual Analog Scale (VAS) Score at Day 84;Change From Baseline in Self-assessment of Pain Based on Visual Analog Scale (VAS) Score at Day 84;Change From Baseline in Self-assessment of Disability Using Health Assessment Questionnaire - Disability Index (HAQ-DI) Score at Day 84;Change From Baseline in Physician's Global Assessment of Disease Activity Scale Based on Visual Analog Scale (VAS) Score at Day 84;Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs);Number of Participants With Treatment Emergent Adverse Events (TEAEs) by Severity;Number of Participants With Grade 3 or Higher Clinically Significant Abnormality for Hematology, Biochemistry, Urinalysis or Coagulation;Number of Participants With Clinically Significant Vital Signs Abnormalities;Number of Participants With Clinically Significant 12-lead Electrocardiogram (ECG) Findings;Plasma Concentration of M2951;Area Under the Concentration-Time Curve From Time Zero to 6 Hours (AUC 0-6h) of M2951;Maximum Observed Plasma Concentration (Cmax) of M2951;Plasma Concentration Observed Immediately Before Dosing on Day 29 (Cpre) of M2951;Time to Reach Maximum Plasma Concentration (Tmax) of M2951;Accumulation Ratio for Area Under the Concentration-Time Curve From Time Zero to 6 Hours (Racc [AUC0-6h]) of M2951;Accumulation Ratio for Observed Maximum Plasma Concentration (Racc [Cmax]) of M2951;Absolute Immunoglobulin Levels at Day 85;Absolute Change From Baseline in Immunoglobulin Levels at Day 85;Absolute B-Cell Levels at Day 85;Absolute Change From Baseline in B-cell Levels at Day 85