Testing Experimental Treatment of Rheumatoid Arthritis

This is a Phase 3, randomized, multicenter, double-blind study to assess the safety and efficacy of GSK3196165 in combination with conventional synthetic disease modifying antirheumatic drugs (csDMARD[s]) or the treatment of adult participants with moderate to severe active rheumatoid arthritis (RA) who have had an inadequate response to biologic disease-modifying antirheumatic drugs (bDMARD[s]) and/or Janus Kinase (JAK) inhibitors. The study will consist of a screening phase of up to 6 weeks followed by 24 week treatment phase in which participants will be randomized in ratio of 6:6:6:1:1:1 to GSK3196165 150 mg subcutaneously (SC) weekly,GSK3196165 90 mg SC weekly, sarilumab 200 mg SC every other week or placebo (three arms) respectively, all in combination with background csDMARD(s). At Week 12, participants in the three placebo arms will switch from placebo to active intervention (either GSK3196165 150 mg SC weekly, GSK3196165 90 mg SC weekly, or sarilumab 200 mg SC every other week). Following the treatment phase, there will be a safety follow-up visit at Week 34 for those participants who do not continue into the long term-extension study.