A Study of RO7123520 to Evaluate the Safety and Efficacy in Participants With Moderately To Severely Active Rheumatoid Arthritis (RA) Who Are Inadequately Responding to Anti-Tumor Necrosis Factor (TNF)-Alpha Therapy

This is a Phase IIa/b double-blind, placebo-controlled, randomized, parallel group, multicenter study to evaluate the safety and efficacy of RO7123520 as adjunctive therapy in participants with RA who are inadequately responding to standard-of-care (methotrexate and anti-TNF-alpha therapy). Part 1 of the study will evaluate safety. Part 2 will evaluate efficacy and safety. Part 3 will evaluate dose-ranging efficacy. Participants will have the option of continuing to the extension period of the study.