A Study to Assess the Efficacy and Safety of RO7790121 in Participants With Moderate to Severe Rheumatoid Arthritis Who Have Not Responded to or Who Cannot Tolerate Tumor Necrosis Factor (TNF) and/or Janus Kinase (JAK Inhibitors)

Inclusion Criteria:

• Has moderate to severe active RA defined by the presence of >=6 swollen joints and >=6 tender joints at screening and baseline (based on 66/68-joint count)

• Diagnosis of RA for >=3 months and also fulfills the 2010 American College ofRheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR)classification criteria for RA

• Demonstrated an inadequate response or loss of response to or intolerance to >=1conventional synthetic disease-modifying antirheumatic drug (csDMARD)

Exclusion Criteria:

• Have failed more than two TNF inhibitors or JAK inhibitors

• Class IV RA according to ACR revised response criteria (Hochberg et al. 1992)

• Past or current use of other biologic disease-modifying antirheumatic drugs (bDMARDs) (excluding TNF inhibitors) or rituximab

• Treatment with investigational therapy within 4 weeks or within 5 half-lives of theinvestigational therapy, whichever is longer, prior to initiation of studytreatment.

• History of any arthritis with onset prior to age 17 years or current diagnosis ofinflammatory joint disease other than RA

• Has been treated with intra-articular, intramuscular, intravenous, trigger point ortender point, intra-bursa, or intra-tendon sheath corticosteroids in the preceding 8weeks prior to the first dose of study drug

• History of a severe allergic reaction or anaphylactic reaction or knownhypersensitivity to any component of the study drug (or its excipients) and/or otherproducts in the same class

• Any major surgery within 6 weeks prior to screening or a major surgery plannedduring the study

• Any serious, chronic and/or unstable pre-existing medical, psychiatric, or other-condition

• History of malignancy, with the exception non-metastatic basal cell or cutaneoussquamous cell cancer adequately treated with electrodesiccation and curettage orresection or in situ cervical cancer adequately treated and cured

• Participants with severe chronic or recurrent viral, bacterial, parasitic, or fungalinfections

• History of active hepatitis B virus (HBV), hepatitis C virus (HCV), or humanimmunodeficiency virus (HIV) infection

• History of organ transplant

• Any identified confirmed congenital or acquired immunodeficiency

• Abnormal laboratory values and liver function test