An Adaptive Phase 2a/2b Study of LY3871801 in Adult Participants With Rheumatoid Arthritis

Who May Qualify: - Have a diagnosis of adult-onset RA for at least 3 months prior to screening as defined by the 2010 ACR/European League Against Rheumatism (EULAR) classification criteria. - Have moderately-to-severely active RA at screening and baseline, defined by the presence of - ≥6 swollen joints based on 66 joint count, and - ≥6 tender joints based on 68 joint count. - Have had a history of failure (an inadequate response, intolerance, or loss of response) to at least 1 conventional synthetic disease modifying anti rheumatic drug (csDMARD) and either 1 biologic (bDMARD), or targeted synthetic (tsDMARD) treatment. Who Should NOT Join This Trial: - Have Class IV RA according to ACR revised criteria - Have presence of 1 or more significant concurrent medical conditions per investigator judgment, including but not limited to - poorly controlled diabetes or hypertension - chronic kidney disease stage IIIa or IIIb, IV, or V - symptomatic heart failure according to New York Heart Association class II, III, or IV - myocardial infarction,unstable angina pectoris, stroke, or transient ischemic attack within the past 12 months before randomization - severe chronic pulmonary disease, for example, requiring oxygen therapy - major chronic inflammatory disease or connective tissue disease other than RA, including but not limited to - systemic lupus erythematosus - psoriatic arthritis - axial spondyloarthritis,including ankylosing spondylitis and non-radiographic axial spondyloarthritis - reactive arthritis - gout - scleroderma - polymyositis - dermatomyositis - active fibromyalgia, or - multiple sclerosis Always talk to your doctor about whether this trial is right for you.