A Study of LY3541860 in Adult Participants With Moderately to Severely Active Rheumatoid Arthritis

Inclusion Criteria: * Have a diagnosis of adult-onset Rheumatoid Arthritis (RA) for at least 3 months prior to screening, as defined by the 2010 ACR/EULAR classification criteria. * Have moderately to severely active RA, at screening (Visit 1) and baseline (Visit 2), defined by the presence of * ≥6 swollen joints based on 66 joint count (and ≥4 swollen joints on 28 joint count), and * ≥6 tender joints based on 68 joint count (and ≥4 tender joints on 28 joint count). * Have active synovitis in ≥1 joint, in hands or wrists, of the investigator choosing at screening, having an MRI synovitis RAMRIS score of ≥2 as determined from the central reading of the images. Exclusion Criteria: * Have a diagnosis or history of malignant disease within 5 years prior to baseline, with the exceptions of * basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for 3 years, or * cervical carcinoma in situ, with no evidence of recurrence within the 5 years prior to baseline. * Have estimated glomerular filtration rate (eGFR) of \<45 milliliter per minute (mL/minute) from serum creatinine using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation. * Have a current or recent active infection. * 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 S…