A Phase 1b Open-label Study to Evaluate Safety of Plamotamab in Participants With Rheumatoid Arthritis

Inclusion Criteria: Adult participants with moderately to severely active RA. * Documented diagnosis of RA and meeting the 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for RA at least 3 months prior to screening * Inadequate response to, loss of response to, or intolerance to available RA therapies. * Stable doses of RA medications prior to screening * Use of highly effective methods of contraception Exclusion Criteria: * Major surgery within 12 weeks prior to screening or planned within 12 months after dosing * Recurrent infections or active clinically significant infection * Active or untreated latent tuberculosis * Cancer or history of cancer or lymphoproliferative disease within the previous 5 years * Uncontrolled cardiovascular, pulmonary, renal, hepatic, endocrine, or gastrointestinal disease Note: Additional, more specific inclusion/exclusion criteria are defined in the protocol.