A Study to Assess the Safety, Tolerability, and Efficacy of Namilumab in Participants With Active Cardiac Sarcoidosis

Inclusion Criteria: * Male or female age ≥18 years * Able and willing to provide written informed consent, which includes compliance with study requirements and restrictions listed in the consent form * History of documented sarcoidosis (must include histological confirmation, from any organ, in the subject's medical history or records) * Meet Heart Rhythm Society Cardiac Sarcoid Diagnostic Criteria (modified) * Female subjects must agree to use an approved highly effective birth control (BC) method * Male subjects must agree to, and attest that, female partners of childbearing potential are using one of the allowed highly effective methods of contraception * Body Mass Index (BMI) \<40 kg/m2 at Screening. * Vaccination for COVID-19 with completion of the primary series at least 2 weeks prior to randomization Exclusion Criteria: * Hospitalized for any respiratory or cardiac illness ≤30 days prior to Screening * Known pulmonary hypertension requiring therapy * Autoimmune disease other than sarcoidosis likely to require treatment during the subject's participation in this study * Symptoms and/or signs of extracardiac sarcoidosis that are likely to warrant treatment in addition to that required for the subject's cardiac disease * Estimated glomerular filtration rate (eGFR) ≤30 mL/min/1.73 m2 (Modification of Diet in Renal Disease \[MDRD\] equation) or requiring renal replacement therapy * Hemoglobin ≤9.5 g/dL * Participation in another interventional clinical trial within 6 mo…