A Study to Evaluate the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Satralizumab in Participants With Thyroid Eye Disease

The purpose of this study is to assess the efficacy, safety, pharmacokinetics, and pharmacodynamics of subcutaneous (SC) satralizumab, a recombinant, humanized anti-interleukin-6 (IL-6) receptor monoclonal antibody, in participants with thyroid eye disease (TED).

Inclusion Criteria: \- Clinical diagnosis of TED based on CAS Exclusion Criteria: * Decrease in CAS or proptosis of \>= 2 points or \>= 2 mm, respectively, in the study eye between Screening and Study Baseline (Day 1) * Requiring immediate surgical ophthalmological intervention or planning corrective surgery or irradiation during the course of the study, in the judgment of the investigator * Identified pre-existing ophthalmic disease that, in the judgment of the investigator, would preclude study participation or complicate interpretation of study results, including corneal decompensation unresponsive to medical management and including ophthalmic diseases that will likely require prohibited therapy during the study * Any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes an individual's safe participation in and completion of the study * Pregnant or breastfeeding, or intention of becoming pregnant during the study or within 3 months after the final dose of satralizumab