Teprotumumab is a monoclonal antibody primarily used in the treatment of thyroid eye disease (TED), a debilitating autoimmune condition associated with Graves’ disease. It targets the insulin-like growth factor 1 receptor (IGF-1R) on orbital fibroblasts, inhibiting signaling pathways that drive inflammation, adipogenesis, and tissue expansion behind the eyes. By blocking IGF-1R, teprotumumab reduces pro-inflammatory cytokines, glycosaminoglycan production, and fat accumulation, leading to clinical improvements such as reduced proptosis (eye bulging), diplopia (double vision), and overall disease activity. The antibody has demonstrated significant efficacy in clinical trials, with patients showing rapid and sustained improvement in signs and symptoms of TED, often within 24 weeks of treatment. It is administered intravenously and is particularly beneficial for patients with active, moderate-to-severe disease. Due to its targeted mechanism, teprotumumab offers a disease-modifying approach rather than just symptomatic relief, representing a major advancement in the management of TED.