SAT-376 Alemtuzumab-Induced Thyroid Eye Disease: Case Series

Abstract Disclosure: O.P. Olujide: None. D.M. Kombo: None. A.E. Cook: None. S.S. Dhage: None. Introduction and background: Alemtuzumab, a humanised monoclonal antibody targeting CD52 glycoprotein found on most mature leukocytes, is used in the treatment of relapsing-remitting multiple sclerosis (MS). It significantly reduces relapse rate and disability progression in both treatment-naive patients and those on disease modifying drugs. Due to its immunomodulatory effects, Alemtuzumab is associated with the development of secondary autoimmunity, with thyroid disease the most common, affecting approximately 30% of patients. Among those with thyroid dysfunction, Graves' disease accounts for up to 70% of cases, while Alemtuzumab-induced thyroid eye disease (AI-TED) is less frequently observed. AI-TED is an inflammatory condition associated with antibody-mediated activation of the thyroid-stimulating hormone receptor (TSHR) in orbital tissues. It has been reported in approximately 14% of patients with Alemtuzumab-induced Graves' disease, although it can also occur independently. Case presentation and Discussion: We reviewed two patients who developed AI-TED between 1-3 years after treatment. The average clinical activity score (CAS) on presentation was 3/7, which also represented the peak score during the active phase of the disease. Both patients were treated with lubricant eye drops, selenium, and intravenous methylprednisolone, with one requiring Mycophenolate Mofetil (MMF) and Azathioprine as second-line agents before achieving remission. We discussed the diagnosis and treatment, along with a review of relevant literature to aid in understanding and managing this condition. Conclusion: As the use of Alemtuzumab in managing MS increases, the incidence of Al-TED is likely to rise. Al-TED can develop several years after treatment, necessitating a high index of suspicion for timely diagnosis, particularly in cases of mild disease. The potential for significant morbidity in moderate to severe TED underscores the importance of early recognition and appropriate treatment. Presentation: Saturday, July 12, 2025