P-126 Tocilizumab for Thyroid Eye Disease: A Case Study on Treatment Response and Outcomes

Abstract Introduction Thyroid eye disease (TED) is a chronic immune-mediated inflammatory disorder associated with thyroid dysfunction. It can lead to significant morbidity, including proptosis, diplopia, and optic neuropathy, requiring multidisciplinary management. While corticosteroids and surgical decompression remain mainstays of treatment, emerging biologic therapies such as tocilizumab have shown promise in refractory cases. Clinical Case A 50-year-old Algerian woman was referred to our hospital with a history of lid retraction, blurred vision, and itchy, painful, teary eyes. Laboratory tests revealed a suppressed TSH (0.02 mIU/L) and elevated free T4 (23.07 pmol/L). A Tc-99m sodium pertechnetate thyroid scan showed diffusely increased uptake (5.9%), confirming hyperthyroidism. She was diagnosed with TED secondary to thyrotoxicosis and managed by a multidisciplinary team, including ophthalmology and endocrinology. Initial treatment with carbimazole (15 mg daily) stabilized her thyroid function, but over eight months, she developed worsening TED, including bilateral exophthalmos (25 mm), restrictive myopathy, and unilateral optic neuropathy with diplopia in primary gaze. Intravenous methylprednisolone followed by a five-month oral corticosteroid taper improved soft tissue inflammation and optic neuropathy but failed to resolve proptosis and diplopia. She was referred for orbital decompression, but the oculoplastic surgeon recommended a trial of tocilizumab. She received six, weekly subcutaneous injections (164 mg, 328 mg, and 640 mg), leading to a reduction in exophthalmos (22 mm bilaterally), resolution of diplopia in primary gaze, and a decrease in her clinical activity score (CAS) from 7 to 4. Despite initial improvement, seven months post-treatment, her proptosis worsened (26 mm), and she developed exposure keratopathy. Persistent TED and failure to consistently achieve euthyroid status prompted a total thyroidectomy, after which she was maintained on 100 µg thyroxine, daily. However, her ophthalmic symptoms remained unchanged, and she is now awaiting orbital decompression. Conclusion This case highlights the challenges of managing severe TED and the potential role of tocilizumab in refractory cases. In this case, while biologic therapy led to short-term improvement, long-term disease control remained difficult, necessitating definitive surgical intervention. Further studies are needed to determine the optimal timing and patient selection for biologic treatments in TED.Figure 1:MRI orbit with contrastMRI orbit with contrast showing bilateral proptosis, bilateral intraocular muscle enlargement (in particular the medial, inferior and superior rectus muscles)