Adjunctive Orbital Radiation Therapy with Teprotumumab in Recalcitrant Thyroid Eye Disease: A Case Report.

Teprotumumab has demonstrated significant efficacy in active, moderate-to-severe thyroid eye disease; however, concerns remain regarding the durability of response, especially in high-risk patients with recalcitrant disease and risk of compressive optic neuropathy. Orbital radiation therapy has historically been shown to reduce the risk of vision loss from compressive optic neuropathy in muscle-predominant phenotypes, but its role in the biologic era remains unclear. We report a patient with recalcitrant, muscle-predominant thyroid eye disease with radiographic apical crowding who experienced repeated disease reactivations despite multiple courses of teprotumumab and immunomodulatory therapies. Following orbital radiation therapy, the patient demonstrated sustained orbital disease stabilization and resolution of compressive optic neuropathy despite recurrence of severe pretibial myxedema and elevated thyroid-stimulating antibodies. This case suggests that adjunctive orbital radiation therapy with teprotumumab may provide durable orbital disease control despite ongoing systemic reactivations and lower the risk of compressive optic neuropathy in high-risk recalcitrant thyroid eye disease, supporting its continued role as a disease-modifying adjunct in select patients.