Teprotumumab Treatment in Patients with Steroid and Surgery-Resistant Dysthyroid Optic Neuropathy: A Case Series

Background: Dysthyroid optic neuropathy (DON) is a rare but serious complication of Graves' orbitopathy (GO) that can lead to permanent vision loss. In a previous study, medical and surgical treatment of DON according to EUGOGO guidelines resulted in partial or no recovery in 30% of patients. Insulin growth factor-1 receptor inhibitor teprotumumab has shown significant improvement of GO symptoms, but little is known about its effect on DON. The aim of this study was to evaluate the efficacy of teprotumumab in treating steroid- and surgery-resistant DON. Methods: This retrospective case series included 6 patients (8 eyes; median age 58 years) with confirmed DON resistant to steroids and orbital decompression (median duration of DON 2 months, interquartile range [IQR 2.0-6.5]) treated at the Hospices Civils de Lyon. Median time from the end of first-line treatment was 34.5 days (IQR: 8.0-61.7). The treatment protocol was 8 intravenous infusions of teprotumumab administered every 3 weeks. Definition of DON recovery was based on changes in best-corrected visual acuity (BCVA) and visual field mean deviation (VF-MD). Results: At the end of teprotumumab treatment, DON recovered in 7/8 (87.5%) of affected eyes, with BCVA improvement in all patients (median 0.30 logMAR [0.24-0.42], p = 0.004) and a median VF-MD improvement of 66% (46-90) (p = 0.024). In 3/6 patients, DON improved after one infusion. All patients showed improvements in clinical activity score and proptosis. Improvements persisted over the follow-up (median from first infusion, 73.8 weeks), with no DON relapse but inflammatory relapse in two patients. Due to adverse events, two patients did not complete all infusions. Conclusions: The data suggest teprotumumab as a promising treatment for steroid- and surgery-resistant DON with rapid symptom improvement and long-lasting recovery. However, these only preliminary results need to be better evaluated by specific clinical trials.