To determine the recurrence and reactivation rates after teprotumumab therapy for active thyroid eye disease.

Retrospective consecutive case series.

This was a study of all patients followed for active thyroid eye disease at the Cole Eye Institute, Cleveland Clinic, treated with teprotumumab between May 2020 and May 2021. Patients with less than 6 months follow-up after completion of infusions were excluded. The primary outcome measure was reactivation, defined as a regression in proptosis (increase of ≥2 mm in either eye and to within ≤2 mm of pre-treatment level and Clinical Activity Score [CAS] worsening of 2 points or greater). Secondary outcome was diplopia response.

A total of 21 patients were included in the study. The average long-term improvement in proptosis in the eye with more proptosis after teprotumumab was 1.57mm (range, –3 to 4 mm). Of the 17 initial responders, there were 8 reactivations (47%) and 2 isolated proptosis regressions (12%); Overall, 7 of 21 patients (33%) responded throughout the study period. Average time to regression was 12.25 months (range, 2-22.5 months). There was no statistically significant change in diplopia at final visit in any subgroup (P = 0.68 to >.99).

At most, 33% of patients demonstrate continued response 2 years after teprotumumab treatment. The proptosis and CAS regression occurs in the setting of disease reactivation in 80% of regressions. Teprotumumab treatment appears to offer minimal long-term improvement in diplopia.