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Purpose Teprotumumab, a monoclonal antibody targeted against the insulin-like growth factor 1 (IGF-1) receptor is a newly effective treatment with FDA approval to improve active moderate to severe thyroid eye disease (TED) by decrease Clinical Activity Score (CAS), proptosis and improve extraocular muscles movement. There are several adverse events related to the patients who were treated with teprotumumab such as hearing loss, hyperglycemia, muscle cramps and inflammatory bowel disease. Geriatric patients always tend to experience more adverse drug reactions. This study will focus on adverse events of teprotumumab in advanced age active thyroid eye disease patients.

Methods A retrospective cohort study was conducted by reviewing the chart of active thyroid eye disease patients who are more than 75 years old at Byers Eye Institute, Stanford University from 2020 until 2022. Demographic data were reviewed for age, sex, underlying diseases and smoking status. Thyroid hormone status, treatment of thyroid dysfunction, CAS, proptosis, severity of disease, number of total infusion of teprotumumab, adverse events and all hospital visits 6 months after last dose of teprotumumab were collected.

Results There were 8 patients with active thyroid eye disease included in this study (age 75-92 years old). There were only 37.5% of patients could complete 8 infusions of teprotumumab. The earliest adverse event was recorded after first infusion. The most common adverse reaction was hearing loss or tinnitus (62.5%). Other adverse events include muscle cramps (50%), hair loss (37.5%), hyperglycemia (25%), memory loss (25%), abnormalities in urinary tract system (12.5%), mood disorder (12.5%), weight loss (12.5%), rash with infusion (12.5%), hyponatremia (12.5%), proctitis (12.5%) and dry skin (12.5%). There was one patient experienced 8 adverse events after 4 infusions of teprotumumab and had to terminate the treatment. All of the active TED patients responded well to the medication as CAS decrease to 0-1 score.

Conclusions Teprotumumab which is an efficient medication for thyroid eye disease can lead to several adverse events in advanced age patient. Due to small numbers of geriatrics patients in each institute, we need more studies for better understanding of adverse events and efficacy of this novel medication. In a meanwhile, patient education, awareness of doctors and patients and close follow up for adverse events is recommended.