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Teprotumumab shows promise in treating chronic-low clinical activity score thyroid eye disease

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Teprotumumab can significantly improve proptosis in patients with chronic thyroid eye disease (TED) who have low levels of inflammation, according to new data presented at ENDO 2023.

This is the first time positive results have been observed in patients with longstanding TED.

The randomized, placebo-controlled trial enrolled patients who had TED for 2-10 years, with either inactive disease or no progression in proptosis, diplopia, or new symptoms for over a year. Patients had a baseline clinical activity score (CAS) of 1 or less, and had experienced an increase in proptosis of  ≥ 3mm before TED or from normal levels. Additionally, the patients had to be euthyroid or mildly hypo/hyperthyroid, with no prior teprotumumab treatment or steroid use within 3 weeks of screening.

Teprotumumab or a placebo were administered every 3 weeks for a total of 21 weeks. The primary endpoint was the improvement in proptosis compared to baseline at week 24, as compared to the placebo group. Secondary endpoints included proptosis responders (those with at least a 2mm improvement), diplopia responders (those with at least a 1-grade improvement on the Gorman scale), and improvement in quality of life measures using the Graves’ Ophthalmopathy-QoL (GO-QoL) visual function and appearance subscales. The study also assessed treatment-emergent adverse events (TEAE) and adverse events of special interest.

The study included 62 patients, with 42 receiving teprotumumab and 20 receiving the placebo. The mean duration of TED was 5.2 years, and 87.1% of the participants were never or former smokers. At baseline, the mean proptosis was 24.4mm, the mean CAS was 0.4, and approximately 29% of patients had diplopia with a mean score of around 2.

The results of the study demonstrated significant improvements in proptosis in the teprotumumab group compared to the placebo group. At week 24, the proptosis improvements from baseline were significantly greater in the teprotumumab group (2.41mm) compared to the placebo group (0.92mm). Proptosis response was observed in 62% of the teprotumumab patients compared to 25% of the placebo group. Diplopia improvement was also seen in the teprotumumab group, with 43% experiencing improvement and 29% achieving complete resolution. Moreover, the teprotumumab group showed significantly greater improvement in visual function on the GO-QoL scale compared to the placebo group.

The safety profile of teprotumumab was found to be comparable to previous reports, with similar proportions of treatment-emergent adverse events observed in both groups. Some adverse events of special interest included hyperglycemia and hearing impairment, which occurred in both the teprotumumab and placebo groups

Douglas RS, et al. Efficacy And Safety Results From The Randomized, Placebo-controlled Multicenter Trial With Teprotumumab In Chronic-Low Clinical Activity Score Thyroid Eye Disease Patients. Presented at: ENDO 2023.