Integrated, pooled efficacy data from the phase 2 and phase 3 OPTIC trials of teprotumumab (Horizon Therapeutics) found that the treatment led to significant reductions in inflammation, proptosis (eye bulging) and diplopia (double vision) in patients with active thyroid eye disease (TED). 

Teprotumumab is an investigational fully human monoclonal antibody that works by inhibiting the insulin-like growth factor 1 receptor (IGF-1R). The two trials included 171 patients with recent onset of TED (less than 9 months) compared with placebo. Patients were treated with either teprotumumab or placebo every 3 weeks for a total of 8 infusions.

Findings from the pooled analysis showed that at week 24, 77.4% of patients treated with teprotumumab experienced a ≥2mm reduction in proptosis with a mean change from baseline of -2.63mm, compared with 14.9% of patients in the placebo group who had a mean change from baseline of -0.31mm (P <.001). The teprotumumab group also had a statistically significant greater diplopia responder rate, defined as the percentage of patients with an improvement of ≥1 grade, of 69.7% compared with 30.5% in placebo (P <.001).

In addition, the teprotumumab group had greater improvements at week 24 from baseline, in the Graves’ Ophthalmology Quality of Life (GO-QoL) Scale vs placebo (15.55 vs 5.92, respectively; P <.001), including visual functioning (16.81 vs 6.10; P <.001) and appearance (13.51 vs 5.78; P =.002). 

Teprotumumab demonstrated a similar profile in both studies with no new safety observations. Investigators determined the only drug-related adverse event in the phase 2 trial was hyperglycemia. Other adverse events included nausea, diarrhea, muscle spasms, hearing impairment, and inflammatory bowel disease in a patient with a recent diagnosis of ileitis and colitis.

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“We are excited by the positive effects demonstrated in the areas that matter most to patients – proptosis, double vision and quality of life – and we are excited about the potential teprotumumab has to be the first FDA-approved treatment for thyroid eye disease,” said Shao-Lee Lin, MD, PhD, and chief scientific officer at Horizon.

Teprotumumab was granted Priority Review by the Food and Drug Administration in September 2019 with a Prescription Drug User Fee Act (PDUFA) date of March 8, 2020.

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