Horizon Therapeutics has enrolled the first subject in the Phase IV clinical trial of Tepezza for the treatment of chronic (inactive) thyroid eye disease (TED).
The first-ever medicine to obtain the US Food and Drug Administration (FDA), Tepezza is intended for treating TED, a critical, progressive and possibly vision-threatening rare autoimmune disease.
TED starts with an acute (active) phase in which inflammatory signs and symptoms, including eye pain; swelling; proptosis or eye bulging; and diplopia or double vision, advances over time.
The randomised, double-masked, placebo-controlled, parallel-group, multicentre trial will assess the efficacy, safety and tolerability of Tepezza versus placebo to treat chronic TED patients.
It will enrol 60 adult subjects aged 18 years and have had a preliminary initial diagnosis of TED for a minimum of three years and under eight years.
The participants will be categorised in a 2:1 ratio to receive an infusion of either Tepezza or a placebo.
At first infusion, subjects will receive 10mg/kg followed by 20mg/kg seven times once every three weeks, totalling eight infusions.
The change from baseline at week 24 in proptosis in the study eye will be the trial’s primary efficacy goal.
The proptosis responder rate, diplopia responder rate, change in orbital pain, muscle volume and in the Graves’ Ophthalmopathy Quality of Life questionnaire appearance and visual functioning subscales, will also be assessed.
Proptosis non-responders, who have concluded the therapy period, can choose to be part of the open-label extension period in which subjects will receive another eight infusions of Tepezza.
Horizon research and development executive vice-president Elizabeth Thompson said: “Thyroid eye disease is complex and changes over time, presenting unique challenges at every stage.
“Tepezza is indicated for thyroid eye disease, which includes both acute and chronic phases, and this trial will expand our understanding of the role it can play in helping people living with chronic disease.”
In June 2021, Horizon and Arrowhead Pharmaceuticals entered a global partnership and licence agreement to develop the former’s ribonucleic acid interference therapeutic, ARO-XDH.