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A study testing teprotumumab compared to placebo in adult patients with moderate-to-severe active thyroid eye disease

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study examines moderate-to-severe active thyroid eye disease, which is a condition associated with Graves' disease where the eyes become inflamed and may bulge forward. The condition can affect the soft tissues around the eyes, cause double vision, and impact daily life. The study will compare teprotumumab, which is given as an injection under the skin, with placebo. Teprotumumab is also known by the code names AMG 632 and HZN-001.

The purpose of the study is to evaluate how well teprotumumab works compared to placebo in reducing eye bulging in people with this condition, and to assess its safety and how well it is tolerated. The study will measure whether the eyes move back into a more normal position by at least 2 millimeters without the other eye getting worse. The study will also look at other aspects of the disease, including signs of inflammation, double vision, and how the condition affects quality of life.

Participants in this study will be randomly assigned to receive either teprotumumab or placebo through injections under the skin. The study will follow participants over a period of time to monitor changes in eye bulging, inflammation scores, double vision, and overall well-being. Participants must have active disease with significant eye bulging and symptoms that started within 15 months before joining the study. Their thyroid hormone levels should be controlled or only mildly abnormal during the study.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment and treatment assignment

    At the beginning of the trial, your condition will be assessed. This includes measuring the bulging of your eyes, called proptosis, which will be measured in millimeters.

    Your Clinical Activity Score, abbreviated as CAS, will be evaluated. This is a score from 0 to 7 that measures how active your thyroid eye disease is. Higher scores indicate more active disease.

    Your thyroid hormone levels will be checked to ensure they are controlled. Specifically, free thyroxine (FT4) and free triiodothyronine (FT3) will be measured.

    If you experience double vision, called diplopia, this will be assessed and graded.

    You will be randomly assigned to receive either teprotumumab or placebo. A placebo is an inactive substance that looks like the actual medication but contains no active ingredient.

    Neither you nor your doctor will know which treatment you are receiving. This is called a double-masked trial.

  2. Step 2

    Treatment period with injections

    You will receive injections under the skin, called subcutaneous injections.

    The injections will contain either teprotumumab or placebo for teprotumumab.

    Before each injection, a urine pregnancy test will be performed if you are a woman of childbearing potential.

    The injections will be administered at regular intervals throughout the treatment period.

  3. Step 3

    Regular monitoring visits

    Throughout the trial, you will attend scheduled visits for monitoring.

    At these visits, measurements of your eye bulging will be taken to track any changes.

    Your Clinical Activity Score will be assessed repeatedly to monitor the activity level of your thyroid eye disease.

    If you have double vision, the severity will be evaluated at each visit.

    Your thyroid hormone levels will be checked to ensure they remain stable. Efforts will be made to keep you in a euthyroid state, which means your thyroid hormone levels are normal.

    Any side effects or changes in your condition will be recorded.

  4. Step 4

    Quality of life assessment

    You will be asked to complete a questionnaire called the Graves' Ophthalmopathy Quality of Life questionnaire, abbreviated as GO-QoL.

    This questionnaire measures how thyroid eye disease affects your daily life and well-being.

    You will complete this questionnaire at baseline and at scheduled time points during the trial.

  5. Step 5

    Final assessment

    At the end of the treatment period, a comprehensive assessment will be conducted.

    The bulging of your eyes will be measured again to determine if there has been a reduction of at least 2 millimeters in the study eye.

    Your Clinical Activity Score will be evaluated to see if it has decreased.

    If you had double vision at the start, it will be assessed to determine if there has been any improvement or resolution.

    The GO-QoL questionnaire will be completed again to evaluate changes in your quality of life.

    All findings will be compared to your baseline measurements taken at the beginning of the trial.

Who can join the trial?

10 criteria

  • You must provide written permission to join the study.
  • You must be willing and able to follow all study requirements for the entire duration.
  • You must be between 18 and 80 years old.
  • You must have a confirmed diagnosis of Graves' disease, which is a condition affecting the thyroid gland, along with active thyroid eye disease. Your most severely affected eye must have a Clinical Activity Score of 3 or higher on a 7-point scale. This score measures how active and inflamed your eye disease is.
  • You must have moderate-to-severe active thyroid eye disease that affects your daily life but is not threatening your vision. This usually includes one or more of the following: upper eyelid pulled back by 2 millimeters or more, moderate or severe swelling and inflammation of the tissues around the eye, or double vision that occurs sometimes or all the time.
  • You must have proptosis, which means your eyeball is pushed forward. This should be at least 3 millimeters more than before your thyroid eye disease started, or at least 3 millimeters more than what is normal for your race and gender.
  • Your active thyroid eye disease symptoms must have started within 15 months before joining the study.
  • Your thyroid hormone levels must be normal or only slightly abnormal. If your levels of free thyroxine and free triiodothyronine, which are thyroid hormones, are too high or too low, they must be less than 50% away from normal limits. Efforts should be made to correct any imbalance and keep your thyroid levels normal throughout the study.
  • You must not need immediate eye surgery and must not be planning any corrective eye surgery or radiation treatment during the study period.
  • If you are a woman who can become pregnant, you must have a negative pregnancy test before starting the study and negative urine pregnancy tests before each treatment dose and throughout your participation.

Who cannot join the trial?

3 criteria

  • The study does not list specific reasons why patients cannot participate
  • General exclusion information has not been provided in the available study documents
  • If you are interested in this study, your doctor will need to review the complete study requirements to determine if you are eligible to participate
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Investigated drugs

  • Teprotumumab

    is a medication given as an injection under the skin that is being tested to see if it can help reduce eye bulging in people with thyroid eye disease. This medication works by targeting specific proteins in the body that may be causing the eye problems associated with an overactive or underactive thyroid gland.

  • Placebo

    is an inactive substance that looks like the real medication but contains no active medicine. It is used in this study to compare against teprotumumab to help determine if the actual medication is working better than no treatment at all.

What is already known about the treatment

Teprotumumab – Teprotumumab is given as an injection under the skin and is being studied in clinical trials for treating moderate-to-severe active thyroid eye disease, a condition where the eyes bulge forward and become inflamed due to thyroid problems. This medication works at the molecular level by blocking a specific protein receptor called IGF-1R, which helps reduce inflammation and swelling in the tissues around the eyes. The main goal of the current research is to see if teprotumumab can reduce eye bulging by at least 2 millimeters compared to a placebo treatment, helping patients with this uncomfortable and vision-affecting condition.

Investigated diseases

Thyroid Eye Disease – Thyroid Eye Disease is an inflammatory condition that affects the tissues and muscles around the eyes. It occurs when the immune system mistakenly attacks the fatty tissue and muscles behind the eyeballs, causing them to swell and become inflamed. This swelling pushes the eyes forward, causing them to bulge outward from their sockets, a condition called proptosis. The disease can also affect eye movement, leading to double vision when the muscles that control eye movement become stiff and swollen. Patients may experience redness, pain, excessive tearing, and sensitivity to light. The condition is often associated with thyroid gland disorders and can affect one or both eyes, with symptoms that may worsen over time during the active phase of the disease.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515702-63-00Protocol codeHZNP-TEP-305Estimated enrolment97 patientsSponsorHorizon Therapeutics USA Inc.

sourced from the EU Clinical Trials Register and site verification

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