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Efgartigimod PH20 SC treatment for adults with thyroid eye disease

A Phase 3, Randomized, Double-Masked, Placebo-Controlled, Multicenter Study to Evaluate the Efficacy, Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of Efgartigimod PH20 SC Administered by Prefilled Syringe in Adult Participants With Thyroid Eye Disease

Phase 3 Interventional argenx · NCT06307626

This study is testing if a new treatment called efgartigimod can help adults with moderate-to-severe thyroid eye disease feel better compared to a placebo.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment108 (estimated)
Ages18 Years and up
SexAll
Sponsorargenx Industry-sponsored
Locations53 sites (Los Angeles, California and 52 other locations)
Trial IDNCT06307626 on ClinicalTrials.gov

What this trial studies

This study evaluates the efficacy, safety, and tolerability of efgartigimod PH20 SC in adults with active, moderate-to-severe thyroid eye disease (TED). Participants will be randomized to receive either the treatment or a placebo during a double-blinded period, followed by a potential observational phase. The study aims to assess pharmacokinetics, pharmacodynamics, and immunogenicity over a duration of approximately 60 to 110 weeks.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with active, moderate-to-severe thyroid eye disease related to autoimmune thyroid conditions.

Not a fit: Patients with stable thyroid eye disease or those who have had symptoms for more than 12 months prior to screening may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly improve the management of thyroid eye disease, enhancing patients' quality of life.

How similar studies have performed: Other studies have shown promise in treating thyroid eye disease with similar approaches, indicating potential for success.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* The participant is at least 18 years of age
* The participant is capable of providing signed informed consent and following with protocol requirements
* The investigator determines active, moderate-to-severe thyroid eye disease (TED) associated with autoimmune thyroid conditions (Graves' disease or Hashimoto's thyroiditis) for the most severely affected eye
* The participant has first onset of active TED symptoms within 12 months before screening
* The participant must have normal thyroid function with the baseline disease under control or have mild hypo or hyperthyroidism at screening. Every effort should be made to correct the mild hypo or hyperthyroidism promptly and to maintain the normal thyroid function for the full duration of the study
* The participant agrees to use birth control consistent with local regulations and the people of child-bearing potential must have a negative blood pregnancy test at screening and a negative urine pregnancy test before receiving the study drug

Exclusion Criteria:

* Optic neuropathy (damage to optic nerve), defined as new visual field defect (blind spot), relative afferent pupillary defect (pupils respond differently to light), or color defect secondary to optic nerve involvement within the 6 months before screening
* Corneal decompensation (swelling of the cornea) unresponsive to medical management
* Previous orbital irradiation or surgery for TED
* Use of some medications before screening (more information is found in the protocol)
* Known autoimmune disease or any medical condition that would interfere with an accurate assessment of clinical symptoms of TED or puts the participant at undue risk
* History of malignancy, cancer, unless considered cured by adequate treatment with no evidence of recurrence for ≥3 years. Adequately treated participants with the following cancers can be included at any time: Basal cell or squamous cell skin cancer, Carcinoma in situ of the cervix, Carcinoma in situ of the breast, Incidental histological findings of prostate cancer
* Clinically significant active infection that is not sufficiently resolved in the investigator's opinion or positive serum test at screening for active infection with any of the following: Hepatitis B virus (HBV), Hepatitis C virus (HCV), HIV
* Current participation in another interventional clinical study or previous participation in an efgartigimod clinical study and at least 1 dose of study drug received or has received at least 1 dose of commercially available efgartigimod
* Known hypersensitivity to study drug or one of its excipients (inactive ingredients)
* History of or current alcohol, drug, or medication abuse within 12 months before screening as assessed by the investigator
* Pregnant or lactating state or intention to become pregnant during the study
* Live or live-attenuated vaccine received \<4 weeks before screening

The complete list of exclusion criteria can be found in the protocol.

Where this trial is running

Los Angeles, California and 52 other locations

+3 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Thyroid Eye Disease
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.