A Study to Assess Efficacy and Safety of Efgartigimod PH20 SC PFS in Adult Participants With Graves' Disease

NCT07570316 | Not Yet Recruiting Phase 3 FDA Drug

• 2 other identifiers: ARGX-113-25-GRD-30022025-524223-42-00
• Study Type: interventional
• Target: 230
• Locations: 0 countries
• Sites: N/A

Brief Summary

The main purpose of this study is to look at how efgartigimod affects thyroid function in adults with Graves' Disease (GD). The study will also check whether efgartigimod is safe and well tolerated. It will look at how efgartigimod is distributed and eliminated in the body, how it changes antibody levels, and how the immune system responds to it. The study consists of a part A double-blinded treatment period, a part B treatment/observation period and a part C open-label treatment/observation period. During the part A and part B treatment periods, participants will receive efgartigimod PH20 SC via Prefilled Syringe (PFS) or placebo. During the part C open-label treatment period, participants will receive efgartigimod PH20 SC PFS. Participation in the different parts of the study will depend on the participant's response to treatment. The total study duration for participants ranges from 63 to 135 weeks, depending on the response to treatment.

Conditions

Graves Disease

Outcome Measures

Primary Outcomes (1)

• Percentage of participants who are euthyroid (fT3, fT4, and TSH within normal ranges) off ATDs at week 24 in part A

  Free triiodothyronine: \[fT3\]; free thyroxine: \[fT4\]; ATDs: antithyroid drugs

  Up to 24 weeks (part A)

Secondary Outcomes (20)

• Time to becoming euthyroid off ATDs in part A

  Up to 24 weeks (part A)

• Percentage of participants who are euthyroid and receiving MMI ≤5 mg/day or CBZ ≤7.5 mg/day at week 24 in part A

  Up to 24 weeks (part A)

• Percentage of participants with fT3 and fT4 levels below the ULN off ATDs at week 24 in part A

  Up to 24 weeks (part A)

• Percentage of participants who are euthyroid off ATDs and TRAb seronegative at week 24 in part A

  Up to 24 weeks (part A)

• Time to becoming euthyroid off ATDs and TRAb seronegative

  Up to 24 weeks (part A) + up to 135 weeks

Study Arms (5)

Part A - efgartigimod PH20 SC PFS

EXPERIMENTAL

Participants will receive efgartigimod PH20 SC Via Prefilled Syringe (PFS) during the part A double-blinded treatment period.

Biological: Efgartigimod PH20 SC

Part A - placebo PH20 SC PFS

PLACEBO COMPARATOR

Participants will receive placebo PH20 SC Via Prefilled Syringe (PFS) during the part A double-blinded treatment period.

Other: Placebo PH20 SC

Part B - efgartigimod PH20 SC PFS

EXPERIMENTAL

Participants will receive efgartigimod PH20 SC Via Prefilled Syringe (PFS) during the part B treatment period.

Biological: Efgartigimod PH20 SC

Part B - placebo PH20 SC PFS

EXPERIMENTAL

Participants will receive placebo PH20 SC Via Prefilled Syringe (PFS) during the part B treatment period.

Other: Placebo PH20 SC

Part C - efgartigimod PH20 SC PFS

EXPERIMENTAL

Participants will receive efgartigimod PH20 SC PFS in the part C open-label treatment period

Biological: Efgartigimod PH20 SC

Interventions

Placebo PH20 SC OTHER

Subcutaneous injection of placebo PH20 via Prefilled Syringe (PFS)

Part A - placebo PH20 SC PFS; Part B - placebo PH20 SC PFS

Efgartigimod PH20 SC BIOLOGICAL

Subcutaneous injection of Efgartigimod PH20 Via Prefilled Syringe (PFS)

Part A - efgartigimod PH20 SC PFS; Part B - efgartigimod PH20 SC PFS; Part C - efgartigimod PH20 SC PFS

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Is at least 18 years of age and the local legal age of consent for clinical studies when signing the ICF.
• Has a documented diagnosis of GD with TRAb (anti-thyrotropin receptor antibody) levels \>=ULN (upper limit of normal) at screening.
• Has active hyperthyroidism due to GD with TSH (thyroid-stimulating hormone) \<0.1 mIU/L at screening.
• Has been treated with MMI (methimazole) or CBZ (carbimazole) for at least 3 months before screening.

You may not qualify if:

• History of hyperthyroidism not caused by GD (eg, toxic adenoma or toxic multinodular goiter).
• History of RAI (radioactive iodine) therapy or received a total thyroidectomy.
• T3- or T4-containing medication or supplement (eg, levothyroxine, liothyronine, desiccated thyroid preparations, or thyroid-support supplements) received \<6 weeks before screening.
• Any complication of hyperthyroidism or underlying medical condition that would put the participant at undue risk. This includes arrhythmia or tachyarrhythmia related to GD, such as atrial fibrillation or atrial flutter not sufficiently controlled with medications.
• Graves' orbitopathy/Thyroid Eye Disease (GO/TED) requiring systemic therapy (eg, corticosteroids), orbital injections, orbital surgery, or orbital radiation, or expected immediate surgical intervention and/or planned corrective surgery/irradiation or medical therapy during the study.

Sponsors & Collaborators

• argenx: lead

MeSH Terms

Conditions

Graves Disease

Condition Hierarchy (Ancestors)

Exophthalmos; Orbital Diseases; Eye Diseases; Goiter; Thyroid Diseases; Endocrine System Diseases; Hyperthyroidism; Autoimmune Diseases; Immune System Diseases

Central Study Contacts

Sabine Coppieters, MD

CONTACT

857-350-4834; clinicaltrials@argenx.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 30, 2026
• First Posted: May 6, 2026
• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 1, 2028
• Study Completion (Estimated): May 1, 2030
• Last Updated: May 6, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share