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NCT Number: NCT07596849

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

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.

More information can be found here: https://clinicaltrials.argenx.com/vitalithy

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Key information

Conditions

Graves Disease Autoimmune Diseases Endocrine System Diseases Exophthalmos Eye Diseases Goiter Hyperthyroidism Immune System Diseases Orbital Diseases Thyroid Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

High Technology Hospital Medcenter LLC, Batumi, Georgia

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

efgartigimod PH20 SC

Biological

Subcutaneous injection of Efgartigimod PH20 Via Prefilled Syringe (PFS)

Placebo PH20 SC

Other

Subcutaneous injection of placebo PH20 via Prefilled Syringe (PFS)

Primary outcomes

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

    Time frame: up to 24 weeks (part A)

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

Secondary outcomes

  1. Time to becoming euthyroid off ATDs in part A

    Time frame: Up to 24 weeks (part A)

    ATDs: antithyroid drugs

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

    Time frame: up to 24 weeks (part A)

    MMI: methimazole (also known as thiamazole); CBZ carbimazole

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

    Time frame: Up to 24 weeks (part A)

    ULN : upper limit of normal; ATDs: antithyroid drugs

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

    Time frame: up to 24 weeks (part A)

    TRAb: anti-TSHR autoantibodies; ATDs: antithyroid drugs

  5. Time to becoming euthyroid off ATDs and TRAb seronegative

    Time frame: up to 24 weeks (part A) + up to 135 weeks

    ATDs: antithyroid drugs; TRAb: anti-TSHR autoantibodies

  6. Time to becoming euthyroid and receiving an ATD dose of MMI ≤5 mg/day or CBZ ≤7.5 mg/day (part A)

    Time frame: up to 24 weeks

    ATDs: antithyroid drugs; MMI: methimazole (also known as thiamazole); CBZ carbimazole

  7. Time to becoming euthyroid

    Time frame: up to 24 weeks (part A) + up to 135 weeks

  8. Time to having fT3 and fT4 levels within normal ranges among participants who had fT3 and/or fT4 more than the ULN at baseline (part A)

    Time frame: up to 24 weeks (part A)

    ULN : upper limit of normal

  9. Time to having TSH within normal ranges among participants who have TSH lower than the LLN at baseline (part A)

    Time frame: up to 24 weeks (part A)

    TSH: thyroid-stimulating hormone; LLN: lower limit of normal

  10. Percentage of participants who remain euthyroid without ATDs

    Time frame: up to 74 weeks (part B)

    ATDs: antithyroid drug

  11. Percentage of participants who remain euthyroid without ATDs and without efgartigimod PH20 SC PFS for 6, 12, and 18 months

    Time frame: up to 74 weeks (part B) + up to 135 weeks

    ATDs: antithyroid drug

  12. Percentage of participants who remain euthyroid without ATDs and without efgartigimod PH20 SC PFS

    Time frame: up to 72 weeks (part C)

    ATDs: antithyroid drug

  13. Incidence of AEs and SAEs

    Time frame: up to 135 weeks

    AEs: adverse events ; SAEs: serious adverse events

  14. Change in ThyPRO-39 over time

    Time frame: Up to 135 weeks

    The Thyroid-Specific Patient-Reported Outcome Short Form (ThyPRO-39) 39 item version of the ThyPRO. Each item is related to a specific aspect of the participant's experience with their thyroid condition. Each item is scored on a 5-point Likert scale, and the scores are then transformed to a 0-to-100 scale. Higher scores indicate worse health status

  15. Change in PROMIS-PF10a over time

    Time frame: up to 135 weeks

    The Patient-Reported Outcomes Measurement Information System Physical Function-10 item (PROMIS-PF10a) is a self- administered physical functioning assessment comprising 10 items that measure respondents' ability to perform common physical tasks. Scoring involves summing the numerical responses to each item; higher scores indicate better physical function.

  16. Efgartigimod serum concentrations over time

    Time frame: up to 24 weeks (part A) + 72 weeks (part C)

  17. Percentage change from baseline in total IgG levels in serum over time

    Time frame: up to 98 weeks

    IgG: immunoglobulin G

  18. Percentage change from baseline in TRAb serum levels over time

    Time frame: up to 135 weeks

    TRAb: anti-TSHR autoantibodies

  19. Incidence of ADA against efgartigimod in serum

    Time frame: up to 24 weeks (part A) + up to 135 weeks

    ADA: antidrug antibody(ies)

  20. Incidence of antibodies against rHuPH20 in plasma

    Time frame: up to 24 weeks (part A) + Up to 135 weeks

    rHuPH20: recombinant human hyaluronidase PH20

  21. Incidence of NAb against efgartigimod in serum and rHuPH20 in plasma

    Time frame: up to 24 weeks (part A) + up to 135 weeks

    NAb: neutralizing antibody(ies); rHuPH20: recombinant human hyaluronidase PH20

Study contacts

Contact information is provided by the study sponsor or research team.

Sabine Coppieters, MD

CONTACT

[email protected]

857-350-4834

Sponsors and collaborators

Lead sponsor

argenx

Industry

Registry information

Official study title

A Phase 3, Randomized, Double-Masked, Placebo-Controlled, Multicenter Study Evaluating the Efficacy and Safety of Efgartigimod PH20 SC PFS in Adult Participants With Graves' Disease Inadequately Controlled With Antithyroid Drugs

Acronym: VitaliThy

Important dates

Study start
2026
Primary completion
2028
Study completion
2030
First posted
May 19, 2026
Registry last updated
Jul 8, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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