A Phase 3 interventional study of efgartigimod PH20 SC and Placebo PH20 SC in Graves Disease, sponsored by argenx. Recruiting at 51 sites in 14 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-03.
Sponsored by argenx · Phase 3, Interventional, and Treatment
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
162 studies on the registry are indexed under Graves Disease; 53 are open to participants now.
This study's planned enrollment of 230 is above the median of 60 across 104 interventional studies indexed under Graves Disease.
Browse Graves Disease studies →argenx is the lead sponsor of 87 studies on the registry; 29 are open to participants now.
Of its 22 completed or terminated interventional studies of FDA-regulated products, 16 (73%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive efgartigimod PH20 SC Via Prefilled Syringe (PFS) during the part A double-blinded treatment period.
Biological: efgartigimod PH20 SC
Participants will receive placebo PH20 SC Via Prefilled Syringe (PFS) during the part A double-blinded treatment period.
Other: Placebo PH20 SC
Participants will receive efgartigimod PH20 SC Via Prefilled Syringe (PFS) during the part B treatment period.
Biological: efgartigimod PH20 SC
Participants will receive placebo PH20 SC Via Prefilled Syringe (PFS) during the part B treatment period.
Other: Placebo PH20 SC
Participants, will receive efgartigimod PH20 SC PFS in the part C open-label treatment period
Biological: efgartigimod PH20 SC
Drug pages: Efgartigimod alfa · Hyaluronidase (human recombinant)
Subcutaneous injection of Efgartigimod PH20 Via Prefilled Syringe (PFS)
Subcutaneous injection of placebo PH20 via Prefilled Syringe (PFS)
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
Time frame: up to 24 weeks (part A)
Time to becoming euthyroid off ATDs in part A
ATDs: antithyroid drugs
Time frame: 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
MMI: methimazole (also known as thiamazole); CBZ carbimazole
Time frame: 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
ULN : upper limit of normal; ATDs: antithyroid drugs
Time frame: Up to 24 weeks (part A)
Percentage of participants who are euthyroid off ATDs and TRAb seronegative at week 24 in part A
TRAb: anti-TSHR autoantibodies; ATDs: antithyroid drugs
Time frame: up to 24 weeks (part A)
Time to becoming euthyroid off ATDs and TRAb seronegative
ATDs: antithyroid drugs; TRAb: anti-TSHR autoantibodies
Time frame: up to 24 weeks (part A) + up to 135 weeks
Time to becoming euthyroid and receiving an ATD dose of MMI ≤5 mg/day or CBZ ≤7.5 mg/day (part A)
ATDs: antithyroid drugs; MMI: methimazole (also known as thiamazole); CBZ carbimazole
Time frame: up to 24 weeks
Time to becoming euthyroid
Time frame: up to 24 weeks (part A) + up to 135 weeks
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)
ULN : upper limit of normal
Time frame: up to 24 weeks (part A)
Time to having TSH within normal ranges among participants who have TSH lower than the LLN at baseline (part A)
TSH: thyroid-stimulating hormone; LLN: lower limit of normal
Time frame: up to 24 weeks (part A)
Percentage of participants who remain euthyroid off ATDs
ATDs: antithyroid drug
Time frame: Up to 50 weeks (part B)
Percentage of participants who are euthyroid and receiving MMI ≤5 mg/day or CBZ ≤7.5 mg/day
ATDs: antithyroid drug
Time frame: Up to 50 weeks (part B)
Percentage of participants who remain euthyroid without ATDs
ATDs: antithyroid drug
Time frame: up to 98 weeks (part B)
Percentage of participants who remain euthyroid without ATDs and without efgartigimod PH20 SC PFS for 6, 12, and 18 months
ATDs: antithyroid drug
Time frame: up to 74 weeks (part B) + up to 135 weeks
Percentage of participants who remain euthyroid without ATDs and without efgartigimod PH20 SC PFS
ATDs: antithyroid drug
Time frame: up to 72 weeks (part C)
Incidence of AEs and SAEs
AEs: adverse events ; SAEs: serious adverse events
Time frame: up to 135 weeks
Change in ThyPRO-39 over time
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
Time frame: Up to 135 weeks
Change in PROMIS-PF10a over time
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.
Time frame: up to 135 weeks
Efgartigimod serum concentrations over time
Time frame: up to 24 weeks (part A) + 72 weeks (part C)
Percentage change from baseline in total IgG levels in serum over time
IgG: immunoglobulin G
Time frame: up to 98 weeks
Percentage change from baseline in TRAb serum levels over time
TRAb: anti-TSHR autoantibodies
Time frame: up to 135 weeks
Incidence of ADA against efgartigimod in serum
ADA: antidrug antibody(ies)
Time frame: up to 24 weeks (part A) + up to 135 weeks
Incidence of antibodies against rHuPH20 in plasma
rHuPH20: recombinant human hyaluronidase PH20
Time frame: up to 24 weeks (part A) + Up to 135 weeks
Incidence of NAb against efgartigimod in serum and rHuPH20 in plasma
NAb: neutralizing antibody(ies); rHuPH20: recombinant human hyaluronidase PH20
Time frame: up to 24 weeks (part A) + up to 135 weeks
Plan to share: No
Started Jun 2026 (actual). Primary completion is estimated for Jun 2028, 24 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drugs tested here: Efgartigimod alfa · Hyaluronidase (human recombinant)