A Study to Assess the Efficacy, Safety, and Tolerability of IMVT-1402 as Treatment for Adult Participants With Graves' Disease

Eligibility Criteria

• * Have documented diagnosis of GD.
• * Have a TSH value \< 0.1 mIU/L as assessed by the local laboratory at the Screening Visit.
• * Meet one of the following at the Screening Visit:
• * Have been on ATD for ≥ 3 months in the period immediately preceding the Screening Visit and both of the following:
• * Are on ATD at the Screening Visit with an ATD dose a specified amount of methimazole or equivalent for the 4-week period immediately preceding the Screening Visit.
• * Are anticipated to be on a stable dose of ATD for the 4-week period immediately preceding Randomization.
• * Have been on ATD for ≥ 6 months in the period immediately preceding the Screening Visit and all of the following:
• * Have been treated with ≥ 15 mg/day methimazole or equivalent at any point during the participant's treatment history.
• * Are on ATD at the Screening Visit with an ATD dose a specified amount of methimazole or equivalent for the 4-week period immediately preceding the Screening Visit.
• * Are anticipated to be on a stable dose of ATD for the 4-week period immediately preceding Randomization.
• * Have previously been treated with radioactive iodine (RAI) therapy or have undergone total thyroidectomy.
• * Have a T3 (Total T3 or FT3, as available and per standard of care at local laboratory) or FT4 value \< lower limit of normal (LLN) as assessed by the local laboratory at the Screening Visit.
• * Have received levothyroxine, desiccated thyroid extract, or T3 at any dose within 6 weeks of the Screening Visit.
• * Have a history of hyperthyroidism not caused by GD (e.g., toxic adenoma or toxic multinodular goiter) and/or history of thyroid storm within 6 months of the Screening Visit.
• * Have an autoimmune disease other than GD requiring treatment that, in the Investigator's judgment, puts the participant at undue risk.
• * Have moderate-to-severe active thyroid eye disease (TED) and are expected to require immediate surgical intervention and/or are planning corrective surgery/irradiation or medical therapy for TED during study participation.