Inclusion Criteria:

Disease-specific

• Have documented diagnosis of GD by at least one of the following:
  • Thyrotoxicosis with contemporaneous positive thyroid scintigraphy consistent with GD.
  • Thyrotoxicosis with positive TRAb and/or thyroidstimulating immunoglobulin (TSI).
• Have a TSH value < 0.1 mIU/L as assessed by the local laboratory at the Screening Visit.
• Have a TRAb value ≥ 3 × ULN as assessed by the central 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 ≥ 20 mg/day methimazole or equivalent (i.e., ≥ 30 mg/day carbimazole, ≥ 200 mg/day propylthiouracil) 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 (i.e., ≥ 20 mg/day carbimazole, ≥ 150 mg/day propylthiouracil) at any point during the participant's treatment history.
    • Are on ATD at the Screening Visit with an ATD dose ≥ 10 mg/day methimazole or equivalent (i.e., ≥ 15 mg/day carbimazole, ≥ 100 mg/day propylthiouracil) 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.

Exclusion Criteria:

Disease-specific

• 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. Note: Participants receiving block-and-replace treatment are not eligible.
• 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 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.
• Have a documented history of noncompliance with ATD therapy

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 11/05/2024. Questions regarding updates should be directed to the study team contact.