• 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 of ≥ 20 mg/day 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.

⁃ Additional inclusion criteria are defined in the protocol.