The purpose of this study is to assess the efficacy and safety of 24 weeks of treatment with batoclimab in adult participants with biochemically documented hyperthyroidism due to GD who have failed to achieve euthyroidism on antithyroid drugs (ATDs).

Inclusion Criteria:

• Have serologically confirmed GD as documented by presence of elevated stimulatory thyrotropin receptor antibody (TSH-R-Ab) level (i.e., > specimen-to-reference ratio of 140%) at the Screening Visit.

• Have active hyperthyroidism due to GD with the following laboratory values at the Screening Visit:

  • TSH < LLN
  • FT3 > upper limit of normal (ULN) and <=5 * ULN
  • FT4 > ULN and <=5 * ULN

Note: Participants who have T3 thyrotoxicosis (i.e TSH <LLN, FT3 > ULN and ≤5× ULN, but FT4 within normal range) at the Screening Visit may be enrolled, if they have serologically confirmed GD as per Inclusion Criterion 1.

• Are willing and capable of giving written informed consent, which includes being able to comply with all aspects of the study treatment and testing schedule.

Exclusion Criteria:

• History of hyperthyroidism not caused by GD (e.g., toxic adenoma or toxic multinodular goiter), and/or history or presence of thyroid storm.
• History of treatment with radioactive iodine or thyroid surgery.
• Total immunoglobulin G (IgG) level <6 grams per liter (g/L) at the Screening Visit.
• Albumin level <3.5 grams per deciliter (g/dL) (<35 g/L) at the Screening Visit.
• Absolute neutrophil count <1000 cells per cubic millimeter (cells/mm^3) at the Screening Visit.

Other, more specific exclusion criteria are defined in the protocol.