A Proof-of-Concept Study to Assess Batoclimab in Participants With Graves' Disease

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.