A Study to Investigate Efficacy and Safety of TOUR006 in Participants 18 to 80 Years of Age With Thyroid Eye Disease

Inclusion Criteria:

• Clinical diagnosis of Graves' disease associated with moderate to severe active TED

• Onset of active TED symptoms within approximately 15 months

• Proptosis (exophthalmos) ≥3 mm above the normal range per investigator judgment (based upon race and gender) for the study eye

• CAS ≥4 (on the 7-item scale) for the study eye

• Presence of TSI >130% of the normal reference standard or >0.55 IU/L (depending onassay method) and laboratory reference ranges

Additional inclusion criteria are defined in the study protocol.

Exclusion Criteria:

• Anticipated need for intervention due to sight-threatening complications or othersignificant and acute deterioration in vision

• Any previous treatment with teprotumumab or other agent that inhibits the IGF-1receptor

• History of systemic (eg, oral or IV) steroid use with a cumulative dose equivalentto >1 g of methylprednisolone for the treatment of TED. Previous oral steroid usewith a cumulative dose of ≤1g methylprednisolone (or equivalent dosage for othersystemic corticosteroid) for the treatment of TED, however, is allowed if thecorticosteroid was discontinued at least 6 weeks before baseline (Day 1) andcompletely tapered by Baseline (if applicable).

• Systemic (oral or IV) corticosteroid use for conditions other than TED within 6weeks of baseline (Day 1) or not completely tapered by baseline (if applicable).

• Any major illness/condition or evidence of an unstable clinical condition that, inthe investigator's judgment, will substantially increase the risk to theparticipant, or confound the interpretation of safety assessments, if they were toparticipate in the study

• Any other condition that, in the opinion of the investigator, would impair theability of the participant to comply with the study procedures or impair the abilityto interpret data from the participant's participation in the study

• Pregnant or lactating

Additional exclusion criteria are defined in the study protocol.