This is a clinical trial assessing the efficacy, safety, and tolerability of an investigational drug, veligrotug (VRDN-001), in participants with chronic thyroid eye disease (TED).

This is a randomized (meaning participants will be assigned to study arms by chance), double-masked (meaning study doctor and participant will not know which study arm participant is assigned to), placebo-controlled study that will include participants with chronic TED. The key objectives of this study are to determine if veligrotug (VRDN-001) is efficacious, safe, and tolerable when administered as 5 IV infusions given every 3 weeks for a total of 12 weeks in participants with chronic TED

Key Inclusion Criteria:

• Must have moderate to severe chronic TED with documented evidence of ocular symptoms or signs that began greater than 15 months prior to screening
• Must have had a clinical diagnosis of TED, with any CAS (0-7)
• Must agree to use highly effective contraception as specified in the protocol
• Female TED participants must have a negative serum pregnancy test at screening

Key Exclusion Criteria:

• Must not have received prior treatment with another anti-IGF-1R therapy
• Must not have received systemic corticosteroids for any condition, including TED, or selenium within 2 weeks prior to first dose
• Must not have received other immunosuppressive drugs or another investigational agent for any condition, including TED, or any other therapy for TED, within 8 weeks prior to first dose
• Must not have received radioactive iodine (RAI) treatment within 8 weeks prior to first dose
• Must not have a pre-existing ophthalmic condition in the study eye that in the opinion of the study doctor would confound interpretation of the study results
• Must not have had previous orbital irradiation or decompression surgery for TED to the study eye's orbit
• Must not have inflammatory bowel disease
• Have abnormal baseline audiometry Pure Tone Average (PTA) assessment or history of significant (as determined by the Investigator) ear pathology, relevant ear surgery or hearing loss.
• Female TED participants must not be pregnant or lactating