The investigational drug, VRDN-001, is a monoclonal antibody that inhibits the activity of a cell surface receptor called insulin-like growth factor-1 receptor (IGF-1R). Inhibition of IGF-1R may help to reduce the inflammation and associated tissue swelling that occurs in patients with thyroid eye disease (TED). The primary objectives of this clinical trial are to provide open-label access to VRDN-001 for participants who were previously non-responders at 3 weeks post the fifth IV infusion (i.e., 15 weeks) in the VRDN-001-101 (THRIVE) and VRDN-001-301 (THRIVE-2) pivotal studies and assess the safety and efficacy of VRDN-001 in participants who were previously treated with VRDN-001 or placebo.

Key Inclusion Criteria:

1. Be able to understand the study procedures and the risks involved and be willing to provide written informed consent before the first study-related activity
2. Have completed at least 5 IV infusions and assessments required to determine proptosis responder status 3 weeks post the fifth IV infusion (i.e., Week 15) as defined in either the VRDN-001-101 or VRDN-001-301 pivotal studies
3. Been a participant in either the VRDN-001-101 or VRDN-001-301 studies and found to be a non-responder as defined within the VRDN-001-101 or VRDN-001-301 study
4. Not require immediate surgical ophthalmological or orbital surgery in the study eye for any reason
5. Must agree to use highly effective contraception as specified in the protocol
6. Female TED participants must have a negative urine pregnancy test at screening
7. Be willing and able to comply with all the requirements of the protocol for the entire duration of the study

Key Exclusion Criteria:

Participants must not:

1. Have received prior treatment with another anti-IGF-1R agent
2. Have received systemic corticosteroids for any condition, including TED, or selenium within 2 weeks prior to first dose
3. Have received other immunosuppressive drugs or another investigational agent for any condition, including TED (other than VRDN-001 or placebo associated with the VRDN-001-101 or VRDN-001-301 pivotal studies), or any other therapy for TED, within 8 weeks prior to first dose
4. Have received radioactive iodine (RAI) treatment within 8 weeks prior to first dose
5. Have had previous orbital irradiation or decompression surgery involving excision of fat for TED to the study eye's orbit
6. Have abnormal hearing test before first dose. Have a history of ear conditions considered significant by study doctor