Inclusion Criteria:
1. Must be 18 to 80 years of age (inclusive) at Screening.
2. Body Mass Index (BMI) of 19 to 34 kg/m2 (inclusive).
3. Must be euthyroid (defined as normal thyroid-stimulating hormone) or have mild hyper- or hypothyroidism (being managed to bring them to a euthyroid state).
4. Best Corrected Visual Acuity (BCVA) score of 20/60 or better at Screening with no history of deterioration noted in the 3 months prior to Screening.
5. Must be willing and able to cease product use prior to VV-14305 (or sham) peribulbar injection if using non-steroidal anti-inflammatory drug (NSAIDs), medications or any herbal supplements, vitamins, or multivitamins with antiplatelet/anticoagulant properties.
6. The study eye and the fellow eye must fall within the pre-defined degree of proptosis and clinical activity score (CAS) as measured at Screening.
7. Participants must be diagnosed with TED prior to Screening and be diagnosed with Graves' disease and progressive moderate to severe TED at Screening.
Exclusion Criteria:
1. History of serious ocular condition(s) other than TED, including but not limited to uveitis, dry age-related macular degeneration (AMD), and wet AMD; Other orbital or ophthalmic diseases, including inflammatory conditions, optic neuropathy, tumors, glaucoma with visual field defect or visual field loss, that in the opinion of the Investigator and/or Medical Monitor is clinically significant.
2. Any medical, cognitive, or psychiatric condition that, in the opinion of the Investigator, could contraindicate the use of the investigational drug, make consistent study assessment and follow-up over the 12-month Post-Treatment Follow-up Period unlikely, or would make the participant an unsafe study candidate.
3. Diagnosed with diabetes (HbA1c ≥6.5%).
4. History of malignancy requiring chemotherapy and/or radiation in the 12 months prior to Screening, except for successfully treated nonmelanoma skin cancers (e.g., basal cell, squamous cell carcinomas), cervical intraepithelial neoplasia, and localized prostate cancer.
5. Known allergy or condition that would contraindicate the use of required study medications.
6. Any Screening assessment or laboratory value that, in the opinion of the Investigator and/or Medical Monitor, is clinically significant and renders the subject not suitable for study participation.
7. Any vaccination or planned vaccination 30 days prior to dosing, 4 weeks post dosing or during period of immunosuppression.
8. Participant requires or, in the opinion of the Investigator, is likely to require immediate surgical ophthalmological/orbital intervention or irradiation of either eye; Has had any prior surgery for TED including orbital decompression, strabismus surgery and any eyelid surgery on either eye.
9. Prior participation in other gene therapy, investigational drug, biologic or device clinical trials within 30 days prior to Screening.
