Inclusion Criteria:

• Subjects must be ≥ 18 years of age at Screening.
• Clinical diagnosis of Graves’ Disease and/or autoimmune Hashimoto’s thyroiditis associated with active moderate to severe TED with a CAS ≥ 4 (on the 7- item scale) for the most severely affected eye (primary study eye) at Screening and Baseline.
• Moderate-to-severe active TED (not sight-threatening but has an appreciable impact on daily life, with onset (as determined by patient records) within 12 months prior to the Baseline visit and usually associated with one or more of the following: lid retraction ≥ 2 mm, moderate or severe soft tissue involvement, exophthalmos ≥ 3 mm above normal for race and gender, and/or inconstant or constant diplopia.
• Subjects must be euthyroid (defined as normal TSH) or, have subclinical hyperthyroidism (defined as normal FT4 and FT3 with TSH below the normal range). Every effort should be made to correct mild hypo- or hyperthyroidism promptly and maintain the euthyroid state for the duration of the clinical trial.
• Does not require immediate surgery, radiotherapy or other ophthalmological intervention at the time of Screening and is not planning for any such treatment during the course of the study.
• Diabetic subjects must have HbA1c < 9.0%. Type 2 diabetic subjects who are not on insulin, must not be prescribed insulin within 60 days prior to screening. If Type 1 or Type 2 diabetic subjects are on insulin, the prescribed total daily insulin dose must not have changed by more than 20% or more than 10 units (whichever is greater) in the 60 days prior to Screening. Subjects must not have severe hypoglycemic events (requiring medical care by health care professional) in the 60 days before screening.
• Women of childbearing potential are required to have a negative serum pregnancy test at time of Screening and a negative urine pregnancy test at each timepoint that is specified in protocol. The definition of childbearing potential also includes women with the onset of menopause < 2 years prior to Screening, women with non-therapy-induced amenorrhea for < 12 months prior to Screening, and women who are considered infertile (sterile) from non-surgical conditions [absence of ovaries and/or uterus]). These women are also required to have a negative serum pregnancy test at time of Screening and a negative urine pregnancy test at each timepoint that is specified in protocol. Women who are sexually active with non-vasectomized male partners must agree to use 2 reliable forms of contraception during the trial. It is recommended that hormonal (ie: oral contraceptive) contraception be one of these contraceptive methods used. Hormonal contraception must be initiated ≥ 21 days prior to Baseline visit and continue for 7 days following the last dose of study drug. When used correctly and consistently, highly effective contraceptive methods including combined oral contraceptives, some intrauterine devices (IUDs), injectables, implants, sexual abstinence or sex with a vasectomized partners have a failure rate < 1% per year.
• Male subjects who are sexually active with a female partner of childbearing potential (as defined above), must agree to use barrier contraceptive method from Screening through 7 days after the last dose of study drug. Otherwise, sexually active male subjects must be surgically sterile.
• Subject is willing and able to sign written informed consent and comply with the protocol for the duration of the study.

Exclusion Criteria:

• Decreased best corrected visual acuity due to optic neuropathy as defined by a decrease in vision of 2 lines on the Snellen chart, new visual field defect, or color defect secondary to optic nerve involvement within the last 6 months.
• Corneal decompensation unresponsive to medical management.
• Decrease in CAS of ≥ 2 points in the primary study eye between Screening and Baseline.
• Decrease in proptosis of ≥ 2 mm in the primary study eye between Screening and Baseline.
• Previous orbital irradiation or surgery.
• Prior IGF-1R inhibitor therapy for any condition.
• Any steroid use (intravenous [IV] or oral) with a cumulative dose equivalent to > 1g of methylprednisolone or equivalent for the treatment of TED within 3 months of Screening. NOTE: previous use of steroid eye drops is allowed if discontinued at least 4 weeks prior to Screening).
• Corticosteroid use (including topical) for conditions other than TED within 4 weeks prior to Screening (inhaled steroids are allowed)
• Use of any other non-steroid immunosuppressive agent within 4 weeks prior to Screening.
• Any previous treatment with anti-IL6 receptor, anti- CD20, (MS4A1) antibodies or monoclonal antibody for immunomodulation within the past 9 months prior to Screening.
• Selenium and/or biotin use as a treatment for TED within 3 weeks prior to screening is disqualifying, not allowed, and must not be restarted during the clinical trial or Follow-up period. In addition, a multivitamin containing selenium and/or biotin must be discontinued at screening and not restarted during the trial.
• Use of an investigational agent for any condition within 30 days prior to Screening or anticipated use during the course of the trial.
• Under no circumstances are subjects who have enrolled in this study permitted to be re-randomized to this study. Note: Prior to enrollment subjects who have failed screening may be allowed to rescreen after consultation with the Medial Monitor.
• Identified pre-existing ophthalmic or other disease that in the judgement of the Investigator, would preclude study participation or complicate interpretation of study results (e.g. including, but not limited to: previous eyelid surgery, corneal disease [other than keratopathy caused by TED that does not meet any other exclusion], uveitis, diabetic macular edema, diabetic retinopathy, retinal vein occlusion, macular degeneration, other retinopathy, retinal detachment, glaucoma, or optic nerve disease or optic nerve injury).
• Ocular surgery other than routine cataract surgery or subsequent YAG laser capsulotomy. (Cataract surgery and YAG laser capsulotomy are allowed if the surgical procedure(s) were performed more than 3 months prior to randomization).
• Biopsy-proven or clinically suspected inflammatory bowel disease (e.g., diarrhea with or without blood or rectal bleeding associated with abdominal pain or cramping/colic, urgency, tenesmus, or incontinence for more than 4 weeks without a confirmed alternative diagnosis OR endoscopic or radiologic evidence of enteritis/colitis without a confirmed alternative diagnosis).
• History of QTcF prolongation; or QTcF prolongation at Screening; mean QTcF interval > 450 msec (males); and > 470 msec (females).
• Use of drugs causing QT interval prolongation within 14 days prior to Day 1 dosing (See Section 12.2 List of QT Prolonging Drugs).
• Bleeding diathesis that in the judgment of the Investigator would preclude inclusion in the clinical trial.
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 3 times the upper limit of normal (ULN) according to age at Screening.
• Serum creatinine > 2 x ULN for the reference range laboratory according to age at Screening.
• Malignant conditions being actively treated or treated in the past 12 months (with the exception of successfully treated basal cell of the skin). Recent (within 3 months of Screening) basal cell of the eyelid skin is excluded.
• Pregnant or lactating women.
• Current drug, marijuana or alcohol abuse, or history of either within the past 1 year, in the opinion of the Investigator, or as reported by the subject.
• In the opinion of the Investigator, any conditions which may pose increased risk of participation for the subject or may interfere with interpretation of study results.
• Positive Human immunodeficiency virus (HIV), hepatitis C, or hepatitis B.

Eligibility last updated 12/2/21. Questions regarding updates should be directed to the study team contact.