This study is the first time that K1-70 will be administered to humans. The principal aim of this study is to obtain safety and tolerability data when K1-70 is administered as an IM injection or as an IV infusion to subjects with Graves' disease.

Current therapy for Graves' disease includes treatment with anti-thyroid drugs, destruction of the thyroid using radioiodine, or total surgical thyroidectomy. Beta-blockers and calcium antagonists may be used to control some of the symptoms of hyperthyroidism.

K1-70 is a thyroid stimulating hormone receptor antagonist that may provide new in vivo diagnostic and therapeutic tools for the management of patients with Graves' disease, patients with thyroid cancer and patients who would benefit from controlling receptor activity.

Graves' disease is one of the most common overt autoimmune disorders. Patients with Graves' disease have thyroid over activity and hyperthyroidism. Symptoms of hyperthyroidism include goitre, fatigue, heat intolerance, sweating, weight loss despite good appetite, shakiness, inappropriate anxiety, palpitations of the heart, shortness of breath, tetchiness and agitation, poor sleep, thirst, nausea and increased frequency of defaecation.

The rationale of this study is to obtain safety and tolerability data when K1-70 is administered as an intramuscular injection or as an IV infusion to subjects with Graves' disease.

This information, together with the pharmacokinetic data, will help establish the doses and dosage regimen suitable for repeat administration to patients.

This is an open-label study. The expected duration of each subject's participation in the study is approximately 18 weeks (including a screening period of up to 4 weeks).

Main Inclusion Criteria:

• age 18-75 years
• have Graves' disease and are being treated with anti-thyroid medications OR not treated with anti-thyroid medications (due to side-effects) and who are clinically and biochemically euthyroid or hyperthyroid
• have a body mass index (weight [kg]/height [m]2) between 18.5 and 35.0 kg/m2

Main Exclusion Criteria:

• current or chronic history of liver disease
• history of cancer within the last 5 years except localised skin cancer
• Graves' orbitopathy with clinical activity score >3/7
• evidence of optic neuropathy and/or corneal breakdown
• significant systemic infection
• history of recurrent or current infection
• splenectomy
• recently had major surgery or plan major surgery
• had thromboembolic event due to a blood clot in the last 12 months
• have clinically significant laboratory tests
• a clinically significant allergic condition (excluding hay fever)
• currently receiving corticosteroids
• smoke more than 10 cigarettes (or its equivalent in nicotine (including use of e-cigarettes)) per day
• history of drug abuse