An Open-label Extension Study for Participants who Completed Study IMVT-1401-3203 - Assess the Efficacy and Safety of Batoclimab for the Treatment of Thyroid Eye Disease (TED).

Thyroid Eye Disease (TED) is a rare autoimmune disorder in which the eye muscles, eyelids, tear glands and fatty tissues behind the eye become inflamed. This can cause the eyes and eyelids to become red, swollen, and the eyes can be pushed forward. For most, the same autoimmune condition that causes TED also results in Graves’ disease (GD). The current treatment options available for active, moderate or severe disease can give short-term relief. There is unmet need for treatments with an optimal safety profile and long-term benefits. GD is typically characterised by the presence of autoantibodies (antibodies that mistakenly target and react with a person’s own tissues/organs). Studies have also indicated that a type of antibody called IgG, which activates a receptor called IGF-1R in patients with GD, may contribute to TED. Batoclimab works by binding to a receptor that IgG antibodies usually bind to, causing the levels of IgG to be reduced in the body. The aim of treatment with Batoclimab is to decrease disease-causing antibody levels quickly and reliably, and then to maintain low levels, which should reduce the symptoms of TED and prevent progression to more serious complications that could require surgical intervention. This study is an extension of IMVT-1401-3201 and has 2 cohorts – an observation cohort (OC) and a treatment cohort (TC). The purpose of the OC is to measure how the efficacy of batoclimab continues in those who had a positive response to it in the previous study. The purpose of the TC is see if batoclimab is safe and improves TED symptoms for those who were classified as a non-responder in the previous study. Participation in the OC will last about 6 months, and in the TC about 7 months.