Evaluation of Batoclimab Efficacy and Safety in an Open-Label Extension Study for Thyroid Eye Disease Treatment in Participants Completing IMVT-1401-3201/3202

The primary objective of this study is to describe the maintenance of efficacy of **batoclimab** as assessed by proptosis in participants with **Thyroid Eye Disease (TED)**. This is clinically relevant as proptosis, or the forward displacement of the eye, is a significant symptom of TED that can impact vision and quality of life. Evaluating the maintenance of efficacy is crucial for understanding the long-term benefits of batoclimab in managing this condition.

Secondary objectives include:

• Describing the efficacy of batoclimab in participants previously treated with placebo who did not achieve a proptosis response in the feeder studies.
• Describing the treatment effect of batoclimab in participants previously treated with batoclimab but did not achieve a proptosis response in the feeder studies.

The clinical trial investigating the maintenance of efficacy of batoclimab in **Thyroid Eye Disease (TED)** involves a total of 107 participants. The study population includes both male and female subjects, with an age range corresponding to categories 3 and 4, which typically represent adults. Participants were selected based on their completion of the Week 24 visit of a feeder study. The trial includes individuals who do not require immediate surgical intervention and are not planning corrective surgery, irradiation, or medical therapy for TED during the study. The population is noted to include vulnerable groups, although specific lifestyle considerations such as diet or physical activity are not detailed. The selection criteria ensure that participants have not permanently discontinued the study drug, maintaining a focus on those who can continue with the open-label treatment cohort.

The clinical trial is designed as an open-label extension study to evaluate the efficacy and safety of **batoclimab** in participants with **Thyroid Eye Disease (TED)**. This study follows a phase III confirmatory trial structure and involves participants who have completed the Week 24 visit of the feeder studies IMVT-1401-3201 or IMVT-1401-3202. The trial aims to assess the maintenance of efficacy of batoclimab, specifically focusing on proptosis response. The study is expected to run until August 31, 2026, with recruitment having commenced on April 30, 2023.

Participants will receive batoclimab as a **solution for injection** administered via subcutaneous use. The maximum daily dose is 680 mg, with a total maximum dose of 12,240 mg over a treatment period of up to 24 weeks. The trial includes several key visits: an inclusion (screening) visit to confirm eligibility, regular follow-up visits to monitor efficacy and safety, and an end-of-study visit to assess the final outcomes. The primary endpoint is the duration of proptosis response off treatment in the study eye for participants who were responders in the feeder studies. Secondary endpoints include the proportion of proptosis responders at Week 24 in participants who were non-responders to placebo or batoclimab in the feeder studies.

Participant involvement is expected to last for the duration of the treatment period, with conditions for early termination including the need for immediate surgical intervention, plans for corrective surgery, irradiation, or medical therapy for TED during the study, or permanent discontinuation of the study drug. The study is not categorized as low intervention and does not involve a pediatric formulation. The trial is conducted under the sponsorship of Immunovant Sciences GmbH, with batoclimab being the investigational product. The study is structured to ensure rigorous assessment of the therapeutic potential of batoclimab in maintaining proptosis response in TED patients.

The clinical trial involves the administration of **Batoclimab**, a **solution for injection** developed by Immunovant Sciences GmbH. Batoclimab is an experimental medication designed for the treatment of **Thyroid Eye Disease (TED)**. The active substance in Batoclimab is a protein-based compound, specifically an anti-human FcRn receptor human monoclonal antibody, known by several synonyms including HL161BKN, HBM-9161, and RVT-1401. The pharmaceutical form of Batoclimab is a solution intended for **subcutaneous use**. The dosing regimen for Batoclimab involves a maximum daily dose of 680 mg, with a total maximum dose of 12,240 mg over a treatment period of up to 24 weeks. The administration schedule and participant compliance are monitored to ensure adherence to the dosing protocol.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are utilized. The focus is solely on assessing the efficacy and safety of Batoclimab in maintaining the therapeutic effects observed in previous studies. The trial is an open-label extension study, meaning that all participants and investigators are aware of the treatment being administered. The primary objective is to evaluate the maintenance of efficacy of Batoclimab as assessed by changes in proptosis, a key symptom of Thyroid Eye Disease.

Efficacy in this clinical trial will be assessed by evaluating the maintenance of efficacy of **batoclimab** in the treatment of Thyroid Eye Disease (TED), specifically through the measurement of proptosis. The primary endpoint is the duration of proptosis response off treatment in the study eye for participants who were batoclimab responders in the feeder studies. Secondary endpoints include the proportion of proptosis responders at Week 24 in the study eye for participants who were placebo non-responders and batoclimab non-responders in the feeder studies.

Measurements will be collected at specified timepoints, including Week 24, to assess the efficacy parameters. The trial is designed as an open-label extension study for participants who have completed the Week 24 visit of the feeder studies IMVT-1401-3201 or IMVT-1401-3202. The study aims to provide a comprehensive evaluation of batoclimab's efficacy in maintaining proptosis response in participants with TED.