A Phase 2b Randomized Study of IMVT-1402 Versus Placebo in Adult Patients with Graves' Disease

Primary objective: To evaluate the efficacy of IMVT‑1402 (600 mg subcutaneous solution) versus placebo in adult patients with Graves’ disease, as determined by changes in total or free T3, free T4, thyroid‑stimulating hormone, and the dose of antithyroid drugs required at Week 26. This assessment aims to determine whether the investigational therapy can achieve biochemical control of hyperthyroidism and reduce reliance on conventional antithyroid medication, thereby informing its potential therapeutic role.

A total of 108 participants were enrolled, comprising both male and female adults aged ≥ 18 years who had a confirmed diagnosis of Graves’ disease and remained hyperthyroid despite ongoing anti‑thyroid drug (ATD) therapy. Candidates were selected on the basis of documented GD, persistent hyperthyroidism while receiving ATD, and the ability to understand trial requirements, provide written informed consent, and adhere to protocol procedures. The trial population reflected generally healthy individuals apart from their thyroid condition, with no specific dietary, physical‑activity, or other lifestyle restrictions reported in the protocol. Key inclusion criteria included adult age (≥ 18 years), diagnosis of GD with uncontrolled hyperthyroidism on ATD, and capacity for informed consent; exclusion criteria were not emphasized in the provided summary.

The study is a randomized, double‑blind, placebo‑controlled phase 2b trial evaluating a single subcutaneous 600 mg dose of IMVT‑1402 versus matching placebo in adult patients with Graves' Disease. After a screening visit to confirm eligibility, participants are randomized 1:1 and receive the investigational product or placebo at the baseline visit. Follow‑up visits are scheduled at weeks 2 and 4 to assess early changes in thyroid hormone levels, then monthly until week 26 to monitor safety, thyroid function, antithyroid drug (ATD) use, and serologic status. The end‑of‑study visit at week 26 determines the primary endpoint, the proportion of participants who are euthyroid and off ATD, and secondary hormonal and serologic outcomes. Participant involvement therefore spans approximately 26 weeks from randomization. Early termination may occur for safety concerns, significant protocol violations, withdrawal of consent, or loss to follow‑up. Recruitment is planned to commence in December 2025 and conclude in May 2027.

The investigational product IMVT-1402 is supplied as a solution for injection for subcutaneous administration. Each dose contains 600 mg of the active substance and is administered in accordance with the study dosing schedule, which specifies the timing and frequency of dosing. The formulation is provided in a pre‑filled syringe designed to ensure uniform delivery, and administration is performed by qualified study personnel. Dosing compliance is monitored through site‑based documentation of each injection, verification of syringe integrity, and periodic review of participant dosing logs.

The comparator used in the trial is a Placebo that is identical in appearance, volume, and administration method to the investigational product but contains no active ingredient. It is also provided as a solution for injection and administered subcutaneously using the same schedule as the active arm. Compliance with placebo administration is tracked using the same procedures applied to the active product, ensuring consistency across treatment groups.

The primary efficacy assessment is the proportion of participants who are euthyroid and discontinue antithyroid drug (ATD) therapy at Week 26. Secondary efficacy assessments include the proportion of participants with total T3 or FT3 and FT4 levels at or below the upper limit of normal (ULN) who are also off ATD at Week 26, and the proportion who are euthyroid, off ATD, and seronegative at the same time point. Additional secondary endpoints evaluate the proportion of participants achieving T3 (total T3 or FT3) and FT4 ≤ ULN at Weeks 2 and 4 in those with elevated values at baseline.

Efficacy parameters are measured using standardized laboratory assays for total T3, free T3 (FT3), free T4 (FT4), thyroid‑stimulating hormone (TSH), and ATD dosing. Blood samples are collected at baseline, Week 2, Week 4, and Week 26. Results are analyzed by comparing the proportion of participants meeting each predefined criterion between the IMVT‑1402 and placebo groups using appropriate statistical methods for categorical outcomes.