A Multicenter Phase 2b Randomized, Double-Masked, Placebo-Controlled Dose-Ranging Study of TOUR006 in Participants with Thyroid Eye Disease

This research project is a multicenter Phase 2b randomized, double-masked, placebo-controlled dose-ranging study of TOUR006 in participants with Thyroid Eye Disease (TED). The study evaluates the efficacy and safety of subcutaneous TOUR006 compared with placebo in adults with moderate to severe active TED. The study's primary objective is to determine whether TOUR006 reduces proptosis (exophthalmos) in affected study eyes. Secondary objectives include exploring efficacy across different dose levels, characterizing efficacy on specified outcome measures, evaluating long-term efficacy outcomes, and characterizing the safety profile of TOUR006.

The trial is classified as therapeutic exploratory (Phase II) and is designed as a dose-ranging study to evaluate both safety and efficacy relative to placebo. The planned participant population comprises adults 18 to 80 years inclusive, with the registered age ranges reported as 18-64 years and 65+ years; the planned enrollment is 81 participants. The study is being conducted across 15 sites in six European countries: France, Italy, Latvia, Poland, Slovakia, and Spain. The trial status is authorised and recruiting in multiple member states, with various national authorisation and recruitment start dates documented. Estimated timelines indicate recruitment beginning in early 2025 with a projected EU/EEA end of trial in mid-2026 and a global end date in late 2026.

Key inclusion criteria require a clinical diagnosis of Graves' disease associated with moderate to severe active TED, symptom onset within approximately 15 months, proptosis at least 3 mm above normal for the study eye per investigator judgment, a Clinical Activity Score (CAS) of 4 on the 7-item scale for the study eye, and presence of thyroid-stimulating immunoglobulin (TSI) above a defined threshold. Principal exclusion criteria include anticipated need for urgent sight-saving interventions, prior treatment with teprotumumab or other IGF-1 receptor inhibitors, and recent or high cumulative systemic steroid exposure beyond specified limits.

The trial's design randomized, double-masked, placebo-controlled, and dose-ranging permits assessment of dose response relationships for TOUR006 while maintaining rigorous controls for bias. The multi-national, multi-site approach enhances the trial's generalizability across diverse clinical settings. Safety assessments are explicitly emphasized among objectives, with long-term efficacy outcomes also included to evaluate durability of any therapeutic benefit. The investigational product formulation components are listed and include L-histidine, mannitol, sucrose, disodium EDTA dihydrate, polysorbate 80, and water for injection.

Regulatory documentation reflects multiple application and substantial modification submissions and consequent authorizations across participating member states, with decisions and conclusion reporting dates recorded for initial and subsequent submissions. This trial represents a structured, industry-sponsored effort to define optimal dosing and to characterize both the clinical impact on proptosis and the safety profile of TOUR006 in adults with active, moderate to severe TED. Results from this Phase 2b study are intended to inform further clinical development decisions regarding TOUR006.