NCT05579327: ReTRIACt

Withdrawal of Tiratricol Treatment in Males With Monocarboxylate Transporter 8 Deficiency (MCT8 Deficiency)

Completed Phase 3 Last updated 8 April 2026

What this trial tests

Phase 3 trial testing Tiratricol in Monocarboxylate Transporter 8 Deficiency in 20 participants. Completed in 3 September 2025.

Timeline

21 July 2023

Primary endpoint
22 July 2025

3 September 2025

Quick facts

Lead sponsor	Rare Thyroid Therapeutics International AB
Phase	Phase 3
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	quadruple
Primary purpose	treatment
Enrollment	20
Start date	21 July 2023
Primary completion	22 July 2025
Estimated completion	3 September 2025
Sites	8 locations across United Kingdom, Netherlands, United States

Drugs / interventions tested

• Tiratricol — full drug profile →
• Placebo

Conditions studied

• Monocarboxylate Transporter 8 Deficiency — all drugs for Monocarboxylate Transporter 8 Deficiency →
• Allan-Herndon-Dudley Syndrome — all drugs for Allan-Herndon-Dudley Syndrome →

Sponsor

Rare Thyroid Therapeutics International AB

Who can join

4 and older, male only, with Monocarboxylate Transporter 8 Deficiency or Allan-Herndon-Dudley Syndrome. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

This is a double-blind, randomized phase 3 multicenter placebo-controlled study in at least 16 evaluable male participants diagnosed with MCT8 deficiency. Male participants, from 4 years of age (at randomization) and having demonstrated stable maintenance treatment with tiratricol, will be randomized to receive placebo or tiratricol for 30 days or until reaching the rescue criterion (serum total triiodothyronine \[T3\] \> upper limit of normal \[ULN\] of the participant's normal range, for a sample collected during the 30-day Randomized Treatment Period). The research hypothesis to be tested is that, for participants in the placebo group, removal of tiratricol will lead to an increase of serum total T3 concentration, measured by liquid chromatography with tandem mass spectrometry (LC/MS/MS), above the ULN and requirement of rescue treatment with tiratricol, compared to those who continue to receive tiratricol.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. TRIAC Therapy Relieves Hyperthyroid Symptoms, Lowering T4, T3, and Metabolic Rate in Resistance to Thyroid Hormone β.
   Moran C, Martin-Grace J, Lyons G, Watson L, et al · · 2026 · cited 1× · PMID 41131705 · DOI 10.1210/clinem/dgaf583