NCT05579327

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

Withdrawal of Tiratricol Treatment in Males With Monocarboxylate Transporter 8 Deficiency (MCT8 Deficiency): A Double-blind, Randomized, Placebo-controlled Study

• Status: Completed
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 20 (actual)
• Sponsor: Rare Thyroid Therapeutics International AB · Industry
• Sex: Male
• Age: 4 Years
• Healthy volunteers: Not accepted

Summary

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.

Detailed description

The Screening Period includes a Screening Visit and a period of open-label treatment in which a stable maintenance dose of tiratricol, essential for progression into the Randomized Treatment Period, will be established. The duration of this period will vary depending on whether the participant is currently receiving treatment with tiratricol at the time of enrollment in the study (Cohort A), or if they are considered to be tiratricol treatment-naïve (Cohort B). Participants are considered to be tiratricol-naïve if they have never previously been administered tiratricol, or have previously received tiratricol but are not receiving tiratricol at the time of enrollment. For participants in Cohort A, once eligibility is confirmed during the Screening Visit, the study starts with a Run-in Period to ensure that participants are being administered a stable dose of tiratricol, as determined by meeting the Stable Dose Criterion. For participants in Cohort B, once eligibility is confirmed during the Screening Visit, the study starts with a Dose Titration Period to allow titration to a stable dose of tiratricol, as determined by meeting the Stable Dose Criterion. The Stable Dose Criterion is defined as at least 4 weeks' treatment (during the period from the start of screening to randomization) at a fixed daily dose that is targeting a serum total T3, measured by LC/MS/MS, at the lower limit of normal (LLN) with at least 2 consecutive serum total T3 results that are within the study titration range: within 20% below the LLN to the 75th percentile of the normal range for serum total T3 (i.e., LLN + 0.75×\[ULN-LLN\]). An evaluable participant is defined as a participant who completes the Randomized Treatment Period either by completing 30 days of double-blind treatment without meeting the rescue criterion or by meeting the rescue criterion.

Conditions

• Monocarboxylate Transporter 8 Deficiency
• Allan-Herndon-Dudley Syndrome

Interventions

Type	Name	Description
DRUG	Tiratricol	Tiratricol tablets are flat tablets that contain 350 µg tiratricol. Treatment will be administered orally or via percutaneous endoscopic gastrostomy (PEG) tube; tablets will be suspended in water and, if needed, mixed with mashed food for oral administration or administered in water through the PEG tube as applicable.
DRUG	Placebo	Placebo tablets will be identical in appearance to tiratricol tablets but contain no tiratricol. Treatment will be administered orally or via PEG tube; tablets will be suspended in water and, if needed, mixed with mashed food for oral administration or administered in water through the PEG tube as applicable. During the Randomized Treatment Period, participants will receive the same number of tablets as the stable dose of open-label tiratricol they were receiving before randomization.

Timeline

• Start date: 2023-07-21
• Primary completion: 2025-07-22
• Completion: 2025-09-03
• First posted: 2022-10-13
• Last updated: 2026-04-08

Locations

8 sites across 3 countries: United States, Netherlands, United Kingdom

Regulatory

• FDA-regulated drug study