Withdrawal of Tiratricol Treatment in Males with Monocarboxylate Transporter 8 Deficiency (MCT8 Deficiency): a Double-blind, Randomized, Placebo-controlled Study
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 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.
• Male participants diagnosed with a pathogenic mutation in the MCT8 gene, confirmed with a genetic test.
• Serum total T3 concentration above the ULN of the age specific normal range:
‣ at the time of diagnosis (or the closest sample taken prior to first ever treatment with tiratricol) for participants who are currently treated with tiratricol
⁃ in the Screening Visit sample, or most recent standard of care sample prior to screening, for participants who have never received and/or currently not receiving tiratricol.
• Participants will be aged 4 years or older at the time of randomization. Participants entering screening who are \<4 years of age but expected to be aged 4 years at randomization should be discussed with the medical monitor.
• Signed and dated informed consent form from the parents or legal guardian.