FDA Approves Emcitate for Peripheral Thyrotoxicosis in MCT8 Deficiency
KEY TAKEAWAYS
- The FDA approved Emcitate for treatment of peripheral thyrotoxicosis in adults and children with MCT8 deficiency.
- MCT8 deficiency is an X-linked disorder caused by pathogenic SLC16A2 variants and is associated with severe neurodevelopmental impairment as well as systemic effects of excess triiodothyronine.
The Food and Drug Administration (FDA) has approved Emcitate (tiratricol; Egetis Therapeutics, Stockholm, Sweden) for the treatment of peripheral thyrotoxicosis in adult and pediatric patients with monocarboxylate transporter 8 (MCT8) deficiency, also known as Allan-Herndon-Dudley syndrome (AHDS). According to a statement from Egetis Therapeutics, Emcitate is the first FDA-approved therapy for people with MCT8 deficiency in the United States.
MCT8 deficiency is a rare X-linked disorder caused by pathogenic variants in the gene SLC16A2, which encodes a transporter involved in thyroid hormone entry into cells, including cells in the central nervous system. Impaired transport results in reduced thyroid hormone activity in the brain together with excessive triiodothyronine exposure in peripheral tissues. Clinically, people with MCT8 deficiency can have severe neurodevelopmental impairment accompanied by systemic complications of chronic thyrotoxicosis, including poor growth, muscle wasting, cardiovascular strain, and metabolic abnormalities.
The FDA approval was supported by a clinical development program that included the ReTRIACt study (NCT05579327), Triac Trial I (NCT0239645 NCT02060474) and II (NCT02396459), an Erasmus Medical Center cohort and survival study, and a US expanded-access program.
Neurologic and Clinical Considerations
- Emcitate is approved specifically for peripheral thyrotoxicosis associated with MCT8 deficiency.
- The approval does not establish improvement in neurodevelopmental impairment or other central nervous system manifestations of the disorder.
- Early identification of MCT8 deficiency remains important because affected individuals typically require coordinated care across neurology, endocrinology, rehabilitation, nutrition, and other specialties.
For neurologists, the approval adds an FDA-approved option for addressing an important systemic component of a disorder whose most prominent clinical manifestations are often neurologic and developmental.
Source
Egetis Therapeutics. Egetis Therapeutics announces U.S. FDA approval of Emcitate (tiratricol) for patients with MCT8 deficiency. News release. September 28, 2026.