The US Food and Drug Administration (FDA) has approved Emcitate (tiratricol) tablets for oral suspension to treat peripheral thyrotoxicosis (excess thyroid hormone levels in the blood that causes symptoms, such as rapid heart rate, increased blood pressure and adverse effects on metabolism) in patients with MCT8 deficiency, also known as Allan-Herndon-Dudley syndrome. Emcitate is the first therapy approved by the FDA to treat symptoms of this very rare, devastating genetic disease. This approval reflects the FDA’s dedication to patients with rare genetic diseases, many of whom have serious unmet medical needs.

Marina Zemskova, MD, Deputy Director—Division of General Endocrinology, Center for Drug Evaluation and Research (CDER), FDA, said, “Until now, patients living with MCT8 deficiency and their families had no FDA-approved treatment option. Emcitate’s approval reflects the FDA’s deep commitment to patients with rare conditions who are in need of meaningful treatment options.”

MCT8 deficiency is a rare genetic disorder that primarily affects males. The condition is caused by a faulty gene that provides instructions for making the MCT8 transporter, a critical protein responsible for carrying thyroid hormone into the brain. Because thyroid hormone cannot cross the blood-brain barrier without the MCT8 transporter, the brain receives too little of this hormone, while excessive levels of the hormone build up in the bloodstream. Many patients with MCT8 deficiency experience a range of debilitating effects, including the inability to walk or sit independently, absent or severely limited speech, intellectual disability, feeding difficulties and chronic stress on the heart and metabolism.

Hylton V Joffe, MD, MMSc, Director of the Office of Cardiology, Hematology, Endocrinology, and Nephrology, CDER, FDA, said, “The challenge in treating MCT8 deficiency has always been that the protein needed to deliver thyroid hormone into cells is the one that isn’t working. This drug sidesteps that problem, as its active ingredient, tiratricol, can enter cells on its own without relying on the broken transporter, leading to a decrease in the elevated blood thyroid hormone levels.”

The effectiveness of Emcitate was evaluated in 2 clinical studies in patients ranging in age from infants to adults, including an international, multi-center, randomised, placebo-controlled trial (NCT05579327) and a longer-term open-label study. Across both studies, patients treated with Emcitate had reductions in excess thyroid hormone levels in the bloodstream and improvements in cardiovascular and metabolic symptoms impacted by thyroid levels, such as systolic blood pressure and heart rate.

Emcitate is taken once daily as a liquid suspension, either by mouth or through a feeding tube for patients who have difficulty swallowing, making it accessible for patients with a wide range of abilities. The most common side effects were diarrhea, vomiting, rash and excessive sweating.

Emcitate was granted Orphan Drug, Rare Pediatric Disease, Fast Track and Breakthrough Therapy designations as well as Priority Review (PR).

The approval of Emcitate was granted to Egetis Therapeutics US Inc.