In a significant milestone for the rare disease community, the FDA approved KYGEVVI (doxecitine and doxribtimine) in November 2025, marking the first and only approved treatment for thymidine kinase 2 deficiency (TK2d). This breakthrough approval represents a transformative moment for patients and families facing this ultra-rare, life-threatening genetic mitochondrial disease that previously had no treatment options beyond supportive care.
KYGEVVI has been approved for use in both adults and pediatric patients who develop symptoms by the age of 12. TK2d is an exceptionally rare genetic mitochondrial disorder affecting fewer than 2 people per 1,000,000 individuals w...