FOR IMMEDIATE RELEASE
Contact:
Emily Grandahl
Marketing Coordinator, MitoAction
emily@mitoaction.org
(888) 648-6228
www.mitoaction.org
FDA Approval of KYGEVVI Marks a Defining Moment for Mitochondrial Disease Community and Families Affected by TK2d
Boston, MA — November 3, 2025— MitoAction proudly announces the U.S. Food and Drug Administration’s (FDA) approval of KYGEVVI® (doxecitine and doxribtimine), a groundbreaking therapy developed by UCB for the treatment of thymidine kinase 2 deficiency (TK2d). This milestone marks a historic step forward for the mitochondrialRelated to the mitochondria. disease community, offering long-awaited hope to patients and families who have endured years without effective treatment options. Remarkably, this approval represents the second FDA authorization for a mitochondrial disease therapy in just six weeks, underscoring the accelerating momentum in mitochondrial medicine and the power of collaboration among patients, researchers, and industry partners driving progress toward meaningful change.
KYGEVVI® has been granted approval by the FDA for the treatment of adults and pediatric patients living with TK2d, with an age of symptom onset on or before 12 years. It is the first and only approved treatment for these patients living with TK2d.
TK2d is an ultra-rare, life-threatening, genetic mitochondrial disease characterized by progressive and severe muscle weakness with no approved treatment options beyond supportive care until now. It is estimated that the worldwide prevalence of TK2d is 1.64 cases per 1,000,000 people.
“The approval of doxecitine and doxribtimine represents a pivotal moment for the TK2d community who previously had no FDA-approved treatment options for this rare genetic mitochondrial disease beyond supportive [palliative] care,” said Donatello Crocetta, Chief Medical Officer at UCB. “We extend heartfelt thanks to the patients, families and friends, advocates, healthcare providers and dedicated clinical trial teams who have partnered with us on this important journey.”
“Today’s decision by the FDA brings hope to so many in our community who have waited years for a breakthrough,” said Kira Mann, CEO of MitoAction. “For those affected by mitochondrial disease, specifically TK2d, this moment represents more than scientific progress, it’s a recognition of their perseverance, courage, and strength. It reminds us that when patients, researchers, regulators, and industry work together, we move closer to a future where effective treatments are not just possible, but within reach.”
About MitoAction
Founded in 2005, MitoAction is a leading national nonprofit dedicated to improving the quality of life for children, adults, and families affected by mitochondrial disease, a complex and often devastating condition. Through education, advocacy, support, and community-building, MitoAction empowers patients and caregivers to navigate daily challenges, connect with critical resources, and engage in groundbreaking initiatives that accelerate research and therapeutic progress. From direct family support programs to national policy advocacy and clinical collaborations, MitoAction is committed to transforming hope into tangible impact, ensuring that no one faces mitochondrial disease alone.
More Information about KYGEVVI®
For more information about KYGEVVI® including prescribing information and instructions for use, please visit https://www.ucb-usa.com/Innovation/Products/KYGEVVI.
