KYGEVVI is the first and only FDA-approved treatment for early-onset TK2d1 

  • For adults and pediatric patients with an age of TK2d symptom onset on or before 12 years
  • Studies found improved survival time is possible
  • KYGEVVI reduced the overall risk of death from treatment start by ~86% when compared to an untreated external control group (95% CI: 61%, 96%)

See the data  

TK2d Symptoms

TK2d is a rare and often fatal mitochondrial disease that causes progressive myopathy.2

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Survival Data

Studies found that KYGEVVI improved overall survival time from treatment start vs matched untreated patients.1

Explore the data 

Dosing & Administration

KYGEVVI is a powder for solution taken orally or via feeding tube.1

Learn more about dosing 

The Music Box: An early-onset TK2d story

Every person with early-onset TK2d experiences their own unique journey to diagnosis and treatment. Watch the journey of a father and his son as they experience the onset of symptoms, search for a diagnosis, and ultimately receive treatment.

Individual results may vary.

 

LET'S CONNECT.

Get more information about KYGEVVI.

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References

  1. KYGEVVI (doxecitine and doxribtimine) U.S. Prescribing Information. Smyrna, GA: UCB, Inc.
  2. Thymidine kinase 2 deficiency. National Organization for Rare Disorders. Updated March 1, 2025. Accessed March 1, 2026. https://rarediseases.org/rare-diseases/thymidine-kinase-2-deficiency/

INDICATION

KYGEVVI is indicated for the treatment of thymidine kinase 2 deficiency (TK2d) in adults and pediatric patients with an age of symptom onset on or before 12 years.

IMPORTANT SAFETY INFORMATION

Increase in Liver Transaminases

Elevated liver transaminase [alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST)] levels were reported in patients treated with KYGEVVI. Obtain baseline liver transaminase (ALT, AST) and total bilirubin levels in patients prior to treatment initiation with KYGEVVI.

INDICATION

KYGEVVI is indicated for the treatment of thymidine kinase 2 deficiency (TK2d) in adults and pediatric patients with an age of symptom onset on or before 12 years.

IMPORTANT SAFETY INFORMATION

Increase in Liver Transaminases

Elevated liver transaminase [alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST)] levels were reported in patients treated with KYGEVVI. Obtain baseline liver transaminase (ALT, AST) and total bilirubin levels in patients prior to treatment initiation with KYGEVVI. If signs or symptoms consistent with liver injury are observed, interrupt treatment with KYGEVVI until liver transaminase (ALT, AST) and total bilirubin levels have either returned to baseline or stabilized at a new baseline value. Consider permanently discontinuing KYGEVVI if signs or symptoms consistent with liver injury persist or worsen. Monitor liver transaminases and total bilirubin levels yearly and as clinically indicated.

Gastrointestinal Adverse Reactions 

Diarrhea and vomiting leading to hospitalization, dose reduction, and permanent discontinuation were reported in patients treated with KYGEVVI. Based on the severity of the diarrhea and/or vomiting, reduce the dosage of KYGEVVI or interrupt treatment until diarrhea and/or vomiting improves or returns to baseline. Consider restarting KYGEVVI at the last tolerated dose, and increase the dose as tolerated. For persistent or recurring diarrhea and/or vomiting, consider discontinuing KYGEVVI permanently and provide supportive care with electrolyte repletion as clinically indicated.

Adverse Reactions

The most common adverse reactions (incidence ≥5%) are diarrhea, abdominal pain (including abdominal pain upper), vomiting, alanine aminotransferase increased (ALT), and aspartate aminotransferase increased (AST).

Please see the full Prescribing Information.