Kygevvi

Opinion

EMA has issued an opinion on this medicine

doxecitine / doxribtimine

Overview

On 29 January 2026, the Committee for Medicinal Products for Human Use (CHMP) adopted a positive opinion, recommending the granting of a marketing authorisation under exceptional circumstances [note 1] for the medicinal product Kygevvi [note 2], intended for the treatment of adults and children with genetically confirmed thymidine kinase 2 deficiency (TK2d) with an age of symptom onset at or before 12 years.

The applicant for this medicinal product is UCB Pharma S.A.

Kygevvi is a PRIME medicine. This scheme optimises the development and accelerates the evaluation of medicines that fulfil an unmet medical need, helping them to reach patients sooner.

Kygevvi will be available as a 2 g / 2 g powder for oral solution. The active substances of Kygevvi, doxecitine and doxribtimine, are pyrimidine nucleosides (ATC code: A16AX29). Doxecitine and doxribtimine are incorporated into the mitochondrial DNA of skeletal muscle, restoring mitochondrial DNA copy number and improving skeletal muscle function in patients with TK2d.

The benefit of Kygevvi is a reduction in the number of motor milestones lost or even a regain of motor milestones, as observed in a pooled analysis of data from a retrospective chart review study (MT-1621-101) and an open-label, single-arm clinical study (TK0102) in patients with TK2d treated with pyrimidine nucleos(t)ides. The most common side effects with Kygevvi are gastrointestinal disorders, including diarrhoea, vomiting, and abdominal pain.

The full indication is:

Kygevvi is indicated for the treatment of paediatric and adult patients with genetically confirmed thymidine kinase 2 deficiency (TK2d) with an age of symptom onset on or before 12 years.

Kygevvi is intended for use with the instructions and supervision of specialist healthcare professionals experienced in the management of patients with mitochondrial disorders.

Detailed recommendations for the use of this product will be described in the summary of product characteristics (SmPC), which will be published on the EMA website in all official European Union languages after the marketing authorisation has been granted by the European Commission.

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Note 1: In exceptional circumstances, an authorisation may be granted subject to certain specific obligations, to be reviewed annually. This happens when the applicant can show that they are unable to provide comprehensive data on the efficacy and safety of the medicinal product, due to the rarity of the condition it is intended for, limited scientific knowledge in the area concerned, or ethical considerations involved in the collection of such data.

Note 2: This product was designated as an orphan medicine during its development. EMA will now review the information available to date to determine if the orphan designation can be maintained

CHMP summary of positive opinion for Kygevvi

Adopted Reference Number: EMA/CHMP/384297/2025

Product details

• Name of medicine:
  Kygevvi
• Active substance:
  • doxecitine
  • Doxribtimine
• International non-proprietary name (INN) or common name:
  • doxecitine
  • doxribtimine
• Therapeutic area (MeSH):
  Mitochondrial Diseases
• Anatomical therapeutic chemical (ATC) code:
  M09A
• EMA product number:
  EMEA/H/C/005119
• Exceptional circumstances:

  This medicine was authorised under exceptional circumstances, because the applicant was unable to provide comprehensive data on the efficacy and safety of the medicine under normal conditions of use. This can happen because the condition to be treated is rare or because collection of full information is not possible or is unethical. For more information, see Pre-authorisation guidance.

• Orphan:

  This medicine was designated an orphan medicine. This means that it was developed for use against a rare, life-threatening or chronically debilitating condition or, for economic reasons, it would be unlikely to have been developed without incentives. For more information, see Orphan designation.

• PRIME: priority medicine:

  This medicine was granted entry to the EMA Priority Medicines (PRIME) scheme during its development. PRIME is a scheme launched by EMA to enhance support for the development of medicines that target an unmet medical need. This voluntary scheme is based on enhanced interaction and early dialogue with developers of promising medicines, to optimise development plans and speed up evaluation so these medicines can reach patients earlier. For more information, see PRIME: priority medicines.

• Marketing authorisation applicant:
  UCB Pharma
• Opinion adopted:
  29/01/2026
• Opinion status:
  Positive