UCB bags first EU approval for rare genetic disease TK2d

Patients in the EU with rare disease thymidine kinase 2 deficiency (TK2d) could be just weeks away from having the first approved therapy, after UCB's Kygevi was recommended by the EMA's human medicines committee.

At its January meeting late last week, the CHMP has recommended that Kygevi (doxecitine and doxribtimine) should be cleared by the European Commission to treat people living with TK2D whose disease started before the age of 12.

It was approved by the FDA (as Kygevvi) with a similar label last November and is due to launch there later this quarter.

The endorsement comes on the back of stellar results for Kygevi in a retrospective study, reported last October, which found that the drug reduced the risk of death by a massive 95% when compared to a historical cohort of untreated patients.

TK2d is an ultra-rare, progressive, and life-threatening mitochondrial myopathy caused by pathogenic variants of the thymidine kinase 2 gene. It leads to mitochondrial DNA depletion, resulting in severe and progressive muscle weakness. Many affected individuals lose mobility, require respiratory support, and need assistance with basic functions such as eating.

After treatment with Kygevvi, delivered as an oral solution, 84% of patients regained one or more motor milestones, suggesting that the medicine improves motor function, and many were able to reduce or stop ventilatory support. The most common side effects reported with Kygevvi were diarrhoea, vomiting and abdominal pain.

The prevalence of Tk2D is still uncertain, but estimates suggest it could affect around 1.64 people per 100 million, which would equate to fewer than 150 cases worldwide. It is thought that the drug compensates for reduced TK2 activity and helps to slow the progression of the disease.

Other CHMP decisions

Also at the January CHMP meeting, Sanofi's Rezurock (belumosudil) was recommended for the treatment of chronic graft-versus-host disease (GvHD) in adults and in children aged 12 years and older with a body weight of at least 40 kg, after being turned down last October. The committee said Rezurock is to be used only "when other treatment options provide limited clinical benefit, are not suitable, or have been exhausted."

Novo Nordisk got a green light for GLP-1 agonist semaglutide – already sold as Ozempic for diabetes and Wegovy for obesity – as a treatment for non-cirrhotic metabolic dysfunction-associated steatohepatitis (MASH) and liver fibrosis under the Kayshild brand name. It is only the second MASH drug to be approved in the EU – after Madrigal Pharma's THR β-selective agonist Rezdiffra (resmetirom) – and was also approved in the US for this indication (as Wegovy) in August 2025.

Gedeon Rochter's Fylrevy (estetrol), a hormone replacement therapy for oestrogen deficiency symptoms in postmenopausal women, was also backed by the CHMP, along with SHINE Europe's radiopharmaceutical precursor Ilumira (lutetium [177Lu] chloride) – used to radiolabel carrier medicines – and Sanofi's trivalent influenza vaccine Supemtek.