A Phase 2 Open-Label Study of Continuation Treatment with Combination Pyrimidine Nucleosides in Patients with Thymidine Kinase 2 Deficiency (TK2)
Thymidine kinase 2 deficiency (TK2d) is a rare genetic condition that weakens muscles and causes extreme tiredness. This research trial is looking at an experimental combination treatment using two medicines, doxecitine and doxribtimine. The trial is designed for adults aged 18 and over who have this rare condition. The main goal of the study is to test the safety of continuing this treatment. Doctors want to see if participants experience any unwanted side effects and whether any side effects cause people to stop taking the medication. They will also measure how the body absorbs and breaks down the medicine through regular blood tests. Finally, doctors will assess whether the treatment leads to noticeable improvements in how patients feel and function each day. It is an open-label study, meaning both the doctors and the patients will know what medication is being taken.
At a glance
What is this study about?
Thymidine kinase 2 deficiency, often called TK2d, is an extremely rare inherited condition. In people with TK2d, the body struggles to maintain the energy factories inside cells, known as mitochondria. Because muscle cells need a huge amount of energy to work properly, people with this condition often experience progressive muscle weakness, severe fatigue, and difficulties with moving, breathing, or eating.
This Phase 2 clinical trial is exploring a potential treatment made up of two building blocks called doxecitine and doxribtimine. The body normally uses these natural substances to help keep cell energy systems healthy. Researchers hope that providing these substances directly will help support muscle cells and slow down or improve the symptoms of TK2d.
The study focuses closely on safety. Researchers want to track any side effects that occur while people take the medication and see how well patients tolerate it over time. They will also measure how much medicine stays in the bloodstream and check whether patients and their doctors notice meaningful improvements in everyday strength and wellbeing.
Key takeaways
- The study tests two experimental medicines, doxecitine and doxribtimine, for adults with TK2d.
- The main focus is checking the safety of the treatment and monitoring any side effects.
- Doctors will measure drug levels in the blood and track improvements in symptoms.
- Participation is open to adults aged 18 and older with a confirmed diagnosis of TK2d.
- Joining is entirely voluntary, and you can withdraw at any time.
Who may be eligible?
This trial is open to adults aged 18 and older who have been diagnosed with thymidine kinase 2 deficiency (TK2d). Both men and women are able to join.
Because this is a continuation study, it is generally aimed at patients who need ongoing treatment for TK2d and who meet specific medical criteria set by the trial team. People taking part must be well enough to attend study visits and complete the required health checks.
There may be reasons why someone cannot join, such as having certain other serious medical conditions or taking medicines that could interfere with the study drug. The study team will review each person's full medical history to make sure taking part is as safe as possible.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- I am aged 18 or older.
- I have a confirmed diagnosis of thymidine kinase 2 deficiency (TK2d).
- I am able and willing to take the study medicines as prescribed.
- I can attend regular clinic appointments and have blood tests taken.
- I am happy to discuss my full medical history with the study doctors.
What does participation involve?
Taking part in this study involves taking the study medicines, doxecitine and doxribtimine, as instructed by the medical team. Because this is an open-label trial, you and your doctor will both know what you are taking.
You will need to attend regular clinic visits so doctors can monitor your health. During these visits, the medical team will carry out health checks, ask about any symptoms or side effects, and take blood samples. These blood tests show how much of the medicine enters your bloodstream throughout the day and how your body handles it. Your doctor will also use simple rating scales to track whether your condition is staying stable or improving. The trial team will explain the exact schedule and total length of the study before you agree to join.
Potential risks and benefits
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Common questions
What does 'open-label' mean?
It means there is no dummy drug (placebo). Both you and the study team will know exactly which medicines you are receiving.
What is the main purpose of this study?
The main goal is to check how safe the medicines are when taken over time and to learn how the body processes them.
Will taking part cure my TK2 deficiency?
No, this trial is not expected to cure the condition, but doctors hope the treatment might help manage symptoms and improve daily strength.
Do I have to pay to take part?
No, clinical trial medicines and study-related tests are provided free of charge, and travel expenses are often covered.
Can I leave the study if I change my mind?
Yes, taking part is completely voluntary. You can stop at any time without giving a reason, and your regular care will continue as normal.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
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