RecruitingRare disease

Study of doxecitine and doxribtimine oral solution for adult patients with Thymidine Kinase 2 (TK2) Deficiency

Verified siteInvestigationalNo placebo

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on a rare genetic condition called Thymidine Kinase 2 (TK2) Deficiency, which affects muscle function and breathing. This disorder is caused by genetic mutations that impact how cells produce energy, leading to muscle weakness and respiratory problems. The study will test a combination of two medications: doxecitine and doxribtimine (also known as MT1621), which are given as an oral solution that patients drink.

The purpose of this research is to determine how well this combination treatment works and how safe it is for adults with TK2 Deficiency. The study will follow participants for 24 months while they receive the medication. During this time, the maximum daily dose will be 800 milligrams per kilogram of body weight.

This is a single-arm study, which means all participants will receive the same treatment combination. The medications will be taken by mouth according to a specific schedule. Participants will need to visit the study center regularly for check-ups to monitor their muscle strength, breathing function, and overall health while taking the medication.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

Step 1
Initial qualification
You will be evaluated to confirm your eligibility if you are over 18 years old and have a genetic diagnosis of TK2 deficiency
Your motor and respiratory functions will be assessed using specific tests, including the North Star Ambulatory Assessment Scale, 6-minute walking test, and breathing capacity measurements
Step 2
Treatment initiation
You will begin taking an oral solution containing two medications: doxecitine and doxribtimine
The treatment period will continue from June 2024 to June 2026
Step 3
Ongoing assessments
Your progress will be monitored to evaluate how well the medication is working
Regular checks of your motor function and breathing capacity will be conducted
Your safety will be monitored throughout the treatment period
Step 4
Contraception requirements
If you are a woman who can become pregnant, you must use effective birth control during the study and for 30 days afterward
If you are a man with a partner who can become pregnant, you must use effective contraception during the study and for 90 days after the last dose
Step 5
Study completion
The study will conclude in June 2026
Final assessments of your motor function and breathing capacity will be performed

Who can join the trial?

15 criteria

Must sign an informed consent document before participating in the study
Must be over 18 years old when signing the consent
Must have a confirmed genetic diagnosis of TK2 deficiency
Must show evidence of moderate to severe disease with motor or breathing problems, demonstrated by at least one of:
- Score below 30 on the North Star Ambulatory Assessment Scale (a test that measures movement ability)
- Walking less than 450 meters in 6 minutes
- Breathing capacity less than 70% when sitting, or dropping more than 10% when lying down, or needing breathing support
- Having disabling symptoms with worsening movement or breathing function
- For women who can become pregnant:
  - Must not plan to become pregnant during the study
  - Must use reliable birth control during the study and for 30 days after
  - Must agree to pregnancy testing during the study
  - For men with partners who can become pregnant:
    
    Must use effective birth control during the study and for 90 days after the last dose
    Must use condoms with spermicide
    Must be willing to follow all study requirements, including:
    
    Attending all study visits
    Following study procedures
    Taking study medication as directed

Who cannot join the trial?

12 criteria

History of hypersensitivity (severe allergic reactions) to the study medications or similar compounds
Pregnant or breastfeeding women
Participation in another clinical trial within the past 30 days
Severe liver problems (as shown by blood tests)
Severe kidney problems (as shown by blood tests)
Uncontrolled cardiovascular disease (heart and blood vessel conditions)
Active or untreated cancer
Significant mental health conditions that could affect participation
Alcohol or drug abuse within the past 6 months
Use of certain medications that might interact with the study drug
Unable to follow study procedures or attend scheduled visits
Any condition that, in the opinion of the study doctor, would make participation unsafe

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Verified sites

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Hospital Universitario 12 De Octubre
Verified
Madrid, Spain

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Investigated drugs

Doxecitine
is a medication designed to treat TK2 deficiency, a rare genetic condition that affects how cells produce energy. It works by helping to restore the normal function of an enzyme called thymidine kinase 2, which is essential for producing DNA building blocks in cells.
Doxribtimine
is used in combination with doxecitine to treat TK2 deficiency. It also helps in supporting cellular energy production and DNA synthesis in patients with this genetic condition. Together, these medications aim to improve muscle function and overall quality of life in adults with TK2 deficiency.

What is already known about the treatment

Doxecitine
An oral medication being studied in clinical trials for the treatment of Thymidine Kinase 2 (TK2) deficiency, a rare genetic condition. This compound works by helping restore normal cellular energy production in mitochondria, acting as a nucleoside supplement that bypasses the defective TK2 enzyme pathway. It belongs to the class of nucleoside analogues and is typically administered in combination with doxribtimine to support cellular DNA synthesis and energy metabolism.
Doxribtimine
A complementary oral medication used alongside doxecitine in the treatment of TK2 deficiency. This nucleoside analogue works synergistically with doxecitine to provide essential building blocks for mitochondrial DNA synthesis, helping to restore cellular energy production in patients with TK2 enzyme deficiency. The medication is part of a novel therapeutic approach being evaluated in clinical trials for its potential in treating rare mitochondrial disorders.

Investigated diseases

Thymidine Kinase 2 Deficiency (TK2d) - A rare genetic condition that affects the body's ability to produce essential building blocks for mitochondrial DNA. The disease primarily impacts muscle function and development, causing progressive muscle weakness. People with TK2d experience difficulty with movements like walking, breathing, and swallowing. The condition typically affects multiple body systems and can develop at various ages. The disease is caused by mutations in the TK2 gene, which leads to reduced production of necessary compounds for mitochondrial function. This disorder belongs to a group of mitochondrial DNA depletion syndromes.