Not recruitingRare disease

Study of Doxecitine and Doxribtimine Oral Solution for Treatment of Patients with Thymidine Kinase 2 (TK2) Deficiency Who Have Previously Received Treatment

Verified siteInvestigational

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What is this trial about?

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

This study focuses on Thymidine Kinase 2 Deficiency (TK2), which is a rare genetic condition affecting the body's ability to produce energy in cells. The study will evaluate a combination treatment consisting of doxecitine and doxribtimine (also known as MT1621), which are pyrimidine nucleosides given as an oral solution.

The purpose of this research is to understand how safe and effective continued treatment with this medication combination is for patients who have previously received similar treatments for their TK2 deficiency. The medication will be given by mouth, with doses calculated based on the patient's weight up to a maximum of 800 milligrams per kilogram per day.

During the study, which may last up to 72 months, participants will continue their current treatment while researchers monitor their health through various tests. The study will track how well patients tolerate the medication and observe any changes in their condition. Researchers will also measure how the medication moves through the bloodstream and assess its taste using a simple rating scale.

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 assessment and enrollment
You will be confirmed to have a genetic mutation in the TK2 gene
A pregnancy test will be required if you are a female 10 years or older
You must be currently receiving treatment with nucleosides for TK2 deficiency
Step 2
Treatment protocol
You will receive a combination of two medications: doxecitine and doxribtimine
The medication will be given as an oral solution that you take by mouth
You will need to maintain your current treatment and exercise routine throughout the study
Step 3
Safety monitoring
Your health will be monitored through regular blood tests
Heart monitoring will be performed using electrocardiograms
Any side effects will be recorded and monitored
Step 4
Regular assessments
Your movement abilities will be tested regularly
Breathing tests will be conducted to check lung function
Your feeding status will be monitored
Quality of life questionnaires will be completed
If you are under 18, your growth will be tracked
Blood samples will be taken to measure drug levels and other markers
Step 5
Study duration
The study runs from September 2019 to June 2025
You will need to continue following all study requirements until your participation ends

Who can join the trial?

12 criteria

Must sign an informed consent form (for parents/legal guardians) or provide assent (for participants when applicable)
Must have confirmed genetic mutations in the TK2 gene (a gene responsible for an important enzyme in cell energy production)
Must not have any other genetic diseases
Must be currently receiving nucleoside treatment (special medications) for TK2 deficiency
check
For female participants:
- Must not be breastfeeding
- Must have a negative pregnancy test if 10 years or older
- Must not plan to become pregnant during the study
- If able to become pregnant, must use effective birth control during the study and for 30 days after
- check
  For male participants:
  - Must use condoms during the study and for 30 days after the last dose
  - Must not donate sperm for 30 days after the last dose
  - Must be willing to maintain current treatment and exercise routines throughout the study
  - Must be willing to follow all study requirements, including attending appointments and taking medications as prescribed

Who cannot join the trial?

10 criteria

Patients who have not previously received treatment with dC/dT, dCMP/dTMP or doxecitine and doxribtimine (these are specific medications used to treat thymidine kinase 2 deficiency)
Individuals who are unable to comply with study procedures and follow-up visits
Patients with known allergies or severe reactions to the study medications
Those who are participating in other clinical trials at the same time
Patients with severe liver or kidney problems that could affect the metabolism of study medications
Pregnant women or women planning to become pregnant during the study period
Breastfeeding mothers
Patients who have had major surgery within 30 days before starting the study
Individuals with serious medical conditions that could interfere with study participation
Patients who cannot provide informed consent or do not have a legal guardian who can provide consent

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Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Verified
Hospital Sant Joan De Deu Barcelona
Esplugues De Llobregat, Spain
Verified
Hospital Universitario 12 De Octubre
Madrid, Spain
Verified
Hospital Vall d’Hebron
Barcelona, Spain

Trial locations

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Investigated drugs

Doxecitine
and doxribtimine are combination medications used to treat a rare genetic condition called Thymidine Kinase 2 (TK2) deficiency. These medications are pyrimidine nucleosides that help replace missing components in cells affected by TK2 deficiency. They work together to support proper cellular function in patients with this condition.
dCMP/dTMP
is a combination treatment that works similarly to doxecitine and doxribtimine. It is another form of pyrimidine nucleoside therapy used to treat TK2 deficiency by helping to restore normal cellular processes in patients with this genetic condition.
dC/dT
(combination pyrimidine nucleosides) is another formulation of treatment that contains similar active components to help patients with TK2 deficiency. Like the other medications in this trial, it works by providing the body with important cellular building blocks that are lacking due to the genetic condition.

What is already known about the treatment

Doxecitine
An investigational pyrimidine nucleoside medication administered orally for the treatment of Thymidine Kinase 2 (TK2) deficiency, a rare genetic condition affecting cellular energy production. The drug works by providing essential building blocks for mitochondrial DNA synthesis, helping to compensate for the defective TK2 enzyme and improve cellular function. Currently being studied in Phase 2 clinical trials, this medication is used in combination with doxribtimine as a continuation therapy for patients previously treated with nucleoside therapies.
Doxribtimine
A complementary pyrimidine nucleoside medication used in combination with doxecitine for treating Thymidine Kinase 2 (TK2) deficiency. This oral medication works synergistically with doxecitine to support mitochondrial DNA synthesis and cellular energy production in patients with TK2 deficiency. The drug is currently under investigation in Phase 2 clinical trials as part of a combination therapy approach, showing promise in addressing this rare genetic disorder.

Investigated diseases

Thymidine Kinase 2 Deficiency - A rare genetic condition that affects the body's ability to produce mitochondrial DNA. The disease causes progressive muscle weakness due to problems with an enzyme called thymidine kinase 2, which is essential for producing DNA building blocks in mitochondria. It primarily affects muscle tissues throughout the body, including those used for movement, breathing, and swallowing. The condition can begin in childhood or adulthood, with varying rates of progression. People with this condition may experience difficulty with physical activities and movements that were previously normal for them.