Two drugs aim to restore energy factories in rare muscle disease
NCT ID NCT06754098
First seen Sep 17, 2026 · Last updated Sep 18, 2026 · Updated 1 time
Summary
Researchers are testing a combination of two drugs, doxecitine and doxribtimine, in adults with thymidine kinase 2 (TK2) deficiency, a rare genetic condition that causes muscle weakness and breathing problems. The study will enroll about 15 adults with moderate to severe disease. Participants will take the drugs by mouth three times a day, and researchers will measure changes in muscle strength, walking ability, breathing, and fatigue, as well as levels of mitochondrial DNA in muscle and urine.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- a combination of two nucleoside drugs, doxecitine and doxribtimine, taken by mouth
- What this could lead to
- If it works, this could offer the first targeted treatment for adults with TK2 deficiency, a rare and often debilitating mitochondrial disease.
- What could go wrong
- This is a small, single-arm phase 2 study with no control group, so any improvements could be due to chance or natural variation. The drug combination may not work or may cause side effects.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 2
Tests whether the treatment actually works, and watches for side effects, in a larger group.
- Participants
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About 15 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Jan 2025
- Expected to finish
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Dec 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 years and older
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Signed informed consent by the subject. 2. Subject must be greater than 18 years of age at time of consent. 3. Genetic diagnosis of TK2 deficiency 4. Subject should have evidence of a moderate to severe disease, with motor and or respiratory involvement, shown by one of the following: 1. North Star Ambulatory Assessment Scale (NSAA) less than 30 2. 6-minute walking test less than 450 meters 3. Force Vital Capacity in the sitting position less than 70 percent or a drop in the decubitus position greater than 10 percent or need for mechanical ventilation. 4. Disabling symptoms and evidence of motor and/or respiratory function progressive decline. 5. Female subjects must have no intention to become pregnant during the study. Female subjects who are of childbearing potential (that is, following menarche until at least 1 year post-menopausal if not anatomically and physiologically incapable of becoming pregnant) must agree and commit to the use of highly effective methods of birth control for the duration of the study and for 30 days after the end of the study, and be willing to have additional pregnancy tests conducted during the study. Acceptable methods are defined as those that result, alone or in combination, in a low failure rate (that is, less than 1 percent per year) when used consistently and correctly, such as surgical sterilization, an intrauterine device, or hormonal contraception in combination with a barrier method. 6. Male subjects with partners of childbearing potential must agree to use effective contraception methods during the study and for at least 90 days after the last dose of the study medication. Acceptable methods include the use of condoms combined with spermicidal foam/gel/film/cream/suppository. 7. Willingness to comply with the study protocol, including but not limited to, all study procedures, study visits, and study drug compliance. Exclusion Criteria: 1. History of liver disease, or liver function test results (alanine aminotransferase \[ALT\], aspartate transaminase \[AST\], or total bilirubin) greater than or equal2 times (2X) the upper limit of normal. Patients with transaminases greater than 2 times (2X) can participate with the approval and monitoring of a doctor specializing in liver toxicity. 2. Participation in a previous trial of any investigational agent for primary mitochondrial disease within 1 year prior to informed consent, or use of any other investigational therapy within 30 days (or 3 half-lives, whichever is longer) prior to informed consent, or participation in other clinical studies, within 30 days prior to informed consent, which in the opinion of the study Sponsor, may potentially confound results from this study. 3. Pregnant (females 10.0 years old or older will have a pregnancy test at screening), or breastfeeding
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Hospital Universitario 12 de Octubre
RECRUITINGMadrid, Madrid, 28041, Spain
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