Active — Not RecruitingPhase 2

An Open-Label Study of Continuation Treatment With Combination Pyrimidine Nucleosides in Patients With TK2 Deficiency

United States, Israel, Spain47 participantsStarted 2019-07-05

Plain-language summary

This is a Phase 2 prospective open-label treatment study of the safety and efficacy of doxecitine and doxribtimine in study participants with thymidine kinase 2 (TK2) deficiency who participated in the retrospective study MT-1621-101 \[NCT03701568\] or who were receiving nucleos(t)ide treatment and were approved by the Sponsor.

Who can participate

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * Signed informed consent by the parent(s) or legally authorized representative (LAR) and/or assent by the study participant (when applicable). * Confirmed genetic mutation in the TK2 gene. * Absence of other genetic disease or polygenic disease. * Current treatment with nucleos(t)ides for TK2 deficiency. Study participants who were not previously enrolled in MT-1621-101 \[NCT03701568\] will require Sponsor approval to ensure that collection of clinical and functional measurements prior to treatment are sufficient to serve as baseline assessments for purposes of evaluating safety and efficacy. * Female study participants must not be breastfeeding, have a negative pregnancy test at screening (females ≥10 years old), and have no intention to become pregnant during the course of the study. Female study participants who are of childbearing potential (ie, following menarche until ≥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. Acceptable methods are defined as those that result, alone or in combination, in a low failure rate (ie, \<1% per year) when used consistently and correctly, such as surgical sterilization, an intrauterine device, or hormonal contraception in combination with a barrier method. In certain countries (if permitted by law), women of childbearing…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Since this is a Phase 2 continuation study for TK2 deficiency and is no longer recruiting, is there any way my care team could find out whether exceptions exist for new participants, or whether a related study might be opening up that I could be considered for?
2The trial is specifically measuring how often serious side effects occur and how often they cause people to stop taking the medication — what does my doctor know so far about the safety profile of this pyrimidine nucleoside combination, and are there any side effects I should be watching for closely?
3TK2 deficiency is a rare mitochondrial disease, so what does my doctor think about how this continuation study's Phase 2 status affects what we currently know about whether this treatment is safe and effective for someone with my specific symptoms or disease severity?
4Are there any approved or standard-of-care treatments for TK2 deficiency that my doctor would recommend I consider first, or alongside learning about this trial, given that the research is still ongoing?
5Since this is described as a 'continuation' study, meaning patients already on the treatment are being followed, how would my doctor evaluate whether the emerging data from this trial should influence my current treatment plan, even if I'm not enrolled?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Incidence of treatment-emergent adverse events (TEAEs)

Timeframe: From first administration of study drug until end of safety follow-up (up to approximately 7 years)

Incidence of TEAEs leading to study drug withdrawal

Timeframe: From first administration of study drug until end of safety follow-up (up to approximately 7 years)

Trial details

NCT IDNCT03845712

SponsorUCB BIOSCIENCES, Inc.

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2026-06-30

View on ClinicalTrials.gov More Thymidine Kinase 2 Deficiency trials

Plain-language summary

Who can participate

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

What they're measuring

Incidence of treatment-emergent adverse events (TEAEs)

Timeframe: From first administration of study drug until end of safety follow-up (up to approximately 7 years)

Incidence of TEAEs leading to study drug withdrawal

Timeframe: From first administration of study drug until end of safety follow-up (up to approximately 7 years)