Thymidine Kinase 2 (TK2)RETRONCT03701568
A RETROspective Study of Patients With TK2d
An observational study of Thymidine Kinase 2 (TK2), run by Zogenix MDS, Inc. at 8 sites in 3 countries.
Trial summary
This is a medical chart review study to collect information for patients who have been taking pyrimidine nucleosides for treatment of TK2 deficiency. Information from the time of onset of symptoms will be collected to describe the pre treatment course of TK2 deficiency. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Thymidine Kinase 2 (TK2)
- What is being tested?
- dC/dT
- How many people
- 38 participants
- Where
- 8 sitesin 3 countries
- Study dates
- 19 Nov 2018to 31 May 2019
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Patients with TK2 deficiency who have received treatment with pyrimidine nucleosides
Who may be able to join
- Signed informed consent by the patient or parent(s)/legally authorized representative (LAR) and/or assent by the patient (when applicable), unless the associated institutional review board (IRB) or ethics committee (EC) provides an appropriate consent waiver
- Confirmed genetic mutation in the TK2 gene
- Availability of medical records for each patient from the time of onset of symptoms
- Patient has taken pyrimidine nucleos(t)ides (dCMP/dTMP and/or dC/dT) as substrate enhancement therapy for TK2 deficiency
- Most recent patient visit at which efficacy and/or safety parameters were collected occurred between 01 June 2018 and 15 December 2018
Who cannot join
- 1. Presence of other genetic disease or polygenic disease
Trial locations and contacts
8 sites in 3 countries.
8 sites in 3 countries
Spain4 sites
Hospital Vall d'Hebron
Barcelona, 08035
Sant Joan de Déu Hospital
Barcelona, 08950
Hospital 12 de Octubre
Madrid, 28041
Hospital Universitario Virgen del Rocio
Seville, 41013
Israel3 sites
Rambam Hospital
Haifa, 3109601
Wolfson Medical Center
Holon, 5822012
Western Galilee Hospital
Nahariya, 89 כביש
United States1 site
Columbia University Medical Center
New York, New York, 10032
About this study
Official title: A RETROspective Study of the Combination of Pyrimidine Nucleos(t)Ides in Patients With Thymidine Kinase 2 Deficiency (TK2)
This is a medical chart review study to collect information for patients who have been taking pyrimidine nucleosides for treatment of TK2 deficiency. Information from the time of onset of symptoms will be collected to describe the pre treatment course of TK2 deficiency.
Read the detailed description
Data to be collected from the time of onset of symptoms related to TK2 deficiency includes medical conditions and/or adverse events (AEs); these should include relationship to TK2 disease and/or pyrimidine nucleosides, as appropriate, as well as date of onset and severity, when available. When available, test reports may be obtained as well as available research biological samples (eg, blood or tissue samples that may be tested for biomarkers of disease and/or effects of medications to treat the mitochondrial disease).
- Conditions
- Thymidine Kinase 2 (TK2)
- Being tested
- dC/dT
- Keywords
- myopathy, muscle weakness, hypotonia, dysphagia, ptosis
- Medical subject headings
- Muscular Diseases, Muscle Weakness, Muscle Hypotonia, Deglutition Disorders, Blepharoptosis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
dC/dTDrug
Also called deoxycytidine/deoxythymidine
Collection of retrospective data from TK2 patients previously treated with dC/dT
What is being measured
The primary outcome is the main question the study is designed to answer.
Diagnosis
genetic testing (previously conducted)
Measured: 3 months
Secondary outcomes (8)
Clinical course
BMI (height in inches and weight in kg will be combined to report BMI in kg/m^2)
Measured: 3 months
Clinical course
achievement, loss, or regaining of developmental motor milestones
Measured: 3 months
Motor function and ambulatory assessments
Change in 6-minute walk test [6MWT] distance (in meters)
Measured: 3 months
Motor function and ambulatory assessments
Motor Function Measure [MFM] 20 or MFM 32
Measured: 3 months
Motor function and ambulatory assessments
Egen Klassifikation
Measured: 3 months
Motor function and ambulatory assessments
North Star Ambulatory Assessment
Measured: 3 months
Motor function and ambulatory assessments
Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders [CHOP INTEND]
Measured: 3 months
Motor function and ambulatory assessments
Hammersmith Functional Motor Scale-Expanded [HFMSE]
Measured: 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Oct 2018
- Study start19 Nov 2018
- Primary completion30 Apr 2019
- Study completion31 May 2019
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Thymidine Kinase 2 (TK2)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case only
- Time perspective
- Retrospective
- Enrolment
- 38 participants (actual)
Sponsor and investigators
- Lead sponsor
- Zogenix MDS, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- UCB Cares, Study director, 001 844 599 2273
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03701568
- Sponsor's protocol ID
- MT-1621-101
- Acronym
- RETRO
- Status last verified
- Aug 2023
- First submitted
- 27 Sep 2018
- Last updated
- 1 Sep 2023
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Dominguez-Gonzalez C, Chiang C, Colson AO, Rebollo Mesa I, Baixauli E, Quan J, VanMeter S, Hirano M. Pyrimidine Nucleos(t)ide Therapy in Patients With Thymidine Kinase 2 Deficiency: A Multicenter Retrospective Chart Review Study. Neurology. 2025 Sep 23;105(6):e213908. doi: 10.1212/WNL.0000000000213908. Epub 2025 Sep 5.
PubMed 40911819
Study at a glance
From the registry record, last updated by the sponsor on 1 Sep 2023. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A RETROspective Study of the Combination of Pyrimidine Nucleos(t)Ides in Patients With Thymidine Kinase 2 Deficiency (TK2)
- ClinicalTrials.gov ID
- NCT03701568
- Acronym / sponsor ID
- RETRO / MT-1621-101
- Conditions
- Thymidine Kinase 2 (TK2)
- Keywords
- myopathy, muscle weakness, hypotonia, dysphagia, ptosis
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 38 participants (actual)
- Lead sponsor
- Zogenix MDS, Inc.Industry (pharma, biotech, devices)
- Study start
- 19 Nov 2018 (actual)
- Primary completion
- 30 Apr 2019 (actual)
- Study completion
- 31 May 2019 (actual)
- First posted
- 10 Oct 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a medical chart review study to collect information for patients who have been taking pyrimidine nucleosides for treatment of TK2 deficiency. Information from the time of onset of symptoms will be collected to describe the pre treatment course of TK2 deficiency.
Detailed description
Data to be collected from the time of onset of symptoms related to TK2 deficiency includes medical conditions and/or adverse events (AEs); these should include relationship to TK2 disease and/or pyrimidine nucleosides, as appropriate, as well as date of onset and severity, when available. When available, test reports may be obtained as well as available research biological samples (eg, blood or tissue samples that may be tested for biomarkers of disease and/or effects of medications to treat the mitochondrial disease).
Study design
- Observational model
- Case only
- Time perspective
- Retrospective
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Patients with TK2 deficiency who have received treatment with pyrimidine nucleosides
Key inclusion criteria (5 listed)
- Signed informed consent by the patient or parent(s)/legally authorized representative (LAR) and/or assent by the patient (when applicable), unless the associated institutional review board (IRB) or ethics committee (EC) provides an appropriate consent waiver
- Confirmed genetic mutation in the TK2 gene
- Availability of medical records for each patient from the time of onset of symptoms
- Patient has taken pyrimidine nucleos(t)ides (dCMP/dTMP and/or dC/dT) as substrate enhancement therapy for TK2 deficiency
- Most recent patient visit at which efficacy and/or safety parameters were collected occurred between 01 June 2018 and 15 December 2018
Key exclusion criteria (1 listed)
- 1. Presence of other genetic disease or polygenic disease
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| dC/dTAlso: deoxycytidine/deoxythymidineCollection of retrospective data from TK2 patients previously treated with dC/dT | Drug | – |
Primary outcome
Diagnosis
Time frame: 3 months
genetic testing (previously conducted)
8 secondary outcomes
Clinical course
Time frame: 3 months
Clinical course
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Motor function and ambulatory assessments
Time frame: 3 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Sep 2023.
- Derived from this study: PubMed 40911819Dominguez-Gonzalez C, Chiang C, Colson AO, Rebollo Mesa I, Baixauli E, Quan J, VanMeter S, Hirano M. Pyrimidine Nucleos(t)ide Therapy in Patients With Thymidine Kinase 2 Deficiency: A Multicenter Retrospective Chart Review Study. Neurology. 2025 Sep 23;105(6):e213908. doi: 10.1212/WNL.0000000000213908. Epub 2025 Sep 5.
- Individual participant dataSharing planned: No
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Active, not recruitingPhase 1/2
Treatment of TK2 Deficiency With Thymidine and Deoxycytidine
Mitochondrial DNA Depletion Syndrome 2 Myopathic Type, Thymidine Kinase 2 Deficiency
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Natural History in Primary Mitochondrial Myopathies
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
UCB Cares study director
001 844 599 2273
8 sites in 3 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Thymidine Kinase 2 (TK2), run by Zogenix MDS, Inc. at 8 sites in 3 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 1 Sep 2023. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 8 sites in Spain, Israel, United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Diagnosis (time frame: 3 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03701568, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Sep 2023.