Ataxia TelangiectasiaPhase 2NCT03759678

N-Acetyl-L-Leucine for Ataxia-Telangiectasia (A-T)

A Phase 2 study testing IB1001 in people with Ataxia Telangiectasia, run by IntraBio Inc at 4 sites in 4 countries.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Trial summary

This is a multinational, multicenter, open-label, rater-blinded prospective Phase II study which will assess the safety and efficacy of N-Acetyl-L-Leucine (IB1001) for the treatment of Ataxia-Telangiectasia (A-T). There are two phases to this study: the Parent Study, and the Extension Phase. Read more about this study

Who is it for?: Ages 6 years and older
Conditions the study is for: Ataxia Telangiectasia
What is being tested?: IB1001
Type of treatment: Pill or oral medicine
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 17 participants
Where: 4 sitesin 4 countries
Study dates: 8 Jan 2020to 27 Oct 2025
Phase: Phase 2
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 6 years and older
All sexes
No healthy volunteers
Child, Adult, Older adult

Who may be able to join

Individuals who meet all of the following criteria are eligible to participate in the study:
Written informed consent signed by the patient and/or their legal representative/ parent
Male or female aged ≥6 years with a confirmed diagnosis of A-T at the time of signing informed consent.
Females of childbearing potential, defined as a premenopausal female capable of becoming pregnant, will be included if they are either sexually inactive (sexually abstinent for 14 days prior to the first dose continuing through 28 days after the last dose) or using one of the following highly effective contraceptives (i.e. results in <1% failure rate when used consistently and correctly) 14 days prior to the first dose continuing through 28 days after the last dose:
intrauterine device (IUD);
surgical sterilization of the partner (vasectomy for 6 months minimum);

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combined (estrogen or progestogen containing) hormonal contraception associated with the inhibition of ovulation (either oral, intravaginal, or transdermal);
progestogen-only hormonal contraception associated with the inhibition of ovulation (either oral, injectable, or implantable);
intrauterine hormone-releasing system (IUS);
bilateral tubal occlusion.
Females of non-childbearing potential must have undergone one of the following sterilization procedures at least 6 months prior to the first dose:
hysteroscopic sterilization;
bilateral tubal ligation or bilateral salpingectomy;
hysterectomy;
bilateral oophorectomy;
OR
be postmenopausal with amenorrhea for at least 1 year prior to the first dose and follicle stimulating hormone (FSH) serum levels consistent with postmenopausal status. FSH analysis for postmenopausal women will be done at screening. FSH levels should be in the postmenopausal range as determined by the central laboratory.
Non-vasectomized male patient agrees to use a condom with spermicide or abstain from sexual intercourse during the study until 90 days beyond the last dose of study medication and the female partner agrees to comply with inclusion criteria 3 or 4. For a vasectomized male who has had his vasectomy 6 months or more prior to study start, it is required that they use a condom during sexual intercourse. A male who has been vasectomized less than 6 months prior to study start must follow the same restrictions as a non-vasectomized male.
If male, the patient agrees not to donate sperm from the first dose until 90 days after dosing.
Patients must fall within:
A Scale for the assessment and rating of ataxia (SARA) score of 5 ≤ X ≤ 33 points (out of 40) AND i. Within the 2-7 range (out of 0-8 range) of the Gait subtest of the SARA scale OR ii. Be able to perform the 9 Hole Peg Test with Dominant Hand (9HPT-D) (SCAFI subtest) in 20 ≤ X ≤150 seconds.
Weight ≥15 kg at screening.
Patients are willing to disclose their existing medications/therapies for (the symptoms) of A-T, including those on the prohibited medication list. Non-prohibited medications/therapies (e.g. concomitant speech therapy, and physiotherapy) are permitted provided:
The Investigator does not believe the medication/therapy will interfere with the study protocol/results
Patients have been on a stable dose/duration and type of therapy for at least 6 weeks before Visit 1 (Baseline 1)
Patients are willing to maintain a stable dose/do not change their therapy throughout the duration of the study.
An understanding of the implications of study participation, provided in the written patient information and informed consent by patients or their legal representative/parent, and demonstrates a willingness to comply with instructions and attend required study visits (for children this criterion will also be assessed in parents or appointed guardians).

Who cannot join

Individuals who meet any of the following criteria are not eligible to participate in the study:
Asymptomatic patients
Patient has clinical features of A-T, but a completely negative result on a previous genetic test for A-T.
Patients who have any of the following:
Chronic diarrhea;
Unexplained visual loss;

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Malignancies;
Insulin-dependent diabetes mellitus.
Known history of hypersensitivity to the N-Acetyl-Leucine (DL-, L-, D-) or derivatives.
History of known hypersensitivity to excipients of Ora-Blend® (namely sucrose, sorbitol, cellulose, carboxymethylcellulose, xanthan gum, carrageenan, dimethicone, methylparaben, and potassium sorbate).
Simultaneous participation in another clinical study or participation in any clinical study involving administration of an investigational medicinal product (IMP; 'study drug') within 6 weeks prior to Visit 1.
Patients with a physical or psychiatric condition which, at the investigator's discretion, may put the patient at risk, may confound the study results, or may interfere with the patient's participation in the clinical study.
Known clinically-significant (at the discretion of the investigator) laboratories in hematology, coagulation, clinical chemistry, or urinalysis, including, but not limited to:
Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >5x upper limit of normal (ULN);
Total bilirubin >1.5x ULN, unless Gilbert's syndrome is present in which case total bilirubin >2x ULN.
Known or persistent use, misuse, or dependency of medication, drugs, or alcohol.
Current or planned pregnancy or women who are breastfeeding.
Patients with severe vision or hearing impairment (that is not corrected by glasses or hearing aids) that, at the investigator's discretion, interferes with their ability to perform study assessments.
Patients who have been diagnosed with arthritis or other musculoskeletal disorders affecting joints, muscles, ligaments, and/or nerves that by themselves affects patient's mobility and, at the investigator's discretion, interferes with their ability to perform study assessments.
Patients unwilling and/or not able to undergo a 6-week washout period from any of the following prohibited medication prior to Visit 1 (Baseline 1) and remain without prohibited medication through Visit 6.
Aminopyridines (including sustained-release form);
N-Acetyl-DL-Leucine (e.g. Tanganil®);
N-Acetyl-L-Leucine (prohibited if not provided as IMP);
Riluzole;
Gabapentin;
Varenicline;
Chlorzoxazone;
Sulfasalazine;
Rosuvastatin.

Trial locations and contacts

4 sites in 4 countries.

Country

City, postcode or hospital

4 sites in 4 countries

United States1 site

University of California - Los Angeles
Los Angeles, California, 90095

Other trials in United States

Germany1 site

University of Giessen
Giessen

Other trials in Germany

Spain1 site

Hospital Universitario La Paz
Madrid, Spain

Other trials in Spain

United Kingdom1 site

Royal Papworth Hospital NHS Foundation Trust
Cambridge, Cambridgeshire, CB2 0AY

Other trials in United Kingdom

About this study

Official title: Effects of N-Acetyl-L-Leucine on Ataxia-Telangiectasia (A-T): A Multinational, Multicenter, Open-label, Rater-blinded Phase II Study

There are two phases to this study: the Parent Study, and the Extension Phase.

The Parent Study evaluates the safety and efficacy of N-Acetyl-L-Leucine (IB1001) for the symptomatic treatment of A-T.

The Extension Phase evaluates the long-term safety and efficacy of IB1001 for the neuroprotective, disease-modifying treatment of A-T.

Read the detailed description

The primary purpose of the study is to evaluate the safety and efficacy of N-Acetyl-L-Leucine (IB1001) in the treatment of A-T investigating the efficacy in terms of improving symptoms, functioning, and quality of life against the defined endpoints in patients with A-T.

Patients will be assessed during three study phases: a baseline period, a 6-week treatment period, and a 6-week post-treatment washout period. If within 6 weeks prior to the initial screening visit, a patient has received any of the prohibited medications defined in the eligibility criteria (irrespective of the preceding treatment duration) a wash-out study-run in of 6 weeks is required prior to the first baseline assessment.

All patients will receive the study drug during this study.

For each individual patient, the study lasts for approximately 3.5 - 4 months during which there are 6 study visits to the study site.

This Extension Phase allows patients who have completed the Parent Study to, at the discretion of the Principal Investigator (PI), continue treatment with N-Acetyl-L-Leucine (IB1001). Patients will receive treatment with IB1001 for two one-year treatment periods, separated by a 6-week washout. All patients will receive the study drug during the treatment period. For each individual patient, the Extension Phase lasts for approximately 25.5 months, during which there are 6 visits to the study site.

Conditions: Ataxia Telangiectasia
Being tested: IB1001
Medical subject headings: Ataxia Telangiectasia

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

IB1001Drug
Also called N-Acetyl-L-Leucine
IB1001 (N-Acetyl-L-Leucine) is a modified amino-acid ester that is orally administered.

Study groups in NCT03759678
Study group	Role	What they receive
Treatment with IB1001	Experimental	6-weeks treatment with IB1001 administered orally. Patients ≥13 years old will receive a total daily dose of 4 g/day (administered as 3 doses per day). Patients 6-12 years old will receive weight-tiered doses: * Patients aged 6-12 years weighing 15 to <25 kg will take 2 g per day: 1 g in the morning and 1 g in the evening. * Patients aged 6-12 years weighing 25 to <35 kg will take 3 g per day: 1 g in the morning, 1 g in the afternoon, and 1 g in the evening. * Patients aged 6-12 years weighing ≥35 kg will take 4 g per day: 2 g in the morning, 1g in the afternoon and 1 g in the evening (as per adults) After the 6-week treatment period, patients will enter a 6-week post-treatment washout period. Receives: Drug: IB1001
Post-Treatment Washout	No intervention	After the 6-week treatment period, patients will enter a 6-week post-treatment washout period.

What is being measured

The primary outcome is the main question the study is designed to answer.

Clinical Impression of Change in Severity (CI-CS) [Fields et al. 2021]
The Clinical Impression of Change in Severity assessment will instruct the blinded rater to consider: compared to the first video, how has the severity of their performance on the 9 Hole Peg Test of the Dominant Hand (9HPT-D) or 8 Meter Walk Test (8MWT) changed (improved or worsened) in 6-weeks as observed in the second video? The Clinical Impression of Change in Severity is evaluated on a 7 point Likert scale (+3=significantly improved to -3= significantly worse).
Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)). Then, the mean change obtained in the post-treatment period was subtracted from the mean change obtained for the treatment with IB1001 period, with a positive value indicating an improvement in the treatment period compared to the post-treatment washout period.
Measured: CI-CS comparing Baseline (Day 1) with IB1001 versus the end of 6-weeks treatment with IB1001 (Approximately Day 42) MINUS the CI-CS comparing the end of 6-weeks treatment with IB1001 (Approximately Day 42) versus the end of 6-weeks post-treatment washout

Secondary outcomes (9)

Key Secondary Endpoint: Change in Severity Based on Average CI-S
The Change in Severity assessment will instruct the blinded rater to consider the severity of the patient at each visit.
The Clinical Impression of Severity (CI-S)-assessment ranged from +3 ="normal not ill at all" to -3="among the most extremely ill patients ".
Change values were calculated for each period, i.e. treatment with IB1001 (change between the baseline period [average for Visit 1 and Visit 2] and end of treatment period [average for Visit 3 and Visit 4]) and post-treatment washout (between end of treatment period [average for Visit 3 and Visit 4] and end of washout period [average for Visit 5 and Visit 6]). Then, the mean change in the post-treatment period was subtracted from the mean change in the treatment with IB1001 period.
Measured: (CI-S comparing baseline period [average for Visit 1 and 2] and end of treatment period [average for Visit 3 and 4]) MINUS (change in CI-S between end of treatment period [average for Visit 3 and 4] and end of washout period [average for Visit 5 and 6])
Secondary Efficacy Endpoint: Individual Components of CI-CS
The Clinical Impression of Change in Severity assessment will instruct the blinded rater to consider: compared to the first video, how has the severity of their performance on the 9 Hole Peg Test of the Dominant Hand (9HPT-D) or 8 Meter Walk Test (8MWT) changed (improved or worsened) in 6-weeks as observed in the second video? The Clinical Impression of Change in Severity is evaluated on a 7 point Likert scale (+3=significantly improved to -3= significantly worse).
Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)).
Measured: Baseline to end of treatment with IB1001 (Parent Study 6-weeks treatment); End of treatment with IB1001 to the end of post 6-week treatment washout.
Secondary Efficacy Endpoint: CI-CS Score Reclassified on a 3-Point Scale
The Clinical Impression of Change in Severity assessment will instruct the blinded rater to consider: compared to the first video, how has the severity of their performance on the 9 Hole Peg Test of the Dominant Hand (9HPT-D) or 8 Meter Walk Test (8MWT) changed (improved or worsened) in 6-weeks as observed in the second video? The Clinical Impression of Change in Severity is evaluated on a 7 point Likert scale (+3=significantly improved to -3= significantly worse).
CI-CS scores <0 were reclassified as worsened (-1), CI-CS scores 0 remained classified as not changed (0), and CI-CS scores >0 were reclassified as improved (+1).
When comparing Visit 4 versus Visit 2 and Visit 6 versus Visit 4, CI-CS scores <0 were reclassified as worsened (-1), CI-CS scores 0 remained classified as not changed (0), and CI-CS scores >0 were reclassified as improved (+1).
Measured: Baseline to end of treatment with IB1001 (Parent Study 6-weeks treatment); End of treatment with IB1001 to the end of post 6-week treatment washout
Secondary Efficacy Endpoint: CI-CS Score for the Non-Primary Anchor Test
The Clinical Impression of Change in Severity assessment will instruct the blinded rater to consider: compared to the first video, how has the severity of their performance on the 9 Hole Peg Test of the Dominant Hand (9HPT-D) or 8 Meter Walk Test (8MWT) changed (improved or worsened) in 6-weeks as observed in the second video? The Clinical Impression of Change in Severity is evaluated on a 7 point Likert scale (+3=significantly improved to -3= significantly worse).
Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)).
Measured: CI-CS of the non-primary anchor test was evaluated, comparing the CI-CS of Visit 4 (end of treatment) versus Visit 2 (baseline) and of Visit 6 (end of washout) versus Visit 4 (end of treatment) as done for the primary anchor test.
Secondary Efficacy Endpoint: Change in the Scale for Assessment and Rating of Ataxia (SARA) Score [Schmitz-Hübsch Etal, 2006; Subramony, 2007]
The Scale for Assessment and Rating of Ataxia has 8 items that are related to gait, stance, sitting, speech, finger-chase test, nose-finger test, fast alternating movements, and heel-shin test. The range is 0-40 points, with a lower score representing neurological improvement and a higher score representing neurological worsening.
Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)).
Measured: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: Spinocerebellar Ataxia Functional Index (SCAFI) [Schmitz-Hübsch et al, 2008]
Spinocerebellar Ataxia Functional Index (SCAFI) is composed of 8 Meter Walk Test, 9-Hole Peg Test of Dominant and Non-Dominant Hand (9HPT-D/9HPT-ND) (the 3 tests are timed assessments; each is done twice and values are averaged; the 8MWT and 9HPT-D and 9HPT-ND values are converted from times to rates, and the results expressed as a composite Z-score of each test relative to baseline) and the PATA rate (counted number how often a patient can repeat the syllables "PATA" within 10 seconds), a measure of speech performance. The scores of these 3 were transformed to Z-scores (=individual's average of both trials to perform the respective task -mean of study population at baseline) / SD of study population at baseline). A Z-score of 0 equates to the population mean at baseline. For all 3, higher Z-scores (above mean) mean better performance. The SCAFI total score was calculated as the arithmetic mean of the non-missing Z-scores for the 3. A higher total score means better performance.
Measured: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: EuroQuol- 5 Dimension (EQ-5D) Quality of Life Scale
For posting, health-related quality of life based on the EQ-5D visual analogue scale (VAS) was presented as a secondary endpoint.
EQ-5D VAS is a 0-100 scale where patients are asked to indicate their overall health, with a score of 0 indicating worst health and a score of 100 indicating best health.
Measured: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: Clinical Global Impression of Severity (Treating Physician, Caregiver, Patient)
The Clinical Global Impression of Severity(CGI-S) evaluates the question "Considering your total (clinical) experience with this particular population, how ill is the patient (how ill are you) at this time?" based on answers from the treating physician, the caregiver, or the patients (if able). This was rated on the following seven-point scale: 1=normal, not at all ill; 2=borderline ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill; 7=among the most extremely ill the patient has been/I have ever been.
Measured: Visits of Parent study: Visit 1 (Day -14), Visit 2 (Day 1), Visit 3 (Day 28), Visit 4 (Day 42), Visit 5 (Day 70), and Visit 6 (Day 84).
Secondary Efficacy Endpoint: Clinical Global Impression of Change (Treating Physician, Caregiver, Patient)
The Clinical Global Impression of Change assessed by the investigator is evaluated on a 7 point Likert scale ranging from 1='very much improved' to 7='very much worse' Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)).
Measured: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

8 Jan 202027 Oct 2025

First posted30 Nov 2018
Study start8 Jan 2020
Primary completion11 Feb 2025
Study completion27 Oct 2025

Why it stopped: Determined priority was to recruit directly to the pivotal Phase III double-blind, placebo-controlled, randomised study (NCT07221292).

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (4)Papers the sponsor has linked to this study.
Other trials for Ataxia TelangiectasiaStudies 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: Interventional
Phase: Phase 2
Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Single group
Model description: Patients will be assessed during three study phases: a baseline period (with or without a study run-in), a treatment period, and a washout period.
Masking: Single blind
Who is masked: Outcomes assessor
Enrolment: 17 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT03759678
Sponsor's protocol ID: IB1001-203
Status last verified: Mar 2026
First submitted: 27 Nov 2018
Last updated: 25 Mar 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No

Publications

Hendrickx N, Mentre F, Hamdan A, Karlsson MO, Hooker AC, Traschutz A, Gagnon C, Schule R, Synofzik M, Comets E; ARCA Study Group, EVIDENCE-RND consortium. Comparing randomized trial designs to estimate treatment effect in rare diseases with longitudinal models: a simulation study showcased by Autosomal Recessive Cerebellar Ataxias using the SARA score. BMC Med Res Methodol. 2025 Jul 30;25(1):179. doi: 10.1186/s12874-025-02626-x.
PubMed 40739200
Brueggemann A, Bicvic A, Goeldlin M, Kalla R, Kerkeni H, Mantokoudis G, Abegg M, Kolnikova M, Mohaupt M, Bremova-Ertl T. Effects of Acetyl-DL-Leucine on Ataxia and Downbeat-Nystagmus in Six Patients With Ataxia Telangiectasia. J Child Neurol. 2022 Jan;37(1):20-27. doi: 10.1177/08830738211028394. Epub 2021 Oct 7.
PubMed 34620022
Churchill GC, Strupp M, Factor C, Bremova-Ertl T, Factor M, Patterson MC, Platt FM, Galione A. Acetylation turns leucine into a drug by membrane transporter switching. Sci Rep. 2021 Aug 4;11(1):15812. doi: 10.1038/s41598-021-95255-5.
PubMed 34349180
Fields T, Patterson M, Bremova-Ertl T, Belcher G, Billington I, Churchill GC, Davis W, Evans W, Flint S, Galione A, Granzer U, Greenfield J, Karl R, Kay R, Lewi D, Mathieson T, Meyer T, Pangonis D, Platt FM, Tsang L, Verburg C, Factor M, Strupp M. A master protocol to investigate a novel therapy acetyl-L-leucine for three ultra-rare neurodegenerative diseases: Niemann-Pick type C, the GM2 gangliosidoses, and ataxia telangiectasia. Trials. 2021 Jan 22;22(1):84. doi: 10.1186/s13063-020-05009-3.
PubMed 33482890

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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A Pivotal Study of N-Acetyl-L-Leucine on Ataxia-Telangiectasia (A-T)
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All Ataxia Telangiectasia trials

Study at a glance

From the registry record, last updated by the sponsor on 25 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Effects of N-Acetyl-L-Leucine on Ataxia-Telangiectasia (A-T): A Multinational, Multicenter, Open-label, Rater-blinded Phase II Study
ClinicalTrials.gov ID: NCT03759678
Acronym / sponsor ID: IB1001-203
Conditions: Ataxia Telangiectasia
Phase: Phase 2
Study type: Interventional
Recruitment status: TerminatedReason stopped: Determined priority was to recruit directly to the pivotal Phase III double-blind, placebo-controlled, randomised study (NCT07221292).
Enrolment: 17 participants (actual)
Lead sponsor: IntraBio IncIndustry (pharma, biotech, devices)
Study start: 8 Jan 2020 (actual)
Primary completion: 11 Feb 2025 (actual)
Study completion: 27 Oct 2025 (actual)
First posted: 30 Nov 2018 (actual)
Results: Posted 25 Mar 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

There are two phases to this study: the Parent Study, and the Extension Phase.

The Parent Study evaluates the safety and efficacy of N-Acetyl-L-Leucine (IB1001) for the symptomatic treatment of A-T.

The Extension Phase evaluates the long-term safety and efficacy of IB1001 for the neuroprotective, disease-modifying treatment of A-T.

Detailed description

All patients will receive the study drug during this study.

For each individual patient, the study lasts for approximately 3.5 - 4 months during which there are 6 study visits to the study site.

Study design

Primary purpose: Treatment
Allocation: Non-randomised
Intervention model: Single group
Masking: Single blind (outcomes assessor)
Number of arms: 2
Model description: Patients will be assessed during three study phases: a baseline period (with or without a study run-in), a treatment period, and a washout period.

Arm	Type	Receives
Treatment with IB1001	Experimental	Drug: IB10016-weeks treatment with IB1001 administered orally. Patients ≥13 years old will receive a total daily dose of 4 g/day (administered as 3 doses per day). Patients 6-12 years old will receive weight-tiered doses: * Patients aged 6-12 years weighing 15 to <25 kg will take 2 g per day: 1 g in the morning and 1 g in the evening. * Patients aged 6-12 years weighing 25 to <35 kg will take 3 g per day: 1 g in the morning, 1 g in the afternoon, and 1 g in the evening. * Patients aged 6-12 years weighing ≥35 kg will take 4 g per day: 2 g in the morning, 1g in the afternoon and 1 g in the evening (as per adults) After the 6-week treatment period, patients will enter a 6-week post-treatment washout period.
Post-Treatment Washout	No intervention	–After the 6-week treatment period, patients will enter a 6-week post-treatment washout period.

Who may qualify

Ages: 6 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult

Key inclusion criteria (27 listed)

Individuals who meet all of the following criteria are eligible to participate in the study:
Written informed consent signed by the patient and/or their legal representative/ parent
Male or female aged ≥6 years with a confirmed diagnosis of A-T at the time of signing informed consent.
Females of childbearing potential, defined as a premenopausal female capable of becoming pregnant, will be included if they are either sexually inactive (sexually abstinent for 14 days prior to the first dose continuing through 28 days after the last dose) or using one of the following highly effective contraceptives (i.e. results in <1% failure rate when used consistently and correctly) 14 days prior to the first dose continuing through 28 days after the last dose:
Females of non-childbearing potential must have undergone one of the following sterilization procedures at least 6 months prior to the first dose:

Key exclusion criteria (29 listed)

Individuals who meet any of the following criteria are not eligible to participate in the study:
Asymptomatic patients
Patient has clinical features of A-T, but a completely negative result on a previous genetic test for A-T.
Patients who have any of the following:
Simultaneous participation in another clinical study or participation in any clinical study involving administration of an investigational medicinal product (IMP; 'study drug') within 6 weeks prior to Visit 1.

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
IB1001Also: N-Acetyl-L-LeucineIB1001 (N-Acetyl-L-Leucine) is a modified amino-acid ester that is orally administered.	Drug	Treatment with IB1001

Primary outcome

Clinical Impression of Change in Severity (CI-CS) [Fields et al. 2021]
Time frame: CI-CS comparing Baseline (Day 1) with IB1001 versus the end of 6-weeks treatment with IB1001 (Approximately Day 42) MINUS the CI-CS comparing the end of 6-weeks treatment with IB1001 (Approximately Day 42) versus the end of 6-weeks post-treatment washout
The Clinical Impression of Change in Severity assessment will instruct the blinded rater to consider: compared to the first video, how has the severity of their performance on the 9 Hole Peg Test of the Dominant Hand (9HPT-D) or 8 Meter Walk Test (8MWT) changed (improved or worsened) in 6-weeks as observed in the second video? The Clinical Impression of Change in Severity is evaluated on a 7 point Likert scale (+3=significantly improved to -3= significantly worse). Change values were calculated for each period, i.e. treatment with IB1001 (comparing the end of treatment (Visit 4) with baseline (Visit 2)) and post-treatment washout (comparing the end of washout (Visit 6) with the end of treatment (Visit 4)). Then, the mean change obtained in the post-treatment period was subtracted from the mean change obtained for the treatment with IB1001 period, with a positive value indicating an improvement in the treatment period compared to the post-treatment washout period.

9 secondary outcomes

Key Secondary Endpoint: Change in Severity Based on Average CI-S
Time frame: (CI-S comparing baseline period [average for Visit 1 and 2] and end of treatment period [average for Visit 3 and 4]) MINUS (change in CI-S between end of treatment period [average for Visit 3 and 4] and end of washout period [average for Visit 5 and 6])
Secondary Efficacy Endpoint: Individual Components of CI-CS
Time frame: Baseline to end of treatment with IB1001 (Parent Study 6-weeks treatment); End of treatment with IB1001 to the end of post 6-week treatment washout.
Secondary Efficacy Endpoint: CI-CS Score Reclassified on a 3-Point Scale
Time frame: Baseline to end of treatment with IB1001 (Parent Study 6-weeks treatment); End of treatment with IB1001 to the end of post 6-week treatment washout
Secondary Efficacy Endpoint: CI-CS Score for the Non-Primary Anchor Test
Time frame: CI-CS of the non-primary anchor test was evaluated, comparing the CI-CS of Visit 4 (end of treatment) versus Visit 2 (baseline) and of Visit 6 (end of washout) versus Visit 4 (end of treatment) as done for the primary anchor test.
Secondary Efficacy Endpoint: Change in the Scale for Assessment and Rating of Ataxia (SARA) Score [Schmitz-Hübsch Etal, 2006; Subramony, 2007]
Time frame: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: Spinocerebellar Ataxia Functional Index (SCAFI) [Schmitz-Hübsch et al, 2008]
Time frame: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: EuroQuol- 5 Dimension (EQ-5D) Quality of Life Scale
Time frame: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)
Secondary Efficacy Endpoint: Clinical Global Impression of Severity (Treating Physician, Caregiver, Patient)
Time frame: Visits of Parent study: Visit 1 (Day -14), Visit 2 (Day 1), Visit 3 (Day 28), Visit 4 (Day 42), Visit 5 (Day 70), and Visit 6 (Day 84).
Secondary Efficacy Endpoint: Clinical Global Impression of Change (Treating Physician, Caregiver, Patient)
Time frame: Baseline (Day 1) to end of treatment with IB1001 (Approximately Day 42); End of treatment with IB1001 (Approximately Day 42) to the end of post-treatment washout (Approximately Day 84)

Results and safety

Results posted to the registry on 25 Mar 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Parent Study	17	16

Primary outcome: Clinical Impression of Change in Severity (CI-CS) [Fields et al. 2021]

Time frame: CI-CS comparing Baseline (Day 1) with IB1001 versus the end of 6-weeks treatment with IB1001 (Approximately Day 42) MINUS the CI-CS comparing the end of 6-weeks treatment with IB1001 (Approximately Day 42) versus the end of 6-weeks post-treatment washout. Mean (Standard Deviation). Unit: Score on a scale

Measure	Parent Study n = 16
Value	0.16 (1.65)

Population analysed: Modified Intention to Treat (mITT) Analysis Set is defined as all patients who receive at least one dose of the study drug and with one video recording during the baseline period (Visit 1 or 2, or both) and treatment period (Visit 3 or Visit 4, or both).

9 secondary outcomes are reported in the full results.

Adverse events

Time frame: For the parent study (treatment with IB1001 and Post-treatment washout): from signing of the informed consent form through to End of Study (Day 84, scheduled at 42 days post last IB1001dose); For the extension phase: from signing of the extension phase informed consent form through to End of Study for the extension phase (Day 767).. Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Treatment With IB1001	1 of 17 (5.9%)	9 of 17 (52.9%)	0 of 17
Post-treatment Washout	0 of 17 (0%)	2 of 17 (11.8%)	0 of 17
Extension Phase	2 of 13 (15.4%)	11 of 13 (84.6%)	1 of 13

Limitations and caveats (from the sponsor): This study was ongoing during the COVID-19 pandemic, and the conduct of this study was impacted by the COVID-19 pandemic. Additionally, it was determined by the Sponsor that a Phase III, double-blind, randomized, placebo- controlled study for A-T should be conducted to support the marketing application with IB1001 for A-T (NCT NCT06673056). Accordingly, the IB1001-203 clinical study was terminated prior to reaching the target recruitment, to prioritize the pivotal Phase III trial.

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 25 Mar 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 40739200Hendrickx N, Mentre F, Hamdan A, Karlsson MO, Hooker AC, Traschutz A, Gagnon C, Schule R, Synofzik M, Comets E; ARCA Study Group, EVIDENCE-RND consortium. Comparing randomized trial designs to estimate treatment effect in rare diseases with longitudinal models: a simulation study showcased by Autosomal Recessive Cerebellar Ataxias using the SARA score. BMC Med Res Methodol. 2025 Jul 30;25(1):179. doi: 10.1186/s12874-025-02626-x.
Derived from this study: PubMed 34620022Brueggemann A, Bicvic A, Goeldlin M, Kalla R, Kerkeni H, Mantokoudis G, Abegg M, Kolnikova M, Mohaupt M, Bremova-Ertl T. Effects of Acetyl-DL-Leucine on Ataxia and Downbeat-Nystagmus in Six Patients With Ataxia Telangiectasia. J Child Neurol. 2022 Jan;37(1):20-27. doi: 10.1177/08830738211028394. Epub 2021 Oct 7.
Derived from this study: PubMed 34349180Churchill GC, Strupp M, Factor C, Bremova-Ertl T, Factor M, Patterson MC, Platt FM, Galione A. Acetylation turns leucine into a drug by membrane transporter switching. Sci Rep. 2021 Aug 4;11(1):15812. doi: 10.1038/s41598-021-95255-5.
Derived from this study: PubMed 33482890Fields T, Patterson M, Bremova-Ertl T, Belcher G, Billington I, Churchill GC, Davis W, Evans W, Flint S, Galione A, Granzer U, Greenfield J, Karl R, Kay R, Lewi D, Mathieson T, Meyer T, Pangonis D, Platt FM, Tsang L, Verburg C, Factor M, Strupp M. A master protocol to investigate a novel therapy acetyl-L-leucine for three ultra-rare neurodegenerative diseases: Niemann-Pick type C, the GM2 gangliosidoses, and ataxia telangiectasia. Trials. 2021 Jan 22;22(1):84. doi: 10.1186/s13063-020-05009-3.

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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.

The record lists no contact. Use the official record to reach the sponsor.

4 sites in 4 countries: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing IB1001 in people with Ataxia Telangiectasia, run by IntraBio Inc at 4 sites in 4 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 27 inclusion and 29 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: stopped early, as of the sponsor's last update on 25 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 4 sites in United States, Germany, Spain, United Kingdom. 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.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 25 Mar 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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?

Clinical Impression of Change in Severity (CI-CS) [Fields et al. 2021] (time frame: CI-CS comparing Baseline (Day 1) with IB1001 versus the end of 6-weeks treatment with IB1001 (Approximately Day 42) MINUS the CI-CS comparing the end of 6-weeks treatment with IB1001 (Approximately Day 42) versus the end of 6-weeks post-treatment washout). 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 NCT03759678, which also lists 4 linked publications.

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 25 Mar 2026.