A Phase III, Randomized, Double-Blind, Placebo-Controlled, Crossover Study to Evaluate the Efficacy of N-Acetyl-L-Leucine in Patients with CACNA1A Disorders

Trial ID: 2025-523828-51-00
Sponsor: Intrabio Limited

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Diseases & Conditions

Neurodevelopmental disorder

Objectives

The primary objective is to evaluate the efficacy of N-Acetyl-L-Leucine for the chronic treatment of CACNA1A disorders using the Scale for the Assessment and Rating of Ataxia (SARA). 5 Secondary objectives include:

Assessment of clinical efficacy regarding neurological signs, symptoms, functioning, and quality of life.
Evaluation of safety and tolerability in weight-tiered doses.

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Participants

This study involves 35 participants diagnosed with CACNA1A disorders. The study population includes both male and female subjects aged 4 years and older. Eligible participants must have a genetically confirmed diagnosis, which encompasses conditions such as episodic ataxia type 2, familial hemiplegic migraine type 1, spinocerebellar ataxia type 6, developmental and epileptic encephalopathy 42, congenital ataxia, or cerebellar hypoplasia. Inclusion is contingent upon a Scale for the Assessment and Rating of Ataxia (SARA) score between 7 and 34, alongside specific requirements for the gait subtest or the 9-Hole Peg Test. Participants must weigh at least 15 kg. Stringent contraception protocols are required for females of childbearing potential and for male participants to prevent pregnancy. Additionally, participants must maintain stable doses of any non-prohibited concurrent therapies, such as physiotherapy, for at least 42 days prior to the initial visit.

Plans and Procedures

This Phase III, randomized, placebo-controlled, double-blind, crossover study is designed to evaluate the efficacy of N-Acetyl-L-Leucine for the chronic treatment of CACNA1A disorders. The primary objective is to assess clinical efficacy using the Scale for the Assessment and Rating of Ataxia (SARA). The study involves a sequence of visits beginning with a screening visit to confirm a genetically confirmed diagnosis and assess eligibility based on specific ataxia symptom thresholds and weight requirements. Following screening, participants will undergo treatment periods where they receive either the oral suspension of N-Acetyl-L-Leucine or a placebo. Due to the crossover design, participants transition between study arms to evaluate the effects of both the active substance and the placebo. The research also monitors secondary endpoints including the Spinocerebellar Ataxia Functional Index (SCAFI), the Functional Scale for the Assessment and Rating of Ataxia (f-SARA), and various quality of life measures. Participants are required to maintain stable doses of any non-prohibited concomitant therapies and adhere to strict contraceptive or abstinence requirements to ensure safety. The study is expected to conclude following the final end-of-study visit. Early termination from the study may occur if participants fail to comply with instructions or if investigators determine that participation is no longer appropriate.

Treatment

The experimental treatment consists of N-Acetyl-L-Leucine, an orphan drug administered as an oral suspension. The specified dosage is 4 g per administration via the oral route.

The control group receives a placebo in the form of granules for suspension.

Efficacy

The efficacy of N-Acetyl-L-Leucine in the chronic treatment of CACNA1A disorders will be evaluated using several clinical parameters. The primary endpoint is the Scale for the Assessment and Rating of Ataxia (SARA), an eight-item clinical rating scale ranging from 0 to 40 used to measure the severity of ataxia.

Secondary efficacy assessments include:

Spinocerebellar Ataxia Functional Index (SCAFI)
Functional Scale for the Assessment and Rating of Ataxia (f-SARA)
Quality of Life EQ-5D-5L for patients aged ≥18 or EQ-5D-Y for pediatric patients
Neuro Quality of Life – Upper Extremity Function (NeuroQOL-UEF), which is assessed by the patient or a caregiver

Inclusion and Exclusion Criteria

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Inclusion Criteria

Written informed consent signed by the patient and/or their legal representative/ parent/ impartial witness
Male or female aged ≥4 years with a genetically confirmed diagnosis of a CACNA1A disorder (including patients with loss-of-function and fain-of-function mutations, e.g. Episodic Ataxia Type 2 [EA2], Familial Hemiplegic Migraine Type 1 [FHM1], Spinocerebellar Ataxia type C (SCA6), Developmental and Epileptic encephalopathy 42 (DEE42), Congenital ataxia or cerebellar hypoplasia due to a CACNA1A mutation ) 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 and confirm to continue 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: a) intrauterine device (IUD); b) surgical sterilization of the partner (vasectomy for 6 months minimum); c) combined (estrogen or progestogen containing) hormonal contraception associated with the inhibition of ovulation (either oral, intravaginal, or transdermal); d) progestogen only hormonal contraception associated with the inhibition of ovulation (either oral, injectable, or implantable); e) intrauterine hormone releasing system (IUS); f) bilateral tubal occlusion.
Females of non-childbearing potential who have undergone one of the following sterilization procedures at least 6 months prior to the first dose: a) hysteroscopic sterilization; b) bilateral salpingectomy; c) hysterectomy; d) 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 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, patient agrees not to donate sperm from the first dose until 90 days after their last dose.
Patients who have ataxia symptoms which (outside of episodes, is applicable) fall within: a) A SARA score of 7 ≤ X ≤ 34 points (out of 40) AND b) Either: i. Within the 2-7 range (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) CACNA1A disorder including those on the prohibited medication list. Non-prohibited medications/therapies (e.g. speech therapy, physiotherapy) are permitted provided: a) The Investigator does not believe the medication/therapy will interfere with the study protocol/results b) Patients have been on a stable dose/duration and type of therapy for at least 42 days before Visit 1 (Baseline 1) c) 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).

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Exclusion Criteria

Patients who have any known hypersensitivity or history of hypersensitivity to: a. Acetyl-Leucine (DL-, L-, D-) or derivatives. b. Excipients the IB1001 sachet (namely isomalt, hypromellose, and strawberry flavor). c. Excipients the placebo sachet (namely isomalt, hypromellose, strawberry flavor, citric acid, microcrystalline cellulose, lactose, denatonium benzoate).
Simultaneous participation in another clinical study or participation in any clinical study involving administration of an investigational medicinal product (IMP; ‘study drug’) for at least 42 days prior to Visit 1. At the discretion of the Investigator, Medical Monitor, and Sponsor, the washout period for specific IMPs may be longer based on the pharmacological activity and pharmacokinetics of the drug.
Patients with a physical, cognitive, or psychiatric condition which, at the Investigator’s discretion and in consultation with the Medical Monitor and Sponsor (as applicable), may put the patient at risk, may confound the study results, or may interfere with the patient’s participation in the clinical study, i.e. reliably perform study assessments.
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 affect patient’s mobility and, at the Investigator’s discretion, interferes with their ability to perform study assessments.
Patients at non-EU trial sites unwilling and/or not able to undergo a 42-day washout period from any of the following prohibited medication prior to Visit 1 (Baseline 1) and remain without prohibited medication through Visit 6. a. N-Acetyl-DL-Leucine (e.g. Tanganil®); b. N-Acetyl-L-Leucine (prohibited if not provided as IMP in the IB1001-304 trial);
Patients at EU trial sites who have had any of the following prohibited medication 42-days prior to Visit 1 (Baseline 1) and unwilling and/or not able to remain without prohibited medication through Visit 6. a. N-Acetyl-DL-Leucine (e.g. Tanganil®); b. N-Acetyl-L-Leucine (prohibited if not provided as IMP in the IB1001-304 trial).