Olivopontocerebellar Atrophy Clinical Trials

• 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, 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:

∙ intrauterine device (IUD);

‣ surgical sterilization of the partner (vasectomy for 6 months minimum);

‣ 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 who have undergone one of the following sterilization procedures at least 6 months prior to the first dose:

∙ hysteroscopic sterilization;

‣ 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 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, 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, if applicable) fall within:

∙ A SARA score of 7 ≤ X ≤ 34 points (out of 40) AND

‣ 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, 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 42 days 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).

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