• Age ≥13 years of age, inclusive, at the time of signing the informed consent form (ICF).

• Subjects must have completed the Parent study APG-20 and, in the opinion of the Investigator and Sponsor, have been compliant with study procedures through Parent study Month 12 visit.

• Negative pregnancy test (urine or serum) for female subjects of childbearing potential

• Female subjects must be postmenopausal (defined as cessation of menses for at least 1 year), surgically sterile (hysterectomy, bilateral oophorectomy, or tubal ligation), or willing to use a highly effective method of contraception (such methods include combined \[estrogen and progestogen containing\] hormonal contraception associated with inhibition of ovulation: oral/intravaginal; transdermal/progestogen-only hormonal contraception associated with inhibition of ovulation: oral/injectable; implantable/intrauterine device \[IUD\]/intrauterine hormone-releasing system \[IUS\]/bilateral tubal occlusion/vasectomized partner/sexual abstinence) for the duration of the study (from the time they sign an ICF, until 4 weeks after the last dose of study treatment). Hormonal contraception alone (including oral, injectable, transdermal, and implantable) is not acceptable; an additional barrier method must be used. Intravaginal hormonal contraception or IUS alone are allowed per Investigator's discretion. Subjects on oral contraceptives will not be required to discontinue medication. Subjects will not be permitted to commence oral contraceptives while taking study treatment during the study.

• Male subjects must be surgically sterile or willing to use an acceptable method of contraception for the duration of the study (from the time they sign an ICF), until 4 weeks after the last dose of study treatment. An acceptable method of contraception would be a barrier method, such as condoms, restraining from having sex, or a partner using the approved methods of contraception for female subjects as per Inclusion Criteria #4.

• Subjects who are blood/egg/sperm donors should be willing to halt donations during the study and for 4 weeks following their last dose of study treatment.

• Subjects who are willing to provide informed consent/assent prior to any study-specific procedures. If a minor, the subject has a parent or legal guardian able to read, understand, and sign the ICF and/or a Child Assent Form (if applicable), communicate with the Investigator, and understand and comply with the protocol requirements. Adolescent subjects must also read and understand the Child Assent Form.

• Subjects who are willing to follow the dietary restrictions recommended by the Investigator.