Open-label Study of Adjunctive GNX Treatment in Children and Adults With TSC-related Epilepsy

Inclusion Criteria:

1. Completion of Study 1042-TSC-3001 or participants who continue to meet study requirements in Study 1042-TSC-2001.
2. Participant/parent(s)/LAR(s) willing and able to give written informed consent/assent, after being properly informed of the nature and risks of the study and prior to engaging in any study-related procedures. If the participant is not qualified or able to provide written informed consent based on age, developmental stage, intellectual capacity, or other factors, parent(s)/LAR(s) must provide assent for study participation, if appropriate.
3. Parent(s)/caregiver(s) is (are) willing and able to maintain an accurate and complete daily seizure diary for the duration of the study.
4. Willing and able to take Investigational product (IP) (suspension) as directed with food TID.
5. Women of childbearing potential (WOCBP) must be using a medically acceptable method of birth control and have a negative quantitative serum beta-human chorionic growth hormone (β-HCG) test collected at the initial visit. Childbearing potential is defined as a female who is biologically capable of becoming pregnant. Medically acceptable methods of birth control include intrauterine devices (that have been in place for at least 1 month prior to the screening visit), hormonal contraceptives (eg, combined oral contraceptives, patch, vaginal ring, injectables, and implants), and surgical sterilization (such as oophorectomy or tubal ligation). When used consistently and correctly, "double-barrier" methods of contraception can be used as an effective alternative to highly effective contraception methods. Contraceptive measures such as Plan B™, sold for emergency use after unprotected sex, are not acceptable methods for routine use
6. Male participants must agree to use highly effective contraceptive methods during the study and for 30 days after the last dose of IP. Highly effective methods of contraception include surgical sterilization (such as a vasectomy) and adequate "double-barrier" methods.

Exclusion Criteria:

1. Pregnant or breastfeeding.
2. An active Central nervous system (CNS) infection, demyelinating disease, or degenerative neurological disease.
3. History of psychogenic nonepileptic seizures.
4. Any disease or condition (other than TSC) at the initial visit that could compromise the hematologic, cardiovascular (including any cardiac conduction defect), pulmonary, renal, gastrointestinal, or hepatic systems; or other conditions that might interfere with the absorption, distribution, metabolism, or excretion of the IP, or would place the participant at increased risk or interfere with the assessment of safety/efficacy. This may include any illness in the past 4 weeks which in the opinion of the investigator may affect seizure frequency.
5. Unwillingness to avoid excessive alcohol use or cannabis use throughout the study.
6. Have active suicidal plan/intent or have had active suicidal thoughts in the past 6 months or a suicide attempt in the past 6 months.
7. Known sensitivity or allergy to any component in the IP(s), progesterone, or other related steroid compounds.
8. Exposed to any other investigational drug (except for GNX in Study 1042-TSC-2001 or Study 1042-TSC-3001) or investigational device within 30 days or fewer than 5 half-lives prior to Visit 1 (first visit of the OLE). For therapies in which half-life cannot be readily established, the Sponsor's medical monitor should be consulted.