This study will assess the efficacy, safety, and tolerability of ganaxolone (GNX) compared with placebo (PBO) as adjunctive therapy to the participant's standard anti-epileptic medication for the treatment of seizures in pediatric patients from 6 months to less than 2 years old with genetically confirmed CDD during a 12-week, DB phase. Pharmacokinetic (PK) assessments and population PK analyses will also be performed during this time. The DB phase will be followed by an optional long-term OL phase at which time all participants will receive GNX as an adjunct to their standard anti-seizure medication. Efficacy, safety and tolerability, and PK assessments will continue to be performed.
A diagnosis of CDD, including molecular confirmation of a pathogenic or likely pathogenic CDKL5 variant and refractory seizures (see Inclusion criterion 5).
The principal investigator (PI) must review the results of the genetic analysis and confirm that gene mutation is likely to be the cause of the epilepsy syndrome.
If the participant has a de novo variant of unknown significance (VUS) in the kinase domain of the CDKL5 gene, parental testing is negative and meets all other inclusion criteria, then the participant can be included.
Genetic mutations will be confirmed by the sponsor's chosen central laboratory. In France, genetic mutations may be confirmed by an approved French organization, in compliance with French legislation prior to Screening/Visit 1.
Have an active CNS infection, demyelinating disease, degenerative neurological disease, or CNS disease deemed progressive as evaluated by brain imaging (magnetic resonance imaging [MRI]).
Have any disease or condition (medical or surgical; other than CDKL5 deficiency) at screening that might compromise the hematologic, cardiovascular, 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.
Has a positive result for tetrahydrocannabinol (THC) test (via urine or plasma drug screen) at the screening visit. Concomitant Epidiolex/Epidyolex (cannabidiol derivative [CBD]) use will be allowed in the DB phase provided the participant has been on a stable dose for at least 1 month prior to screening and is expected to remain on a stable dose without a foreseeable change for the duration of the DB phase.
Use of a CBD preparation other than Epidiolex/Epidyolex for 1 month prior to screening.