A Study to Investigate the Efficacy and Safety of ZX008 (Fenfluramine Hydrochloride) as an Adjunctive Therapy in Children and Adults With Lennox-Gastaut Syndrome

Key Inclusion Criteria:

- Male or non-pregnant, non-lactating female, age 2 to 35 years, inclusive as of the day
of the Screening Visit.

- Clinical diagnosis of Lennox-Gastaut syndrome, where seizures that result in drops are
not completely controlled by current antiepileptic treatments.

- Onset of seizures at 11 years of age or younger.

- Abnormal cognitive development.

- Must be receiving at least 1 concomitant AED and up to 4 concomitant anti-epileptic
treatments.

Key Exclusion Criteria:

- Etiology of seizures is a degenerative neurological disease.

- History of hemiclonic seizures in the first year of life.

- Subject only has drop seizures in clusters, where individual seizures cannot be
counted reliably.

- Pulmonary arterial hypertension.

- Current or past history of cardiovascular or cerebrovascular disease, such as cardiac
valvulopathy, myocardial infarction or stroke.

- Receiving concomitant therapy with: centrally-acting anorectic agents;
monoamineoxidase inhibitors; any centrally-acting compound with clinically appreciable
amount of serotonin agonist or antagonist properties, including serotonin reuptake
inhibition; atomoxetine, or other centrally-acting noradrenergic agonist;
cyproheptadine.

- Taking felbamate for less than 1 year prior to screening and/or does not have stable
liver function and hematology laboratory tests, and/or the dose has not been stable
for at least 60 days prior to the Screening Visit.

- Currently receiving an investigational product.

- Institutionalized in a general nursing home (ie, in a facility that does not
specialize in epilepsy care).

- A clinically significant condition, or has had clinically relevant symptoms or a
clinically significant illness in the 4 weeks prior to the Screening Visit, other than
epilepsy, that would negatively impact study participation, collection of study data,
or pose a risk to the subject.