Safety, Tolerability, and Efficacy of PLX-200 in Patients With CLN3

This is a phase 3, double-blind, placebo-controlled, dose-titration study to evaluate escalating weight-based dose levels of PLX-200, provided as a solution that contains 15 mg/mL PLX-200 and administered orally using a syringe, as needed, twice daily (BID), 30 minutes before breakfast and dinner. Participants will enter the Titration Period, during which the starting dose of PLX-200 or placebo will be based on patient weight. Each patient's dose will be titrated upward on a weekly basis during the Titration Period, until he or she reaches a maximally tolerated dose (MTD) or the Week 5 dose for their weight category. The patient will then enter the Maintenance Period at the final Titration Period dose for a maximum of 60 weeks. Safety, efficacy, and pharmacokinetics will be assessed periodically. Thereafter, all patients will have the opportunity to receive active treatment in an Open-Label Extension (OLE) for an additional 36 weeks.