Study to Investigate LP352 in Subjects With Developmental and Epileptic Encephalopathies

This is a randomized, double-blind, parallel-group, dose-escalation, placebo-controlled study of LP352 in adults and adolescents with developmental and epileptic encephalopathies (DEE) with an average of ≥ 4 observed/countable motor seizures per 4-week period during the 12 weeks before screening while on stable antiseizure medicine (ASM). Subjects will be randomized 4:1 to LP352 or placebo. The study will have a baseline period of 28 days, followed by a 15 day up-titration period during which time subjects will titrate up to their highest tolerated doses, and a 60-day maintenance period. After Day 75, subjects will be tapered down over a period of up to 15 days, with a follow-up visit 30 days after last dose. Enrolled subjects will be allowed to continue treatment with up to 4 concomitant ASMs at a stable dose.