An Open Label Extension Study in Subjects With Fragile X Syndrome

Three studies sponsored by Seaside Therapeutics, Inc., are currently evaluating the efficacy of STX209 for management of typical problem behaviors in subjects with FXS. These are Study 209FX301, "A Randomized, Double-Blind, Placebo-Controlled Study of the Efficacy, Safety, and Tolerability of STX209 (Arbaclofen) Administered for the Treatment of Social Withdrawal in Adolescents and Adults with Fragile X Syndrome;" Study 209FX302, "A Randomized, Double-Blind, Placebo-Controlled, Fixed- Dose Study of the Efficacy, Safety, and Tolerability of STX209 (Arbaclofen) Administered for the Treatment of Social Withdrawal in Children with Fragile X Syndrome;" and Study 22002, "An Open-Label Extension Study to Evaluate the Safety, Tolerability and Pharmacokinetics of STX209 in Subjects with Fragile X Syndrome." This study will enroll subjects who have completed Protocols 209FX301, 209FX302, or are currently participating in Protocol 22002 into a long-term, open-label study. The open-label extension protocol will provide data on the long-term safety and tolerability of STX209 among subjects with FXS who receive treatment under conditions reflective of their typical medical care rather than in their previously completed study.