209AS209: An Open-Label Extension Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of STX209 (Arbaclofen) in Subjects with Autism Spectrum Disorders

The objective of this study is to explore the efficacy, safety, and tolerability of STX209 (Arbaclofen) administered for the treatment of social withdrawal in subjects with autism spectrum disorders (ASD). All participants will receive 48 weeks of treatment in an open-label study. The 48 week treatment period will be followed by up to 4 weeks of titrated withdrawal, and an up to 31 day follow-up period. Efficacy measures will be Aberrant Behavior Checklist - Community Edition (ABC-C), Clinical Global Impression - Severity and Improvement (CGI-S and CGI-I), and Vineland Adaptive Behavior Scales II (VABS-II). Safety measures are detailed in the protocol.