Positive results from study of STX 209 (Seaside Therapeutics) for patients with Fragile X Syndrome

A new study shows STX 209 (arbaclofen), from Seaside Therapeutics, is effective for addressing the social withdrawal and challenging behaviors characteristic of Fragile X Syndrome, making it the first such discovery and potentially the first for autism spectrum disorder. The Phase II clinical trial initially recruited 63 subjects at 12 sites across the US and participants ranged in age from 6 to 39 years. The effects of the medication were scored on variables of the Aberrant Behavior Checklist, a behavior-rating scale for the assessment of drug-treatment effects. The study found improvement for the full study population on the social-avoidance subscale, an analysis validated by secondary ratings from parent observation of improvement in subjects' three most problematic behaviors. It found that the medication was the same as placebo, however, on the subscale for irritability.

"This study will help to signal the beginning of a new era of targeted treatments for genetic disorders that have historically been regarded as beyond the reach of pharmacotherapy," says Dr. Elizabeth Berry-Kravis, at Rush University Medical Center in the US. Two Phase III studies for the drug, one in adolescents and adults (ages 12 to 50) and one in children (ages 5 to 11) with Fragile X Syndrome, are currently enrolling participants.