Seaside Therapeutics’ clinical trials for the drug Arbaclofen placarbil have recently been shutdown due to funding issues. On May 15, 2013, the sponsor of Arbaclofen sent an announcement to the clinics involved in the administration of the drug stating “We regret to inform you that Study 209FX303 [An Open-Label Extension Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of STX209 (arbaclofen) in subjects with Fragile X Syndrome] is being terminated immediately. The closure of the study is due to resource limitations at Seaside Therapeutics, Inc., and is not related to any known safety issues in patients dosed with STX209.”
Arbaclofen, a novel prodrug of R-baclofen, was being tested to see if it could help reduce the symptoms a closely related genetic condition to autism spectrum disorder known as “fragile X syndrome.” Fragile X is the most widespread single-gene cause of autism, which is also an inherited cause of mental retardation among males. Fragile X, like autism, is characterized by social anxiety, such as poor eye contact, gaze aversion, challenges forming peer relationships, and prolonged time to commence social interaction. One of the main hypotheses regarding the cause of autism and fragile X is that there is an overabundance of synaptic excitation, which is what Seaside Therapeutics was attempting to help correct. The drug’s research and developed had passed Phase 2 of the clinical trial, moving it to Phase 3. Regardless of the fact that an estimated third of the patients in the trial improved with Arbaclofen, it did not show enough promise to receive funding from the Food and Drug Administration (FDA).
Those in the autism community received Arbaclofen with great expectations, which is why many are disappointed that the third phase of the trial cannot be funded. Arbaclofen would have been the first medication to treat the core symptoms of both autism and fragile X. One participant in particular, 12-year-old Matthew Zolecki, had been taking the drug for over three years and had become more calm, less anxious, more communicative, and happier overall, including his family. His mother, Melissa, is now worried about how Matthew will respond to being weaned off of this medication, as he has made so much progress due to it. Many parents found Arbaclofen to be a life changing medication for their children and are now working to pressure the government to resume these trials by bringing awareness to the situation. A Facebook page has even been created to promote the reinstatement of funding to Seaside Therapeutics by Roche Pharmaceuticals, who pulled out of the joint effort with Seaside, called “Fragile X and Autism Families for STX209.” A website has also surfaced called STX209 Stories, where families can share their stories in regard to Arbaclofen and to maintain public updates of how their children are doing without it.
In the meantime, Seaside Therapeutics has a third trial of Arbaclofen being conducted for children with fragile X syndrome between the ages of 5 and 11-years-old. This trial is expected to be completed by the end of this summer. If Arbaclofen is shown to be effective in this trial, Seaside Therapeutics will contact the FDA to see what the next step is to get the drug approved.