Seaside Therapeutics Announces End of Arbaclofen (STX209) Extension Study

Seaside TherapeuticsLate yesterday afternoon the NFXF, along with all of the study locations, was contacted by Seaside Therapeutics and informed that the “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. The closure of the study is due to resource limitations at Seaside Therapeutics, Inc., and is not related to any known safety issue in patients taking the drug.”

Everyone who is participating in this study will be contacted by your individual clinic. Please remember there are many people for each site to contact and this could take some time. Every participant will be given instructions on the process of tapering your child off of the drug which could take anywhere from 1 to 4 weeks, depending on the current dose. You will then have an opportunity to work with your child’s doctor to determine the next, best step in your child’s treatment.

It is our understanding that Seaside will continue to analyze the data from the trials and work for FDA approval if these trials show benefit that is sufficient for approval.

All of us at the NFXF know that for many of you the news that your son or daughter will need to soon stop taking arbaclofen is very upsetting. We have heard your descriptions of the improvements you have observed in your child during the trial, or the extension, and we know how worried you are about the change.

Over the past few months our executive director, Robert Miller, has had the opportunity to meet with the Fragile X teams at other pharmaceutical companies and he says they all appear to be fully committed to their own drug development and clinical trials.

So please, work closely with your child’s doctor and remain hopeful and optimistic that new and better treatments are still forthcoming.

We will continue to keep you informed of the current drug trial available to families on our website. You can see a currently listing of current ongoing clinical trials at


  • I emailed Bill Gates today and asked for his help. I explained to him that there are hundreds of families that need his help. STX 209 has had a very positive influence on my son. He now speaks in sentences and is a social butterfly! I urge others to email him too at info@gatesfoundation and explain to him how STX 209 has affected your child.

    Thank You,
    Jill Harrison

  • How woefully tragic that the clinic trials have ended for this encouraging medication. May it only be temporary. So many families have been relying on it, and it was making a difference. So much money in the pharmaceuticals and medical research industry that surely there are funds to keep this pioneering work going. There are some very, very wealthy people who need to step forward to save this work.

  • I certainly appreciate the efforts of the folks at the fragile x organization, but to manipulate people to fund research that’s poorly designed and has a very small chance to succeed, with very small benefits even if it does.. Wasn’t Mark Baer a research scientist working on Fragile X? He then discovers Arbaclofen and patents it and tries to create financial gain from his work? I’d like to see the scientific community spend a lot more time on Minocycline. It’s a much better shot on goal. Scientists and drug companies don’t want to further studies of Minocyline, they can’t get paid for it. If your child has Fragile X, ask your doc about giving it a shot.

  • W Polsce nawet nie słyszelismy o tym leku- a tu sa tez setki tysiecy dzieci z fraX i tym podobne. Pomocy!!! dajcie i nam szanse!!! Gdyby tylko ludzie wiedzieli o tym to zapewne woleli przeznaczyc pieniazki na Aberclofen a nie czasem bezsensownie wydawac na nieskuteczne czy wielolwtnie rehabilitacje, ktore czasem daja tylko maly krok do przodu!Wydam kazdy pieniadz by dostac ten lek! I takich rodzin jest duzo! Polska o Aberclofen STX209 nic nie wie!!

  • Thank you so much for this great information. My son is 33 years old and he suffer of Autism. I would like to hear more.

  • Thank you!

  • yet another failed shot on goal with Elizabeth Berry-kravis as the lead investigator. How many drusg is that now in the last 10-12 years?

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