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News from the Fragile X community highlights the challenges of clinical trials.

Below is an article from the New York Times written by Andrew Pollack.

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Holly Usrey-Roos will never forget when her son, Parker, then 10, accidentally broke a drinking glass and said, “I’m sorry, Mom. I love you.”

It was the first time she had ever heard her son say he loved her — or say much of anything for that matter. Parker, now 14, has fragile X syndrome, which causes intellectual disability and autistic behavior.

Ms. Usrey-Roos is certain that Parker’s new verbal ability resulted from an experimental drug he was taking in a clinical trial, and has continued to take for three years since then. She said she no longer had to wear sweaters to cover up the bruises on her arms she used to get from Parker hitting or biting her.

Now, however, the drug is being taken away. It has not met the goals set for it in clinical trials testing it as a treatment for either autism or fragile X syndrome. And Seaside Therapeutics, the company developing it, is running out of money and says it can no longer afford to supply the drug to former participants in its trials.

The setback is a blow in the effort to treat autism since the drug, arbaclofen, was one of the furthest along in clinical trials. And the company’s decision has caused both heartbreak and outrage among some parents.

“I waited 10 and a half years for him to tell me he loved me,” said Ms. Usrey-Roos, who lives in Canton, Ill. “With fragile X, you’re like living in a box and someone is holding the lid down. The medication opened the lid and let Parker out.”

“I don’t want to go back to the way life was,” she added.

The situation raises questions about what, if anything, drug companies owe to patients participating in their clinical trials. It also points out the difficulties in developing drugs to treat autism and fragile X syndrome. If the drug worked so well in some patients, why has it not succeeded so far in clinical trials?

Read the full article …

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RETT SYNDROME RESEARCH TRUST WEBSITE

Last month brought me to Houston, Texas to attend a fascinating meeting organized by Huda Zoghbi and Morgan Sheng and co-sponsored by RSRT. Entitled Disorders of Synaptic Dysfunction, the event was the inaugural symposium of the recently established Jan and Dan Duncan Neurological Research Institute, directed by Dr. Zoghbi.

The two-day meeting brought together a heterogeneous group of scientists from academia (senior and junior faculty as well as post-docs and graduate students), industry, NIH and other funding agencies.

The focus was not on  a single disease but rather on a group of disorders (Rett, Angelman, Fragile X, autism, Tuberous Sclerosis) that share a common cellular phenotype: abnormal synapse activity.

It’s no surprise that some of the talks that generated the most buzz came from labs that are doing very clinically relevant research. These include the labs of Mark Bear at MIT, working on Fragile X, and Ben Philpot at UNC whose lab works on Angelman Syndrome.

Like Rett Syndrome, Fragile X is a single gene disorder, caused by mutations in a gene called Fmr1. When Fmr1 is mutated, protein synthesis fails to shut down, leading to excess. Some years ago Dr. Bear proposed that compounds which can block a certain type of receptor, mGluR5 (which triggers the burst of synaptic protein synthesis) might counteract over-expression of protein and thereby cancel out the damaging effect of Fmr1 deficiency. His theory has proved correct, and clinical trials of mGluR5 antagonists are currently ongoing at multiple pharmaceutical companies.

I first met Dr. Bear almost a decade ago, when he was just beginning to formulate what is now commonly known as the mGluR5 theory of Fragile X.  His lab is currently funded by RSRT to explore protein synthesis in the Rett mouse models. Dr. Bear hypothesizes that Rett may be due to under-expression of proteins. If his hypothesis holds up, pharmacological manipulations of mGluR signaling will be pursued.

Ben Philpot’s talk also generated excitement. He discussed a high-throughput screen that has yielded a compound which can activate the silenced Angelman Syndrome gene, UBE3A. Dr. Philpot is currently funded by RSRT to pursue a similar approach for the silent MECP2 gene on the inactive X chromosome.

Mike Greenberg spoke about MECP2 and shared unpublished data that has come about from his collaboration with Adrian Bird via the RSRT funded MECP2 Consortium. (More on that in the months to come.)

Jackie Crawley of the NIH gave a brilliant talk on how “autistic mice” are being characterized to yield a plethora of new information.  For me the highlight of her talk was hearing recordings of mouse “speech”. She shared a variety recordings and I was taken aback by the complexity and richness of the sounds, which left me yearning for an analysis of Rett mouse vocalizations.

After a lively cocktail hour it was back to work with dinner plates in hand. Drs. Zoghbi and Sheng divided the attendees into three working groups: 1) dysfunction of proteins of the synapse 2) dysfunction of nuclear/cytoplasmic proteins 3) young investigators and junior faculty.  Masquerading as a 30-something I happily joined the third group.  I was struck by the fearlessness and boldness of these young scientists. There were not shy about criticizing the status quo and what could be done differently to enhance the research progress. I came away feeling buoyed and reassured that science is in good hands with this new generation.

The following several hours of discussion, led by Rodney Samaco and Mingshan Xue and facilitated by NIMH Director, Tom Insel, were intellectually stimulating and entertaining. Below is a visual output of our intense discussion.

A few personal reflections on the symposium

  • Over and over again throughout the meeting I heard comments from autism researchers such as: “Where would we be without the syndromic autism animal models like Rett and Fragile X? We’ve learned so much from them”.  More than once I found myself thinking that as horrible as Rett is at least the genetics of the disorder are clear-cut – Rett’s silver lining.
  • The meeting provided an opportunity to meet some scientists with whom I had communicated by email and/or phone, but never met in person. People like Pat Levitt, Freda Miller and Michael Palfreyman.  It was a reminder of how many people over the years have taken the time to discuss their work and possible synergies to Rett Syndrome.
  • Drs. Zoghbi and Sheng kept everyone busy from the moment the meeting started to the moment we left, including an intense working dinner. I tend to do the same thing  at meetings that I organize, but always feel like I’m being a bit of a slave driver. Never again, however, will I feel guilty. If Dr. Zoghbi thinks it’s acceptable, then so do I!

Kudos to Drs. Zoghbi and Sheng for a stimulating meeting and thank you both for inviting me.

Science Translational Medicine, which co-organized the meeting, will be publishing a white paper on the proceedings.
RSRT will let you know when the paper is available.
RETT SYNDROME RESEARCH TRUST WEBSITE

Mark Bear, PhD of MIT

Mark Bear, Ph.D. of MIT is the most recent addition to RSRT’s portfolio of funded scientists. Prof. Bear studies synapses, the gaps between nerve cells where chemical or electrical signals are exchanged. The strengthening and weakening of synapses contributes to learning and memory but when impaired can lead to neurological disorders.

Much of the excitement in the Fragile X community comes courtesy of the Bear lab. His discoveries have spawned a series of clinical trials.
Forbes
New York Times
Bloomberg

Monica Coenraads, Executive Director of RSRT, recently caught up with Prof. Bear to discuss his Fragile X research and how it might extend to Rett Syndrome.

MC: Prof. Bear, thank you for taking time to discuss your research with us. Many of our readers will have heard of the ongoing Fragile X clinical trials and are eager to understand how your research might also impact Rett Syndrome. Please explain the so called “mGluR Theory of Fragile X” which was discovered in your lab.

MB: Sure. Synaptic function requires the synthesis of proteins in the synapses, so that supply can keep up with demand.  Demand is registered, in part, by activating metabotropic glutamate receptors (mGluR).  So the more active the synapses are, the more glutamate is released and the more protein is made. Like in many systems there are checks and balances, and one of those is the negative regulation of protein synthesis by FMRP, the protein made by the Fragile X gene, FMR1.  Normal synaptic function requires a sense of balance between driving protein synthesis through mGluRs, and inhibiting protein synthesis through FMRP. In Fragile X the FMRP protein is missing so it’s like driving a car with no brakes – your foot is on the gas but there is no way to stop. So there’s excessive protein synthesis which leads to a myriad of deleterious consequences. The approach that holds a lot of promise is to inhibit mGluR which in essence takes your foot off the gas.

Now that theory has been pretty widely validated and at least in the animal models of Fragile X  many features of the disorder can be corrected by inhibiting mGluR.

MC:  You theorize that Rett Syndrome is at the other end of the spectrum, instead of too much protein synthesis, there’s too little protein synthesis. What’s behind this hypothesis for you?

MB: Once we had the success in Fragile X, we started thinking more broadly about other single gene disorders that are characterized by autism, seizures, and impaired learning. I was influenced by a paper that was published by Christian Rosenmund and Huda Zoghbi. They analyzed synaptic connectivity of hippocampal-cultured neurons that either were over or under expressing MeCP2, the Rett Syndrome protein.  They found that reducing expression of MeCP2 reduced the connectivity, and over expressing it increased the connectivity.

We think about Fragile X as a hyper-connectivity disorder: too much protein synthesis, too many synapses, or too much synaptic turnover…and so, the Rosenmund/Zoghbi results made me think about Rett in terms of diminished protein synthesis. Also, in terms of morphology in Rett tissues we see signs of reduced connectivity –for example too few spines on dendrites.

MC: You were recently at a Fragile X meeting in Edinburgh where you spent some time discussing your theory with Adrian Bird. Tell us a bit about that.

MB: I was starting to mull this theory over then I ran into Adrian and had a great conversation with him. He was very encouraging – he didn’t think that this was a ridiculous idea. So that really got me charged up.  We agreed that the most exciting thing is that we have drugs that can correct both excessive and diminished protein synthesis.

MC: Prof. Bird called me after you and he had this discussion – he was charged up too. I organized a conference call and the three of us rather quickly decided on a collaboration and a division of labor with regards to experiments. Please tell our readers a bit about the drugs that are in existence.

MB: There are two types of mGluR drugs that have been developed. One of them is the negative modulators that will inhibit mGluR. These would be used for Fragile X. The others are positive modulators that will promote mGluR activation – these might be helpful for Rett.  The negative modulators were developed originally as a potential treatment for generalized anxiety disorder  with the goal of creating the next generation of anxiolytics. That’s what motivated industry and  they invested hundreds of millions of dollars into developing these compounds. We are really lucky in that there’s already a lot of great chemistry around our target. The positive modulators were developed for schizophrenia.

MC:  Novartis recently released data on a phase 2 clinical trial for Fragile X.  What did you think of the outcome of that trial?

MB: I think the best news is that they’ve decided to go forward into phase 3. Overall I think there is tremendous hope for disorders like Rett and Fragile X even for interventions in adults. So we are extremely optimistic and very energized to help people affected by Rett. And we thank RSRT for giving us funds to explore the disease and for facilitating a collaboration with Adrian.

MC: Talk to us about Seaside Therapeutics, the biotech that you started to develop drugs for neurodevelopmental disorders.

MB: When we first realized that mGluR inhibitors might be beneficial for individuals with Fragile X we reached out to big Pharma and we got a very cool reception. In those days, about ten years ago, big Pharma had very little interest in rare genetic disorders. As a consequence, I founded Seaside. So far we have been pretty successful in advancing a drug that shows great promise in both Fragile X and autism.  Seaside is committed to tackling the single gene disorders. And although we do not currently have a Rett program, there easily could be if we get a promising lead, so we are eager to get to work.

MC: I remember sitting in your office at MIT 6 or 7 years ago talking to you about Rett Syndrome. It’s taken a bit of time but I’m so pleased that you are now working on Rett. Our readers and I wish you much luck. We hope to hear of your success soon.