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Results of the Roche Trial of RO4917523 for Fragile X Syndrome

As some of you may be aware, Roche have just released an outline of the findings from their recent clinical trials in fragile X. Unfortunately these findings were negative, i.e. they found that the drug did not work for fragile X. As a result, Roche have stopped the development of this drug for fragile X syndrome. More details are below.

The clinical trials were based on the idea that there is a problem with the way that nerve cells develop connections with each other in fragile X syndrome. It was hoped that the medicine Roche were testing (RO4917523) could improve this process. It is worth noting that this is the same idea that was behind the recent unsuccessful trials by another company, Novartis.

Roche carried out two trials, only one of which was in the UK. Both trials compared the new medicine to a placebo (or dummy) medicine for 12 weeks; this was to see if the new medicine was more effective or had more side effects than the placebo.

The first trial was worldwide, including the UK, and contained over 180 adolescents and adults with fragile X. In this study people were either given placebo, a low dose of the new medicine or a higher dose of the new medicine. No differences were found between the medicine and the placebo on a wide variety of clinical features, including anxiety, behavioural problems and autistic traits. This is strong evidence that the medicine is not effective for fragile X over a 12 week treatment period.

The second trial was only run in the USA and was for children aged between 5 and 14. This was a smaller study containing less than 50 people which was designed mainly to see if the medicine was safe in younger children. In terms of side effects they found that some children became more aggressive when on the medicine, although this was thought to be only mildly or moderately severe. Although the trial was designed to mainly consider safety, they did include some measures of potential effectiveness. They have not released the results of these, but my opinion would be that if they had very clear evidence of a positive effect they would be planning more studies in younger people, which they are not.

Overall, Roche were very clear that the lack of positive findings from their studies mean that they cannot justify doing further clinical trials with this medicine in fragile X.

Although disappointing, these results were not unexpected given the negative results that Novartis reported recently using a very similar medicine.

However, there continues to be a lot of interest in developing new treatments for fragile X which work differently to the Roche and Novartis medicines. At the moment there are at least three different medicines being trialled in people with fragile X in the USA; we hope that if these preliminary studies prove successful we will be able to convince the companies involved to run them in the UK. There are also many other potential medicines for fragile X which are being developed in laboratories around the world, as well as other non-medical approaches which are being tested. I remain optimistic that the sheer amount of research that is now being conducted in fragile X worldwide, along with our ever greater understanding of the nature of the condition will lead to the development of effective treatments.

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