Setback for gene therapy

Reuters has reported the results of a clinical trial of the drug ProSavin, which is manufactured by the biotechnology company Oxford Biomedica. While there was some improvement in the people with Parkinson's who were administered the drug, this was small. And it was difficult to assess the result as there was no control group who would have been given a placebo.

ProSavin is actually a gene therapy product. Essentially, a gene is inserted into nerve cells in the area of the brain that is affected by Parkinson's. These are cells that are still alive, although a lot of the surrounding nerve cells have already died. The gene that is put into the nerve cells helps them to work more efficiently.

The outcomes of gene therapy trials have been mixed. The results of a US gene therapy trial published earlier in 2011 reported a benefit for people who were treated.

However, another trial last year showed some small benefits but these were no better than existing treatments (PDF file).

We have no doubt that gene therapy remains a viable option for the treatment of Parkinson's in the future. And it can be difficult to directly compare the different trials as they all used specific genes which are given for diverse time periods.

But in the longer term, the success or failure of the trials will help to tell us which genes may be best to use. Then we can concentrate on how best to give them so that they will have the maximum benefit.


Anonymous said...

Did you only read that one line comment from Reuters before writing this?

The full release sounds very encouraging to me

Parkinson's UK said...

Thanks for your comments.

Overall the results from this very early-stage trial of the gene therapy ProSavin have been encouraging with participants experiencing improvements in their movement symptoms even at relatively low doses of the treatment.

The results released last week are slightly disappointing as participants receiving the highest dose of ProSavin haven't shown further improvement compared to those on lower doses.

But because it's such a small study without a 'control group', it's too soon to judge how reliable these initial findings might be. The most important thing is that the treatment appears to be safe, and there are some encouraging signs of improvement in Parkinson's symptoms.

We look forward to larger and more comprehensive studies of ProSavin that will be able to tell us much more about how effective it might be for people with Parkinson's.

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