At the recent annual American Association of Neurological Surgeons meeting, researchers presented the results of a Phase I clinical trial designed to test the safety and tolerability of a gene therapy approach for GDNF in Parkinson's.

Gene therapy involves the introduction of normal genes into cells in place of missing or defective ones in order to correct medical conditions with DNA (genetic material) rather than drugs. In Parkinson's, this is achieved by introducing new DNA into brain cells using disease-free, engineered viruses (viral vectors) into the brain. The vector passes its genetic material to the cells so that the therapeutic gene can work locally in the brain where it is needed. The new DNA enables those cells to start producing proteins that they usually do not produce.

Glial cell line-derived neurotrophic factor (or GDNF) is a protein that has been shown to be neuroprotective for dopamine neurons, the cells in the brain that are badly affected by Parkinson's. In this trial researchers introduced GDNF-producing DNA into neurons enabling them to produce GDNF to help rejuvenate the remaining dopamine neurons. This gene therapy approach is a very different method of treatment delivery to that used in the recent Bristol-based GDNF clinical trial which was part-funded by The Cure Parkinson's Trust 

This new clinical trial involved 13 people with advanced Parkinson's. The results suggested that the treatment was safe and well tolerated and brain imaging data indicates a 54% increase in dopamine activity in the brain, and clinical assessments indicated a stabilisation of motor symptoms over the course of the study.

It is important to understand that all of the participants in this small study were aware that they were on the GDNF treatment, so there is the possibility of a placebo response (improvements not based on biological effect of the treatment), but the researchers are now seeking to conduct a larger Phase II follow-up clinical trial to increase putaminal coverage (the putamen is the area in the brain affected by dopamine loss) and possibly reverse Parkinson's progression.  

Read the full article here.

Further reading:

The GDNF Trial - Bristol

Can Neurotrophic Factors Be Neuroprotective in Parkinson's Disease?