Gene therapy gives hope to Parkinson's sufferers

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Gene therapy for Parkinson's disease has come a step closer with the publication of trial results showing the ground-breaking treatment is effective.

The trial was small - comparing 22 patients with advanced Parkinson's who received the therapy, with 23 who received a sham treatment - but it indicates the human gene injections into the brain may offer hope for patients in need of new options to treat the disease.

Following the phase 2 trial, the American company developing the treatment, Neurologix, said it was negotiating with the US authorities about setting up a phase 3 trial.

A phase 3 trial, if successful, is usually the last step before commercial release of a drug or therapy.

The therapy was conceived in Auckland by neuroscientist Professor Matthew During, who divides his time between Auckland University and Ohio State University in the US.

The results were "great news", he said.

"Since this is also the first gene therapy study for a neurological disease to achieve success in a rigorous randomised, double-blind design compared with a sham group, this is also a crucial step forward toward finally bringing gene therapy into clinical practice for patients with debilitating brain disorders."

The patients who received the gene therapy experienced, on average, a 23 per cent improvement in motor functions, compared with 13 per cent improvement for those given sham surgery.

Fifty per cent of the treatment group experienced moderate to large improvements in their symptoms, compared with 14 per cent of those in the sham surgery group.

The therapy, given under local anaesthetic, involves drilling a hole in the skull and using a hollow needle and catheter to insert the genes into the brain.

The genes are carried by a disabled and harmless virus to the sub-thalamic nucleus, a part of the brain that is extremely overactive in people with Parkinson's.

Once in place, the gene, called GAD, prods brain cells into producing more of a neurotransmitter substance called GABA, which calms overactivity.

The support group Parkinson's NZ welcomed the trial results.

"We're delighted that the phase 2 study has shown to be so successful," chief executive Deirdre O'Sullivan said yesterday. "It holds a lot of hope for people with Parkinson's."

Dr Thomas Foltynie, of the Institute of Neurology in London, said the results were "welcome encouragement" for patients, but the size of the improvement in the treatment group was "quite modest" compared with the results that could be achieved with deep brain stimulation.

THE DISEASE

* Parkinson's disease is caused by having insufficient dopamine, a neurotransmitter substance in the brain.

* More than 10,000 people in New Zealand have Parkinson's.

* Symptoms can include trembling, slow movements, depression, trouble swallowing, and loss of the sense of smell.

* There is no cure.

* Drug treatments can control symptoms, but their effectiveness can wane.

* Some patients receive deep-brain stimulation, a surgical implant of an electrode operated by a pacemaker-like device.
- additional reporting, agencies