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Three members of the human gene therapy research team (L-R) Professor Elizabeth Rakoczy, Dr Aaron Magno and Associate Professor May Lei    Photo: Lions Eye Institute

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Forty Australian patients with wet aged-related macular degeneration (AMD) have been recruited to trial pioneering gene therapy that researchers say is promising.

A previous trial restored sight in dogs within one month of receiving the therapy, and plans are underway for phase three clinical trials in up to 1,000 Americans.

The patient trial, which is the only gene therapy in Australia that has progressed to human trials, involves receiving one injection of a healthy human gene delivered into retinal cells by a harmless carrier virus.

Principal clinical investigator Professor Ian Constable from the Lions Eye Institute in Perth said the introduced DNA became incorporated into the cells that had genetic defects causing them to over-produce a damaging protein.

‘The cells become little bio-factories and start producing the antidote,’ he said.

The researchers hope the treatment will eventually replace the only effective treatment for wet AMD, monthly injections into the eye that cost up to $6 billion worldwide a year.

Professor Constable said the gene therapy was proving to be well tolerated and promising in the human trials that started two years ago.

Early results on safety and efficacy from the first eight patients were reported to the Association for Research in Vision and Ophthalmology (ARVO) annual conference in Florida in May by principal scientific investigator Professor Elizabeth Rakoczy.

‘To date, the safety profile is excellent, we have found no serious adverse effects in the eye and so far we have promising data on how it works,’ Professor Constable said.

He said wet AMD occurred when there was an overproduction of the protein vascular endothelial growth factor (VEGF) in the retina.

VEGF helps support oxygen supply to tissue when circulation is inadequate but when too much VEGF is produced, it can cause disease, including blood vessel disease in the eye.

Existing monthly treatment injections of anti-VEGF drugs limit production of the protein.

‘The gene therapy involves a single injection of a modified and harmless version of a virus containing a specific gene that stimulates supply of a protein that then blocks over-production of VEGF,’ Professor Constable said.

He said it was the first research in Australia using gene therapy in ophthalmology or any other medical field.

‘This is research of international significance and a huge academic achievement for The University of Western Australia, the university’s Centre for Ophthalmology and Visual Science and the Lions Eye Institute,’ Professor Constable said.

The science behind the treatment began more than 20 years ago when Professor Constable recruited Professor Rakoczy, a molecular ophthalmologist, to the institute.

Laboratory and pre-clinical research was funded by the National Health and Medical Research Council and conducted in Perth, Beijing and Singapore. The research started in a mouse model and progressed to Briard dogs, in which sight was restored within a month of receiving treatment.

Professor Constable said that despite the very promising interim results, more testing was required.

‘After the Perth trial, multi-centre studies will have to be run in the United States and US Food and Drug Administration approval sought, but we believe we are on track to test the investigational therapy in more patients and, if proven safe and effective, make it widely available,’ he said.

Rights to the technology have been licensed by US company Avalanche Biotechnologies, which has raised more than $80 million from New York venture capitalists.

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