Experimental Gene Therapy for Blindness Will Proceed Even if Targeted Genetics Goes Dark

6/3/09

[Editors note: corrects times in previous version for third patient through maze ]

Among the more impressive presentations at the annual meeting of the American Society for Gene Therapy in San Diego last week was this video provided by researchers at University College London. It shows a man with a form of hereditary blindness navigating a maze before and after gene therapy treatment.

The trial was sponsored in part by Targeted Genetics, the Seattle-based gene therapy pioneer now struggling to avoid bankruptcy. Targeted provided the vector – a harmless virus called an adeno-associated virus – that carried a sight-preserving gene into the man’s retinal cells. A question raised during the San Diego meeting was what will happen to such research if Targeted Genetics goes out of business?

The study involved three patients with a rare degenerative condition called Leber’s congenital amaurosis. Because of a defect in the RPE65 gene, the rod photoreceptors in the retina do not respond to light. Blindness results when patients reach their 30s.

The patients, ages 17 to 23, had little or no vision in dim light but retained limited vision in good light. Each received healthy copies of the RPE65 gene in one eye; the second eye served as a control. After treatment, none of the patients had any improvement in their ability to read an eye chart and two participants showed no improvement at all.

But the third patient could see better through his treated eye in dim light after gene therapy, and breezed through the maze in 14 seconds with no errors. Before treatment, he needed 77 seconds to get through the maze and he bumped into obstacles eight times. The results were published as a brief report in the New England Journal of Medicine last year.

Researchers believe the third patient improved because he had better vision when the trial began; they now plan to try the gene therapy in younger, less advanced patients.

The study was one of two clinical trials supported by Targeted; the second involved a cardiac gene therapy under development at San Diego’s Celladon. Robin Ali, senior investigator on the UCL study, said in an email that alternative sources of clinical-grade vector are available for small-scale academic studies, so work on the blindness therapy can continue even if Targeted goes under.

But bringing such a therapy to market without Targeted could be a challenge, he said. Investment in gene therapy has been dwindling, and Targeted was among the few remaining companies with the expertise to take academic research into the marketplace, Ali said. That capability will be missed if the company shuts down. “If they were to close, it would leave a gap in the market that would take time to fill,” he said.

David Bodine, president of the society and chief of the National Human Genome Research Institute’s genetics and molecular biology branch, said Targeted would be missed. “They provided a place where the work could get done,” he said.

Targeted, which has enough cash to fund operations through the end of June, hasn’t called it quits. The company is exploring all its options, including a merger, a sale of assets, or farming out manufacturing, said CEO Susan Robinson. “We are looking at everything,” she said. “We hope to find a path forward.”

Denise Gellene is a former Los Angeles Times science writer and regular contributor to Xconomy. You can reach her at dgellene@xconomy.com Follow @

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