Gene Therapy Shows Promise for Visually Impaired

Spark Therapeutics’ experimental gene therapy showed improved vision in patients with hereditary vision impairment. The company hopes to gain U.S. Food and Drug Administration approval to become first gene therapy to reach the United States market, according to the Wall Street Journal.

The Philadelphia-based biotechnology startup released the results of its clinical trial in a news release, however only included few details. These results seem to show promise from the safety concerns the gene therapy field has faced in previous years. In the late 1990s and early 2000s, gene therapy research came to halt because study participants developed cancer or died after receiving that kind of therapy.

Gene therapy includes injecting genetic material into a person’s cells to treat or prevent certain diseases, according to WSJ. Around the world, gene therapy is picking up. The European Commission approved the Uniqure NV’s Glybera, the western world’s first gene therapy. Glybera is used for the treatment of people with a rare enzyme deficiency.

peripheralvisionMutations in a gene known as RPE65 that cause visual impairments such as loss of night- and peripheral-vision to complete blindness are targeted through Spark’s gene therapy. SPK-RPE65, the name for Spark’s therapy, includes a copy of a functional RPE65 gene inside of a type of virus that is stripped of its viral DNA, according to the WSJ. The virus is only the delivery system for the gene when it is injected in the eyes.

The study contained 19 participants with confirmed RPE65 mutations and nine people who did not receive the gene therapy. Participants had to navigate through indoor obstacle courses with various levels of lighting. Researchers videotaped the participants through the course to track their outcomes, according to Spark Chief Executive Jeffrey D. Marrazzo. The functional vision in patients who received the therapy improved after a year of treatment in comparison to the control group. The patients who received the therapy also improved their sensitivity to light in comparison with the control group.

Although there were no serious side effects to the therapy, Spark noted side effects related to the injection of the therapy. Some participants experienced eye inflammation or elevated intraocular pressure, according to the WSJ.

Although the Spark results do not quantify measurable visual improvements in the participants, Debra Thompson, professor of ophthalmology and visual sciences at the University of Michigan’s Kellogg Eye Center, said the study appears to be significant. “Even small gains in visual function can make a huge difference in quality of life,” she said.


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