Spark Therapeutics announced on Monday, Oct. 5 that its experimental gene therapy called SPK-RPE65 exhibited positive results in its phase 3 clinical trial. The findings now show promise in restoring the vision of patients stricken with a type of inherited retinal dystrophies (IRDs).

The biochemical firm said that their lead drug was able to fulfill the goals set by the company in terms of improving vision and light sensitivity of participants with IRDs, who were formerly at risk of being completely blind.

The clinical trial to test the efficiency of the drug involved 31 individuals diagnosed with Leber congenital amaurosis, which is a retinal genetic mutation that can result in blindness or night blindness. The participants were aged between 4 and 44 years old. None of the participants were totally blind or had flawless vision.

The participants were injected with the drug and subjected to a follow-up testing after a year. In the test, the patients were asked to course through a path that had black arrows on a white floor, some steps and other hurdles. The primary variable was the amount of light that the patient required in order to get a passing mark on the test. Seven levels of light were involved in the study, the brightest of which can be compared to a well-lit office and the darkest, to a summer night without an apparent moon.

Of the 31 participants, 21 were included in the intervention group, who received the actual treatment, and 10 were included in the control group who were not injected with the drug.

Spark CEO Jeffrey D. Marrazzo said that the results of the assessment after a year revealed that about two-thirds of patients improved their vision to the maximum degree. The rest also showed improvement, however, it was not considered statistically significant.

The clinical trial was also said to have not met the goals for visual acuity test, which is performed by reading an eye chart.

Additional data will be presented at future medical conferences, including the Retina Society Annual Scientific Meeting, which will be held on Saturday, Oct. 10.

In a statement, Dr. Albert M. Maguire, the principal clinical trial investigator and an ophthalmology professor from the University of Pennsylvania's Perelman School of Medicine said that their team had discovered a significant restoration of vision among patients who were approaching the stage of total blindness. Majority of the participants exhibited maximum possible effects as measured via a visual function test and confirmed by enhancement of retinal sensitivity in both eyes. "If approved, SPK-RPE65 should have a positive, meaningful impact on the lives of patients with this debilitating condition," he added.

Spark Therapeutics plans to submit a Biologics License Application to the U.S. Food and Drug Administration (FDA) by 2016.

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