Philadelphia drugmaker Spark Therapeutics announced new data Wednesday from a Phase 3 trial of its experimental gene therapy for patients with rare inherited blindness.
The Philadelphia biotech, spun out of Children's Hospital of Philadelphia, said eight of nine patients showed the "maximum improvement measurable" on the primary end-point at one year.
An additional 20 patients followed for two years have sustained the improvements in both bilateral mobility and full-field light sensitivity, the company said.
The treatment, voretigene neparvovec, formerly SPK-RPE65, injects genes directly into the retina of the eye.
"We now have substantially more data," said president and chief scientific officer Katherine A. High, "and have seen 27 of 29, or 93 percent, of subjects respond, importantly demonstrating gains in functional vision."
The company said it was on track to complete a regulatory filing with the Food and Drug Administration to commercialize the gene therapy in early 2017.
If approved by the FDA, Spark's lead drug candidate would be the first U.S. gene treatment that uses genes as medicine.
The new-drug filing would be "the potentially first-ever biologics license application submission of a gene therapy for a genetic disease," said Jeffrey D. Marrazzo, Spark cofounder and CEO.
Spark, spun out of decades of research by High at Children's Hospital, on Wednesday reported a loss of $28.7 million, or $1.04 a share, in the second quarter. CHOP is the largest shareholder in the publicly traded company.
Spark posted revenue of $1.3 million in the three months ended June 30 related to a collaboration with Pfizer. It ended the quarter with a balance sheet of $379.1 million in cash, cash equivalents, and marketable securities.
Spark shares fell 1.28 percent, or 76 cents, to close at $58.49.