FDA approves Spark's gene therapy for rare blindness pioneered at CHOP

The first gene therapy to restore sight to individuals who suffer from a rare inherited form of blindness was approved Tuesday by the U.S. Food and Drug Administration.

The treatment, developed by the Philadelphia drugmaker Spark Therapeutics and researchers at Children's Hospital of Philadelphia and the University of Pennsylvania, represents the first U.S. therapy for a disease caused by mutations in a specific gene.

"Today's approval marks another first in the field of gene therapy — both in how the therapy works and in expanding the use of gene therapy beyond the treatment of cancer," said FDA Commissioner Scott Gottlieb. "This milestone reinforces the potential of this breakthrough approach in treating a wide range of challenging diseases."

Spark Therapeutics' stock traded lower after the announcement, likely because of uncertainty about pricing. Spark won't announce a price for the treatment until after the first of the year. Analysts have assumed a $1 million price, or $500,000 per eye.

In an interview, Spark CEO Jeffrey Marrazzo said Tuesday that the company tried to evaluate what restoration of functional vision is worth "in economic terms" in health-care savings, quality-of-life improvements, and allowing people to have jobs. "We believe the treatment is worth more than $1 million."

Spark will provide "an update on price" and the discussions underway with health insurers in early January, Marrazzo said.

The drug's approval culminates "decades of research that has resulted in three gene-therapy approvals this year for patients with serious and rare diseases," the FDA said.

The other gene therapies — Novartis' Kymriah and Kite Pharmaceuticals' Yescarta  — bio-engineer immune-system T cells to attack certain blood cancers. Kymriah's technology also was developed at Penn and CHOP.

"Gene therapy will become a mainstay in treating, and maybe curing, many of our most devastating and intractable illnesses," Gottlieb said. "At the FDA, we're focused on establishing the right policy framework to capitalize on this scientific opening."

Spark's treatment, to be known by the brand name Luxturna, is intended to be a one-time treatment.

"A number of chronic ultra-orphan therapies have annual costs per patient of $400,000," Phil Nadeau, an analyst  at Cowen & Co., said in a client note. "We therefore think that the price of $500,000 per procedure is reasonable for a once-per-lifetime therapy that has the potential to be curative."

In October, an FDA advisory committee unanimously recommended approval of Luxturna. At that hearing, Joan O'Brien, chair of the University of Pennsylvania's department of ophthalmology and director of Scheie Eye Institute, predicted that the therapy would propel research into gene-therapy treatments for other inherited retinal diseases. More than 260 genes are known to cause such diseases.

Patients who received the Luxturna gene therapy during clinical trials told the committee how it transformed their lives. Though it does not completely restore vision, it enables patients to see by producing an enzyme that converts light into electrical signals that are interpreted by the brain.

Christian Guardino, 17, said he lived in darkness the first 12 years of his life, and found it difficult to relate socially to his peers. After receiving the pioneering treatment in Philadelphia, the high school senior from Patchogue, N.Y., said that almost overnight he got his first look at the moon, the stars, and a sunset.

"This gene therapy completely changed my life and gave me sight that I never had," said Guardino, who fulfilled another dream in June, when he sang his way to the semifinals of NBC's  America's Got Talent.

Spark's treatment, which injects a copy of a healthy gene directly into the retina, was developed at CHOP. It is based on decades of research by Katherine A. High, Spark's cofounder and president, along with Penn ophthalmologist Jean Bennett and her husband, Albert Maguire, a Penn ophthalmologist and CHOP physician.

"Today's landmark approval is a great moment for science and for the many individuals and families who live with genetic disease," High said in a statement.

The treatment has potential side effects, including macular thinning, ocular pressure, cataracts, retinal tears, and eye inflammation. Physicians who treated patients in clinical trials said most side effects occurred early and resolved over time.

Spark's therapy is approved for children and adults with defects in a gene called RPE65. Patients go blind within the first year to 10 years of life. About 3,500 people in the United States and Europe live with the disabling effects.

The field of gene therapy has seen big clinical breakthroughs in recent years after many years of disappointment and failures. The Luxturna research began decades ago. Bennett was part of the team that cloned the gene in a laboratory before testing it in animals. Maguire performed many of the procedures at CHOP to deliver the gene therapy to the retina.

Spark shares closed up 0.53 percent, or 26 cents, to $49.20 on Tuesday.

The stock fell last week on new study data for a hemophilia A drug. Two patients received low-dose infusions, aimed at improving a blood-clotting protein that hemophilia patients lack. When the dose potency was doubled for two other patients, the factor or clotting level remained the same as at the lower dose. Investors had assumed Spark's results would show twice the factor or clotting level at the higher dose potency. When that didn't happen, the stock took a hit.