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Spark Therapeutics gene therapy hits goals in blindness study

Spark Therapeutics' gene therapy for rare, inherited forms of blindness met the goals of a late-stage study, and the company said it plans to file for U.S. regulatory approval next year.

Shares of Spark jumped 70 percent in premarket trading following the report. (Get the latest quote here.)

It could be the first gene therapy product on the market in the U.S., a historic milestone for a technology that aims to cure disease with just one treatment.

The therapy, SPK-RPE65, improved both functional vision and light sensitivity among patients with retinal dystrophies associated with mutations in a gene known as RPE65, the Philadelphia-based company said Monday in a statement. No drug-related safety concerns were seen in the study.

About 3,500 people in the U.S. and five largest European countries have these genetic mutations, which ultimately lead to complete vision loss, Spark Chief Executive Officer Jeff Marrazzo said in a telephone interview. Patients progressively lose the ability to see initially in dim light, then at all. The gene therapy delivers a functional copy of the RPE65 gene through eye surgery to make up for the mutated version that causes vision loss.

"We saw substantial restoration of vision in patients who were progressing toward complete blindness," Albert Maguire, professor of ophthalmology at the University of Pennsylvania's Perelman School of Medicine and principal investigator in the trial, said in the company's statement. "The majority of the subjects given SPK-RPE65 derived the maximum possible benefit that we could measure on the primary visual function test, and this impressive effect was confirmed by a parallel improvement in retinal sensitivity."

More details will be released over the coming months; the results presented Monday were top-line data on the 31 patients in the trial, which was in the third and final phase generally required before regulatory approval. Patients in the study were split into two groups, 21 who received the treatment and 10 who didn't, and followed for a year.

Spark said the therapy hit its primary goal, of improvement in patients' ability to navigate through a mobility course in varying light levels, as well as two of three secondary goals, including light sensitivity.

Improvement in visual acuity, measured by ability to read a standard eye chart, wasn't statistically significant. Further data will be presented at upcoming medical meetings, starting with the Retina Society Annual Scientific Meeting on Oct. 10 in Paris, Spark said.

The field of gene therapy has had a tortured history, suffering a near collapse in 1999 after an 18-year-old trial participant died. The field has been ramping back up in recent years, with multiple companies aiming to cure maladies by supplying a functional gene to make up for one that leads to disease. Drugmakers from Bluebird Bio to BioMarin to Biogen are also now working in the space.

Because of that history, Marrazzo heralded the safety results in Spark's trial as well as those for efficacy.

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"This is gene therapy, and we're talking about a study where our safety results are really frankly boring, which is exactly what you want," Marrazzo said. "You want a whole lot of nothing."

Spark's medicine received breakthrough therapy designation by the FDA, giving it the potential for an accelerated pathway through the approval process.

Marrazzo said the company is already thinking about pricing and payment models, as gene therapy aims to be delivered only once, rather than chronically.

Medicines for rare diseases can typically cost more than $300,000 to $500,000 a year for each patient in the U.S.; how to price a drug for a rare disease that functionally cures it with just one administration is an unanswered question here. There is a gene therapy on the market in Europe, UniQure's Glybera, which was priced at more than $1 million for each treatment.

Spark is likely to navigate those new waters amid a U.S. election cycle that's already put drug prices in the spotlight. But Marrazzo, 37, says the political focus on drug prices doesn't worry him, citing five years he spent working for Pennsylvania Governor Ed Rendell on, among other things, drug pricing and health policy.

"I came from this world," Marrazzo said. "I understand the way these people think. It is an important dialogue to be having. I think we have data now that I feel very, very good about. That's the type of thing that we should be sitting down and having a real discussion about: what that means."

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Marrazzo said the company is already talking with policymakers and insurers about the plan to pay for gene therapies.

"You can expect we will be doing that, and we will be doing in a way that is trying to lead to an ultimate result where these types of treatments are accelerated in their development over and above other things, which frankly patients have to take over and over again for the rest of their lives," Marrazzo said. "American ingenuity can do a lot better."