(Bloomberg) — A gene therapy maker showed this week it could make blind children and adults see. But the big question left is how long the effect will last.
Much depends on the answer, including how much the company can charge for the drug — a price tag some say could be more than $1 million a patient.
On Saturday, the Philadelphia biotech firm, Spark Therapeutics Inc., reported encouraging data on that front. Spark's gene therapy, which treats certain rare inherited eye disorders that cause blindness, has maintained for three years the improved vision of patients who completed an early-stage trial, the company said.
In a widely anticipated presentation on Saturday at a conference in Paris, Spark also revealed more details of a final-stage trial, showing how it helped improve vision in 31 people. Together, the two data sets may help Spark's treatment become the first gene therapy to market in the U.S.
After years of setbacks, a resurgence of gene therapy — curing diseases by injecting new genes into the body — has come this year from improved technology and promising early trials. Spark, along with biotech companies like UniQure NV, Bluebird Bio Inc. and Applied Genetic Technologies Corp., are all developing treatments for disorders caused by mutations in a patient's genetic code — inherited eye disorders, hemophilia and sickle cell anemia are leading candidates.
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"It's a really cool moment," said Jeff Marrazzo, Spark's chief executive officer, by telephone Friday. Earlier in the week, Spark had announced that the final-stage trial was positive, without providing details. "I think the amount of e-mails I got from other gene therapy CEOs indicates everyone was very happy."
Marrazzo, 37, was part of the group that founded Spark, which was a built on work from a team of researchers at the University of Pennsylvania and the Children's Hospital of Philadelphia. The company went public on Jan. 30, and shares are up more than double their IPO price, valuing the company at $1.21 billion.
Both pieces of data Spark has released this week show that "with lots of expertise, if you pick the correct target, and run a well controlled study, and get all the little details right, you can do this," he said on his way to the airport to attend the Retina Society Annual Scientific Meeting in Paris, where the three-year data was revealed.
Spark's gene therapy "is the hottest thing in medicine right now," said Julia Haller, ophthalmologist-in-chief at the Wills Eye Hospital and president of the Retina Society. Correcting genetic defects that make people sick "has been the holy grail for a long time and now we are a huge step closer." Haller, who was an unpaid consultant for the final-stage trial, spoke in an interview before the new results were presented.
Moonless night walk
Spark's treatment, SPK-RPE65, is injected directly into the eye, using a virus to deliver a correct gene to a patient whose original gene is mutated. For its final-stage trial, Spark measured the amount of light a participant needed to navigate a mobility course, which entails following arrows on the floor and avoiding obstacles. Participants were tested at seven different lighting levels, the lowest corresponding to a moonless summer night and the highest to a brightly lit office.
After a year, patients treated in both eyes improved by 1.9 light levels, compared with an improvement of 0.2 levels in the control subjects who hadn't been treated, according to an analysis of the 29 patients, a mix of children and adults, who completed the trial. Two patients in the cohort dropped out before treatment was administered and were not included in the analysis, said principal investigator Stephen Russell of the University of Iowa, who ran the trial.
Since the final-stage trial only has tracked patients for a year, Spark also presented at the conference the longer-term data on patients who had been treated in an earlier study and were available for follow-up. Out of eight patients who would have qualified for the final-stage trial, all seven who were available for follow-up after three years sustained their improvement, Russell said in a telephone interview.
Convincing curve
The data are "really convincing" and bode well for the long term, said Russell.
The finding of durability may help ease concerns that Spark's therapy wouldn't hold up to the promise reflected in the biotech company's stock ticker — ONCE. In theory, if gene therapy can fix or replace a broken or missing gene, effects could last for the rest of a patient's lifetime.
Two academic studies that didn't use Spark's treatment, published in May in the New England Journal of Medicine, found that the effect of gene therapy for the same category of eye disease appeared to wane with time. Spark's shares tumbled that day as investors worried that the treatments may not hold up, even if they work initially.
