An experimental Spark Therapeutics gene therapy intended to treat rare eye diseases that lead to blindness has won the unanimous backing of an advisory panel to the FDA.
Following a daylong hearing that included presentations from Philadelphia-based Spark (NASDAQ: ONCE), FDA staff, ophthalmologists, and patients, the panel of independent eye experts voted 16-0 on the question of whether the treatment’s benefits outweigh its risks. Spark CEO Jeff Marrazzo (pictured above, right) called the vote an “historic moment.”
“This is the first ever gene therapy of its kind to get to this stage of development, to get to an [FDA advisory committee],” he said. “To get a unanimous recommendation of approval is pretty significant.”
If the FDA approves the Spark drug, voretigene neparvovec (Luxturna), it would mark the first therapy approved by the agency that replaces a faulty gene with a working one, offering a long-lasting treatment, and perhaps even a cure. Though the panel’s vote is advisory, FDA staff do consider the discussion and recommendation of these committees. An FDA decision is expected by Jan. 12.
Trading of Spark shares was halted during Thursday’s hearing. But in after hours trading, Spark shares rose 7.2 percent to $92.43 per share.
The drug is meant to treat patients who have inherited retinal diseases caused by mutations to the RPE65 gene. The company says more than 3,500 people in the U.S. and the five major European markets have eye diseases associated with this faulty gene. Injected into the eye, the Spark drug uses copies of viruses that are engineered to deliver a working version of the gene to the retina.
Spark tested its gene therapy in a clinical trial that randomized 31 patients to receive the treatment or nothing at all. To test their vision, the patients, ranging in age from 4 to 44, had to navigate a course under varying levels of light. The course included obstacles that people visually encounter in daily life, such as stair steps. It’s a test that Spark worked with the FDA to develop as a way to gauge the visual improvement of patients in the Phase 3 study. Marrazzo says the test was intended only for the clinical trial. If the drug receives FDA approval, the test would no longer be used for patients.
Patients who participated in the trial told the FDA panel about the impact that losing their vision had on their ability to play with friends, attend school, or hold a job. (Spark reimbursed the expenses of the patients traveling to the FDA hearing in Maryland.) Some noted that even though the treatment did not completely restore their vision, the vision they could gain improved the quality of their lives. Patient Katelyn Corey told the FDA panel that she noticed the improvement quickly.
“Within days of the first surgery, I could see vibrant colors again,” she said. “I was no longer living in a black-and-white film.”
Clinicians offered favorable comments about the efficacy and safety of the Spark therapy. University of California, San Francisco ophthalmology professor Eugene de Juan, whose 30 years of experience treating patients with retinal disease includes performing more than 600 retinal injections, called the Spark results “extremely impressive.” Regarding the safety of the treatment, de Juan said that the injection required of the Spark therapy is well within the skill set of a trained retinal surgeon. Christine Kay, an ophthalmologist who practices in Gainesville, FL, said she would be comfortable recommending Spark’s treatment to her patients. She said the side effects of the Spark therapy are mild, and were related to the surgical procedure. “These patients have no other options,” Kay said. “Without treatment, they will progress to blindness.”
(Spark offered to reimburse de Juan’s travel expenses, but he says he refused. Spark did pay for Kay’s travel, but she said she has no other financial ties to the company.)
Panelists were in broad agreement about the benefit of the Spark therapy. But several said that they hoped the treatment could help patients under four years of age. The company is proposing that the treatment be approved for patients at least three years of age. Marrazzo later explained that Spark is recommending that age because at that point, the size of the child’s eye is close to the size of an adult’s eye. That means surgeons could perform the procedure using standard instruments made for adults. But he added that it would be up to a physician to decide whether to treat a young patient.
The FDA review documents raised questions about whether the therapy that Spark intends to be a one-time treatment might end up needing additional doses. Marrazzo said that Spark has data extending four years showing that patients continue to benefit from their treatment.
“The data suggest that it could be very long-lasting, if not lifelong,” he said.
Photo by Spark Therapeutics.