Experimental Gene Therapy Completes Critical Regulatory Step

May 26th, 2017 by FFB Canada

For a long time, gene therapy—the idea that genes could be used as a medical treatment—was just that: an idea. Last week, that idea took a leap forward towards becoming a reality when the company, Spark Therapeutics, completed a key application to the Food and Drug Administration (FDA). If successful, this application would make Spark’s lead drug candidate, voretigene neparvovec, the first approved gene therapy to treat a blinding eye disease.

Many different gene therapy clinical trials are currently underway. These trials are testing gene therapy as a potential treatment for inherited retinal diseases, such as choroideremia, juvenile retinoschisis, Stargardts Disease, Usher Syndrome and other forms of retinitis pigmentosa (RP). Gene therapy targets the genetic cause of an inherited disease by replacing the defective (or “mutated”) gene with a new one. After the body has this new, functioning copy of the gene, it should be able to start producing the necessary cellular materials, such as proteins, that have the power to stop the progression of the disease. There is hope that gene therapy might even have the power to restore vision by restoring the function to cells that are important for vision.

Spark’s submission was made to the FDA on May 18, 2017. Now, the FDA is reviewing the submission for voretigene neparvovac, a one-time gene therapy for patients living with vision loss caused by a mutation in the RPE65 gene. The FDA has 60 days to review the application to determine if it is complete and if so, the application will be filed and the review period will begin.

FFB Young Leader, Jack McCormick, recently shared his story of living with LCA at an FFB fundraiser: Comic Vision. Jack’s speech, which he delivered on May 18, was particularly meaningful because he had just read the press release from Spark, announcing that a treatment for his eye disease is one giant step closer to becoming a reality.

Spark’s submission included data from three clinical trials that enrolled 41 participants, including the first randomized, controlled Phase 3 trial for a gene therapy. Clinical trials are experiments that test whether a new intervention, such as a gene therapy, will work in people. Clinical trials are done in different “phases” to minimize the amount of risk that patients are exposed to when they participate in studies to determine if a new intervention is safe and effective. By the time a clinical trial reaches “Phase 3” it usually involves a larger study with the capacity to assess both safety and effectiveness in different patient populations. Phase 3 clinical trials usually compare the new intervention (such as the gene therapy) to the currently available treatments or a placebo. A placebo is a fake intervention, like a sugar pill. Patient participants and the doctors running the trial may not know if participants are receiving the new intervention or the alternative (control). This is known as a randomized controlled trial.

Spark’s journey highlights the long road of clinical research that is needed to transform basic scientific discoveries into innovative, effective, and accessible therapies for patients.

At the FFB, we get excited about the different kinds of discoveries that are paving the way for new treatments for blinding eye diseases. This announcement by Spark is not a classic eureka moment in the laboratory, but rather a eureka moment in the regulatory world that is paving the way for the future of gene therapy to treat a variety of different genetic diseases.