Spark Therapeutics’ late-stage gene therapy for inherited blindness takes a $73M step forward

child's eyeChildren’s Hospital of Philadelphia spinout with the potential to be the first to win U.S. FDA approval of a gene therapy is now funded through the rest of development of its lead treatment for inherited blindness.

Spark Therapeutics is in the middle of a Phase 3 clinical trial that will determine whether the gene therapy it’s developed can successfully restore some vision to people with rare degenerative eye diseases caused by mutations in the RPE65 gene. There’s currently no treatment available for these diseases.

To allow Spark to continue that study and prepare for commercialization, the company has just closed an oversubscribed $72.8 million Series B financing. Investors including Sofinnova Ventures, Brookside, Deerfield, Rock Springs Capital, T. Rowe Price, Wellington and CHOP participated.

Developed at CHOP’s Center for Cellular and Molecular Therapeutics, the therapy uses a neutralized virus as a vehicle to deliver a function gene to targeted cells in the eye. Once there, it enables production of a critical protein that’s missing as a result of a mutation and causes vision loss.


In earlier studies, the company reported that some children who were nearly blind as the result of a RPE65 mutation were able to recognize faces and walk without aid after receiving the treatment.

“One major difference between Spark’s approach and others under development is that gene therapy has the potential to be a one-time, curative treatment, rather than a treatment patients would need to take for life,” said CEO Jeffrey Marrazzo in an email.

The current Phase 3 open-label, randomized, controlled study includes 16 patients who are receiving the therapy through a subretinal injection and eight patients in the control arm. They’re being monitored for improvements to orientation, mobility, navigational ability and performance on vision tests.

Marrazzo said data is expected in 2015.

In addition to the lead therapy, funding will also support growth in Spark’s other gene therapy programs in hemophilia B and other rare diseases.

Although the concept of gene therapy has been around for decades, it’s only recently advanced to the point where regulatory agencies are acknowledging it as safe and effective enough to approve for sale. A number of companies including Amgen, BlueBird Bio and Advantagene are working toward U.S. approval for gene therapy treatments for cancer or rare diseases.

A number of researchers from the Center for Cellular and Molecular Therapeutics are involved with Philadelphia-based Spark, including two scientific co-founders, Dr. Katherine High and J. Fraser Wright, who serve as advisers.

[Image credit: Flickr user Derekgavey]

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