Spark Therapeutics Completes Rolling Biologics License Application Submission to FDA for Investigational Gene Therapy Voretigene Neparvovec

PHILADELPHIA, May 18, 2017 -- Spark Therapeutics (NASDAQ:ONCE), a fully integrated gene therapy company dedicated to challenging the inevitability of genetic disease, today announced the completion of the rolling submission of a Biologics License Application (BLA) with the U.S. Food and Drug Administration (FDA) for voretigene neparvovec, an investigational, one-time gene therapy for the treatment of patients with vision loss due to confirmed biallelic RPE65 mutation-associated retinal disease. The BLA submission includes data from three clinical trials that enrolled 41 participants with RPE65-mediated IRD, including the first randomized, controlled Phase 3 trial for a gene therapy for a genetic disease.

FDA will have 60 days to review the submission to determine if it is complete. If deemed complete, the application will be considered filed and the review period will begin.

“Completion of the rolling BLA is another step forward in our goal to bring this investigational gene therapy to people living with RPE65-mediated IRD who currently have no approved pharmacologic treatment options,” said Jeffrey D. Marrazzo, chief executive officer. “We look forward to working closely with FDA, with the hope of bringing voretigene neparvovec, the first potential gene therapy for a genetic disease in the U.S., to patients as quickly as possible.”

About Spark Therapeutics
Spark Therapeutics, a fully integrated company, strives to challenge the inevitability of genetic disease by discovering, developing, and delivering gene therapies that address inherited retinal diseases (IRDs), neurodegenerative diseases, as well as diseases that can be addressed by targeting the liver. Our validated platform successfully has delivered proof-of-concept data with investigational gene therapies in the retina and liver. Our most advanced investigational candidate, voretigene neparvovec, in development for the treatment of biallelic RPE65-mediated IRD, has received orphan designations in the U.S. and European Union, and breakthrough therapy designation in the U.S. The pipeline also includes SPK-7001 in a Phase 1/2 trial for choroideremia, and two hemophilia development programs: SPK-9001 (which also has received both breakthrough therapy and orphan product designations by the FDA, and access to the PRIority MEdicines (PRIME) Program by the EMA) in a Phase 1/2 trial for hemophilia B being developed in collaboration with Pfizer, and SPK-8011, in a Phase 1/2 trial for hemophilia A to which Spark Therapeutics retains global commercialization rights. To learn more about us and our growing pipeline, visit www.sparktx.com.

Cautionary note on forward-looking statements
This release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding the company's product candidates, including voretigene neparvovec, SPK-7001, SPK-9001 and SPK-8011. Any forward-looking statements are based on management's current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, the risk that: (i) our BLA submitted to the FDA may not be accepted, or, if accepted, may not be approved; (ii) the data from our Phase 3 clinical trial of voretigene neparvovec may not support labeling for all biallelic RPE65 mutations other than Leber congenital amaurosis (LCA); and (iii) the improvements in functional vision demonstrated by voretigene neparvovec in our clinical trials may not be sustained over extended periods of time. For a discussion of other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the "Risk Factors" section, as well as discussions of potential risks, uncertainties and other important factors, in our Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q and other filings we make with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and Spark undertakes no duty to update this information unless required by law.`

Investor Contact:		
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