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Gene Therapy: Spark Therapeutics’ New FDA Orphan Drug Designation For Retinitis Pigmentosa

March 22, 2015

There are currently no FDA approved therapies to improve or restore vision in patients with the rare eye disease Retinitis Pigmentosa (RP).

RP is a group of inherited genetic disorders characterized by progressive peripheral vision loss and night vision difficulties followed by eventual central vision loss and blindness in many cases. RP is typically diagnosed in adolescents and young adults. The rate of progression and degree of visual loss varies from person to person. Approximately 100,000 people living in the US and between 0.03% and 0.04% of the global population suffer from RP.

I – Spark Therapeutics’ Gene Therapy For RP

In October 2013, Children’s Hospital of Philadelphia (CHOP) invests $50 million in Spark Therapeutics (ST), a new biotech start-up that develops gene therapies for orphan diseases. ST’s initial product programs use Adeno-Associated Virus (AAV) vector technology, which is designed to “encapsulate a genetic sequence that has been demonstrated to be an effective vehicle for delivering genetic material into targeted cells.” ST assumes control of two gene therapy clinical trials that started at CHOP:

•   Phase III study for Inherited Retinal Dystrophies (IRDs) caused by autosomal recessive mutations in the RPE65 gene – most advanced product candidate, SPK-RPE65

•   Phase I/II study for Hemophilia B – product candidate SPK-FIX.

In September 2013, ST receives FDA Orphan Drug Designation (ODD) for SPK-CHM, a gene therapy for Choroideremia. Choroideremia is a rare, genetic disorder causing progressive vision loss, ultimately leading to complete blindness. It is characterized by deletions or mutations in the CHM gene.

In September 2014, FierceBiotech, names ST as one of 2014’s “Fierce 15 biotechnology companies”.

In November 2014, ST announces that the company’s lead gene therapy product candidate, SPK-RPE65, receives the coveted FDA Breakthrough Therapy Designation (BTD). The BTD is for Nyctalopia or night blindness in people with Leber’s congenital amaurosis because of RPE65 gene mutations. The gene therapy receives FDA ODD in June 2008 for this indication.

Pfizer and ST announce in December 2014, a collaboration agreement to :

•   Develop SPK-FIX, a program that uses a bio-engineered AAV vector (gene therapy) for the potential treatment of Hemophilia B

•   Initiate Phase I/II clinical trials in 1st half of 2015 for the SPK-FIX program.

In February 2015, ST announces the closing of its very successful Initial Public Offering (IPO). On March 18th, ST receives FDA ODD for the indication RP.

FDA ODD Database Record For Spark Therapeutics’ RP Indication

Generic Name: Adeno-associated viral vector type 2 expressing human recombinant retinal pigment epithelial 65KDa protein gene
Trade Name: n/a
Date Designated: 03-18-2015
Orphan Designation: Retinitis Pigmentosa due to autosomal recessive RPE65 gene mutations
Orphan Designation Status: Designated
FDA Orphan Approval Status: Not FDA Approved for Orphan Indication
Sponsor: Spark Therapeutics, Inc. 3737 Market Street Suite 1300 Philadelphia, PA 19104


II – RetroSense Therapeutics’ Gene Therapy For RP

Another company that receives the FDA ODD for gene therapy for RP is RetroSense Therapeutics. In October 2014, the FDA grants the Ann Arbor, Michigan-based biotechnology company, ODD for its gene therapy for RP. RetroSense Therapeutics is developing gene therapy to restore functional vision in patients suffering from blindness due to RP and advanced dry-AMD.

RetroSense Therapeutics’ lead gene therapy product candidate, RST-001, is being developed initially for RP. RST-001 is a gene therapy that delivers a photosensitivity gene (channelrhodopsin-2) to retinal cells, to restore the ability of eyes to sense light. RST-001 is an injection into the eye, where channelrhodopsin-2 is encapsulated in a virus vector that delivers the gene. Once the gene is delivered to the retinal cell, it begins to produce light-sensitive protein.

FDA ODD Database Record For RetroSense Therapeutics’ RP Indication

Generic Name: Non-replicating recombinant adeno-associated virus vector containing a fragment of the gene encoding channelrhodopsin-2 protein
Trade Name: n/a
Date Designated: 10-20-2014
Orphan Designation: Retinitis Pigmentosa
Orphan Designation Status: Designated
FDA Orphan Approval Status: Not FDA Approved for Orphan Indication
Sponsor: RetroSense Therapeutics, LLC 330 East Liberty Street, LL Ann Arbor, MI 48104


Please Note: “Eye Iris XX” by che (“Petr Novák, Wikipedia”) [CC-BY-SA-3.0] | Wikimedia Commons.

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