D-Fi Gene Therapy (formerly designated FCX-007) for Dystrophic EB (DEB)

D-Fi Gene Therapy (formerly designated FCX-007) for Dystrophic EB (DEB)


At a Glance

  • A progressive, devastatingly painful and debilitating, genetic blistering disease that is diagnosed at infancy and often leads to death
  • Prevalence of recessive dystrophic EB (RDEB)—a severe form of DEB1—estimated as 3,200 patients in the U.S.2
  • Current treatments – including bandaging and antibiotics – only address symptoms
  • First gene therapy to offer the potential to address the underlying cause of DEB by providing functional type VII collagen (COL7) locally to affected areas

About DEB and RDEB

Dystrophic epidermolysis bullosa (DEB) is one of the four major types of epidermolysis bullosa (EB), a genetic connective tissue disorder that causes the skin to be extremely fragile. Blisters and wounds form in response to any kind of friction or trauma, like rubbing or scratching. In mild cases, blistering may be limited to the hands, feet, knees and elbows, while more severe cases have widespread blistering and areas of missing skin often present at birth.

Recessive dystrophic epidermolysis bullosa (RDEB)—a severe form of DEB—is a progressive, devastatingly painful and debilitating disorder. RDEB is an autosomal recessive disorder, meaning that a child has inherited copies of the defective gene from both parents3. RDEB patients do not produce functional type VII collagen (COL7) due to a mutation in the COL7A1 gene. COL7—a protein—is the main component of anchoring fibrils that hold together the layers of skin. Without these fibrils, skin layers separate causing severe blistering, open wounds and scarring in response to any kind of friction or trauma. Children who inherit the condition are often called “butterfly children” because their skin is as fragile as a butterfly’s wings.

Castle Creek Biosciences RDEB Diagram

There are approximately 3,200 patients in the United States suffering from RDEB. Presently, there is no cure for this orphan disease. RDEB patients have the highest rate of morbidity and mortality of all genetic blistering disorders. It affects both genders and every racial and ethnic background equally.

Current treatments for RDEB—including daily bandaging, antibiotics, feeding tubes, and hand and esophageal surgeries—address only the symptoms.

About D-Fi

Castle Creek Biosciences’ D-Fi (formerly designated FCX-007), is being developed to address the deficiency of functional type VII collagen protein (COL7) in patients with dystrophic epidermolysis bullosa (DEB). D-Fi is comprised of autologously-derived dermal fibroblasts genetically modified with a lentiviral vector containing the COL7A1 gene, to express COL7. D-Fi is locally administered by injection directly into the papillary dermis of wounds of DEB where the COL7 protein can support the formation of anchoring fibrils in the skin, thereby avoiding systemic treatment.

The U. S. Food and Drug Administration has granted Orphan Drug designation to D-Fi for the treatment of Dystrophic Epidermolysis Bullosa, which includes RDEB. In addition, D-Fi has been granted Rare Pediatric Disease designation, Fast Track designation and Regenerative Medicine Advanced Therapy (RMAT) designation by the FDA for treatment of RDEB.

How Does D-Fi Gene Therapy Work?

Dermal fibroblasts are collected from the patient, cultured and genetically modified to provide functional COL7 and then injected locally into the affected areas. 

Learn more

Explore Advocacy & Educational Resources

  1. The Dystrophic Epidermolysis Bullosa Research Association of America. EB in Depth. https://www.debra.org/about-eb/eb-depth. Accessed July 2020
  2. Based on claims data analysis.
  3. Stanford Medicine, Epidermolysis Bullosa Clinic Frequently Asked Questions