FDA Approves Topical Gene Therapy for Treating Wounds Associated with Rare Genetic Skin Disorder

FDA announced on May 19, 2023 that it granted approval to Krystal Biotech, a US-based biotechnology company focused on genetic medicines for rare diseases, for the company’s product, Vyjuvek (beremagene geperpavec-svdt), a herpes-simplex virus type 1 (HSV-1) vector-based gene therapy. The indication is for treating wounds in patients six months of age and older who have dystrophic epidermolysis bullosa (DEB) with mutation(s) in the collagen type VII alpha 1 chain (COL7A1) gene. According to an agency press release, Vyjuvek is the first topical gene therapy approved for this indication.

DEB is a genetic disorder affecting the connective tissue in the skin and nails. It is caused by mutation(s) in the COL7A1 gene, which encodes type VII collagen (COL7), an essential protein that helps strengthen and stabilize the outer and middle layers of the skin, according to the agency’s press release. A COL7A1 deficiency leads to separation of skin layers, which causes painful and debilitating blisters and wounds. The disorder usually shows at birth and is divided into two major types depending on the inheritance pattern: recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB).

Symptoms can vary. Individuals with DDEB typically experience mild cases; blistering primarily affects the hands, feet, knees, and elbows. In comparison, RDEB cases can be painful and debilitating, and often involves widespread blistering that can lead to vision loss, disfigurement, and other serious medical complications that can be fatal, according to the FDA press release.

Vyjuvek is a genetically modified herpes-simplex virus that is used to deliver normal copies of the COL7A1 gene to the wounds, which then helps to hold the layers of skin together, maintaining the integrity of the skin. The FDA release reports that Vyjuvek has also been modified such that it cannot replicate in normal cells. According to clinical study results, 65% of Vyjuvek-treated wounds completely closed compared to only 26% complete-wound-closure in placebo-treated subjects.

“Vyjuvek is the first FDA-approved gene therapy treatment for DEB, a rare and serious genetic skin disorder,” said Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in the release. “Today’s action demonstrates [FDA]’s ongoing commitment to supporting the development and evaluation of new treatments that address unmet needs for rare diseases or conditions.”

Source: FDA