The US Food and Drug Administration has approved Vyjuvek, a gene therapy based on herpes simplex virus type 1 (HSV-1) vector, for the treatment of wounds in patients 6 months of age and older with epidermolytic bullous dystrophy (DEB) with mutation(s) in the gene type VII alpha 1 (COL7A1) collagen chain.
Vyjuvek’s approval was given to Krystal Biotech, Inc. The company submitted for approval in June 2022.
DEB is a genetic disorder that affects the connective tissue of the skin and nails and is caused by mutations in the COL7A1 gene. This gene encodes type VII collagen (COL7), which is an essential protein that helps strengthen and stabilize the outer and middle layers of skin.
When COL7A1 is deficient, the skin layers can separate, causing painful and debilitating blisters and sores. DEB usually presents itself at birth and is divided into two main types depending on the pattern of inheritance: recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB).
DEB symptoms vary
Symptoms can vary greatly among affected people. Individuals with DDEB usually have a mild case with blisters primarily affecting the hands, feet, knees, and elbows. Cases of RDEB can be painful and debilitating, often involving extensive blisters that can cause vision loss, disability, and other serious medical complications, which can be fatal.
About Vyjuvek Krystal Biotech
Vyjuvek is a genetically modified herpes simplex virus that is used to deliver a normal copy of the COL7A1 gene to wounds. COL7 molecules organize themselves into long, thin bundles that form the anchoring fibrils that hold the epidermis (skin) and dermis together, which are important for maintaining skin integrity. Vyjuvek has also been modified to remove its ability to replicate in normal cells.
Vyjuvek is mixed into a gel excipient (non-active ingredient) prior to topical application. A healthcare professional evenly applies Vyjuvek gel in drops to a patient’s wound once a week.
Vyjuvek study details
The safety and effectiveness of Vyjuvek was established primarily in a randomized, double-blind, placebo-controlled study involving a total of 31 subjects with DEB, including 30 subjects with RDEB and one subject with DDEB. In that study, two DEB wounds of comparable size in each patient were identified and randomized to receive weekly administration of topical Vyjuvek or placebo.
Subjects’ ages ranged from 1 year to 44 years (mean age 17 years). Efficacy was established by better wound healing, which was defined as the difference in the proportion of complete (100%) wound closure confirmed between Vyjuvek-treated and placebo-treated wounds at 24 weeks.
Sixty-five percent of Vyjuvek-treated wounds were completely closed while only 26% of placebo-treated wounds were completely closed.
Moreover, in a different clinical study, two young patients with RDEB (6 and 7 months old, respectively) received weekly topical Vyjuvek with no new safety findings.
Biotechnology companies deal with DEBs
Other companies also deal with dystrophic epidermolysis bullosa. In June last year, Amryt Pharma’s topical gel Filsuvez received European Union (EU) approval for the treatment of partial thickness wounds associated with dystrophic EB and joints in patients aged 6 months and over.
In November, Replay announced the launch of Telaria, a herpes simplex virus gene therapy company targeting rare skin diseases.