Krystal Biotech treats dystrophic epidermolysis bullosa using its flagship commercial product, VYJUVEK, which is the world's first approved redosable topical gene therapy. DEB is caused by mutations in the COL7A1 gene, resulting in a deficiency of functional type VII collagen that keeps skin layers anchored together. VYJUVEK utilizes a modified, non-replicating herpes simplex virus type 1 vector to deliver functional copies of the human COL7A1 gene directly into the patient's skin cells. When applied topically to wounds, the engineered vector enters the cells and prompts them to produce normal collagen protein, thereby healing existing wounds, restoring structural integrity to the skin, and preventing recurring blister formation over time without triggering adverse systemic immune responses.