B-VEC (KB103, bercolagene telserpavec) is a gene therapy being developed by Krystal Biotech to treat dystrophic epidermolysis bullosa (DEB), a rare type of EB. The condition is characterized by blistering of the skin because patients lack type 7 collagen (COL7) due to mutations in the COL7A1 gene.

How does B-VEC work?

COL7 keeps the skin’s upper layer, the epidermis, attached to its lower layer, the dermis. A lack of COL7 causes the epidermis to separate from the dermis, leading to blisters. B-VEC delivers a healthy or functional copy of the human COL7A1 gene directly to the patient’s skin cells using a modified virus as a carrier to allow them to produce normal COL7 protein, therefore preventing skin blistering.

B-Vec in clinical trials

B-VEC is currently under investigation in a Phase 1/2 clinical trial called GEM-1 (NCT03536143).

The Phase 1 portion of the study recruited two adult patients with recessive DEB. In each patient, two wounds were chosen at random and treated with topical B-VEC or a placebo.

In the Phase 2 portion of the trial, four adults (ages 22, 19, 21, and 33) and two children (ages 14 and 15) were recruited. In two of the adult patients and the two children, three wounds were chosen in each at random and were treated with either B-VEC or a placebo in a 2:1 ratio. The other two adult patients were recruited later and had two wounds chosen at random to be treated with B-VEC or a placebo in a 1:1 ratio.

The wounds were analyzed with imaging techniques and biopsies monthly.

Krystal announced updated results from the study in October 2019. One patient dropped out of the study after 30 days due to an inability to travel to the trial site. Ten wounds were treated in total with B-VEC. Of those 10 wounds, seven were categorized as recurring and three as chronic. Recurring wounds were those that were open for less than 12 weeks but opened and closed spontaneously while chronic wounds were those that had been open for more than 12 weeks.

Nine out of the ten wounds treated with B-VEC closed during the first administration period (90 days). The average time to wound closure was 17.4 days and the average time the wounds had stayed closed by the end of the last measured time point was 113 days. The wound that did not close during the initial treatment was reported to be a chronic wound of more than four years. That wound had closed by 42% at the end of 90 days. It was then treated with a second administration of B-VEC and closed in seven days, and remained that way for more than 100 days. Imaging and histology results from the two adult patients who enrolled later showed functional COL7 protein at the wound site.

Krystal is currently recruiting up to 20 patients with DEB for an observational study (NCT04214002) where the natural history of wounds will be monitored for up to four months. The data from this study will be used to design a potential new Phase 3 clinical trial of B-VEC. The study is recruiting patients at Stanford University in California.

Other information

The U.S. Food and Drug Administration granted B-VEC orphan drug status in November 2017 as well as regenerative medicine advanced therapy designation in June 2019.

The European Medicines Agency awarded B-VEC priority medicine designation in April 2019.

All of these designations are designed to expedite the process of getting treatments approved and available to patients.

Krystal Biotech opened a new gene therapy facility, called Astra, in Pittsburgh, PA, to test and produce its treatments at a much larger scale, if approved.


Last updated: Feb. 10, 2020


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