Krystal Biotech B-VEC awaiting approval

In a few weeks, the US Food and Drug Administration (FDA) will decide whether to approve this new therapy for butterfly children.

The US company Krystal Biotech has developed a gene therapy (B-VEC) based on a genetically modified herpes simplex 1 virus (HSV-1; the cause of fever blisters). A technology platform called STAR-D was patented, in which a vector that is no longer capable of reproducing and is based on HSV-1 can "infect" a whole series of skin cells. In the process, the genetic material of the virus itself is not incorporated into the genome of the target cells. Only the gene for the collagen is "unloaded". Another advantage: gene therapy is applied "topically", i.e. by applying it directly to the skin. Gene therapies previously intended for other applications are administered "systemically" via infusion. However, this also exposes the gene vectors to the immune system and can cause side effects.

The US Food and Drug Administration (FDA) could make a decision on approval as early as 19 May. This should be based on a phase III clinical trial (efficacy and safety) published in mid-December in the New England Journal of Medicine. In the scientific study (DOI: 10.1056/NEJMoa2206663), Shireen Guide from the University of California and co-authors had treated 31 patients aged more than six months. In each subject, a pair of Epidermidis bullosa wounds were randomly and "blindly" treated once a week with either B-VEC or a placebo preparation. This ran for 26 weeks.

The results were good. After six months, two-thirds (67 percent) of the wounds that were really treated had healed. With placebo, this was the case in only 22 percent of the open skin areas. After only three months, the corresponding success rates were 71 percent (B-VEC) and 20 percent (placebo). The side effects were minor.
According to the scientists, even larger and longer studies should investigate how long the effect of the treatment lasts. So it is quite possible that the FDA will issue a provisional approval with the obligation to conduct further scientific studies in this regard.