New gene-therapy gel shows promise for treating rare 'butterfly disease'

A new gel that contains DNA shows promise in helping people with "butterfly disease," a condition in which the skin erupts in blisters when placed under the slightest pressure, even a light touch. 

Researchers tested this gel-based form of gene therapy in a small trial of six adults and three children with the rare inherited disease, known by the scientific name "epidermolysis bullosa," according to a statement from Stanford Medicine. 

Specifically, the trial participants had a subtype of epidermolysis bullosa (EB) called recessive dystrophic epidermolysis bullosa (RDEB), which means their cells lack the genetic instructions to build a protein called collagen VII. Normally, this collagen would bind several layers of skin together, thus preventing these layers from painfully rubbing against each other. In people with RDEB, these skin layers scrape past each other, and this abracsion drives the formation of blisters and chronic wounds that can remain unhealed for months or years, according to Stanford.

There are several experimental treatments for EB, which involve skin grafts and engineered stem cells with working copies of the EB-related genes, for example, Science reported. Compared with these treatments, the new gene therapy is much simpler to apply, and based on the early trial results, it's "arguably the most successful [such therapy] to date," David Schaffer, a bioengineer at the University of California, Berkeley, who was not involved with the study, told Science.

The trial results were published Monday (March 28) in the journal Nature Medicine.

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The gene therapy involves applying a gel-based ointment directly to patients' skin wounds. The gel contains a modified version of the herpes simplex virus 1, the herpesvirus that normally causes cold sores, according to Science. The virus in the gel has been modified such that it can no longer replicate in human cells. Instead, the virus acts as a vessel for two functional copies of COL7A1, the gene that codes for collagen VII.

During the recent trial, the researchers applied this gel to one wound on each participant over a 25-day period. They also applied a placebo gel to a different wound, for comparison. 

The wounds treated with the placebo healed and reopened or blistered again at varying rates throughout the trial, the team reported. In contrast, all but one of the wounds treated with the gene therapy closed within three months after the 25-day treatment period ended. The remaining treated wound closed and remained healed for eight months after a second round of treatment. 

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Biopsies of the trial participants' skin suggested that their skin cells started making collagen VII as soon as nine days after the start of treatment, and for some, that protein production lasted for upward of three months, according to Stanford. That said, eventually, collagen VII degrades and the treated skin turns over, so in general, the gel would need to be periodically reapplied, Science reported.

"It's not a permanent cure, but it's a way to really keep on top of the wounds," trial leader Dr. Peter Marinkovich, director of the Blistering Disease Clinic at Stanford Health Care and an associate professor of dermatology at the Stanford University School of Medicine, told Science. "It significantly improves patients' quality of life."

The results of a larger trial were recently announced by Krystal Biotech Inc., one of the trials' funders, but these results haven't been published in full yet. The company plans to apply for approval from the Food and Drug Administration within the year, according to Stanford. 

Originally published on Live Science.