Gene therapy in the form of a gel for butterfly babies approved in the USA

A topical gene therapy against a rare skin disease. It is distributed in drops of gel over the lesions, in a not so different way from a cream, once a week, and helps the skin to regenerate, healing the wounds caused by the disease. It is called beremagene geperpavec and has recently been approved in the US by the Food and Drug Administration, earning the title of first topical gene therapy. In Europe the manufacturing company predicts may come next year.

Epidermolysis bullosa, a disease that destroys the skin

The gene therapy in question is indicated for a disease known as dystrophic epidermolysis bullosa, a serious genetic disease that destroys skin, mucous membranes and nails. Those affected suffer from blisters and ulcers, in an invasive, painful way, and in the most serious forms even risk their lives. The DEB (from the English acronym dystrophic epidermolysis bullosa) it is a form of epidermolysis bullosa, a group of rare genetic diseases in which the anatomy of the skin is altered, destroying it.

Only a few years ago, Italian research also made its contribution to combating these diseases. Then the approach – carried out by the team of Michele De Luca and Graziella Pellegrini of the University of Reggio Emilia – had been to use stem cells and gene therapy to have flaps of skin reconstructed in the laboratory to then be transplanted into butterfly babies (as the young patients suffering from epidermolysis bullosa are called).

A gene therapy directly on the skin

This time the approach (for a different subtype of disease) was different and simpler. The idea, validated by clinical trials, was to administer gene therapy directly to diseased skin. Beremagene geperpavec uses a modified herpes-simplex virus (which is not capable of replicating itself) as the carrier of the correct form of the gene which in DEB, due to mutations, does not work (specifically the alpha chain 1 of type 7 collagen, COL7A1). In this way it is possible to re-establish the production of a protein – type VII collagen – which helps fight the fragility of the skin by reinforcing its structure, specifically by helping to anchor the epidermis to the dermis, recall the FDA.

In the clinical trials performed, gene therapy worked. In particular in one of these the researchers pitted gene therapy directly against a placebo on patients: one wound was treated and another was not. Six months later, 67% of the wounds treated with the gene therapy had healed compared with 22% of those given the placebo, and side effects had been mostly mild, with reports of redness, itching, chills, flushing and a runny nose.

Since gene therapy is used topically – and is approved from six months of age – it requires some attention from patients and caregivers. In fact, the FDA recommends not touching the treated wounds and their bandages for 24 hours, and in the case of cleaning them, using gloves for dressings, observing proper hand hygiene and disinfecting the bandages themselves before throwing them away with an alcohol-based virucidal mixture, treating the waste separately.