> Epidermolysis bullosa: a first patient successfully treated by gene therapy
Epidermolysis bullosa is a group of rare and hereditary pathologies where blisters form at the surface of the skin and mucous membranes, either spontaneously or following minimal injury. A team of Italian researchers led by Michele De Luca (University of Modena and The Veneto Eye Bank Foundation) and financed by the French and Italian Téléthons within a joint call for tender has – for the first time – succeeded in treating by gene therapy a patient affected with junctional epidermolysis bullosa, a serious genetic skin disease. In this disease, deficiency of the laminin 5 gene is expressed by an absence of adherence between the epidermis and dermis. By the transplant of laminin 5-expressing skin stem cells treated by gene therapy, the researchers were able to reconstitute an epidermis which adhered to the dermis on two chronic blisters situated on the thighs. This was observed from the 8^th day and during the twelve months of follow-up. This pilot trial in a first patient should soon lead to the setting up of a clinical trial for the same disease in France.

> Adenosine Deaminase Deficiency: 8 children treated by gene therapy  
Since 2000 the gene therapy trial in severe combined immune deficiency by adenosine deaminase deficiency (ADA-SCID) led by the team of Maria Grazia Roncarlo of TIGET in Milan has resulted in 8 children being treated. In practice the trial consisted of placing the ADA gene – the absence of whose enzyme is at the origin of the disease – in the stem cells of the bone marrow. Once corrected, the cells are re-injected into the patient who at the same time receives low-dose chemotherapy to make a little room for these cells. “Of the eight children treated, we have noted that most have benefited clinically, and so far one has been cured of the disease,” says Alessandro Aiuti, a physician in the Italian team.

> From the large animal to humans: gene therapy to restore vision
Leber congenital amaurosis is a particular form of pigmentary retinitis causing early-onset near-blindness in children.
Last October the team in Nantes led by Fabienne Rolling used an innovative gene therapy technique to restore vision to dog models of the disease. Using an AAV (adeno-associated virus) type 4 vector equipped with a human RPE65 gene promoter, the team from Nantes were able to direct transgene expression solely to the retinal epithelium – centre of the dysfunction – while avoiding the photoreceptors. Moreover, by using a specific promoter of the RPE65 gene rather than a viral promoter the researchers were able to avoid risks of possible complications – two elements which ensured the biosafety of the therapy and raised the possibility of a clinical trial in humans.
This work represents a vital step in the development of gene therapy for this currently untreatable genetic disease. The team in Nantes is now working towards the setting up of a trial in humans. Fabienne Rolling believes that the first patients will be treated in two or three years’ time. Patient identification will begin during the first quarter of 2007 and continue until mid-2008. Clinical batch production is planned for 2008 and the first patient injections should take place during the first quarter of 2009.

> Duchenne myopathy: exon-skipping trial
The Dutch biotechnology company Prosensa has just launched a clinical trial of exon skipping in Duchenne myopathy. The aim of this AFM-supported study is to verify the tolerance and safety of this approach.
The study consists of using antisense RNAs developed by Judith van Deutekom’s team from the Leiden University Medical Center (The Netherlands). Broadly, antisense RNAs are the small pieces of DNA that intervene during the process of transcription from gene to protein. They bind to a specific place in pre-messenger RNA during its maturation into messenger RNA. The cell machinery translates only a part of the gene and gives a shorter protein. The researchers used antisense RNAs to induce the cell machinery to skip the mutated part of the gene and thus re-establish the production of truncated, but functional, dystrophin. These antisense RNAs target a particular piece of the gene, exon 51. In fact, the main characteristic of the children receiving this treatment is to present an genetic anomaly likely to be obstructed by the skipping of this exon. To date, 4 patients have received the treatment and biopsies of two of them have been carried out. First results show both very good tolerance and the expression of “quasi-dystrophin.”
Still at the pre-clinical phase, Luis Garcia’s team at Généthon is developing another approach to re-establish functional dystrophin expression, also using exon skipping with antisense RNAs. But unlike in the work being done by Prosensa, these RNAs are produced directly in the cells through the transfer of U7, a small gene modified to encode these RNAs. The advantage of this approach is that – once in place – the modified U7 gene produces antisense RNAs as and when the cell needs them. The difficulty is that the gene is delivered by a viral vector likely to set off immune reactions that it must be able to control.

> Gamma-Sarcoglycanopathy: start-up of a gene therapy trial
Généthon, the French biotherapy laboratory financed by Téléthon donations will begin the first gene therapy trial in humans for a neuromuscular disease, gamma-sarcoglycanopathy. It has just obtained authorisation from Afssaps (the French Health Products Safety Agency) as well as approval of the CPP (Committee for the Protection of Persons). This phase I trial will take place at the Pitié-Salpêtrière Hospîtal (Paris) under the responsibility of Professor Serge Herson, principal investigator, and in collaboration with the Institute of Myology. The aim will be to test the injection of an AAV vector (liberated by the Gene and Cell Therapy Establishment at Généthon) carrier of the gamma-sarcoglycan gene in order to verify its harmlessness and good tolerance in volunteer patients. At this stage of development, no therapeutic benefit is foreseen. Nine patients will be recruited, and the first will be treated before the end of the year. Généthon is the promoter of this trial.

> Transplant of stem cells derived from blood vessels improves muscle function in dog models of Duchenne myopathy
A group of Italian and French researchers from the Institut San Raffaele in Milan in collaboration with the University of Pavia and the Veterinary School of Alfort have just demonstrated the effectiveness of cell therapy in dog models of Duchenne muscular dystrophy. The researchers showed that stem cells associated with blood vessels, known as mesoangioblasts, coming from a healthy donor dog and injected into the blood circulation allow dystrophin expression, restoration of morphology and improvement of muscle function. This pre-clinical study was carried out by the team of Stéphane Blot at the Veterinary School of Alfort.
Muscles –like all organs – are criss-crossed by blood vessels. Previous studies have shown that mesoangioblasts were capable of crossing blood vessel walls and moving through tissue to colonise different parts of the body. Thus the researchers isolated the mesoangioblasts taken from the muscles of healthy puppies. These cells were then injected directly into the general circulation of the diseased dogs in the hope that they would be converted into muscle fibres. The results were positive in 4 out of the 6 dogs thus treated and dystrophin-expressing muscle fibres were observed. A significant improvement in motility was also noticed in two of the dogs.
This result is the fruit of a long-term effort by the Italian team led by Prof Guilo Cossu who notes that “…this cell therapy protocol has been largely successful and reinforces the idea of a clinical trial in humans.”