A time considered a stalemate, gene therapy, which consists of healing by modifying a deficient gene, multiplies the successes and promises that can be made. The Telethon, which is held Friday and Saturday, has strongly supported this path for 25 years.
"Defeat the disease is finally possible" is the mantra of Telethon 2018. Some examples to be convinced.
"In 1987, we were in another world. Very few rare diseases were known, says Serge Braun, scientific director of Telethon. Very few teams were interested in rare diseases, let alone industrialists. Today, half of the genes responsible for rare diseases are known. And we decipher the functioning of pathologies. At the Telethon, we made the bet of gene therapies very early, even when skepticism has taken hold. "
After a first success in 2000, with a treatment for bubble babies (children born with a deficient immune system), gene therapies did not immediately reinforce the hopes placed in them. One of the big difficulties was developing the right "vectors" to carry the gene-drug into cells.
These vectors are usually (harmless) viruses that insert the gene into the patient's DNA and correct a deficient gene.
Healing of blood diseases
The most accessible therapies are related to blood diseases, because it is possible to collect stem cells, treat them and reinject them into the general circulation. That's what happened with baby bubbles. This is now the case for beta-thalassemia (a genetic disorder affecting the production of hemoglobin) for which a drug has been developed. On one of the forms of beta-thalassemia (the Asian form), we speak of total healing.
For the other form, we speak of healing for some cases and improvement (fewer necessary transfusions) for others. An accelerated marketing application was filed in October for Europe.
The second level of difficulty concerns local treatments, on organs of limited size, such as the eye. Here too, a first gene therapy drug, for retinitis pigmentosa, has recently been developed. Only problem, it will be sold about 850 000 dollars (700 000 €) in the United States. The question of the cost of these first gene therapies is a recurring subject.
Advances on myopathies
Third level of difficulty: drugs treating the whole body, which is particularly the case of myopathies (muscle diseases), initial targets of the Telethon which has since opened to research on all rare diseases.
Genethon (the Telethon research organization) and several American universities have been working since 2009 on gene therapy for myotubular myopathy. A very fast muscle degeneration, which kills 50% of children who are affected before 18 months, and reduces the others to the state of rag dolls, unable to sit alone or to breathe without assistance.
A first clinical trial on seven babies has given notable results, many of them can do without respiratory assistance, arriving to catch objects ... Another clinical trial should start in France within a few weeks.
Other clinical trials, on other forms of myopathy, are also underway.
Targeted liver disease
An Italian researcher who arrived at Genethon in 2014 worked on a vector to correct the gene of a very rare liver disease, Crigler-Najjar syndrome.
People with this condition should stay ten to twelve hours a day naked under phototherapy lamps to prevent abnormal accumulation of bilirubin, a substance made by the liver that causes neurological damage if it is too concentrated.
A drug candidate has been used in a single injection to provide long-term cure for the disease in animals. A European clinical trial that will include 17 patients over ten years old (the age of liver maturity) started on Wednesday. In this first phase, it must evaluate the tolerance of the product, define the optimal dose and evaluate the therapeutic efficacy in humans.
Genethon has invested 18 million euros for the development of this possible drug. The Telethon is held on Friday 7 and Saturday 8 December. Donations can be made on telethon.com or by calling 3637.