Genic therapy

Hope for the baby-bubbles

(Le Express.fr, 23/10/03)

One year ago, the experimental treatment of genic therapy was suspended after two children had contracted a disease of blood. The team of the Necker hospital believes to have found the key of the problem. The tests should begin again

At 7 months, Armand failed to die one of the most banal infantile diseases, chicken pox. Because of long weeks ran out before the doctors include/understand finally why it did not cure any. The boy was in fact carrying a genetic anomaly which made it unable to be defended against the infections. Placed in a sterile bubble, Armand profited at once from a still experimental treatment consisting in replacing defective gene by another, healthy. Then waiting of the first visible effects started. Three long months of a combat with unequal weapons between the vulnerable organization of the baby and an enough frightening virus to attack an eye, then with its brain.

"the genic therapy is not the panacea"

The day of the victory remained engraved in the spirit of his/her father. "My wife was deeply discouraged following a new push of chicken pox, remembers it, when it was opinion that the buttons started to disappear." For Armand, the cure signs the good of exit of its plastic prison. Its severe combined immunizing deficit (DICS) related to X chromosome was indeed corrected.

Armand, now cured, is one of the 14 children reached of a genetic anomaly to have profited from this treatment.

Armand is the sixth baby-bubble treated by genic therapy, in France. First world, which related to 10 patients in four years, at the Necker hospital, Paris. The test is however suspended since October 2002. Because the two neat boys right before Armand developed a disease of blood close to leukaemia. Looked after by chemotherapy, they are today in remission. The team of Necker (1) has just delivered the analysis of their cases in the Science review of October 17. "Some of our assumptions must still be validated on mice of laboratory, explains Pr Alain Fischer, but we have good hope to be able to take again the genic therapy within a time of the one year order." One v $# x0153;u divided by the parents of Armand. The idea that baby-bubbles are currently private treatment "which saved [ their ] wire" decided to leave anonymity. "the genic therapy is not the panacea, recognizes the father. But the bone-marrow graft that Armand would have received in the place could have failed." Truth. By this already old technique, the chances of survival at five years are 3 out of 4 in the absence of compatible donor.


To date, the 14 children treated by genic therapy in the world (9 in France, 1 in Australia and 4 in the United Kingdom) are alive and in good health. Only one did not react to the treatment, but profited from a Clerc's Office. Are the researchers today able to explain why two of them fell sick? Yes. Can they how avoid it thereafter? Perhaps... In the two problematic cases, the lymphocytes T, these white globules which were missing with the birth to them, suddenly multiplied in an abnormal way. The problem would go back in fact to the initial stages of the technique of genic therapy. Cells of osseous marrow are taken at the patient. The objective is to correct their genome so that they are able, once reinjected in the organization, to generate white globules normally. These cells are thus infected by retroviruses carrying new gene. But each virus fits where good seems to him in the genome of its victim. It behaves like a car without pilot, and the researchers cannot radio-control it yet. However, among the possible sites, some dangerous, because are located too much close to genes likely, if they are hustled, to start process of a cancerous type.

Too young treaties

In the cells which proliferated in the blood of the two patients, the new gene precisely was located near another, implied in leukaemias, the LMO2. The small patients had thus received corrected cells at the risk. But the researchers think that the other boys received some too. Which factor specific to first caused the disordered state? The most convincing track is that of their age. These children, whose family antecedents were known, were diagnosed and treated very young people, respectively with 1 and 3 months. Pr Fischer plans, if this data proved to be a deciding factor, to reserve the genic therapy with the children of more than 4 months. "A forces to pass from hospital in hospital without the good diagnosis being posed, Armand had already 7 months when it arrived at Necker", notices his mother. An evil for a good?


(1) Pr Alain Fischer, Dr. Marina Cavazzana-Calvo, Dr. Salima Hacein-Bey-Abina. Their work was financed by French Association against the myopathies, thanks to the gifts of T�l�thon.