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Good news for gene therapy

14 June 2004
By BioNews
Appeared in BioNews 262

A French gene therapy trial halted after two participants developed leukaemia looks set to restart after a 22-month suspension, reports Nature. Scientists at the Necker hospital in Paris successfully treated nine children with an  inherited immune system disorder called X-linked severe combined immune deficiency (X-SCID). But the trial, along with similar trials in the US, was suspended while researchers investigated the cause of the blood cancer. However, the trial in France, and also one in the US, are now set to restart, researchers revealed at a recent meeting of the American Society of Gene Therapy.

Children affected by SCID have a faulty gene that means they have no working immune system, so their bodies cannot fight infections. This life-threatening condition is sometimes called 'bubble boy' disease, as unless they can be successfully treated with a matched bone marrow transplant, patients must spend their lives in a sterile environment. To carry out the gene therapy treatment, the French researchers harvested bone marrow from the patients, from which they isolated blood stem cells. They then infected these cells with a retrovirus (a virus that inserts its genetic material into the host cell's DNA) carrying a working gene, before returning the modified cells back to the patients.

Eleven boys with X-linked severe combined immune deficiency (X-SCID) underwent experimental gene therapy treatment at the French hospital, but the trial was halted in October 2002, after one of the boys developed leukaemia symptoms. When a second patient developed leukaemia in January 2003, similar trials in several countries were suspended. In both cases, researchers found that the retrovirus had inserted its genetic material close to the 'on-switch' of a cancer-causing gene called LMO2. It is thought that this event caused the unregulated growth of the bone marrow cells, which in turn triggered the leukaemia, although other factors could have been involved. The two boys are reported to have responded well to chemotherapy and bone marrow transplant treatment, and are now in remission.

Scientists at Great Ormond Street Hospital in London have treated seven children with X-SCID, none of whom have developed leukaemia. Alain Fischer, who leads the French team, says he plans to minimise the risk of future side effects by only treating children older than six months, and by limiting the number of corrected cells injected during the treatment. Donald Kohn, leader of one of the US X-SCID trials, welcomed the news that the gene therapy treatment was to resume. 'No therapy is without risk, and now that we've had time to look back, we realise that this therapy, even with the risk, may be better than the current treatment', he said.

Gene therapists hopeful as trials resume with childhood disease
Nature |  10 June 2004
2 February 2009 - by Dr Megan Allyse 
Researchers in Italy and Israel have announced that they have successfully used gene therapy to treat ten children who suffer from a rare form of severe combined immunodeficiency (SCID) called ADA-SCID. The trial marks one of the first successful uses of gene therapy since past trials of...
27 April 2006 - by BioNews 
Replacement genes used to treat an inherited immune disorder could trigger cancer, new research carried out on rodents suggests. The study, published in the journal Nature, shows that treating mice with a normal copy of the gene defective in X-linked severe combined immune deficiency (X-SCID) results in cancer of the...
8 April 2005 - by BioNews 
A gene therapy technique that repairs faulty genes by 'editing' their DNA could lead to new treatments for inherited blood disorders and HIV, say US researchers. The approach could help address safety concerns over current gene therapy methods, many of which rely on specially adapted viruses to deliver working genes...
13 March 2005 - by BioNews 
Doctors at Great Ormond Street Hospital (GOSH) for Children and the Institute of Child Health have successfully treated a second disease using pioneering gene therapy treatment. The four-year old boy who received the therapy was affected by ada-SCID, a life-threatening immune deficiency condition. He is now attending pre-school and living...
7 March 2005 - by BioNews 
The US Food and Drug Administration (FDA) has recommended that gene therapy treatments for an inherited immune disorder are limited to those who have no alternative. The move follows news that a third child in a similar French trial has developed leukaemia. The trial for X-linked severe combined immunodeficiency disorder...
17 October 2003 - by BioNews 
US and European scientists have published results confirming that a gene therapy technique triggered leukaemia in two boys taking part in a trial at the Necker hospital, Paris. Their findings, which appear in Science, show that the virus used to deliver the therapeutic gene activated a cancer-causing gene. Eleven boys...
20 January 2003 - by BioNews 
More US gene therapy trials were suspended last week, after news that a second patient receiving treatment for a rare immune disease at the Necker Hospital in Paris is showing symptoms of leukaemia. The US Food and Drug Administration (FDA) had already halted three trials in October, after hearing that...
7 October 2002 - by BioNews 
Gene therapy trials taking place in France and the US were suspended last week after a boy being treated at the Paris Necker Hospital developed leukaemia-like symptoms following treatment. French public health officials ordered a halt to the trials while they undertook an investigation and the decision was quickly mirrored...
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