One of the boys with no immune system being treated with pioneering gene therapy at Great Ormond Street has developed leukaemia, his doctors say. They said cancer was an “acknowledged risk” of this treatment for X-SCID, which is commonly known as “boy in the bubble syndrome”.
A trial in France of a similar therapy was halted in 2002 after four of eleven children developed leukaemia.
Ten children with X-SCID have so far been treated at the London hospital.
| Gene therapy appears to offer a less intrusive treatment, for those patients without a good bone marrow donor, and if we continue to make advances, may become the treatment of choice.
Great Ormond Street
All of these children “have seen clinical benefit”, Professor Adrian Thrasher and Professor Bobby Gaspar, consultant immunologists on the gene therapy programme, said in a statement.
“This unfortunate event is the first such development on our programme.”
X-SCID is caused by mutations in the IL2RG gene, which governs the behaviour of a protein involved in the development of a number of immune system cells.
Without the protein, the cells cannot develop normally, and are unable to protect the body.
The gene therapy works by replacing a defective gene.
Prior to treatment, the outlook for children with X-CID who did not have a suitable bone marrow donor was bleak.
They had to live in sterile conditions or risk picking up a life-threatening infection. They often died very young.
But there had been warnings that there was a risk of cancer.
A US study last year published last year looked at the long-term effect of infecting the IL2RG gene into mice: A third of the animals developed a form of cancer, with most doing so when they were about 10 months old.
A few years previously a French trial was halted prematurely after three of ten boys treated were diagnosed with T-Cell leukaemia.
Nine of them had been cured of their original condition. Three went on to be cured from leukaemia, but one died.
Last year, doctors at Great Ormond Street dismissed the findings of the US study as “unhelpful”.
Great Ormond Street said what they hoped would be safer formulations of the genetic medicine were being prepared for clinical trials next year at several centres.
“Every child matters,” they said in a statement.
“Families are counselled very carefully before taking part in these treatments. Gene therapy appears to offer a less intrusive treatment, for those patients without a good bone marrow donor, and if we continue to make advances, may become the treatment of choice.
“All patients are monitored carefully as part of their care plan.”
Story from BBC NEWS:
Published: 2007/12/18 09:59:26 GMT
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