Gene therapy scare as patient develops leukaemia

by JAMES CHAPMAN, Daily Mail

The safety of pioneering gene therapy experiments was called into question last night as doctors revealed that a young patient has developed leukaemia.

The three-year-old boy is one of 15 children born with defective immune systems given the therapy in a joint exercise between two hospitals in Britain and France.

The treatment appeared to be going well until the child, who would have been otherwise condemned to life in a sterile plastic bubble, developed the cancer.

Initial investigations suggest his illness has been triggered by the treatment, which uses a genetically-modified virus to cure a genetic defect.

Experts suspect that as well as silencing the defective gene that causes Xlinked severe combined immunodeficiency (SCID), the technique switched on a gene implicated in leukaemia.

French doctors treating the boy announced they were suspending their trials while the case is investigated.

But experts at London's Great Ormond Street Hospital, which is also pioneering the treatment, said they would continue to offer it because they were convinced the benefits outweighed the risks.

The advisory committee set up by the Government to oversee gene therapy studies said that it would be 'unjustifiable' to withdraw consent for the British trials.

The case will come as a fresh blow to the field of gene therapy, which aims to cure disease by replacing or 'knocking out' faulty genes.

Major concerns were expressed three years ago when American Jesse Gelsinger, 18, who suffered from a rare metabolic condition, died four days after a gene therapy injection into his liver.

It was later discovered that his immune system had attacked the virus that was ferrying the genes into the organ, which caused multiple organ failure.

By contrast the treatment of children with SCID - known as 'baby in the bubble syndrome' - was a dazzling success and had convinced many that gene therapy had the potential to revolutionise medicine.

Only affecting boys, the disorder means sufferers have no functioning immune system to fight off infection.

So far, Great Ormond Street has successfully treated three children and an adult.

In the first British success story, twoyearold Rhys Evans, from Cardiff, was apparently cured of the condition.

A further 11 patients have been treated at the Necker Children's Hospital in Paris.

The Department of Health's Gene Therapy Advisory Committee held an emergency meeting to consider whether it should suspend trials.

Chairman Norman Nevin said: 'This was an extremely difficult issue to consider

'However, because the treatment options are so limited, we have decided on ethical grounds that approval should continue.'

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