UK gene therapy report published

The UK's Gene Therapy Advisory Committee (GTAC) published its ninth annual report last week. It has also released a set of recommendations on gene therapy trials that use retroviruses, the technique used by scientists at the Necker hospital in Paris to treat an inherited immune disorder . Eleven boys with X-linked severe combined immune deficiency (X-SCID) underwent experimental gene therapy treatment at the French hospital, two of whom have since developed leukaemia. 'The success achieved by the French group in treating infants with X-SCID using gene therapy must not be overlooked' said GTAC chairman Norman Nevin. 'However, such trials must proceed with caution' he added.

Children affected by SCID have a faulty gene that means they have no working immune system, so their bodies cannot fight infections. Scientists at the Necker Hospital used a retrovirus to deliver a working gene to the immune cells in the bone marrow. Although the treatment was successful in nine of the boys, in two of the patients, the virus switched on a gene that triggered leukaemia. In the UK, doctors at Great Ormond Street Hospital in London have treated five X-SCID patients using a similar technique, none of whom have shown any leukaemia-type symptoms. A joint working party of GTAC and the Committee on the Safety of Medicines (CSM) met in March 2003 to review the safety of retroviral gene therapy trials. It recommended more research into gene therapy using retroviruses, and more long-term monitoring of patients in existing trials.

After weighing up the benefits and risks of the treatment, GTAC decided that 'it would be unethical to withdraw its approval of the UK X-SCID study'. But Nevin said that recruitment into the trials should only be on a case-by-case basis, and that an expert working group should be set up to review the safety of retroviruses.