Second success for UK gene therapy researchers

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 a life 'largely free of restrictions', say the team, who announced their success to coincide with the official opening of the new Wolfson Centre for Gene Therapy of Childhood Disease.

Mustaf, whose second name was not released, was diagnosed with ADA-SCID shortly after his birth, in September 2000. Children affected by SCID (severe combined immune deficiency) have a faulty gene that means their immune systems do not work properly, so their bodies cannot fight infections effectively. Some patients can be treated with a matched bone marrow transplant, but no suitable donor was available for Mustaf. Instead, he received regular enzyme replacement therapy - regular doses of the enzyme adenosine deaminase (ADA), which is missing in ADA-SCID patients. In December 2003 he became the first ADA-SCID patient at GOSH to be offered gene therapy. Doctors took a sample of his bone marrow, and used a harmless virus to deliver a working gene to his blood stem cells, which they then returned to his body. They also had to give Mustaf a mild dose of chemotherapy before the gene treatment, to kill off his existing bone marrow cells and make 'space' for the treated cells to grow and proliferate.

After spending five weeks in isolation, Mustaf was allowed to go home, although he is still receiving antibiotics and antibodies to bolster his immunity. However, these will shortly be withdrawn if his own immune system continues to develop, say the doctors. 'He has made steady progress and his immune system is already better than it was with enzyme replacement therapy', said team leader Adrian Thrasher. The trial was partly financed by the charity Jeans for Genes, which holds an annual fundraising day to raise money for research into new treatments for genetic conditions. The Department of Health, the Primary Immunodeficiency Association and the Child Health Research Action Trust also supported the trial.

Mustaf is the first ADA-SCID patient to be treated using gene therapy in the UK, although five patients have been successfully treated in Italy. The GOSH team has also used gene therapy to treat seven children and one adult affected by another immune disease, called X-SCID (X-linked severe combined immunodeficiency). The good news follows recent concerns over the safety of some gene therapy treatments, after a third child in a French X-SCID trial developed leukaemia. Critics say that gene therapy has failed to live up to its promise as a revolutionary new medical treatment. But Thrasher says that the time taken for gene therapy to produce successes is 'no different to that of other significant advances'. He also pointed out that 'unrealistic expectation has overshadowed genuine advances, and has focused attention more on clinical failures and unnecessary mistakes'.