PHG Foundation | www.phgfoundation.org
Doctors at the Necker-Enfants Malades clinic in Paris have revealed that one of the eight children with X-linked severe combined immunodeficiency (X-SCID) whom they treated by gene therapy (see article in April 2002 newsletter) has developed leukaemia (see report in BBC news on-line). The remaining children who responded to the gene therapy treatment are still well, but their health is being closely monitored. A British child who received the pioneering treatment earlier this year is also so far still well. The UK Gene Therapy Advisory Committee (GTAC) has decided not to halt ongoing gene therapy trials for X-SCID at Great Ormond Street Hospital, though extra safeguards are being put in place. Trials have been halted in the US and France. It may be that the same features that made this form of gene therapy so successful - the use of a viral vector and the fact that blood stem cells were the target cells – also increase the risk that some of the altered cells may become cancerous. Nevertheless, in view of the seriousness of the disease and the fact that the only other treatment, bone marrow transplantation, is only possible for a minority of sufferers, the GTAC decision to continue UK trials seems justified. The families of children entering any trials will be fully counselled about the potential risks. The French child who has developed leukaemia is said to be responding well to chemotherapy.