In a meeting held last month, a US Food and Drug Administration committee
put a clinical hold on three experimental trials that use retrovirus-mediated
gene transfer to treat X-linked severe combined immunodeficiency disease (X-SCID),
which is caused by a defect in the GammaC gene.
The committee convened after a French boy recently became the third
child to develop leukemia after receiving gene therapy for treatment of the
condition. The child was one of a number of children with X-SCID treated by
French researchers, who put a healthy copy of GammaC into
a modified mouse leukemia virus. The virus is capable of inserting the gene
into embryonic blood cells that are then infused into the patient. Two of
the group’s patients, including the child who died recently, had developed
leukemia several years ago, and another patient has apparently developed the
cancer as well.
Hampton T. Gene Therapy Trials on Hold. JAMA. 2005;293(16):1966. doi:10.1001/jama.293.16.1966-d