Researchers at the Institut Pasteur and the Hôpital Necker (Paris) have reported positive results in using gene therapy to treat two patients with a rare genetic disease. Despite the commercial insignificance of the news and the fact that the study involved a condition that is particularly amenable to this type of treatment, there appears to be broad agreement that the results represent a crucial proof of concept for gene therapy.
The French group conducted autologous gene therapy on two infants with a maternally inherited form of severe combined immunodeficiency (SCID-X1). The disease is caused by a single mutation of a gene that encodes a signaling molecule involved in lymphocyte development, and the disease is believed to affect only a few hundred people worldwide. The researchers used several newly refined techniques to insert a corrected copy of the gene into isolated hematopoietic stem cells. After treatment, close monitoring showed the patients were producing normal populations of lymphocytes, and they were able to leave their germ-free “bubble” environments at the hospital within 3 months; they were still healthy 11 months after the therapy. “The clinical benefits we observe had never been achieved before” for gene therapy treatment of SCID, says Alain Fischer, a researcher at the Hôpital Necker and senior author on the April 28 study (Science 288, 669–672). In contrast to earlier gene therapy experiments on patients with SCID, the two infants did not simultaneously receive conventional treatments such as bone marrow transplants.
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