About to hit the news bulletins is another gene therapy death. This is the third. In September 1999 the death of an 18 year-old boy was attributed to gene therapy with an adenoviral vector delivered directly into his liver. He had Ornithine Transcarbamylase Deficiency, an inherited disorder that meant his liver was unable to break down ammonia. Over the following 4 days his condition deteriorated rapidly, and he died a severe immune reaction to the adenovirus.
The second death occurred in a small French trial for X-SCID (the boys-in-a-bubble disease). 12 children in France received gene therapy and four developed acute T cell leukaemia and one died in October 2005. 10 children have been treated in England with a similar protocol have not developed leukemia.
Earlier this week a patient died in an American trial of gene therapy for patients with severe rheumatoid arthritis. The trial involved the administration of an Adeno-associated virus expressing an inhibitor for TNF-alpha. 127 patients have so far been safely treated with this vector. this patient died of acute hepatitis. It is not yet clear what the role the gene therapy played in the death.
Gene therapy remains one of the safest forms of treatment, but as with all experimental therapy there are unforeseen hazards. Thousands of patients worldwide have received various forms of gene therapy, mostly for cancer.
Gene therapy involves introducing a foreign gene into the patient either to replace something that is missing or to invoke an immune response. There are many ways of doing this but commonly a partially inactivated virus is used. Currently many congenital diseases are being treated. Where the missing gene has been identified a virus is used to slip in a replacement copy. Hemophilia, congenital blindness, muscular dystrophy, various immune deficiencies and cystic fibrosis are all disease that show promising early results.
I have sat on the British Gene Therapy Advisory Committee for the past 5 and half years. I am constantly amazed at the quality of the science and equally at the quality of regulation. The people involved in this work are seriously bright and scrupulously honest.