Thursday, February 16, 2006

Gene Therapy

I spent yesterday in the Gene Therapy Advisory Committee. This is a fascinating committee. All gene therapy protocols have to come before us to be approved. The level of debate is terrific. The committee comprises molecular biologists, cancer specialists, geneticists, virologists, experts on medicinal product regukations, pathologists, immunologists, cardiologists, ethicists, patient representatives and a bishop (who has an immunology PhD). The committee might well to extend its brief to take in stem cell research and xenotransplantation (transplants from animals - and if you think that is disgusting, remember that many people are walking around with pig heart valves). Perhaps the government believes in putting all its dangerous eggs in the same basket.

Yesterday, we had a discussion on "What is gene therapy?"

Many of the studies that we scrutinize are vaccine studies. A foreign gene is introduced into the body with the purpose of getting the body to make the protein coded for by that gene, in such a way that it will be rejected by the body with a strong immune response. Should such vaccines be called gene therapy? We decide that they should. Usually the gene is placed inside a virus. The virus infects a human cell and induces this cell to manufacture the foreign protein, which is then presented to the immune system. Any therapy that induces one of your cells to make a protein encoded by a foreign gene has to be gene therapy.

There are new vaccines on the way where the foreign gene is inside a bacterium such as salmonella. The salmonella has to get inside a human cell to survive. Should this also be called gene therapy? No, because this vacine used the bacterium's machinary to make the foreign protein not the human cells. A fine difference, but you have to draw the line somewhere.

Gene therapy was all about trying to treat single gene disorders. However, two thirds of the protocols we deal with are about treating cancer. Now we have to consider a protocol designed to treat a single gene disorder. The ethical problem here is whether the risks of gene therapy outweigh the benefits in a condition where there is already a satisfactory treatment. The missing proetein can be administered intravenously twice weekly to prevent the consequences of the disease. On the other hand we have seen a young boy die in America when the therapist didn't stick to the rules, and three chillden in France have developed leukemia in a different kind of genetic experiment. Should patients be put at these risks for the convenience of not having to give themselves injections twice a week? It is impossible to calculate how big the risks are. The medical community is divided and vehemently so. Perhaps the bishop will guide us.


Vance Esler said...

I for one am anxious for targeted therapies to become the norm. Chemotherapy, when you think of it, is so unsophisticated. It is like carpet-bombing a city, hoping the good guys survive and the bad guys do not.

Terry Hamblin said...

I once gave a lecture when I usedthe carpet bombing analogy. Campath is directed against CD52 and like the B52 it causes a lot of collateral damage.

Vance Esler said...

Off-topic, but due to lack of an email address: I discovered that I work with a fellow you may remember, Seah Lim. You were his PhD examiner.

Terry Hamblin said...


I remember him well. I was the external examiner while he was at Cardiff. My email is