So that when we treat these patients, the surgeon tries to debulk the tumor. Characteristically, they receive radiation therapy in a whole brain format to try to kill as many brain tumor cells as possible. That may slow it down so as to make the tumor quiescent for a matter of months, or perhaps a year. As you know it has terrible prognosis. Almost everyone has a recurrence and dies of the tumor.
Chemotherapy is ineffective.
Gene therapy has not been effective for a variety of reasons, perhaps because again, of the heterogeneous nature of the tumor that certain chemotherapy agents may work on some tumor populations, but others will be resistant and escape. The gene therapy was not effective presumably because of delivery issues in terms of getting the virus with the abnormal enzyme coating into the cell. They were able to affect only a very small percentage of cell so that it was not transmitted into enough cells to get a good effect. Delivery has been an issue although the idea was great, because you would give them a defective gene, thymidine kinase, I believe, and then try to hit it with the drug that we use to treat herpes simplex, but that unfortunately has not pulled through. So that s sort of my thinking.