out infection. 
Severe edema: Edema secondary to necrosis and breakdown of the transduced 
tumor ceils may occur. The magnitude of such edema, if it occurs at all, is unkown. As 
a precaution, all patients will be treated with high-dose steroids and peri-operative 
mannitol as preventive/therapeutic measures. If edema around the tumor is not 
responsive to therapy, it can result in permanent, significant neurological deficits or 
death. 
Surgical Procedures: The surgical procedures (both stereotaxic and open surgery) 
carry a risk for loss of neurological function, non-neurological complications and death. 
The risk depends on the preoperative condition of the patient, size and location of the 
tumor, and associated diseases (e.g. Ischemic heart disease, renal failure, COPD etc.). 
The risk for an individual patient will be determined prior to the decision on the 
appropriate line of therapy and will be discussed with the patient prior to surgery. 
B. The development of replication-competent retrovirus. 
This has been discussed (Section V.D.). 
C. Prolonged survival of the PA317 murine cells in vivo. 
The PA317 cells are murine cells that survive 7-10 days in syngeneic (H- 
2^) mice and 7-14 days in rats bearing brain tumors. Xenogeneic antigens on 
transplanted tissue induce immune rejection in immunocompetent humans. Therefore, 
the immune response of the patient will be expected to eliminate ail of the injected 
producer line cells. The time to rejection is difficult to estimate since the brain is a 
partially immunologically privileged site, patients with brain tumors are 
immunosuppressed due to the presence of the tumor, and the patients will be receiving 
high-doses of exogenous corticosteroid therapy. Lastly, on day 7 we will initiate 
treatment with GCV that will destroy any remaining PA317 cells. 
D. Dissemination of GITKSVNa. 
Our MoMLV amphotropic retroviral vectors are directly inactivated by 
human complement (without antibody). Therefore, escape of free vector into the 
cerebral spinal fluid or the vascular space should result in immediate inactivation. The 
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