Recombinant DNA Advisory Committee - 2/10-11/92 
confined to the peritoneal cavity who have undergone surgery and chemotherapy 
treatment. Patients eligible for this study have microscopic tumors or macroscopic tumors 
less than 1 centimeter. Of the patients with macroscopic tumors less than 1 centimeter, 
70% will have had their tumor surgically debulked to a microscopic size. There is no 
treatment for ovarian carcinoma patients with microscopic tumors, because their tumors 
are resistant to chemotherapy and radiation. 
Dr. Freeman described a study conducted by Hunter et al., at the University of 
Massachusetts, involving ovarian cancer patients in relapse. The patients were studied in 
two ways: (1) tumor examination at the time of second laparoscopy; and (2) the effect on 
treatment of whole body radiation, chemotherapy, or neither. These patients were 
diagnosed as having ovarian cancer then treated with surgery and chemotherapy. After 
several months, a laparoscopy was performed. If the patients had either microscopic 
tumor disease or macroscopic tumor disease less than 2 centimeters, these patients were 
classified as non-responders. These are the types of patients who are eligible for our 
study. Another eligible group of patients are those who have macroscopic disease greater 
than 2 centimeters that have not responded to treatment. Ovarian cancer is a fatal disease 
at the point where patients have microscopic or macroscopic disease. If these patients are 
treated with either abdominal radiation, high-dose Cytoxan, or nothing, all patients have 
the same end results. 
Dr. Freeman addressed some of the safety issues presented by the reviewers. Since the 
HSV-TK( + ) ovarian cancer cells will be grown in culture, they can be readily assayed for 
viruses. These cells are sensitive to ganciclovir. The cells will be irradiated prior to 
injection and this procedure will provide an additional measure of safety. Since these cells 
are allogeneic, they should eventually be rejected by the patient's immune system. Other 
general safety tests are also performed on these cell lines. 
Dr. Freeman presented data addressing the issue of whether or not DNA from HSV-TK 
cells is transferred to nearby cells. Mice were injected with TK( + ) cells, treated with 
ganciclovir, and sacrificed at 24, 31, or 42 days post treatment. DNA preparations were 
made from various tissue samples and assayed by PCR to detect the presence of the vector 
in these cells. Agarose gels revealed that there were no detectable levels of the HSV-TK 
gene in the tissue samples. Tissue culture experiments were performed using k-balb cells 
and apoptotic vesicles obtained from TK( + ) tumor cells that had been exposed to 
ganciclovir. K-balb cells were assayed for the presence of the neomycin resistance gene. 
The results to date have been negative; however, these studies are continuing. Dr. 
Freeman then addressed the question of whether apoptotic vesicles could be used alone 
instead of tumor cells. Tumor experiments had been performed, one in vitro and one in 
vivo. At a ratio of 10 TK( + ) tumor cells to 1 TK(-) cell, no effect was observed in tissue 
culture. In vivo, no tumoricidal effect was seen; however, some prolongation of survival 
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Recombinant DNA Research, Volume 15 
