Human ovarian cancer xenograft model

The peritoneal ovarian tumor model was developed in female nude nu/nu mice of 4–6 weeks of age (about 20 g in body weight). Mice were obtained from the National Cancer Institute-Frederick Cancer Center Animal Facilities, MD, USA, and were maintained in a barrier facility on HEPA-filtered racks in pathogen-free conditions with 12-h light/12-h dark cycles. All animal studies were conducted under an approved protocol (#2000-06) in accordance with the principles and procedures outlined in the program description of Animal Care and Use Program of the Center for Biologics Evaluation and Research, US FDA, MD, USA.

For tumor cell injection, for ovarian cancer model, ovarian cancer cells, A2780-Gluc cells (2 × 10⁶/200 μl/mouse) were injected directly into peritoneum. On day 4 post-tumor cell transplantation, mice were randomly divided into different therapeutic groups and a control group (5–6 mice in first and second experiment and 12 mice per group in the third experiment). These mice had similar weight in various groups. Mice were injected with excipient PBS or IL-4-PE (50 μg/kg resuspended in 0.2% human serum albumin) or mixture of PEGylated IFN-α2b and IFN-γ both in PBS at a conc. of 200 ng/ml each, on alternated days for a total of three injections. One group of mice was injected with the combination of all three agents simultaneously at the same concentrations. All injections were given ip.

In earlier experiments, mice were imaged weekly to monitor the tumor growth in real-time. But unfortunately, the noninvasive quantitative measurement of external visible bioluminescence area (total photon flux) did not correlate well with actual tumor size. We discontinued the in vivo imaging and performed later experiments for overall survival of mice. In the third experiment (n = 12), two mice were sacrificed 1 week after the last injection for monitoring early growth of tumors. The remainder of the mice were monitored for their survival for up to 175 days. Body weights of mice were measured and mice with extremely distended abdomens were sacrificed and photographed immediately, tumors and organs were harvested for tumor weight, toxicological and histological studies.