Murine Ovarian Cancer Model Research Articles

Light Dosimetry for Intraperitoneal Photodynamic Therapy in a Murine Xenograft Model of Human Epithelial Ovarian Carcinoma

Few studies have been published to date measuring spatially resolved fluence rates in complex tissue geometries. Here the light distributions of three different intraperitoneal light delivery geometries in a murine ovarian cancer model were investigated to assess their influence on the tumorcidal efficacy of photodynamic therapy (PDT). In vivo fluence rate measurements in the peritoneal cavities of mice, with the light intensity being mapped in three transverse planes, were performed using fiber-optic detectors. Three different source fiber designs and placements were tested for their ability to provide uniform irradiation of the peritoneal cavity. The biological response to a PDT protocol comprising three separate treatments administered at 72 h intervals, each consisting of a 0.25 mg kg-1 intraperitoneal injection of benzoporphyrin derivative-mono acid ring A followed 90 min later by delivery of 15 J of 690 nm light, was measured. The tissue response was evaluated by measuring the number of remaining visible lesions and the total residual tumor mass. Fluence rate measurements showed large variations in the fluence rate distribution for similar intended treatments. The most uniform and reproducible illumination was achieved using two 18 mm long cylindrical emitting optical fibers. The biological response was comparable to that produced when a flat-cleaved end optical fiber is used to illuminate the four quadrants of the abdomen sequentially. While a good reproducibility in tumor induction in this animal model exists, no correlation was found between the fluence rate distribution measured in one group of animals and the biological response in a separate group of similarly treated animals. Due to the large intra-animal variability in fluence rate distribution, representative fluence rate mapping in complex tissue geometries is of limited value when applied to an individual PDT treatment. Thus, surveillance of the fluence rate during individual treatments will be required for acceptable PDT dosimetry. To improve the versatility of this particular animal model for PDT research, a large number of extended sources are required to increase uniformity of the illumination in order to reduce unwanted cytotoxic side effects resulting from foci of high fluence rates. In this way, subsequent increase of the total energy delivered to the tumor may be possible.

Treatment of ovarian cancer with photodynamic therapy and immunoconjugates in a murine ovarian cancer model.

In photodynamic therapy (PDT), photosensitisers accumulate somewhat preferentially in malignant tissues; photoactivation with appropriate wavelength of light release toxic molecular species which lead to tumour tissue death. In order to target ovarian cancer with increased specificity, a chlorin-based photosensitiser (chlorin e6 monoethylendiamine monoamide) was conjugated to OC125, a monoclonal antibody recognising an antigen expressed in 80% of non-mucinous ovarian cancers. In previous work, this immunoconjugate (IC) was shown to be selectively phototoxic to cancer cells from ovarian cancer patients ex vivo and to localise preferentially in ovarian cancer tissue in vivo. In this study we report results from in vivo phototoxicology and photodynamic treatment studies using this IC in a murine model for ovarian cancer. A comparison of single vs multiple treatments was also made. For in vivo experimentation, Balb C nude mice were injected with 30 x 10(6) NIH:OVCAR 3 cancer cells to create an ascitic tumour model. Animals were then given intraperitoneal injections of the immunoconjugate (0.5 mg kg-1). Twenty-four hours later the intraperitoneal surfaces were exposed to 656 nm light from an argon-ion pumped-dye laser (50 mW, 656 nm), using a cylindrical diffusing tip fibre. The overall treatment was given either once or multiply. No animals died from treatment complications. Twenty-four hours following one and three PDT treatments, the percentage of viable tumour cells in the ascites of the treated animals analysed ex vivo was 34% and 5% of control for one and three treatments respectively. With respect to survival, all control mice (n = 18) died between 30 and 50 days. However, for those treated three times (n = 10), 40% were still alive after 50 days, and for those treated four times (n = 12) 58% were alive after 50 days. Evaluation with log-rank test revealed a significant survival with intraperitoneal PDT compared with controls (P = 0.0006). These preliminary results suggest that PDT with an OC125 immunoconjugate may be an effective therapy for the management of advanced ovarian cancer. Clinical application of this therapy needs to be further optimised and may require multiple treatments, similar to fractionated radiation therapy and cyclic chemotherapy, in order to control malignant disease with acceptable toxicity to normal tissue.

Use of a murine model for comparison of intravenous and intraperitoneal cisplatin in the treatment of microscopic ovarian cancer

The most effective method for the delivery of cisplatin chemotherapy in the treatment of epithelial ovarian cancer limited to the presence of microscopic intraperitoneal disease is a controversial issue. The use of intravenous (iv) versus intraperitioneal (ip) cisplatin was evaluated in a murine tumor model of human epithelial ovarian cancer. Using single dose cisplatin therapy for microscopic disease limited to positive cytology of abdominal disease and microscopic peritoneal involvement, ip therapy had significantly greater ( P < 0.001) survival time than iv therapy (28 ± 1.6 days vs. 23 ± 1.6 days, respectively). Once ascites and macroscopically evident intraperitoneal tumor became apparent, no difference could be found in survival time based on iv versus ip therapy (16 ± 3 days for both groups); though both forms of therapy significantly ( P < 0.05) prolonged survival in mice with macroscopic disease when compared to control animals (13 ± 1.2 days). The evidence presented implies that ip cisplatin therapy is significantly more effective than iv therapy when dealing with microscopic intraperitoneal disease.

Antitumor effect of the streptococcal preparation OK-432 in a murine model of ovarian cancer.

The antitumor effects of the streptococcal preparation OK-432 were analyzed in a murine ovarian teratocarcinoma (MOT) model. Administration of OK-432 i.p. prevented tumor outgrowth in 75% of mice challenged with 10(3) MOT cells i.p. 24 h previously. Treatment was less successful in mice challenged with 10(4) or 10(5) cells, preventing tumor growth in 25% of the former and only 5% of the latter group. Tumor-challenged mice cured by injections of OK-432 were not rendered resistant to a subsequent challenge with 10(3) MOT cells 75 days after initial treatment. Only the i.p. route of administration was effective as i.v. OK-432 did not prolong survival of tumor-challenged mice. An antitumor response was detected as early as 24 h after i.p. treatment. This correlated temporally with an influx of neutrophils into the peritoneal cavity. Peritoneal cells obtained between 6 and 24 h after treatment were capable of lysing MOT targets in vitro. A single cell cytotoxicity assay demonstrated that peritoneal neutrophils, elicited by i.p. injection of OK-432, could bind to and lyse MOT targets. These data indicate that OK-432 is effective against small tumor cell inocula in this murine model of ovarian cancer and, furthermore, that the neutrophilic response into the peritoneal cavity plays a role in tumor rejection.

Successful immunotherapy with intraperitoneal Corynebacterium parvum in a murine ovarian cancer model is associated with the recruitment of tumor-lytic neutrophils into the peritoneal cavity.

The rejection of a murine ovarian teratocarcinoma (MOT) after i.p. injection of Corynebacterium parvum was investigated. Treatment with C. parvum (1400 micrograms) 24 hr after i.p. inoculation of a lethal number of tumor cells (10(5] induced an antitumor effect that cured 75 to 95% of the mice. Morphologic analysis and an in vivo cytotoxicity assay that measured the rate of disappearance of radioactivity from the peritoneal cavity after injection of 125IUdR-labeled tumor cells indicated that the antitumor effect was initiated during the first 24 hr after C. parvum injection. During this period of time, host effector cells retrieved from the peritoneal cavity prevented tumor growth in a Winn assay and lysed radiolabeled MOT targets in a 4-hr Cr-release assay. After separation of peritoneal inflammatory cells on a Percoll gradient, neutrophil-enriched fractions demonstrated significant in vitro tumor lysis, but neutrophil-depleted populations were ineffective. Microscopic analysis of lysis at the single cell level confirmed that neutrophils were binding to and lysing MOT targets. Further characterization of these tumor cytolytic neutrophils revealed that they are nylon wool-adherent, not generated in indomethacin-pretreated mice (but effectively generated in whole body-irradiated mice), and achieve lysis within 30 min after binding to MOT targets. These results indicate that neutrophils must be considered potential antitumor effectors that can be recruited by treatment with biologic response modifiers.

Cytotoxic lymphocytes, interferon, and tumor rejection in the peritoneal cavity of a murine ovarian cancer model using immunotherapy with biologic response modifiers

Cytotoxic lymphocytes, interferon, and tumor rejection in the peritoneal cavity of a murine ovarian cancer model using immunotherapy with biologic response modifiers