Treatment of malignant ascites due to recurrent/refractory ovarian cancer: the use of interferon-α or interferon-α plus chemotherapy in vivo and in vitro

Intraperitoneal treatment with interferon (IFN) for malignant ascites due to advanced ovarian carcinoma refractory to chemotherapy gave an objective response rate of 36% ($\text{7}\text{19}$ patients treated). In vitro studies demonstrated that cytotoxicity of peripheral blood monocytes/macrophages was stimulated by IFN. However, peritoneal exudate cells obtained after intraperitoneal treatment with interferon were not stimulated to kill autologous tumour cells. Clinical response was therefore most probably due to a direct inhibitory effect of IFN on growth of malignant cells rather than due to an immune modulatory effect. Using a newly established ovarian cancer cell line (UWOV1), synergy between the growth inhibitory/antitumour effects of IFN and cisplatin was demonstrated at clinically achievable concentrations of each agent. IFN plus cisplatin proved to be more effective than intraperitoneal cisplatin alone in control of peritoneal carcinomatosis. The response rate was $\text{5}\text{7}$ (77%) for combined modality therapy vs. $\text{2}\text{9}$ (22%) for intraperitoneal chemotherapy alone. Both in vitro and in vivo studies suggest a role for interperitoneal therapy for control of refractory ascites in ovarian cancer.