The present invention provides a pharmaceutical composition, comprising a non-infectious, non-integrating polynucleotide construct comprising a polynucleotide encoding an interferon omega or interferon alpha and one or more cationic compounds. The present invention also provides methods of treating cancer in a mammal, comprising administering into a tissue of the mammal a non-infectious, non-integrating polynucleotide construct comprising a polynucleotide encoding a cytokine. In addition, the present invention also relates to the methodology for selective transfection of malignant cells with polynucleotides expressing therapeutic or prophylactic molecules in intracavity tumor bearing mammals. More specifically, the present invention provides a methodology for the suppression of an intra-cavity dissemination of malignant cells, such as intraperitoneal dissemination.
