Cancer treatment method utilizing plasmids suitable for IL-2 expression

A method for treating cancer in a human patient, comprising:

• administering in vivo directly into a tumor of said patient a DNA plasmid formulated with a cationic lipid;
• wherein said plasmid comprises:
• (1) a first polynucleotide encoding a mature human interleukin 2 (IL-2) polypeptide;
• (2) a second polynucleotide encoding a peptide leader operably linked to said first polynucleotide, wherein said peptide leader directs secretion of said IL-2;
• and
• (3) a promoter operably associated with said first and second polynucleotides;
• wherein said plasmid and cationic lipid are administered in an amount sufficient that uptake of said plasmid into the cells of said tumor occurs, and sufficient expression and secretion of said IL-2 results, to reduce tumor growth.