Immunization by electroporation with 30 μg of a DNA plasmid encoding MAGE-A3 isoform significantly enhanced Th1 (IgG2a, IFN-γ) and Th2 (IgG1, IL-4) responses, and delayed tumor growth when compared to mice immunized with empty vector in the murine lung cancer LLC model. This evidence concerns the gene MAGEA3 and neoplasm.