An isolated nucleic acid molecule comprising either: one or more nucleic acid sequences selected from the group consisting of: a nucleic acid sequence that encodes SEQ ID NO:2, a nucleic acid sequence that encodes an immunogenic fragment of SEQ ID NO:2 comprising at least 90% of the entire length of SEQ ID NO:2, a nucleic acid sequence that encodes an immunogenic protein that is at least 98% identical to SEQ ID NO:2, a nucleic acid sequence that encodes SEQ ID NO:4, a nucleic acid sequence that encodes an immunogenic fragment of SEQ ID NO:4 comprising at least 90% of the entire length of SEQ ID NO:4, a nucleic acid sequence that encodes an immunogenic protein that is at least 98% identical to SEQ ID NO:4; or one or more nucleic acid sequences selected from the group consisting of: SEQ ID NO: 1, an immunogenic fragment of SEQ ID NO:1 comprising at least 90% of the entire length of SEQ ID NO:1, a nucleic acid sequence that is at least 98% identical to SEQ ID NO:1, an immunogenic fragment of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:1 comprising at least 90% of the entire length of the nucleic acid sequence that is at least 98% identical to SEQ ID NO:1, SEQ ID NO: 3, an immunogenic fragment of SEQ ID NO:3 comprising at least 90% of the entire length of SEQ ID NO:3, a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3, and an immunogenic fragment of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3 comprising at least 90% of the entire length of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3, wherein the one or more nucleic acid sequences encode a WT1 protein, wherein the WT1 protein comprises modified zinc fingers (for example SEQ ID NO: 1 or SEQ ID NO: 2) or does not comprise zinc fingers (for example SEQ ID NO: 3 or SEQ ID NO: 4) and wherein the modified zinc fingers comprise one or more mutations such that one or more of residues 312, 317, 330, 334, 342, 347, 360, and 364 of SEQ ID NO:2 are glycine. one or more nucleic acid sequences selected from the group consisting of: a nucleic acid sequence that encodes SEQ ID NO:2, a nucleic acid sequence that encodes an immunogenic fragment of SEQ ID NO:2 comprising at least 90% of the entire length of SEQ ID NO:2, a nucleic acid sequence that encodes an immunogenic protein that is at least 98% identical to SEQ ID NO:2, a nucleic acid sequence that encodes SEQ ID NO:4, a nucleic acid sequence that encodes an immunogenic fragment of SEQ ID NO:4 comprising at least 90% of the entire length of SEQ ID NO:4, a nucleic acid sequence that encodes an immunogenic protein that is at least 98% identical to SEQ ID NO:4; or one or more nucleic acid sequences selected from the group consisting of: SEQ ID NO: 1, an immunogenic fragment of SEQ ID NO:1 comprising at least 90% of the entire length of SEQ ID NO:1, a nucleic acid sequence that is at least 98% identical to SEQ ID NO:1, an immunogenic fragment of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:1 comprising at least 90% of the entire length of the nucleic acid sequence that is at least 98% identical to SEQ ID NO:1, SEQ ID NO: 3, an immunogenic fragment of SEQ ID NO:3 comprising at least 90% of the entire length of SEQ ID NO:3, a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3, and an immunogenic fragment of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3 comprising at least 90% of the entire length of a nucleic acid sequence that is at least 98% identical to SEQ ID NO:3, wherein the one or more nucleic acid sequences encode a WT1 protein, wherein the WT1 protein comprises modified zinc fingers (for example SEQ ID NO: 1 or SEQ ID NO: 2) or does not comprise zinc fingers (for example SEQ ID NO: 3 or SEQ ID NO: 4) and wherein the modified zinc fingers comprise one or more mutations such that one or more of residues 312, 317, 330, 334, 342, 347, 360, and 364 of SEQ ID NO:2 are glycine.