Construction of a triple modified p53 containing DNA vaccine to enhance processing and presentation of the p53 antigen.

More effective and less toxic treatments are urgently needed in the treatment of patients with cancer. The tumour suppressor protein p53 is a tumour-associated antigen that could serve that purpose when applied in an immunologic approval to cancer. It is mutated in approximately 50% of the tumours resulting in p53 overexpression, which can serve as target for therapy. To improve the immunisation results in patients with p53 overexpression tumours we constructed a DNA vaccine that could lead to improved processing and presentation of p53 peptides in the MHC-class I. We constructed a triple modified p53 fusion protein containing DNA vaccine by (1) addition of a xeno-antigen (mouse or rat p53 fragment), (2) potentiation of intra-cytoplasmatic accumulation of p53 by deleting the nuclear signalling part, (3) improving the processing to peptides of p53 by addition of ubiquitin. In-vitro experiments confirmed correct construction of the DNA vaccine. Preliminary testing in normal and HLA-A2 mice of this triple modified p53 containing DNA construct meant for human application showed a trend towards a superior immunogenicity.