P53 is the most commonly mutated gene in human cancers; it has been found to be mutated in almost 50% of ovarian cancers. Genetic mutation of p53 results in stabilization and increase in the level of the protein. In some cases, overexpression of p53 protein could also occur in tumors without detectable mutation in the open reading frame. Therefore, p53 could function as an antigen through two different mechanisms, as a mutant "foreign" protein and as a selfoverexpressed protein. The p53:264 - 272 wild type peptide has been shown to have high affinity for HLA-A2. It has also been shown to be naturally processed and endogenously