Culturing PBMCs with overlapping peptides derived from the sequence of the tumor antigen and IL-2 plus IL-15 prior to analysis by flow cytometry or ELISPOT assay appears to be quite sensitive, but can also induce false positives by stimulating naive T cells. Direct ex vivo methods appear to not be sensitive enough and the use of labeled multimers is limited by HLA type and the ability to identify epitopes.