We used a pair of equally lethal BALB/c colon adenocarcinomas, CT26 wild-type (CT26WT) and CT26.CL25 that expressed a tumor antigen, β-galactosidase (β-gal) to show that PDT treatment can elicit a systemic antigen/epitope specific anti-tumor immune response sufficiently robust to lead to regression of distant, well-established, antigen positive tumors outside the treatment field. This evidence concerns the gene DDX53 and neoplasm.