A dual-photosensitizer strategy employing HPPH and Photofrin has also been suggested, where an initial low-dose PDT for immune stimulation is followed by a high-dose treatment for tumor eradication, leading to increased tumor-specific CD8+ T cell activation and reduced metastasis in CT26 colon and 4T1 breast carcinoma models (145). This evidence concerns the gene CD8A and neoplasm.