Given that cis-CD80:PD-L1 negatively affects the CTLA-4:CD80 interaction40, the unchanged CTLA-4 levels of CT26 tumours after PDT suggest that αCTLA-4 + PDT combinations may take advantage from the increase in the expression of CD80 and PD-L1 in this cell line. This evidence concerns the gene CD80 and neoplasm.