Our retrospective analysis in a published dataset of individuals with PDAC22, together with the initial meta-analysis in individuals with metastatic melanoma and renal cancer3,5,69, suggests that nearly all tumors with high CDA expression before treatment will not respond to ICB (anti-PD-1 or anti-CTLA-4 in melanoma, anti-PD-1 in renal cancer and three cycles of anti-PD-1/anti-CTLA-4 combined with radiation on cycle two in individuals with PDAC). Here, CTLA4 is linked to metastatic melanoma.