CD274 and breast carcinoma: While copper-based radioligands and imaging tracers can be used in PD-L1-expressing tumors, including melanoma [169,170], restricting copper levels within tumors may enhance antimelanoma immunotherapy by limiting immune evasion associated with high levels of PD-L1, and can synergistically improve the outcome of ICIs as recently shown in breast cancer [171] and melanoma [172].