In the past decade, studies onCTCs have gone beyond simple enumeration.The analysis of feature-rich CTCs, that may possess attributes ofthe primary tumor as well as metastasis, can provide clinically actionableinformation.1−4 For example, the expression of PD-L1 in tumor tissues, used as abiomarker for the selection of patients eligible for ICI therapy,is also evaluated using CTCs.43−45 The upregulation of PD-L1 enablescancer cells to evade immune response by inhibiting the activationof immune cells. Here, CD274 is linked to neoplasm.