CD274 and breast cancer: The average amount of CTC was 55/100 μL of blood (in the range from 5 to 805), CTC expressing PD-L1 were found in 94.5% of patients with BC; in patients expressing PD-L1 and PD-L2, the cell fraction of the PD-L1-positive CTCs was significantly higher than the fraction of the PD-L2-positive CTCs (54.6% versus 28.7%; p <0.001).