Wang et al. measured PD-L1 expression in circulating tumour cells (CTCs) before radio- or chemoradiotherapy in NSCLC and found PD-L1 positive patients (≥5% of CTCs positive for PD-L1) associated with shorter PFS [79] Patients with an increased PD-L1 expression on tumour cells after CRT had significantly worse overall survival [80]. Here, CD274 is linked to non-small cell lung carcinoma.