PDCD1 and non-small cell lung carcinoma: In this prospective observational study, plasma cytokine levels and PD-1, PD-L1 and PD-L2 expression was evaluated in circulating CD3+, CD3+CD4+ and CD3+CD8+ cells from 70 treatment-naïve patients with advanced NSCLC (Stage IIIB and IV) and from 10 healthy donors.