Distribution and clinical significance of CTLA4, PD-1 and PD-L1 in peripheral blood of patients with small-cell lung cancer.

Abstract

7574 Background: Cytotoxic T lymphocyte associated antigen 4 (CTLA4), programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) are key components of immune checkpoints and the most attractive targets in immunotherapy for cancer. These antigens are abundant in tumor samples, however their distribution and clinical value in liquid biopsy (such as blood) of small-cell lung cancer (SCLC) patients remains unclear. Methods: 60 healthy and 230 chemotherapy-naive patients with SCLC were recruited. Venous blood samples were collected prior to chemotherapy (baseline) and after the second cycle of chemotherapy (2nd cycle), and flow cytometry was used to analyze the level of CTLA4, PD-1 or PD-L1 with or without CD3, CD4, CD8 or CD25. Immunohistochemistry was used to detect PD-L1 expression in SCLC cell line H446. Results: Cells of CTLA4+, CD3+CTLA4+ and CD4+CTLA4+ in SCLC were (1.06±1.51)%, (4.12±5.30)% and (3.95±2.80)%, respectively and PD-1+, CD3+PD-1+, and CD4+PD-1+ were (7.96±3.38)%, (25.86±8.49) % and (20...