Effects of tumor-infiltrating CD8+ T cells, PD1/PD-L1 axis, and expression patterns of HLA class I on the prognosis of patients with malignant pleural mesothelioma who underwent extra-pleural pneumonectomy

Preoperative neutrophil-to-lymphocyte ratio correlates with PD-L1 expression in immune cells of patients with malignant pleural mesothelioma and predicts prognosis

“…PD-L1 is a well-known immune checkpoint molecule that suppresses T cell-induced anti-tumor immunity 12 . Previous studies have reported that in patients with MPM, PD-L1 overexpression in the tumor microenvironment (TME) is a poor prognostic factor 13 – 15 , but other studies, including our previous study, revealed that PD-L1 status has no influence on the prognosis of patients with MPM 16 – 18 . Although the prognostic impact of PD-L1 status in patients with MPM is controversial, the expression status of PD-L1 can be used as a preoperative prognostic marker because it can be determined via pleural biopsy.…”

“…Formalin-fixed paraffin-embedded blocks from 61 MPM patients were obtained from the archives of the National Hospital Organization Yamaguchi Ube Medical Center. IHC was performed on surgically resected tissues using a mouse monoclonal anti-PD-L1 antibody (1:100, clone SP142, Spring Bioscience, Pleasanton, CA, USA), according to a previously described protocol 18 . The scoring criteria for PD-L1 expression by tumor cells (PD-L1 TC) and immune cells (PD-L1 IC) were used to assess the percentage of total tumor and immune cells, respectively, as per a previously described method 18 , 28 .…”

“…IHC was performed on surgically resected tissues using a mouse monoclonal anti-PD-L1 antibody (1:100, clone SP142, Spring Bioscience, Pleasanton, CA, USA), according to a previously described protocol 18 . The scoring criteria for PD-L1 expression by tumor cells (PD-L1 TC) and immune cells (PD-L1 IC) were used to assess the percentage of total tumor and immune cells, respectively, as per a previously described method 18 , 28 . Immunoreactivity for PD-L1 was scored by two investigators (R.O.…”

Editorial: Complexity of tumor microenvironment: A major culprit in cancer development

“…The tumor microenvironment (TME) is a complex landscape composed of intrinsic and extrinsic elements besides tumor cells including various immune cells, tumor-related stromal cells, and endothelial cells along with extracellular matrix components ( 1 – 3 ). Notably, the ability of tumor cells to invade surrounding tissues or metastasize through blood and lymphatic vessels implicitly involves cooperation with elements of the TME ( 4 – 6 ). In this regard, infiltrating immune cells such as T cells, B cells, macrophages, dendritic cells, monocytes, neutrophils, and mast cells have been associated with cancer development and progression ( 6 – 8 ).…”

“…Notably, the ability of tumor cells to invade surrounding tissues or metastasize through blood and lymphatic vessels implicitly involves cooperation with elements of the TME ( 4 – 6 ). In this regard, infiltrating immune cells such as T cells, B cells, macrophages, dendritic cells, monocytes, neutrophils, and mast cells have been associated with cancer development and progression ( 6 – 8 ). Additionally, these cells stimulate the host immune response by releasing cytokines, cytokine receptors, and other factors, which directly or indirectly promote or alternatively inhibit tumor cell proliferation ( 9 , 10 ).…”