High expression of PD-L1 was associated with the presence of EGFR mutations in surgically resected NSCLC and was an independent negative prognostic factor for this disease.

Purpose: Therapies targeted to the immune checkpoint mediated by PD-1 and PD-L1 show antitumor activity in a subset of patients with non-small cell lung cancer (NSCLC). We have now examined PD-L1 expression and its regulation in NSCLC positive for the EML4-ALK fusion gene.Experimental Design: The expression of PD-L1 at the protein and mRNA levels in NSCLC cell lines was examined by flow cytometry and by reverse transcription and real-time PCR analysis, respectively. The expression of PD-L1 in 134 surgically resected NSCLC specimens was evaluated by immunohistochemical analysis.Results: The PD-L1 expression level was higher in NSCLC cell lines positive for EML4-ALK than in those negative for the fusion gene. Forced expression of EML4-ALK in Ba/F3 cells markedly increased PD-L1 expression, whereas endogenous PD-L1 expression in EML4-ALK-positive NSCLC cells was attenuated by treatment with the specific ALK inhibitor alectinib or by RNAi with ALK siRNAs. Furthermore, expression of PD-L1 was downregulated by inhibitors of the MEK-ERK and PI3K-AKT signaling pathways in NSCLC cells positive for either EML4-ALK or activating mutations of the EGFR. Finally, the expression level of PD-L1 was positively associated with the presence of EML4-ALK in NSCLC specimens.Conclusions: Our findings that both EML4-ALK and mutant EGFR upregulate PD-L1 by activating PI3K-AKT and MEK-ERK signaling pathways in NSCLC reveal a direct link between oncogenic drivers and PD-L1 expression.

No abstract

Peptide-based specific immunotherapy has resulted in tumor regression in some melanoma patients. However, tumor Ags and peptides for specific immunotherapy, except for treatment of melanomas, have not yet been well identified. In this study, we report a gene encoding a new squamous cell carcinoma (SCC) Ag recognized by cells of the HLA-A24-restricted and tumor-specific CTL line. This gene with 3958-bp length was transcribed from the chromosome 6q22 with six exons, and its mRNA was ubiquitously expressed in both SCCs and normal tissues, and partly expressed in adenocarcinomas. The deduced 958-aa sequence encoded by this gene showed no similarity to any known amino acid sequences. This gene product had a characteristic of an endoplasmic reticulum-resident protein. A 100-kDa protein was detected in the vast majority of SCCs from various tissues, in majority of renal cell carcinomas and brain tumors, and in about one-third of melanomas and adenocarcinomas from various organs other than the breast. In contrast, it was not expressed at all in any of the normal cells or tissues tested, including the testis and fetal liver. Three different peptides at positions 93–101, 161–169, and 899–907 of this Ag were recognized by this CTL line, and all of them induced HLA-A24-restricted and tumor-specific CTLs from PBMCs of SCC patients. Therefore, these peptides may be useful for peptide-based specific immunotherapy of HLA-A24+ patients with SCC in various organs, as well as for treatment of other cancer.

Purpose: The immune checkpoint of the programmed death 1/programmed death ligand 1 (PD-1/PD-L1) pathway is believed to play an important role in evasion of host antitumor immune surveillance in various malignancies; however, little is known about its role in thymic carcinoma. This study investigated PD-1/PD-L1 expression and its association with clinicopathologic features, the expression of immune-related proteins in tumor-infiltrating lymphocytes (TIL), and patient prognosis. Experimental Design: PD-L1 and PD-1 expression was evaluated by IHC in 25 thymic carcinoma tissue specimens. Copy number alterations of the PD-L1 gene in 11 cases were assessed in formalin-fixed, paraffin-embedded material using qRT-PCR. Results: Compared with normal subjects, 3 thymic carcinoma patients showed an increase in PD-L1 copy number, whereas 8 did not. PD-L1 was significantly overexpressed in cases with copy number gain as compared with normal cases. High PD-L1 expression was associated with higher disease-free and overall survival rates as compared to cases with low expression. Prognostic analysis revealed low PD-L1 expression and high number of PD-1+ TILs as significant predictors of poor survival, together with Masaoka–Koga stage IVa/IVb disease and incomplete resection. In the quantitative analysis of TILs, PD-L1 expression correlated proportionally with the number of infiltrating CTLs. Conclusions: Here, for the first time, we report that PD-L1 and PD-1 expression might be useful prognostic predictors in thymic carcinoma. Further studies are expected to substantiate the prognostic value of PD-L1 and PD-1 expression, and the potential efficacy of targeting the PD-1/PD-L1 pathway in thymic carcinoma via immunotherapy. Clin Cancer Res; 22(18); 4727–34. ©2016 AACR.