Our results imply that EGFR-TKIs could not only directly inhibit tumor cell viability but also indirectly enhance antitumor immunity through the downregulation of PD-L1. Anti-PD-1/PD-L1 antibodies could be an optional therapy for EGFR-TKI sensitive patients, especially for EGFR-TKIs resistant NSCLC patients with EGFR mutation. Combination of EGFR-TKIs and anti-PD-1/PD-L1 antibodies treatment in NSCLC is not supported by the current study but warrant more studies to move into clinical practice.

PD-L1 expression is a feature of Epstein-Barr virus (EBV) associated malignancies such as nasopharyngeal carcinoma (NPC). Here, we found that EBV-induced latent membrane protein 1 (LMP1) and IFN-γ pathways cooperate to regulate programmed cell death protein 1 ligand (PD-L1). Expression of PD-L1 was higher in EBV positive NPC cell lines compared with EBV negative cell lines. PD-L1 expression could be increased by exogenous and endogenous induction of LMP1 induced PD-L1. In agreement, expression of PD-L1 was suppressed by knocking down LMP1 in EBV positive cell lines. We further demonstrated that LMP1 up-regulated PD-L1 through STAT3, AP-1, and NF-κB pathways. Besides, IFN-γ was independent of but synergetic with LMP1 in up-regulating PD-L1 in NPC. Furthermore, we showed that PD-L1 was associated with worse disease-free survival in NPC patients. These results imply that blocking both the LMP1 oncogenic pathway and PD-1/PD-L1 checkpoints may be a promising therapeutic approach for EBV positive NPC patients.

BackgroundsRecent clinical trials have shown that immune-checkpoint blockade yields remarkable response in a subset of non–small cell lung cancer (NSCLC) patients. However, few studies directly focus on the association between epidermal growth factor receptor (EGFR) mutational status and programmed cell death-ligand 1 (PD-L1) expression. We examined whether PD-L1 is related to clinicopathologic factors and prognosis in patients with advanced NSCLC treated with EGFR-tyrosine kinase inhibitors (EGFR-TKIs).MethodsOne-hundred and seventy patients with advanced NSCLC were explored. Paraffin-embedded tumour sections were stained with PD-L1 antibody. EGFR mutation was examined by fluorescent quantitative polymerase chain reaction (PCR). The correlations between PD-L1 expression and EGFR status and survival parameters were analyzed.ResultsThe overall frequency of PD-L1 over-expression was 65.9% (112/170). In lung adenocarcinoma, PD-L1 tended to be associated with mutant EGFR (PD-L1 overexpression in mutant and wild-type EGFR, 64/89 (71.9%) vs. 32/56 (57.1%), respectively; p=0.067). Subgroup analyses showed that high PD-L1 expression was associated with significantly shorter overall survival (OS) in EGFR wild-type patients (p=0.029) but not in EGFR mutant patients (p=0.932) treated with EGFR-TKIs. Even more, for EGFR mutant patients, higher expression of PD-L1 might only signal better outcome with TKIs.ConclusionsHigh PD-L1 expression was likely to be associated with the presence of EGFR mutation in advanced lung adenocarcinoma. For EGFR wild-type patients, the PD-L1 over expression can be considered as a poor prognostic indicator of OS.

BackgroundsIt has been extensively proved that the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is superior to that of cytotoxic chemotherapy in advanced non-small cell lung cancer (NSCLC) patients harboring sensitive EGFR mutations. However, the question of whether the efficacy of EGFR-TKIs differs between exon 19 deletion and exon 21 L858R mutation has not been yet statistically answered.MethodsSubgroup data on hazard ratio (HR) for progression-free survival (PFS) of correlative studies were extracted and synthesized based on random-effect model. Comparison of outcomes between specific mutations was estimated through indirect and direct methods, respectively.ResultsA total of 13 studies of advanced NSCLC patients with either 19 or 21 exon alteration receiving first-line EGFR-TKIs were included. Based on the data from six clinical trials for indirect meta-analysis, the pooled HRTKI/chemotherapy for PFS were 0.28 (95% CI 0.20–0.38, P<0.001) in patients with 19 exon deletion and 0.47 (95% CI 0.35–0.64, P<0.001) in those with exon 21 L858R mutation. Indirect comparison revealed that the patients with exon 19 deletion had longer PFS than those with exon 21 L858R mutation (HR19 exon deletion/exon 21 L858R mutation  = 0.59, 95% CI 0.38–0.92; P = 0.019). Additionally, direct meta-analysis showed similar result (HR19 exon deletion/exon 21 L858R mutation  = 0.75, 95% CI 0.65 to 0.85; P<0.001) by incorporating another seven studies.ConclusionsFor advanced NSCLC patients, exon 19 deletion might be associated with longer PFS compared to L858 mutation at exon 21 after first-line EGFR-TKIs.

Driver mutations were reported to upregulate programmed death-ligand 1 (PD-L1) expression. However, how PD-L1 expression and immune function was affected by ALK-TKIs and anti-PD-1/PD-L1 treatment in ALK positive non-small-cell lung cancer (NSCLC) remains poorly understood. In the present study, western-blot, real-time PCR, flow cytometry and immunofluorescence were employed to explore how PD-L1 was regulated by ALK fusion protein. ALK-TKIs and relevant inhibitors were used to identify the downstream signaling pathways involved in PD-L1 regulation. Cell apoptosis, viability and Elisa test were used to study the immune suppression by ALK activation and immune reactivation by ALK-TKIs and/or PD-1 blocking in tumor cells and DC-CIK cells co-culture system. We found that PD-L1 expression was associated with EGFR mutations and ALK fusion genes in NSCLC cell lines. Over-expression of ALK fusion protein increased PD-L1 expression. PD-L1 mediated by ALK fusion protein increased the apoptosis of T cells in tumor cells and DC-CIK cells co-culture system. Inhibiting ALK by sensitive TKIs could enhance the production of IFNγ. Anti-PD-1 antibody was effective in both crizotinib sensitive and resistant NSCLC cells. Synergistic tumor killing effects were not observed with ALK-TKIs and anti-PD-1 antibody combination in co-culture system. ALK-TKIs not only directly inhibited tumor viability but also indirectly enhanced the antitumor immunity via the downregulation of PD-L1. Anti-PD-1/PD-L1 antibodies could be an optional therapy for crizotinib sensitive, especially crizotinib resistant NSCLC patients with ALK fusion gene. Combination of ALK-TKIs and anti-PD-1/PD-L1 antibodies treatment for ALK positive NSCLC warrants more data before moving into clinical practice.