EML4-ALK enhances programmed cell death-ligand 1 expression in pulmonary adenocarcinoma via hypoxia-inducible factor (HIF)-1α and STAT3

Regulation and Function of the PD-L1 Checkpoint

Expression of programmed death-ligand 1 (PD-L1) is frequently observed in human cancers. Binding of PD-L1 to its receptor PD-1 on activated T cells inhibits anti-tumor immunity by counteracting T cell-activating signals. Antibody-based PD-1-PD-L1 inhibitors can induce durable tumor remissions in patients with diverse advanced cancers, and thus expression of PD-L1 on tumor cells and other cells in the tumor microenviroment is of major clinical relevance. Here we review the roles of the PD-1-PD-L1 axis in cancer, focusing on recent findings on the mechanisms that regulate PD-L1 expression at the transcriptional, posttranscriptional, and protein level. We place this knowledge in the context of observations in the clinic and discuss how it may inform the design of more precise and effective cancer immune checkpoint therapies.

Improving immune-vascular crosstalk for cancer immunotherapy

The vasculature of tumours is highly abnormal and dysfunctional. Consequently, immune effector cells have an impaired ability to penetrate solid tumours and often exhibit compromised functions. Normalization of the tumour vasculature can enhance tissue perfusion and improve immune effector cell infiltration, leading to immunotherapy potentiation. However, recent studies have demonstrated that the stimulation of immune cell functions can also help to normalize tumour vessels. In this Opinion article, we propose that the reciprocal regulation between tumour vascular normalization and immune reprogramming forms a reinforcing loop that reconditions the tumour immune microenvironment to induce durable antitumour immunity. A deeper understanding of these pathways could pave the way for identifying new biomarkers and developing more effective combination treatment strategies for patients with cancer.

Association between PD-L1 expression and driver gene status in non-small-cell lung cancer: a meta-analysis

OBJECTIVE

To assess the association between PD-L1 expression and driver gene mutations in patients with non-small-cell lung cancer (NSCLC).

METHOD

We performed a meta-analysis of 26 studies (7541 patients) which were published from 2015 to 2017. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated to describe the correlation. Subgroup analysis was performed based on population characteristics, types of PD-L1 antibodies and quality of individual studies.

RESULTS

A lower frequency of PD-L1 positivity was observed in NSCLCs harboring EGFR mutation (OR: 0.64, 95% CI, 0.45-0.91, p = 0.014). A negative correlation was also found at 1% (OR: 0.35, 95% CI, 0.22-0.55, p = 0.000) and 50% (OR: 0.33, 95% CI, 0.14-0.81, p = 0.015) cutoff for PD-L1 positive, elderly age group (OR: 0.56, 95% CI, 0.35-0.89, p = 0.013), female dominant group (OR: 0.55, 95% CI, 0.29-0.94, p = 0.030) and smoker dominant group (OR: 0.52, 95% CI, 0.29-0.96, p = 0.035). No significant differences in PD-L1 expression were observed among patients with different ALK, BRAF, HER2, PIK3CA status and MET expression level. Higher level of PD-L1 was found in tumors with KRAS mutation (OR: 1.45, 95% CI, 1.18-1.80, p = 0.001). PD-L1 expression level was not significantly different between triple (EGFR/ALK/KRAS) wild type NSCLCs and those with EGFR/ALK/KRAS mutation.

CONCLUSIONS

PD-L1 expression in EGFR mutated NSCLCs were lower than those in EGFR wild type NSCLCs, while tumors with KRAS mutation showed higher levels of PD-L1.

Osimertinib (AZD9291) decreases programmed death ligand-1 in EGFR-mutated non-small cell lung cancer cells

Osimertinib (AZD9291) is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that has been approved for the treatment of EGFR-mutated non-small cell lung cancer (NSCLC). In NSCLC patients, an EGFR mutation is likely to be correlated with high levels of expression of programmed death ligand-1 (PD-L1). Here, we showed that osimertinib decreased PD-L1 expression in human EGFR mutant NSCLC cells in vitro. Osimertinib (125 nmol/L) markedly suppressed PD-L1 mRNA expression in both NCI-H1975 and HCC827 cells. Pretreatment with the N-linked glycosylation inhibitor tunicamycin, osimertinib clearly decreased the production of new PD-L1 protein probably due to a reduction in mRNA. After blocking transcription and translation processes with actinomycin D and cycloheximide, respectively, osimertinib continued to reduce the expression of PD-L1, demonstrating that osimertinib might degrade PD-L1 at the post-translational level, which was confirmed by a cycloheximide chase assay, revealing that osimertinib (125 nmol/L) decreased the half-life of PD-L1 from approximately 17.8 h and 13.8 h to 8.6 h and 4.6 h, respectively, in NCI-H1975 and HCC827 cells. Pretreatment with the proteasome inhibitors (MG-132 or bortezomib) blocked the osimertinib-induced degradation of PD-L1, but an inhibitor of autophagy (chloroquine) did not. In addition, inhibition of GSK3β by LiCl prevented osimertinib-induced PD-L1 degradation. The results demonstrate that osimertinib reduces PD-L1 mRNA expression and induces its protein degradation, suggesting that osimertinib may reactivate the immune activity of T cells in the tumor microenvironment in EGFR-mutated NSCLC patients.

CD274 (PDL1) and JAK2 genomic amplifications in pulmonary squamous-cell and adenocarcinoma patients

AIMS

CD274 (PDL1) and JAK2 (9p24.1) gene amplifications have been recently described in pulmonary carcinomas in association with programmed death-ligand 1 (PD-L1) expression. Furthermore, PTEN loss has been explored preclinically in relation to PD-L1 expression. Our aim was to determine whether these genomic alterations affect PD-L1 expression levels in non-small-cell lung cancer.

METHODS AND RESULTS

PD-L1 and PTEN expression determined by immunohistochemistry (IHC), and CD274, JAK2 and PTEN copy number alterations (CNAs) determined by fluorescence in-situ hybridisation, were studied in 171 pulmonary carcinoma specimens. PD-L1 expression was positive in 40 cases (23.3%), and CD274 amplification was present in 14 tumours (8.8%). Concordance between both events was found in 12 of 14 amplified cases (P = 0.0001). We found nine JAK2-amplified cases (5.7%), seven with PD-L1 expression (P = 0.0006). Moreover, six of the seven cases had JAK2 and CD274 coamplification (9p24.1 genomic amplification). Remarkably, the average PD-L1 IHC score was higher in these amplified cases (230 versus 80; P = 0.001). Non-statistical associations were observed between PD-L1 expression and PTEN loss and PTEN deletions.

CONCLUSIONS

We describe a subset of patients (8.2%) who had 9p24.1 amplifications resulting in high expression of PD-L1. Our results provide evidence for genomic up-regulation of PD-L1 expression in non-small-cell lung cancer.

The combination of checkpoint immunotherapy and targeted therapy in cancer

The therapeutic possibilities for patients with metastatic melanoma have changed due to the development of targeted therapies that inhibit oncogenic signaling pathways as well as immune modulating therapies that unleash the patient antitumor immunity. These therapeutic changes have impressively increased the median overall survival of the patients. Considering the dramatic but transient responses that occur with targeted therapies for a subgroup of patients and the durable responses that can be achieved with immunotherapy in a subset of patients, a lot of effort is ongoing for the clinical development of combinations of these two therapeutic approaches. Herein we discuss the existing preclinical and clinical data for the combination of targeted therapies and immunotherapy focusing mainly on melanoma and non-small cell lung cancer (NSCLC).

Correlation between p-STAT3 overexpression and prognosis in lung cancer: A systematic review and meta-analysis

Objective

Previous studies have shown the correlation between p-STAT3 overexpression and prognosis in a variety of human tumors. However, their correlation in lung cancer remains controversial. We performed a systematic review and meta-analysis to explore the correlation between p-STAT3 overexpression and prognosis in lung cancer patients.

Methods

We searched PubMed, Embase, Web of Science, CNKI, VIP, and WanFang Data to identify relevant studies. Two reviewers independently screened the literature search results, extracted data, and assessed the methodological quality of the included studies. Then, meta-analysis was performed by using Review Manager 5.3 and STATA 14 software. A random-effect model was employed to evaluate all related pooled results. Statistical heterogeneity of each study was assessed by I². Publication bias was determined by funnel plot and the Begg’s or Egger’s tests.

Results

Eventually, 13 studies were included in present meta-analysis. Among these 13 studies, 8 studies were associated with the overall survival of lung cancer and 10 studies with other clinicopathological characteristics. The results of this meta-analysis suggested that p-STAT3 overexpression may be a poor prognosis biomarker in lung cancer (HR: 1.23; 95% CI: 1.04–1.46; P = 0.02). In terms of other clinicopathological characteristics, p-STAT3 overexpression was more frequent to advanced TNM stages ranging from III to IV (OR: 1.92; 95% CI: 1.13–3.27; P = 0.02) and lymphatic node metastasis (OR: 1.81; 95% CI: 1.20–2.72; P = 0.004). But, it was not associated with tumor differentiation (OR: 0.82; 95% CI: 0.44–1.53; P = 0.54).

Conclusion

p-STAT3 overexpression has significant correlation with poorer overall survival of lung cancer patients, as well as with more advanced TNM stages and lymph node metastasis. Thus, it may serve a biomarker for poor prognosis in lung cancer. Nevertheless, our findings should be confirmed by large prospective studies.

The roles of signal transducer and activator of transcription factor 3 in tumor angiogenesis

Angiogenesis is the development of new blood vessels, which is required for tumor growth and metastasis. Signal transducer and activator of transcription factor 3 (STAT3) is a transcription factor that regulates a variety of cellular events including proliferation, differentiation and apoptosis. Previous studies revealed that activation of STAT3 promotes tumor angiogenesis. In this review, we described the activities of STAT3 signaling in different cell types involved in angiogenesis. Particularly, we elucidated the molecular mechanisms of STAT3-mediated gene regulation in angiogenic endothelial cells in response to external stimulations such as hypoxia and inflammation. The potential for STAT3 as a therapeutic target was also discussed. Overall, this review provides mechanistic insights for the roles of STAT3 signaling in tumor angiogenesis.

A systematic and genome-wide correlation meta-analysis of PD-L1 expression and targetable NSCLC driver genes

BACKGROUND

Studies have shown that the ligand of programmed cell death protein 1 (B7-H1, CD274 or PD-L1) is related to lung cancer driver genes. Although studies have examined the association between lung cancer driver gene mutations or expression and PD-L1 expression, the present studies have not been mined the correlation systematically and genome-widely.

METHODS

All relevant published PD-L1 articles with driver genes data and the RNA-seq dataset from The Cancer Genome Atlas (TCGA) were analyzed. We performed meta-analysis for data included in the selected literature, and then independently explored the correlation between genes by co-expression analysis of RNA-seq data in the TCGA database.

RESULTS

A sum of 9,934 lung cancer cases were collected from 34 published studies. Higher PD-L1 expression was associated with wild-type epidermal growth factor receptor (EGFR) [odds ratio (OR): 0.68, 95% confidence interval (CI): 0.48-0.96, P=0.03], Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation (OR: 1.27, 95% CI: 1.02-1.58, P=0.03) or non-adenocarcinoma histology (OR: 0.68, 95% CI: 0.47-0.98, P=0.04). In addition, our analysis from TCGA data indicated that, compared with lung adenocarcinoma, the expression of PD-L1 was significantly higher than that of squamous cell carcinoma patients (P=0.023). The expression of targetable driver genes showed no correlations with PD-L1 expression in non-small cell lung cancer (NSCLC).

CONCLUSIONS

Our results suggest the presence of EGFR wild-type, KRAS gene mutations or squamous cell carcinoma were associated with high PD-L1expression, which provides potential benefited population for the administration of PD-1/PD-L1 blockade in human lung cancer.

Diagnosis and Treatment of Anaplastic Lymphoma Kinase-Positive Non-Small Cell Lung Cancer

Anaplastic lymphoma kinase (ALK) gene rearrangements occur in a small portion of patients with non-small cell lung cancer (NSCLC). These gene rearrangements lead to constitutive activation of the ALK kinase and subsequent ALK-driven tumor formation. Patients with tumors harboring such rearrangements are highly sensitive to ALK inhibitors, such as crizotinib, ceritinib, and alectinib. Resistance to these kinase inhibitors occurs through several mechanisms, resulting in ongoing clinical challenges. This review summarizes the biology of ALK-positive lung cancer, methods for diagnosing ALK-positive NSCLC, current FDA-approved ALK inhibitors, mechanisms of resistance to ALK inhibition, and potential strategies to combat resistance.

Combined Radiotherapy and Anti-PD-L1 Antibody Synergistically Enhances Antitumor Effect in Non-Small Cell Lung Cancer

INTRODUCTION

Immune escape frequently occurs and restricts the durability of the antitumor immune response to radiotherapy. Programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) are important immune checkpoint molecules that could cause tumor cells to escape the host immune response. The aim of the study was to explore the role of PD-L1 in radioresistance and the antitumor effect of combined radiotherapy and anti-PD-L1 therapy in NSCLC.

METHODS

The role of the phosphoinositide 3-kinase/protein kinase B signal transducer and activator of transcription 3, epithelial-mesenchymal transition, and tripartite motif containing 21 in regulating PD-L1 expression after radiotherapy was investigated by small interfering-PD-L1-RNA transfection, immunohistochemistry, Western blot, and immunoprecipitation. The synergistic effect of radiotherapy and anti-PD-L1 antibody was evaluated in a mouse model. PD-L1 expression on tumor specimens was examined in a retrospective cohort of patients who received concurrent chemoradiotherapy.

RESULTS

PD-L1 expression was increased in vivo and in vitro after conventionally fractionated radiation. Radiotherapy in combination with anti-PD-L1 antibody synergistically enhanced antitumor immunity by promoting CD8-positive T-cell infiltration and reducing the accumulation of myeloid-derived suppressor cells and tumor-infiltrating regulatory T cells in a mouse model. Radiotherapy may up-regulate PD-L1 expression through the phosphoinositide 3-kinase/AKT and signal transducer and activator of transcription 3 pathways. PD-L1 may also stimulate cell migration and facilitate the epithelial-mesenchymal transition process to induce radioresistance. Moreover, down-regulating PD-L1 could alleviate radioresistance by promoting apoptosis. Intriguingly, patients with negative PD-L1 expression had a significantly higher objective response rate (88% versus 43.1% [p < 0.001]) and disease control rate (100% versus 86.2% [p = 0.026]) than those with positive PD-L1 expression after delivery of radiotherapy.

CONCLUSIONS

Conventionally fractionated radiotherapy in combination with anti-PD-L1 antibody shows a synergistic antitumor immunity in NSCLC. Furthermore, PD-L1 expression may be a significant clinical predictive factor for treatment response to radiotherapy in NSCLC.

ING5 knockdown enhances migration and invasion of lung cancer cells by inducing EMT via EGFR/PI3K/Akt and IL-6/STAT3 signaling pathways

ING5 belongs to the Inhibitor of Growth (ING) candidate tumor suppressor family, whose functions have been involved in the regulation of chromatin remodeling, cell cycle progression, proliferation and apoptosis. Our previous study has shown that ING5 overexpression inhibits lung cancer aggressiveness via suppressing epithelial to mesenchymal transition (EMT). However, the mechanisms remain largely unknown. In the current study, by Phospho-Kinase array and western blot, we have defined significantly upregulated EGFR/PI3K/Akt and IL-6/STAT3 oncogenic signaling pathways in ING5 knockdown A549 cells, which could be downregulated by ING5 overexpression. PI3K inhibitor ZSTK474 or STAT3 inhibitor Niclosamide not only abolished ING5 knockdown-promoted proliferation, colony formation, migration and invasion of lung cancer A549 cells, but also impaired ING5 knockdown-stimulated metastasis of cancer cells in mouse xenograft models with tail vein injection of A549 cells. Furthermore, treatment with ZSTK474 or Niclosamide decreased protein level of EGFR, p-Akt, IL-6 and p-STAT3, and reversed ING5 knockdown-promoted EMT, as indicated by downregulated expression of EMT marker E-cadherin, an epithelial marker, increased expression of N-cadherin, a mesenchymal marker, and EMT-related transcription factors including Snail, Slug, Smad3 and Twist. Taken together, these results demonstrate that loss of ING5 enhances aggressiveness of lung cancer cells by promoting EMT via activation of EGFR/PI3K/Akt and IL-6/STAT3 signaling pathways.

PD-1 and PD-L1 expression in 132 recurrent nasopharyngeal carcinoma: the correlation with anemia and outcomes

The expression of Programmed death-1 (PD-1) / programmed death-ligand 1 (PD-L1) has been reported to be reliable prognostic factors in various malignances including primary nasopharyngeal carcinoma (NPC). However, the exact role of PD-1/PD-L1 in recurrent NPC remains unclear. In this study, we aimed to investigate the relationship between the expression of PD-1 / PD-L1 and the clinical-pathology as well the outcomes of recurrent NPC patients (n = 132). The expression of PD-1 and PD-L1 was measured by immunohistochemistry staining. The relationship between PD-1 / PD-L1 and factors involved in clinic-pathology and outcomes of patients with NPC was assessed by correlation analysis. To further explore the association between PD-L1 and anemia, immunofluorescence analysis was performed to investigate the correlation of PD-L1 with hypoxia inducible factor-1α (HIF-1α). We observed that advanced rT classification and anemia status before salvage treatment was associated with high level of PD-L1 in recurrent NPC patients, and PD-L1 and was co-located with HIF-1α in recurrent tumors by immunofluorescence analysis. Moreover, our result suggested that PD-L1 might be a negative indicator for recurrent NPC patients as well as age, rT classification, anemia and tumor necrosis at diagnose of recurrence. Taken together, our results revealed that PD-L1 might be a potential prognostic biomarker for recurrent NPC patients, and advanced re-stage, anemia might represent as candidate biomarkers for evaluating patients’ response to anti-PD-1 / PD-L1-treatment. However, further studies are needed to clarify the underlying mechanism of hypoxia in immunosuppression process induced by PD-1 / PD-L1 axis.

ALK alterations and inhibition in lung cancer

The advent of precision medicine in non-small cell lung cancer has remarkably altered the direction of research and improved clinical outcomes. The identification of molecular subsets with differential response to targeted therapies began with the identification of epidermal growth factor receptor mutated tumors in subsets of non-small cell lung cancer (NSCLC). Emboldened by unprecedented response rates to kinase inhibitors seen in that subset, the oncologic community searched for other molecular subsets featuring oncogene addiction. An early result of this search was the discovery of NSCLC driven by activating rearrangements of the anaplastic lymphoma kinase (ALK) gene. In an astoundingly brief period following the recognition of ALK-positive NSCLC, details of the biology, clinicopathologic features, development of targeted inhibitors, mechanisms of therapeutic resistance, and new generations of treatment were elucidated. This review summarizes the current understanding of the pathologic features, diagnostic approach, treatment options, resistance mechanisms, and future research areas for ALK-positive NSCLC.

Adding checkpoint inhibitors to tyrosine kinase inhibitors targeting EGFR/ALK in non-small cell lung cancer: a new therapeutic strategy

After the massive approval of checkpoint inhibitors in the treatment of numerous malignancies and settings, checkpoint inhibitors-based combination therapies are emerging as a new therapeutic modality. Nivolumab and pembrolizumab (anti-PD1 agents) were recently approved as second-line treatment in NSCLC after progression on platinum-doublets. In parallel, targeting EGFR/ALK in NSCLC using tyrosine kinase inhibitors (TKI) demonstrated remarkable outcomes and was approved as standard treatment, in patients with EGFR mutation or ALK rearrangement. Combining TKI targeting EGFR/ALK with checkpoint inhibitors seems a promising therapeutic option and is being evaluated in different trials. We aimed in this paper to elucidate the rationale behind this combination, to report the premilinary results of ongoing trials evaluating this association and finally, to discuss briefly the possible future indication of this treatment modality.