MET expression plays differing roles in non-small-cell lung cancer patients with or without EGFR mutation

MET overexpression correlated with prognosis of EGFR-mutant treatment‑naïve advanced lung adenocarcinoma: a real‑world retrospective study

BACKGROUND

About 50-60% treatment-naïve advanced non-small-cell lung cancers were coexistence of epidermal growth factor receptor (EGFR) and mesenchymal epithelial transition (MET) overexpression. However, few studies demonstrated the prognostic value of MET protein expression in untreated EGFR-mutant lung adenocarcinoma (LUAD).

METHODS

A total of 235 EGFR-mutant untreated advanced LUAD patients were retrospectively enrolled. MET expression was determined using immunohistochemistry, and MET positivity was defined as 2 + or 3 + using the METmab scoring algorithm. Progression-free survival (PFS) and overall survival (OS) were analysed according to MET expression status. Independent factors predicting prognosis were identified using multivariate Cox regression analyses.

RESULTS

Of the 235 patients, 113 (48.1%) harboured exon 19 deletion (19_del), 103 (43.8%) had exon 21 L858R mutations, and 19 (8.1%) had other mutation types, including exon 21 L861Q, exon 18 G719A/C, exon 20 S768I, and L858R/19_del double mutations. MET-positive expression was observed in 192 (81.7%) cases. There was no significant difference in baseline clinicopathological characteristics between MET positivity and MET negativity groups. Patients were stratified by different EGFR mutation subtypes. MET-positive patients in the L858R mutation subgroup had markedly shorter PFS and OS than MET-negative patients (median PFS: 13 versus 27.5 months, p < 0.001; median OS: 29 versus not reached, p = 0.008), but no significant difference was observed in the 19_del subgroup. Multivariate Cox regression analyses indicated that MET positivity was an independent predictor for poor PFS and OS in L858R subgroup (PFS: HR = 3.059, 95% CI 1.552-6.029, p = 0.001; OS: HR = 3.511, 95% CI 1.346-9.160, p = 0.010). Additionally, an inferior survival outcome of MET positivity was observed in the L858R mutation subgroup when treated with EGFR-tyrosine kinase inhibitor (TKI) monotherapy as the first-line regimen (median PFS: 13 versus 36.5 months, p < 0.001; median OS: 29 versus not reached, p = 0.012) but not with EGFR-TKI plus platinum doublet chemotherapy.

CONCLUSIONS

MET positive expression was an independent predictor of poor outcomes in untreated EGFR L858R mutation advanced LUAD patients treated with first-line EGFR-TKI monotherapy.

Engineering c-Met-CAR NK-92 cells as a promising therapeutic candidate for lung adenocarcinoma

Mesenchymal-epithelial transition factor (C-Met) has been acknowledged as a significant therapeutic target for treating lung adenocarcinoma (LUAD). However, the potential application of chimeric antigen receptors (CAR)-modified natural killer (NK) cells targeting c-Met in LUAD is rarely explored. In this study, bioinformatic databases were searched and a tissue microarray (TMA) was enrolled to investigate expression status and prognostic role of c-Met in LUAD. Then, four types of c-Met-CAR structures were designed and prepared. The engineering CAR-NK cells containing c-Met-CARs were transfected, verified and characterized. The tumor-inhibitory role of c-Met-CAR-NK cells was finally evaluated in vitro and in vivo. The results demonstrated that c-Met expression elevated and confirmed that high c-Met expression was significantly associated with unfavorable prognosis in LUAD. Then, C-Met-CAR-NK cells were successfully constructed and DAP10 designed in CAR structure was a favorable stimulator for NK cell activation. CCN4 containing DAP10 co-stimulator exhibited the strongest cytotoxicity compared with other CAR-NK cells. Furthermore, CCN4 cells also exerted the prominent tumor-inhibitory effect on xenograft tumor growth. Collectively, this study suggests that DAP10 is a potent stimulator in CAR structure for NK cell activation, and CCN4-based immunotherapy may represent a promising strategy for the treatment of c-Met-positive LUAD.

MET overexpression in EGFR L858R mutant treatment-naïve advanced lung adenocarcinoma correlated with poor prognosis: a real-world retrospective study

BACKGROUND

Mesenchymal epithelial transition (MET) overexpression has been reported in approximately 50-60% of epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancers. However, the prognostic significance of MET overexpression has not been established in advanced lung adenocarcinoma (ADC) patients with EGFR-sensitive mutations.

METHODS

A retrospective study was performed on a total of 406 treatment-naïve advanced ADC patients with EGFR mutation detection and MET expression information. EGFR mutations were detected by next-generation sequencing or amplification refractory mutation system-polymerase chain reaction. Immuno-histochemistry staining of MET expression was evaluated by H-score and overexpression was defined as an H-score ≥ 200. Overall survival (OS) and progression-free survival (PFS) were analyzed according to MET expression.

RESULTS

Among the 406 patients, 208 patients had EGFR mutations, including 102 exon 19_del mutations, 94 L858R mutations and 12 other types of mutations. Of 110 patients with concomitant EGFR mutations and MET overexpression, 61 (59.8%) patients had 19_del mutations, 44 (46.8%) patients had L858R mutations and five (41.7%) patients had others. Patients with MET overexpression had a markedly shorter PFS and OS than patients with MET H-score < 200 in the EGFR L858R mutation subgroup (median PFS: 12 versus 26 months, p = 0.001; median OS: 24 versus 32 months, p = 0.038), whereas no significant difference was observed in 19_del mutation subgroup. Multivariate Cox analysis showed that MET overexpression was an independent poor prognostic factor for PFS and OS in patients with the L858R mutations (HR = 3.064, 95% CI 1.705-5.507, p < 0.001; HR = 2.043, 95% CI 1.000-4.172; p = 0.049), rather than 19_del.

CONCLUSIONS

MET overexpression is a poor prognostic factor for advanced ADC patients with the EGFR L858R mutation.

Spotlight on Tepotinib and Capmatinib for Non-Small Cell Lung Cancer with MET Exon 14 Skipping Mutation

Mesenchymal-epithelial transition (MET) receptor tyrosine kinase is overexpressed, amplified, or mutated in 1–20% of NSCLC. MET dysregulation is associated with a poor prognosis. Recently, development of targeted therapies against MET exon 14 mutations has demonstrated efficacy and tolerability in early trials. Here we focus on tepotinib and capmatinib in regards to molecular characteristics, early preclinical and clinical data, and the emerging role in future studies and clinical practice.

New Targets in Lung Cancer (Excluding EGFR, ALK, ROS1)

PURPOSE OF REVIEW

Over the last two decades, the identification of targetable oncogene drivers has revolutionized the therapeutic landscape of non-small cell lung cancer (NSCLC). The extraordinary progresses made in molecular biology prompted the identification of several rare molecularly defined subgroups. In this review, we will focus on the novel and emerging actionable oncogenic drivers in NSCLC.

RECENT FINDINGS

Recently, novel oncogene drivers emerged as promising therapeutic targets besides the well-established EGFR mutations, and ALK/ROS1 rearrangements, considerably expanding the list of potential exploitable genetic aberrations. However, the therapeutic algorithm in these patients is far less defined. The identification of uncommon oncogene drivers is reshaping the diagnostic and therapeutic approach to NSCLC. The introduction of novel highly selective inhibitors is expanding the use of targeted therapies to rare and ultra-rare subsets of patients, further increasing the therapeutic armamentarium of advanced NSCLC.

Secondary Resistant Mutations to Small Molecule Inhibitors in Cancer Cells

Secondary resistant mutations in cancer cells arise in response to certain small molecule inhibitors. These mutations inevitably cause recurrence and often progression to a more aggressive form. Resistant mutations may manifest in various forms. For example, some mutations decrease or abrogate the affinity of the drug for the protein. Others restore the function of the enzyme even in the presence of the inhibitor. In some cases, resistance is acquired through activation of a parallel pathway which bypasses the function of the drug targeted pathway. The Catalogue of Somatic Mutations in Cancer (COSMIC) produced a compendium of resistant mutations to small molecule inhibitors reported in the literature. Here, we build on these data and provide a comprehensive review of resistant mutations in cancers. We also discuss mechanistic parallels of resistance.

The Prognostic Role of MET Protein Expression Among Surgically Resected Non-small Cell Lung Cancer Patients: A Meta-Analysis

Objectives: MET protein expression has been reported to be in relevance with the survival of NSCLC patients in various studies, yet the results were inconsistent. The purpose of our study set out to determine the prognostic role of both c-MET and p-MET expression among NSCLC that underwent surgical resection.

Methods: Data were obtained from retrospective cohort studies by searching on PubMed, Cochrane Library, EMBASE and Web of Science, and a meta-analysis was performed to assess the prognostic role of MET expression among NSCLC.

Results: Totally 18 literatures including 5,572 surgically resected NSCLC cases staged I-IV were included for data synthesis. The positive rate of c-MET and p-MET was 1,753/4,315 and 135/1,257. The pooled hazard ratios (HRs) regarding c-MET and p-MET expression for overall survival (OS) was 1.623 (95% CI: 1.176–2.240, p = 0.003) and 1.710 (95% CI: 0.823–3.533, p = 0.15), respectively. Subgroup analysis results on Asian (HR = 2.115, p < 0.001), adenocarcinoma (HR = 2.220, p < 0.001) and rabbit polyclonal antibodies (HR = 2.107, p < 0.001) etc. were also indicative.

Conclusion: C-MET over-expression among NSCLC patients that underwent surgical resection is a prognostic factor that indicated adverse survival on OS. Whereas, p-met didn't appear to have an impact on the prognosis of NSCLC. The studies are need and the topic could be re-valued by then.

Crizotinib in advanced non-small-cell lung cancer with concomitant ALK rearrangement and c-Met overexpression

Objective

Crizotinib can target against mesenchymal-epithelial transition (MET) and anaplastic lymphoma kinase (ALK), which has been considered as a multi-targeted tyrosine kinase inhibitor (TKI). The objective of this study was to explore the efficacy of crizotinib in advanced non-small-cell lung cancer (NSCLC) with concomitant ALK rearrangement and c-Met overexpression.

Methods

Totally, 4622 advanced NSCLC patients from two institutes (3762 patients at the Guangdong Lung Cancer Institute from January 2011 to December 2016 and 860 cases at the Perking Cancer Hospital from January 2015 to December 2016) were screened for ALK rearrangement with any method of IHC, RACE-coupled PCR or FISH. C-Met expression was performed by IHC in ALK-rearranged patients, and more than 50% of cells with high staining were defined as c-Met overexpression. The efficacy of crizotinib was explored in the ALK-rearranged patients with or without c-Met overexpression.

Results

Sixteen patients were identified with c-Met overexpression in 160 ALK-rearranged cases, with the incidence of 10.0% (16/160). A total of 116 ALK-rearranged patients received the treatment of crizotinib. Objective response rate (ORR) was 86.7% (13/15) in ALK-rearranged patients with c-Met overexpression and 59.4% (60/101)in those without c-Met overexpression, P = 0.041. Median PFS showed a trend of superiority in c-Met overexpression group (15.2 versus 11.0 months, P = 0.263). Median overall survival (OS) showed a significant difference for ALK-rearranged patients with c-Met overexpression group of 33.5 months with the hazard ratio (HR) of 3.2.

Conclusions

C-Met overexpression co-exists with ALK rearrangement in a small population of advanced NSCLC. There may be a trend of favorable efficacy of crizotinib in such co-altered patients.

Expression of MET in circulating tumor cells correlates with expression in tumor tissue from advanced-stage lung cancer patients

Given the difficulty in obtaining adequate tissue in NSCLC, we investigated the utility of circulating tumor cells (CTCs) for MET status assessment in NSCLC patients. We used two platforms for CTC capture, and assessed MET expression in CTCs and matched-bronchial biopsies in patients with advanced-stage III/IV lung adenocarcinoma. Baseline peripheral blood was collected from 256 advanced-stage III/IV NSCLC patients from Genentech clinical trials, and from 106 patients with advanced-stage III/IV lung adenocarcinoma treated at the Department of Pneumology, Pasteur Hospital, Nice. CTCs were enriched using CellSearch (Genentech), or ISET technologies (Pasteur Hospital). MET expression was evaluated by immunofluorescence on CellSearch, and by immunocytochemistry on ISET-enriched CTCs and on matched FFPE tissue sections (Pasteur Hospital). CTCs were detected in 83 of 256 (32%) patients evaluated on CellSearch, with 30 samples (12%) exhibiting ≥ 5 CTCs/7.5 ml blood. On ISET, CTC were observed in 80 of 106 patients (75%), and 79 patients (75%) exhibited ≥ 5 CTCs/4 ml blood. MET expression on ISET CTCs was positive in 72% of cases, and the MET expression on matched-patient tissue was positive in 65% patients using the Onartuzumab IHC scoring algorithm (93% concordance). Quantification of MET expression using H-scores showed strong correlation between MET expression in tissue and CTCs (Spearman correlation, 0.93). MET status in CTCs isolated on ISET filters from blood samples of advanced-stage NSCLC patients correlated strongly with MET status in tumor tissue, illustrating the potential for using CTCs as a non-invasive, real-time biopsy to determine MET status of patients entering clinical trials.

Preferential Localization of MET Expression at the Invasion Front and in Spreading Cells Through Air Spaces in Non-Small Cell Lung Carcinomas

The involvement of the HGF/MET pathway in acquisition of an invasive phenotype in non-small cell lung carcinomas (NSCLCs) suggests that MET inhibitors might prove effective against these cancers, but clinical trials have yielded conflicting results. The aim of our study was to evaluate how intratumoral heterogeneity (ITH) of MET staining affects the determination of MET status for therapeutic purposes. We analyzed 64 NSCLC samples, including 33 adenocarcinomas (ADCs) and 31 squamous cell carcinomas (SCCs). We used immunohistochemistry to detect MET and phospho-MET on whole slides and determined the MET SP44 immunoscore and the H-score. A high METMab score (2+/3+) was observed in 34% of NSCLCs and was more prevalent in ADCs (52%) than in SCCs (16%). We found ITH in 73% of ADCs and 77% of SCCs, with higher levels of MET and phospho-MET at the invasion front (in 52% of ADCs and 22% of SCCs) and in tumor cells spreading through air spaces in ADCs. Within-sample ITH was high in 40% of the ADCs and 29% of the SCCs. When different samples from the same tumor were compared, discordant assessments (high MET vs. low MET) were made for 12% of the ADCs and 10% of the SCCs. C-MET and phospho-MET overexpression occurred preferentially in ADCs and in areas involved in tumor progression, in support of the view that MET activation plays a role in the development of an invasive phenotype in NSCLC. To use MET status adequately as a biomarker, one must take the resulting high level of ITH into account.

MEK inhibitors against MET-amplified non-small cell lung cancer

Several receptor tyrosine kinases (RTKs) including EGFR, ALK, and MET have been identified as therapeutic targets in non-small cell lung cancer (NSCLC). Among the downstream pathways of RTKs, the MAPK pathway is particularly important for cancer cell proliferation, differentiation, and survival. In this study, the effects of MEK inhibitors (trametinib and PD0325901) in several NSCLC cell lines with driver gene alterations, especially RTK genes, were tested in vitro using an MTT assay, and a wide range of sensitivities was found. In particular, all the EGFR-mutated cell lines were resistant to MEK inhibitors, whereas all the MET-amplified cell lines were sensitive. A bioinformatics technique and western blot analyses showed that the PI3K/AKT pathway is more activated in EGFR-mutated NSCLC than in MET-amplified NSCLC, and a PI3K inhibitor enhanced the sensitivity to trametinib in the EGFR-mutated cell lines, suggesting that this pathway is associated with resistance to MEK inhibitors. Although the HCC827 cell line (EGFR mutation) was resistant to MEK inhibitors, the HCC827CNXR cell line, whose driver gene shifts from EGFR to MET, exhibited enhanced sensitivity to MEK inhibitors, indicating the biological importance of the MAPK pathway for MET-amplified NCSLC. Furthermore, a synergistic effect of crizotinib (a MET inhibitor) and trametinib was observed in MET-amplified NCLC cell lines. Our findings indicate that the MAPK pathway is biologically important for MET-amplified NSCLC and strongly encourage the development of combination therapy with a MET inhibitor and a MEK inhibitor against MET-amplified NSCLC.

Clinical Significance of C-MET Overexpression and Epidermal Growth Factor Receptor Mutation in Platinum-Based Adjuvant Chemotherapy Outcome in Surgically Resected Lung Adenocarcinoma

PURPOSE

We retrospectively assessed the role of C-MET expression and epidermal growth factor receptor (EGFR) mutation on survival following platinum-based adjuvant chemotherapy. The impact of C-MET on survival was also investigated in relation to EGFR mutation status.

METHODS

We enrolled 311 patients with resected lung adenocarcinoma (high-risk stage 1B-3A), and performed immunohistochemistry (IHC) using C-MET- and mutant EGFR (EGFRmut)-specific antibodies in tissue microarrays.

RESULTS

Adjuvant chemotherapy was administered to 151 patients, 96 of whom relapsed and 85 died by the end of the study. On IHC, C-MET and EGFRmut were positive in 141 (45.3 %) and 88 (28.3 %) cases, respectively. On univariate analysis, adjuvant chemotherapy prolonged relapse-free survival (RFS) and overall survival (OS) in C-MET(+) patients (RFS p = 0.035; OS p = 0.013) but not in C-MET(-) patients. On multivariate analysis, adjuvant chemotherapy was a positive independent prognostic factor in C-MET(+) (RFS p = 0.013; OS p = 0.006) but not in C-MET(-) patients. In addition, univariate analysis showed no effect of EGFRmut status on RFS and OS after chemotherapy, whereas multivariate analysis revealed that adjuvant chemotherapy increased RFS in both EGFRmut(+) and EGFRmut(-) patients [EGFRmut(+) p = 0.033; EGFRmut(-) p = 0.030]. C-MET was a negative prognostic factor for RFS (p = 0.045) and OS (p = 0.007) in the EGFRmut(-) group but not in the EGFRmut(+) group, on multivariate analysis.

CONCLUSIONS

Our data indicate that patients with C-MET overexpression should be considered for adjuvant chemotherapy, and that C-MET negatively correlates with survival in patients with wild-type, but not mutant, EGFR.

Genistein inhibits A549 human lung cancer cell proliferation via miR-27a and MET signaling

Genistein is a soybean isoflavone; in its aglycone it has various biological activities. Animal experiments, clinical studies and epidemiological investigations suggest that genistein has preventative and curative functions for a number of diseases, particularly in cancer. The present study explored the potential anti-cancer effect of genistein by observing its role in inhibiting A549 human lung cancer cell proliferation and investigating the possible mechanism. A549 cells were exposed to various concentrations of genistein (0, 10, 25, 50, 100 and 200 µM; dissolved in physiological saline) for 1, 2 and 3 days. Subsequently, the viability of A549 cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell apoptosis was examined using a flow cytometer, caspase 3/9 activity was measured using commercial kits, reverse transcription quantitative polymerase chain reaction was used to analyze the miR-27a expression and western blotting was used to investigate MET protein expression. The results suggested a significant inhibition of A549 cell growth following treatment with genistein in a time- and dose-dependent manner. The current study also indicated that treatment with genistein significantly induces cell apoptosis and promotes caspase-3/9 activation of A549 cells in a dose-dependent manner. Further functional assays revealed that the anti-cancer effect of genistein activated microRNA-27a (miR-27a) expression levels and reduced MET protein expression in A549 cells. In conclusion, the present study demonstrates that genistein inhibits A549 human lung cancer cell proliferation. Furthermore, this study reports, for the first time, a correlation between the anti-cancer effect of genistein and miR-27a-mediated MET signaling.

Soluble c-Met Levels Correlated With Tissue c-Met Protein Expression in Patients With Advanced Non-Small-Cell Lung Cancer

BACKGROUND

Immunohistochemistry (IHC) and fluorescent in situ hybridization are reliable methods for identifying c-Met protein expression or c-Met gene amplification. However, each technique requires a high-quality tissue sample, which might not be available. The aim of the present study was to investigate the correlation between the soluble c-Met level and tissue c-Met protein expression and the relationship between these markers and patient prognosis.

MATERIALS AND METHODS

In 198 patients with advanced non-small-cell lung cancer, tumor tissue c-Met expression was determined using IHC according to the H score criteria. Positivity was defined as ≥ 50% of cells with strong staining (IHC 3+). The concentration of c-Met protein in paired plasma samples was measured using a human soluble c-Met quantitative enzyme-linked immunosorbent assay kit, and the predictive value was determined using receiver operating characteristic curve analysis.

RESULTS

Of the 198 patients, 140 (70.7%) had tissue c-Met^- findings and 58 (29.3%) tissue c-Met⁺ findings. Receiver operating characteristic curve analysis showed 67.2% specificity and 65.0% sensitivity for predicting tissue c-Met positivity at a plasma c-Met cutoff of 766 ng/mL. The correlation between the soluble c-Met level and tissue c-Met protein expression was significant (Pearson's r = 0.309; P < .001). Patients with high soluble c-Met levels (> 766 ng/mL) had poorer overall survival than patients with low soluble c-Met levels (9.5 vs. 22.2 months; P < .001). Multivariate analyses demonstrated the same result (hazard ratio, 2.15; 95% confidence interval, 1.334-3.446; P = .002).

CONCLUSION

A significant correlation was found between the plasma soluble c-Met levels and tissue c-Met protein expression in patients with advanced non-small-cell lung cancer. A high level of soluble c-Met was associated with a poor prognosis.

Clinicopathological significance and concordance analysis of c-MET immunohistochemistry in non-small cell lung cancers: A meta-analysis

OBJECTIVE

The aim of this study was to investigate the clinicopathological significance and concordance rate of c-MET immunohistochemistry (IHC) in non-small cell lung cancer (NSCLC) through meta-analysis and diagnostic test accuracy review.

METHODS

The current study included 4454 NSCLC cases of 22 eligible studies. The meta-analysis examined the correlation between c-MET IHC expression and clinicopathological parameters. We investigated concordance rate between c-MET IHC and genetic alteration and performed subgroup analysis based on c-MET IHC cut-off value.

RESULTS

The estimated positive rate of c-MET IHC was 0.440 (95% confidence interval [CI] 0.355-0.529). The positive rate of c-MET IHC was significantly high in non-squamous cell carcinomas and tumors with stage III-IV. However, there was no significant difference between c-MET IHC positivity and sex, smoking, and lymph node metastasis. The c-MET IHC positivity was significantly correlated with poor overall survival (hazard ratio 1.551, 95% CI 1.101-2.184). In c-MET IHC-positive and negative groups, the concordance rate was 0.941 (95% CI 0.885-0.971) and 0.300 (95% CI 0.196-0.429), respectively. The pooled sensitivity and specificity of the high cut-off subgroup for c-MET IHC was 1.00 (95% CI 0.92-1.00) and 0.78 (95% CI 0.75-0.81), respectively. The diagnostic odds ratio and the area under curve on summary receiver operating characteristic curve were 76.56 (95% CI 8.23-712.41) and 0.9949, respectively.

CONCLUSION

The c-MET IHC could be useful for screening of c-MET genetic alteration in NSCLC patients. Detailed criteria for c-MET IHC evaluation are necessary to determine how to best apply this approach in daily practice.

Comprehensive gene and microRNA expression profiling reveals miR-206 inhibits MET in lung cancer metastasis

MiRNAs associated with the metastasis of lung cancer remain largely unexplored. In this study, gene and miRNA expression profiling were performed to analyze the global expression of mRNAs and miRNAs in human high- and low-metastatic lung cancer cell strains. By developing an integrated bioinformatics analysis, six miRNAs (miR-424-3p, miR-450b-5p, miR-335-5p, miR-34a-5p, miR-302b-3p and miR-206) showed higher target gene degrees in the miRNA-gene network and might be potential metastasis-related miRNAs. Using the qRT-PCR method, the six miRNAs were further confirmed to show a significant expression difference between human lung cancer and normal tissue samples. Since miR-206 showed lower expression both in lung cancer tissues and cell lines, it was used as an example for further functional verification. The wound healing assay and transwell invasion assay showed that miR-206 mimics significantly inhibited the cell migration and invasion of the high-metastatic lung cancer 95D cell strain. One of its predicted targets in our miRNA-gene network, MET, was also obviously decreased at the protein level when miR-206 was overexpressed. Instead, miR-206 inhibitors increased MET protein expression, cell migration and invasion of the low-metastatic lung cancer 95C cell strain. Meanwhile, the luciferase assay showed that MET was a direct target of miR-206. Furthermore, MET gene silence showed a similar anti-migration and anti-invasion effect with miR-206 mimics in 95D cells and could partially attenuate the migration- and invasion-promoting effect of miR-206 inhibitors in 95C cells, suggesting that miR-206 targets MET in lung cancer metastasis. Finally, we also demonstrated that miR-206 can significantly inhibit lung cancer proliferation and metastasis in mouse models. In conclusion, our study provided a miRNA-gene regulatory network in lung cancer metastasis and further demonstrated the roles of miR-206 and MET in this process, which enhances the understanding of the regulatory mechanism in lung cancer metastasis.

Prognostic Impact of Multiple Clinicopathologic Risk Factors and c-MET Overexpression in Patients Who Have Undergone Resection of Stage IB Non-Small-Cell Lung Cancer

BACKGROUND

Several studies have suggested risk factors for poor survival in stage IB non-small-cell lung cancer (NSCLC) patients. However, these factors are not definite indicators of adjuvant chemotherapy for stage IB cancer, and most of them can be used to consider adjuvant chemotherapy. We aimed to determine the clinicopathologic factors and assess whether c-MET is a prognostic factor in stage IB NSCLC patients who have undergone surgery. Additionally, we determined the relevance of the factors and the recurrence pattern in these patients.

PATIENTS AND METHODS

This study included 115 patients who underwent resection of pathologic stage IB NSCLC between January 2005 and December 2013. We retrospectively reviewed the clinicopathologic data and performed immunohistochemical analysis for c-MET. Recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS) were evaluated according to clinicopathologic factors and c-MET expression.

RESULTS

Lymphovascular invasion (LVI) and c-MET overexpression were significantly associated with poor RFS. A large tumor with visceral pleural invasion (VPI) or LVI, moderate/poor differentiation with LVI, and VPI with LVI were negative prognostic factors for RFS and CSS. c-MET overexpression with a large tumor, VPI, or LVI was an independent prognostic factor for poor RFS and CSS, and LVI was a significant factor for distant recurrence.

CONCLUSION

LVI and c-MET overexpression might be associated with poor prognosis in stage IB NSCLC patients. Additionally, survival might be poor in stage IB patients with multiple pathologic risk factors. Moreover, there is a high possibility of distant recurrence in patients with LVI.

Prognostic impact and potential interaction of EGFR and c-Met in the progression of esophageal squamous cell carcinoma

This study is to examine EGFR and c-Met variation in precancerous lesion, early esophageal squamous cell carcinoma (ESCC), and advanced ESCC and to explore their prognostic significance. EGFR and c-Met were detected by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Of 158 endoscopy resection (ER) specimens, c-Met high expression and FISH positive were 44.9 and 12.6 %, respectively. EGFR high expression and FISH positive were 2.5 and 19.6 %, respectively. Of 84 surgical specimens, c-Met high expression and FISH positive were 50 and 8.3 %, respectively. EGFR high expression and FISH positive were 7.1 and 28.5 %, respectively. A significant correlation was observed between c-Met and EGFR FISH positive both in ER (P < 0.001) and surgical specimens (P = 0.029). Patients with EGFR high expression had poorer disease-free survival (DFS) and overall survival (OS) (P = 0.031 and P = 0.013) in c-Met high-expression group but not in c-Met low-expression group (P = 0.301 and P = 0.439). C-Met FISH positive did not represent a statistically significant adverse prognosis until 24 months later (P = 0.027 and 0.048). EGFR and c-Met might be involved in the tumorigenesis and development of ESCC. EGFR high expression has different prognostic significance in patients with differing c-Met expression status. C-Met FISH positive represent delayed prognostic factor.

[Mechanism of c-MET in Non-small Cell Lung Cancer and Its Treatment and Testing]

Hepatocyte growth factor/c-MET (HGF/c-MET) signaling pathway can be abnormal activated by many mechanisms such as c-MET mutation, amplification and the overexpression of HGF, and it plays an important role in the development of non-small cell lung cancer (NSCLC), as well as in the tolerance of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) in NSCLC. Therefore, c-MET is a new molecular target for the therapy of NSCLC since EGFR and ALK. At present, although the c-MET inhibitors have shown a potential prospect in some clinical trials, its assessment of safety and effectiveness in clinical applications, and the choice of testing methods and standards still need a further discussion. In this paper, we summarized the mechanism of c-MET in NSCLC, as well as its treatment prospect and selection of testing methods.

Predictive and prognostic value of de novo MET expression in patients with advanced non-small-cell lung cancer

BACKGROUND

Cellular-mesenchymal-epithelial transition (MET) protein has recently been identified as a novel target that shows promise for the treatment of non-small-cell lung cancer (NSCLC). However, the relationship between de novo MET expression and patient outcomes remains unclear.

METHODS

We reviewed the data of patients who had been diagnosed with NSCLC between December 2013 and October 2014. All the patients were evaluated for MET expression status. MET-positive was defined as having an H-score ≥ 60 by immunohistochemistry analysis. MET expression was analyzed in 158 patients who were negative for the common driver genes, including EGFR, ALK, KRAS and ROS1. A chi-squared test was used to assess the clinicopathological parameters. Multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

MET data were available for analysis in 158 advanced NSCLC patients. Of these, based on the MET H-score criteria, the IHC-positive rate was 48.1% (76/158). There were more patients with adenocarcinoma in the MET-positive group compared with the MET-negative group (P=0.01). Nine patients with lymphoepithelioma-like carcinoma had no MET expression. There was no significant difference in overall survival (OS) between MET-positive and -negative patients. There was also no significant difference in the efficacy (Z=-0.44, P=0.66) or progression free survival (PFS) of first-line chemotherapy between the MET-positive and -negative patients (mPFS 6.8 months [95% CI: 5.4-8.2] vs. 5.9 months [5.5-6.3], P=0.92). In the cell model, the MET-positive cell showed no difference in chemotherapy but with a increase in percentage of growth inhibition upon treatment with MET inhibitor INC280 compared to MET-negative cell.

CONCLUSION

Our data showed that de novo MET expression was not rare. It was not a predictive or prognostic factor for stage IV NSCLC patients, but this should be confirmed in larger population cohort.

cMET in NSCLC: Can We Cut off the Head of the Hydra? From the Pathway to the Resistance

In the last decade, the tyrosine kinase receptor cMET, together with its ligand hepatocyte growth factor (HGF), has become a target in non-small cell lung cancer (NSCLC). Signalization via cMET stimulates several oncological processes amongst which are cell motility, invasion and metastasis. It also confers resistance against several currently used targeted therapies, e.g., epidermal growth factor receptor (EGFR) inhibitors. In this review, we will discuss the basic structure of cMET and the most important signaling pathways. We will also look into aberrations in the signaling and the effects thereof in cancer growth, with the focus on NSCLC. Finally, we will discuss the role of cMET as resistance mechanism.

Targeting the MET pathway for potential treatment of NSCLC

INTRODUCTION

The mesenchymal-epithelial transition (MET) protein is the only known receptor for hepatocyte growth factor and has recently been identified as a novel promising target in several human cancers, including NSCLC. Activation of the MET signaling pathway can occur via different mechanisms. A number of compounds targeting MET have been evaluated in clinical trials, and recent clinical data have begun to afford some insight into the tumor types and patient populations that might benefit from treatment with MET pathway inhibitors.

AREAS COVERED

We review recent publications and information disclosed at public conferences and summarize the epidemiology of dysregulation of MET signaling, and the associations thereof with other driver genes and therapeutic inhibitors useful to treat NSCLC.

EXPERT OPINION

The MET pathway is emerging as a target for advanced NSCLC that is either resistant to EGFR tyrosine kinase inhibitors or that arises de novo. MET inhibitors currently being evaluated in clinical trials have yielded compelling evidence of clinical activities when used to treat various solid tumors, especially NSCLC. Remaining challenges are the identification of patient populations who might benefit from the use of MET inhibitors, and the most effective diagnostic methods for such patients.

Non-Small Cell Lung Carcinoma Biomarker Testing: The Pathologist's Perspective

Biomarker testing has become standard of care for patients diagnosed with non-small cell lung carcinoma (NSCLC). Although, it can be successfully performed in circulating tumor cells, at present, the vast majority of investigations are carried out using direct tumor sampling, either through aspiration methods, which render most often isolated cells, or tissue sampling, that could range from minute biopsies to large resections. Consequently, pathologists play a central role in this process. Recent evidence suggests that refining NSCLC diagnosis might be clinically significant, particularly in cases of lung adenocarcinomas (ADC), which in turn, has prompted a new proposal for the histologic classification of such pulmonary neoplasms. These changes, in conjunction with the mandatory incorporation of biomarker testing in routine NSCLC tissue processing, have directly affected the pathologist’s role in lung cancer work-up. This new role pathologists must play is complex and demanding, and requires a close interaction with surgeons, oncologists, radiologists, and molecular pathologists. Pathologists often find themselves as the central figure in the coordination of a process, that involves assuring that the tumor samples are properly fixed, but without disruption of the DNA structure, obtaining the proper diagnosis with a minimum of tissue waste, providing pre-analytical evaluation of tumor samples selected for biomarker testing, which includes assessment of the proportion of tumor to normal tissues, as well as cell viability, and assuring that this entire process happens in a timely fashion. Therefore, it is part of the pathologist’s responsibilities to assure that the samples received in their laboratories, be processed in a manner that allows for optimal biomarker testing. This article goal is to discuss the essential role pathologists must play in NSCLC biomarker testing, as well as to provide a summarized review of the main NSCLC biomarkers of clinical interest.