Functional expression and mutations of c-Met and its therapeutic inhibition with SU11274 and small interfering RNA in non-small cell lung cancer

Phase 1/2 study of rilotumumab (AMG 102), a hepatocyte growth factor inhibitor, and erlotinib in patients with advanced non-small cell lung cancer

BACKGROUND

Activation of the mesenchymal-epidermal transition factor (MET) tyrosine kinase and its ligand, hepatocyte growth factor (HGF), is implicated in resistance to epidermal growth factor receptor (EGFR) inhibitors. In this phase 1/2 trial, rilotumumab (an anti-HGF antibody) combined with erlotinib was evaluated in patients with metastatic, previously treated non-small cell lung cancer.

METHODS

In phase 1, a dose de-escalation design was adopted with rilotumumab starting at 15 mg/kg intravenously every 3 weeks and oral erlotinib 150 mg daily. In phase 2, the disease control rate (DCR) (according to Response Evaluation Criteria in Solid Tumors) of the combination was evaluated using a Simon 2-stage design. The biomarkers examined included 10 plasma-circulating molecules associated with the EGFR and MET pathways.

RESULTS

Without indications for de-escalation, the recommended phase 2 dose was dose level 0. Overall, 45 response-evaluable patients were enrolled (13 with squamous carcinoma, 32 with adenocarcinoma; 2 had confirmed EGFR mutations, 33 had confirmed wild-type [WT] EGFR, and 7 had KRAS mutations). The DCR for all patients was 60% (90% confidence interval [CI], 47.1%-71.3%). Median progression-free survival was 2.6 months (90% CI, 1.4-2.7 months), and median overall survival was 6.6 months (90% CI, 5.6-8.9 months). Among patients with WT EGFR, the DCR was 60.6% (90% CI, 46.3%-73.3%), median progression-free survival was 2.6 months (90% CI, 1.4-2.7 months), and median overall survival was 7.0 months (90% CI, 5.6-13.4 months). Elevated baseline levels of neuregulin 1 were associated with longer progression-free survival (hazard ratio, 0.41; 95% CI, 0.19-0.87), whereas elevated amphiregulin levels were associated with more rapid progression (hazard ratio, 2.14; 95% CI, 1.48-3.08).

CONCLUSIONS

Combined rilotumumab and erlotinib had an acceptable safety profile, and the DCR met the prespecified criteria for success. In the EGFR WT group, the DCR exceeded published reports for erlotinib alone. High circulating levels of neuregulin 1 may indicate sensitivity to this combination. Cancer 2017;123:2936-44. © 2017 American Cancer Society.

MET in human cancer: germline and somatic mutations

Since the initial discovery of missense MET mutations in hereditary papillary renal carcinoma (HPRC), activating MET mutations have been identified in a diverse range of human cancers. MET mutations have been identified in several functional domains including the kinase, juxtamembrane, and Sema domains. Studies of these mutations have been invaluable for our understanding of the tumor initiating activity of MET, receptor tyrosine kinase (RTK) recycling and regulation, and mechanisms of resistance to kinase inhibition. These studies also demonstrate that mutationally activated MET plays a significant role in a wide range of cancers and RTKs can promote tumor progression through diverse mechanisms. This review will cover the various MET mutations that have been identified, their mechanism of action, and the significant role that mutationally-activated MET plays in tumor initiation, progression, and therapeutic resistance.

Potential Antitumor Activity of SIM-89 in Non-Small Cell Lung Cancer Cells

PURPOSE

c-Met and its ligand, hepatocyte growth factor (HGF), play a critical role in oncogenesis and metastatic progression. The aim of this study was to identify inhibited enzymogram and to test the antitumor activity of SIM-89 (a c-Met receptor tyrosine kinase inhibitor) in non-small cell lung cancer.

MATERIALS AND METHODS

Z'-LYTE kinase assay was employed to screen the kinase enzymogram, and mechanism of action (MOA) analysis was used to identify the inhibited kinases. Cell proliferation was then analyzed by CCK8 assay, and cell migration was determined by transwell assay. The gene expression and the phosphorylation of c-Met were examined by realtime-PCR and western blotting, respectively. Finally, the secretion of HGF was detected by ELISA assay.

RESULTS

c-Met, activated protein kinase (AMPK), and tyrosine kinase A (TRKA) were inhibited by SIM-89 with the IC₅₀ values of 297 nmol/L, 1.31 μmol/L, and 150.2 nmol/L, respectively. SIM-89 exerted adenosine triphosphate (ATP) competitive inhibition on c-Met. Moreover, the expressions of STAT1, JAK1, and c-Met in H460 cells were decreased by SIM-89 treatment, and c-Met phosphorylation was suppressed in A549, H441, H1299, and B16F10 cells by the treatment. In addition, SIM-89 treatment significantly decreased the level of HGF, which accounted for the activation of c-Met receptor tyrosine kinase. Finally, we showed cell proliferation inhibition and cell migration suppression in H460 and H1299 cells after SIM-89 treatment.

CONCLUSION

In conclusion, SIM-89 inhibits tumor cell proliferation, migration and HGF autocrine, suggesting it's potential antitumor activity.

Migration of oral squamous cell carcinoma cells are induced by HGF/c-Met signalling via lamellipodia and filopodia formation

The activation of receptor tyrosine kinases (RTKs) results in cellular effects including cell proliferation, survival, migration and invasion; RTKs also play an important role in tumourigenesis. It has been reported that EGFR signalling controls the migration of oral squamous cell carcinoma (OSCC) SAS and HSC3 cells but not of HSC4 cells, although the proliferation of HSC4 cells is regulated by EGF/EGFR. In the present study, we investigated the roles of EGFR and the c-Met signalling pathway in cell migration via filopodia and lamellipodia formation, which may be prerequisites for migration. To explore the role of c-Met in cell migration, we inhibited c-Met RTK activity using the c-Met inhibitor SU11274 and activated c-Met using hepatocyte growth factor (HGF) in three OSCC cell lines HSC4, SAS and Ca9-22 and investigated migration potency using a wound healing assay. We showed that inhibition of c-Met significantly suppressed, and activation of c-Met significantly promoted, the migration of OSCC cells. Additionally, the migration of SAS and Ca9-22 cells was inhibited by the EGFR inhibitors AG1478 and cetuximab and promoted by EGF treatment. Moreover, migration potency was correlated with lamellipodia formation. Furthermore, western blot analyses demonstrated that SU11274 decreased and HGF increased lamellipodin protein levels as well as phosphorylated c-Met levels. Collectively, we demonstrated that c-Met signalling induced lamellipodia formation by upregulating lamellipodin, thereby promoting the migration of OSCC cells.

AXL and MET receptor tyrosine kinases are essential for lung cancer metastasis

The AXL and MET receptors regulate key processes in tumor growth, metastasis, and drug resistance; thus, they have recently been implicated as promising therapeutic targets in various tumors. We investigated the metastatic potential and crosstalk between these receptors in non‑small cell lung cancer (NSCLC). We found that the treatment of NSCLC cells with hepatocyte growth factor (HGF) and growth arrest-specific 6 (Gas6), as ligands for MET and AXL, respectively, promoted their migration and invasion ability. However, treatment with inhibitors of each of these receptors significantly reduced the migratory and invasiveness of the cells, although their inhibitory rates varied according to the inhibition of each receptor. In addition, the suppression of each receptor by shRNA resulted in reduced migration and invasiveness. Notably, the suppression of AXL was more effective than the suppression of MET in the inhibition of migration and invasion. In accordance with in vitro results, when the cells were transferred via tail vein injection, AXL inhibition was more efficient in attenuating metastasis than MET inhibition. Clinically, AXL or MET expression is associated with a poor prognosis in primary tumors of NSCLC. In summary, AXL and MET can regulate tumor metastasis, but AXL was shown to be more potent than MET in lung metastasis. Thus, we conclude that AXL might be a suitable therapeutic target for the inhibition of lung metastasis.

MiR-206 inhibits HGF-induced epithelial-mesenchymal transition and angiogenesis in non-small cell lung cancer via c-Met /PI3k/Akt/mTOR pathway

MiR-206 is low expression in lung cancers and associated with cancer metastasis. However, the roles of miR-206 in epithelial-mesenchymal transition (EMT) and angiogenesis in lung cancer remain unknown. In this study, we find that hepatocyte growth factor (HGF) induces EMT, invasion and migration in A549 and 95D lung cancer cells, and these processes could be markedly inhibited by miR-206 overexpression. Moreover, we demonstrate that miR-206 directly targets c-Met and inhibits its downstream PI3k/Akt/mTOR signaling pathway. In contrast, miR-206 inhibitors promote the expression of c-Met and activate the PI3k/Akt/mTOR signaling, and this effect could be attenuated by the PI3K inhibitor. Moreover, c-Met overexpression assay further confirms the significant inhibitory effect of miR-206 on HGF-induced EMT, cell migration and invasion. Notably, we also find that miR-206 effectively inhibits HGF-induced tube formation and migration of human umbilical vein endothelial cells (HUVECs), and the mechanism is also related to inhibition of PI3k/Akt/mTOR signaling. Finally, we reveal the inhibitory effect of miR-206 on EMT and angiogenesis in xenograft tumor mice model. Taken together, miR-206 inhibits HGF-induced EMT and angiogenesis in lung cancer by suppressing c-Met/PI3k/Akt/mTOR signaling. Therefore, miR-206 might be a potential target for the therapeutic strategy against EMT and angiogenesis of lung cancer.

MET/HGF pathway activation as a paradigm of resistance to targeted therapies

Resistance to targeted therapeutics is a key issue limiting the long-term utility of these medications in the management of molecularly selected subsets of cancer patients, including patients with non-small cell lung cancer harboring oncogenic alterations affecting EGFR, ALK and other genes. Bypass resistance mediated by activation of MET kinase has emerged as a frequent, validated and pivotal resistance mechanism in multiple types of cancers. Biochemical understanding is accumulating to explain the unique role of MET in such bypass pathways, providing alternate downstream activation opportunities and intricate interactions during epithelial-mesenchymal transitions. Multiple diagnostic testing platforms have become available for selecting appropriate patients for MET targeting in a variety of settings. Importantly, in light of the failures of several earlier clinical studies of MET targeting agents, a large array of recent and current MET-focused trials are incorporating stricter patient selection and more robust predictive biomarkers providing hope for validation of MET targeting as a clinically impactful strategy.

MET: roles in epithelial-mesenchymal transition and cancer stemness

In a number of cancers, deregulated MET pathway leads to aberrantly activated proliferative and invasive signaling programs that promote malignant transformation, cell motility and migration, angiogenesis, survival in hypoxia, and invasion. A better understanding of oncogenic MET signaling will help us to discover effective therapeutic approaches and to identify which tumors are likely to respond to MET-targeted cancer therapy. In this review, we will summarize the roles of MET signaling in cancer, with particular focus on epithelial-mesenchymal transition (EMT) and cancer stemness. Then, we will provide update on MET targeting agents and discuss the challenges that should be overcome for the development of an effective therapy.

Targeting MET in Lung Cancer: Will Expectations Finally Be MET?

The hepatocyte growth factor receptor (MET) is a potential therapeutic target in a number of cancers, including NSCLC. In NSCLC, MET pathway activation is thought to occur through a diverse set of mechanisms that influence properties affecting cancer cell survival, growth, and invasiveness. Preclinical and clinical evidence suggests a role for MET activation as both a primary oncogenic driver in subsets of lung cancer and as a secondary driver of acquired resistance to targeted therapy in other genomic subsets. In this review, we explore the biology and clinical significance behind MET proto-oncogene receptor tyrosine kinase (MET) exon 14 alterations and MET amplification in NSCLC, the role of MET amplification in the setting of acquired resistance to EGFR tyrosine kinase inhibitor therapy in EGFR-mutant NSCLC, and the history of MET pathway inhibitor drug development in NSCLC, highlighting current strategies that enrich for biomarkers likely to be predictive of response. Whereas previous trials that focused on MET pathway-directed targeted therapy in unselected or MET-overexpressing NSCLC yielded largely negative results, more recent investigations focusing on MET exon 14 alterations and MET amplification have been notable for meaningful clinical responses to MET inhibitor therapy in a substantial proportion of patients.

MET exon 14 juxtamembrane splicing mutations: clinical and therapeutical perspectives for cancer therapy

The MET proto-oncogene plays crucial roles in cell growth and proliferation, survival and apoptosis, epithelial-mesenchymal transition (EMT) and invasion, potentially conditioning the development and progression of the carcinogenesis process. The MET-associated aberrant signaling could be triggered by a variety of mechanisms, such as mutations, gene amplification, increased gene copy number and Met/HGF protein expression. Among the various MET alterations, MET exon 14 splicing abnormalities, causing the loss of the Met juxtamembrane (JM) domain, recently emerged as a new potential oncogenic driver and have been identified and validated across different cancer and histology subtypes. Moreover, this aberration was found to be mutually exclusive with other recognized drivers, thus strongly nominating its potential oncogenic role. Recently, the clinical activity of anti-Met-targeted therapy was demonstrated particularly in patients harboring MET exon 14 skipping lung cancer, resulting in a renewed enthusiasm to further test MET precision therapy in prospective trials. In this review, the key preclinical and clinical data regarding MET exon 14 skipping splicing variants as an actionable genomic aberration in cancer are described, and the perspectives deriving from the validation of such alteration as a potential target, which may further allow driving the therapeutic approach in this molecularly selected patients' subgroup, are explored.

GPR171 expression enhances proliferation and metastasis of lung cancer cells

G protein-coupled receptors (GPCRs) are among the most significant therapeutic targets and some of them promote the growth and metastasis of cancer. Here, we show that an increase in the levels of GPR171 is crucial for lung cancer tumor progression in vitro and in vivo. Immunostaining of clinical samples indicated that GPR171 was overexpressed in 46.8% of lung carcinoma tissues. Depletion of GPR171 with an anti-GPR171 antibody decreased proliferation of lung carcinoma cells and attenuated tumor progression in a mouse xenograft model. Knockdown of GPR171 also inhibited migration and invasion of the lung cancer cell lines. Notably, inhibition of GPR171 synergistically enhanced the tumoricidal activity of an epidermal growth factor receptor (EGFR) inhibitor in lung cancer cells. These results indicate that GPR171 blockade is a promising antineoplastic strategy and provide a preclinical rationale for combined inhibition of GPR171 and EGFR.

A comprehensive analysis of clinical outcomes in lung cancer patients harboring a MET exon 14 skipping mutation compared to other driver mutations in an East Asian population

INTRODUCTION

Recurrent somatic splice-site alterations at MET exon 14 (MET^Δ14), which result in exon skipping and MET proto-oncogene, receptor tyrosine kinase (MET) activation, have been characterised. However, their demographic features and clinical outcomes in East Asian lung cancer patients have yet to be determined.

METHODS

A one-step reverse transcription-polymerase chain reaction (RT-PCR), using RNA samples from 850 East Asian lung cancer patients, was performed in order to detect MET^Δ14 and five other major driver mutations, including those in the EGFR, KRAS, ALK, HER2, and ROS1 genes. Immunohistochemistry (IHC) was used to confirm the overexpression of MET in patients harbouring the MET^Δ14 mutation. We analysed the demographic data and clinical outcomes of MET^Δ14 mutation positive lung cancer patients and compared them to those of MET^Δ14 mutation negative lung cancer patients.

RESULTS

In total, 27 lung adenocarcinoma (ADC) patients and 1 squamous cell carcinoma patient with the MET^Δ14 mutation were identified. The overall incidence was 3.3% for lung cancer and 4.0% for lung ADC. IHC demonstrated that the majority of lung cancer patients harboring a MET^Δ14 mutation exhibited a strong cytoplasmic expression of MET. MET^Δ14 mutation positive patients were generally quite elderly individuals. Stage IV MET^Δ14 mutation positive lung cancer patients receiving no specific anti-MET therapy were observed to have a similar overall survival (OS) compared to patients in the all negative group (P>0.05). In the multivariate analysis, mutation status was found not to be a major risk factor for OS in lung cancer patients without appropriate tyrosine kinase inhibitors treatment.

CONCLUSIONS

The OS of MET^Δ14 mutation positive lung cancer patients is comparable to that of the major driver gene mutation negative lung cancer patients.

The race to target MET exon 14 skipping alterations in non-small cell lung cancer: The Why, the How, the Who, the Unknown, and the Inevitable

A number of small molecule tyrosine kinase inhibitors (TKIs) have now been approved for the treatment of non-small cell lung cancers (NSCLC), including those targeted against epidermal growth factor receptor, anaplastic lymphoma kinase, and ROS1. Despite a wealth of agents developed to target the receptor tyrosine kinase, MET, clinical outcomes have as yet been disappointing, leading to pessimism about the role of MET in the pathogenesis of NSCLC. However, in recent years, there has been a renewed interest in MET exon 14 alterations as potential drivers of lung cancer. MET exon 14 alterations, which result in increased MET protein levels due to disrupted ubiquitin-mediated degradation, occur at a prevalence of around 3% in adenocarcinomas and around 2% in other lung neoplasms, making them attractive targets for the treatment of lung cancer. At least five MET-targeted TKIs, including crizotinib, cabozantinib, capmatinib, tepotinib, and glesatinib, are being investigated clinically for patients with MET exon 14 altered-NSCLC. A further two compounds have shown activity in preclinical models. In this article, we review the current clinical and preclinical data available for these TKIs, along with a number of other potential therapeutic options, including antibodies and immunotherapy. A number of questions remain unanswered regarding the future of MET TKIs, but unfortunately, the development of resistance to targeted therapies is inevitable. Resistance is expected to arise as a result of receptor tyrosine kinase mutation or from upregulation of MET ligand expression; potential strategies to overcome resistance are proposed.

The End of Nihilism: Systemic Therapy of Advanced Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer death in the United States and many other parts of the world. Non-small cell lung cancer (NSCLC) comprises 85-90% of lung cancers. Historically, the expected survival of patients with advanced disease has been estimated in months. In recent years, however, lung cancer has come to be seen as a treatable disease with multiple therapeutic options. Enormous advances in the understanding of its pathways and mechanisms have enabled personalized therapy in NSCLC. The evolving approach to therapy focuses on genomic profiling of the tumors to find molecular targets and develop specific agents for individualized therapy. In addition, maintenance therapy has emerged as a valid approach, and the choice of chemotherapy now varies by histology. Most recently, immunotherapy with checkpoint inhibitors has shown promising results, with impressive durations of response and a tolerable toxicity profile. Together, these discoveries have improved overall survival substantially in patient populations that have access to these advancements. We review the clinical data surrounding these impressive improvements.

New and emerging targeted treatments in advanced non-small-cell lung cancer

Targeted therapies are substantially changing the management of lung cancers. These treatments include drugs that target driver mutations, those that target presumed important molecules in cancer cell proliferation and survival, and those that inhibit immune checkpoint molecules. This area of research progresses day by day, with novel target discoveries, novel drug development, and use of novel combination treatments. Researchers and clinicians have also extensively investigated the predictive biomarkers and the molecular mechanisms underlying inherent or acquired resistance to these targeted therapies. We review recent progress in the development of targeted treatments for patients with advanced non-small-cell lung cancer, especially focusing on data from published clinical trials.

Automated tumor analysis for molecular profiling in lung cancer

The discovery and clinical application of molecular biomarkers in solid tumors, increasingly relies on nucleic acid extraction from FFPE tissue sections and subsequent molecular profiling. This in turn requires the pathological review of haematoxylin & eosin (H&E) stained slides, to ensure sample quality, tumor DNA sufficiency by visually estimating the percentage tumor nuclei and tumor annotation for manual macrodissection. In this study on NSCLC, we demonstrate considerable variation in tumor nuclei percentage between pathologists, potentially undermining the precision of NSCLC molecular evaluation and emphasising the need for quantitative tumor evaluation. We subsequently describe the development and validation of a system called TissueMark for automated tumor annotation and percentage tumor nuclei measurement in NSCLC using computerized image analysis. Evaluation of 245 NSCLC slides showed precise automated tumor annotation of cases using Tissuemark, strong concordance with manually drawn boundaries and identical EGFR mutational status, following manual macrodissection from the image analysis generated tumor boundaries. Automated analysis of cell counts for % tumor measurements by Tissuemark showed reduced variability and significant correlation (p < 0.001) with benchmark tumor cell counts. This study demonstrates a robust image analysis technology that can facilitate the automated quantitative analysis of tissue samples for molecular profiling in discovery and diagnostics.

Hypoxia-Driven Mechanism of Vemurafenib Resistance in Melanoma

Melanoma is molecularly and structurally heterogeneous, with some tumor cells existing under hypoxic conditions. Our cell growth assays showed that under controlled hypoxic conditions, BRAF(V600E) melanoma cells rapidly became resistant to vemurafenib. By employing both a three-dimensional (3D) spheroid model and a two-dimensional (2D) hypoxic culture system to model hypoxia in vivo, we identified upregulation of HGF/MET signaling as a major mechanism associated with vemurafenib resistance as compared with 2D standard tissue culture in ambient air. We further confirmed that the upregulation of HGF/MET signaling was evident in drug-resistant melanoma patient tissues and mouse xenografts. Pharmacologic inhibition of the c-Met/Akt pathway restored the sensitivity of melanoma spheroids or 2D hypoxic cultures to vemurafenib. Mol Cancer Ther; 15(10); 2442-54. ©2016 AACR.

Mechanism of c-Met and EGFR tyrosine kinase inhibitor resistance through epithelial mesenchymal transition in non-small cell lung cancer

According to currently available estimates from Cancer Research UK, 14.1 million new lung cancer cases were diagnosed and a staggering 8.2 million people worldwide died from lung cancer in 2012. EGFR and c-Met are two tyrosine kinase receptors most commonly overexpressed or mutated in Non-small Cell Lung Cancer (NSCLC) resulting in increased proliferation and survival of lung cancer cells. Tyrosine kinase inhibitors (TKIs), such as erlotinib, approved by the FDA as first/second line therapy for NSCLC patients have limited clinical efficacy due to acquired resistance. In this manuscript, we investigate and discuss the role of epithelial mesenchymal transition (EMT) in the development of resistance against EGFR and c-Met TKIs in NSCLC. Our findings show that Zeb-1, a transcriptional repressor of E-Cadherin, is upregulated in TKI-resistant cells causing EMT. We observed that TKI-resistant cells have increased gene and protein expression of EMT related proteins such as Vimentin, N-Cadherin, β-Catenin and Zeb-1, while expression of E-Cadherin, an important cell adhesion molecule, was suppressed. We also confirmed that TKI-resistant cells display mesenchymal cell type morphology, and have upregulation of β-Catenin which may regulate expression of Zeb-1, a transcriptional repressor of E-Cadherin in TKI-resistant NSCLC cells. Finally, we show that down-regulating Zeb-1 by inducing miR-200a or β-Catenin siRNA can increase drug sensitivity of TKI-resistant cells.

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.

MicroRNA-206 inhibits the viability and migration of human lung adenocarcinoma cells partly by targeting MET

MicroRNA (miRNA)-based targeting in cancer has emerged as a potential therapeutic strategy. miR-206 has recently been implicated in cancer. However, the role and molecular mechanism of miR-206 in lung adenocarcinoma are still unclear. The present study revealed that miR-206 was downregulated in human lung adenocarcinoma tissues. Overexpression of miR-206 in human lung adenocarcinoma-derived cells significantly inhibited cell viability and migration. Further experiments indicated that the overexpression of miR-206 decreased the expression of MET at the messenger RNA and protein levels via direct targeting of MET in a 3'-untranslated region-dependent manner. The knockdown of MET by small interfering RNA partly led to a phenocopy effect of miR-206. In conclusion, the present study identified miR-206 as a potential tumor suppressor of lung adenocarcinoma that exerts its functions, in part, by negative regulation of MET.

Biomarker development in MET-targeted therapy

Activation of the MET receptor tyrosine kinase by its ligand, hepatocyte growth factor (HGF), has been implicated in a variety of cellular processes, including cell proliferation, survival, migration, motility and invasion, all of which may be enhanced in human cancers. Aberrantly activated MET/HGF signaling correlates with tumorigenesis and metastasis, and is regarded as a robust target for the development of novel anti-cancer treatments. Various clinical trials were conducted to evaluate the safety and efficacy of selective HGF/MET inhibitors in cancer patients. There is currently no optimal or standardized method for accurate and reliable assessment of MET levels, or other biomarkers that are predictive of the patient response to MET-targeted therapeutics. In this review, we discuss the importance of accurate HGF/MET signal detection as a predictive biomarker to guide patient selection for clinical trials of MET-targeted therapies in human cancers.

Identifying the Appropriate FISH Criteria for Defining MET Copy Number-Driven Lung Adenocarcinoma through Oncogene Overlap Analysis

INTRODUCTION

Mesenchymal-epithelial transition factor gene (MET) gene copy number gain may be a predictive biomarker for mesenchymal-epithelial transition factor (MET) inhibition in lung cancer, but the most appropriate method and criteria for defining MET positivity are uncertain.

METHODS

MET copy number was assessed by fluorescence in situ hybridization in lung adenocarcinoma. Positivity criteria included mean MET per cell values greater than 5 (low [≥5 to <6], intermediate [≥6 to <7], and high [≥7]) and mean MET-to-chromosome 7 centromere ratios (MET/CEP7) of at least 1.8 (low [≥1.8 to ≤2.2], intermediate [>2.2 to <5], and high [≥5]). Associated clinical and molecular characteristics were captured.

RESULTS

Of 686 cases, 99 (14%) had a mean MET per cell value of 5 or greater, 52 of 1164 (4.5%) had a MET/CEP7 ratio of 1.8 or higher. Other oncogenic drivers (in EGFR, KRAS, anaplastic lymphoma receptor tyrosine kinase gene [ALK], erb-b2 receptor tyrosine kinase 2 gene [ERBB2], BRAF, NRAS, ROS1, or ret proto-oncogene [RET]) were detectable in 56% of the group with a mean MET per cell value of 5 or higher and 47% of the group with a MET/CEP7 ratio of 1.8 or higher, suggesting that many MET-positive cases are not truly MET addicted. The rates of concomitant drivers in the groups of patients in the low, indeterminate, and high categories of mean MET per cell were 32 of 52 (62%), 12 of 19 (63%), and 11 of 27 (41%) (p = 0.2), and the rates of concomitant drivers in the low, intermediate, and high categories of MET/CEP7 ratios were 15 of 29 (52%), 9 of 18 (50%), and 0 of 4 (0%), respectively (p = 0.04). A MET/CEP7 ratio of 1.8 or higher in the absence of other oncogenes was associated with a higher rate of adrenal metastases (p = 0.03) but not with never-smoking status.

CONCLUSIONS

A fluorescence in situ hybridization MET/CEP7 ratio of 5 or higher defined a "MET-positive" group with no oncogenic overlap. As this method and criteria are also associated with the highest response rate to MET inhibition, it represents the clearest definition of a MET copy number gain-addicted state. However, a MET-associated phenotype may also exist across cases with a MET/CEP7 of 1.8 or higher when no other oncogene overlap occurs.

The Unique Characteristics of MET Exon 14 Mutation in Chinese Patients with NSCLC

INTRODUCTION

Predictive biomarkers of mesenchymal-to-epithelial transition factor (MET)-targeted therapy remain elusive. Since the discovery of the MNNG HOS Transforming gene (MET) exon 14 mutation, it has been found to have the best potential to become one precise biomarker for MET-targeted therapy. Here, we present the unique characteristics of MET exon 14 mutations in Chinese patients with NSCLC.

METHODS

A total of 1296 patients with NSCLC were screened for MET exon 14 mutations. Next-generation sequencing was performed on the DNA of 968 patients and Sanger sequencing was conducted on complementary DNA of the other 328 patients. Immunohistochemical analysis and fluorescence in situ hybridization were also performed on all specimens.

RESULTS

Twelve patients had MET exon 14 mutations. These accounted for only 0.9% of adenocarcinoma. Thus, the mutations were present at less than half the frequency of their occurrence in Western patients (0.9% versus 3% in Chinese and white patients, respectively, χ(2) = 15.1, p < 0.001). Samples from six patients with MET exon 14 mutations were analyzed using immunohistochemical analysis and fluorescence in situ hybridization. We found no significant relationships among the mutation, MET amplification, and MET overexpression. In two patients who received crizotinib, only one patient (who exhibited MET amplification) experienced a partial response; the progression-free survival was 9 months. However, it remains unclear whether the sensitivity of this patient to crizotinib was conferred by the MET exon 14 mutation per se or by MET amplification. In the other patient with concomitant MET exon 14 skipping and KRAS G12D mutation, the disease progressed in only 1 month.

CONCLUSIONS

MET exon 14 mutation per se may not be sufficiently robust for use in defining a subset of NSCLCs. Further research on MET exon 14 mutations, MET amplification, and MET overexpression is required. Maybe a panel of biomarkers will be necessary in the future.

Mutation testing for directing upfront targeted therapy and post-progression combination therapy strategies in lung adenocarcinoma

Introduction: Advances in the biology of non-small-cell lung cancer, especially adenocarcinoma, reveal multiple molecular subtypes driving oncogenesis. Accordingly, individualized targeted therapeutics are based on mutational diagnostics.

Areas covered: Advances in strategies and techniques for individualized treatment, particularly of adenocarcinoma, are described through literature review. Approved therapies are established for some molecular subsets, with new driver mutations emerging that represent increasing proportions of patients. Actionable mutations are denovo oncogenic drivers or acquired resistance mediators, and mutational profiling is important for directing therapy. Patients should be monitored for emerging actionable resistance mutations. Liquid biopsy and associated multiplex diagnostics will be important means to monitor patients during treatment.

Expert commentary: Outcomes with targeted agents may be improved by integrating mutation screens during treatment to optimize subsequent therapy. In order for this to be translated into impactful patient benefit, appropriate platforms and strategies need to be optimized and then implemented universally.

MET receptor juxtamembrane exon 14 alternative spliced variant: novel cancer genomic predictive biomarker

Clinical studies on MET-targeting cancer therapeutics have yielded mixed results in recent years, and MET-relevant predictive biomarkers remain elusive. New studies now reveal METex14 alternative splicing aberrations to represent potential predictive cancer genomic biomarker, hence renewing optimism and directions in the quest for optimized MET-targeting personalized cancer therapy.

MET expression and copy number heterogeneity in nonsquamous non-small cell lung cancer (nsNSCLC)

OBJECTIVE

We aimed to assess MET intratumoral heterogeneity and its potential impact on biomarker-based patient selection as well as potential surrogate biomarkers of MET activation.

METHODS

Our study included 120 patients with non-squamous Non-small-cell Lung Cancer (nsNSCLC), of which 47 were incorporated in tissue microarrays (TMA). Four morphologically distinct tumor areas were selected to assess MET heterogeneity. MET positivity by immunohistochemistry (IHC) was defined as an above-median H-score and by +2/+3 staining intensity in >50% of tumor cells (Metmab criteria). MET FISH positivity was defined by MET/CEP7 ratio ≥ 2.0 and/or MET ≥ 5.0. MET staining pattern (cytoplasmic vs. membranous) and mesenchymal markers were investigated as surrogates of MET activation.

RESULTS

Median MET H-score was 140 (range 0-400) and 47.8% of patients were MET positive by Metmab criteria. Eight cases (6.8%) were MET FISH positive and showed higher H-scores (p = 0.021). MET positivity by IHC changed in up to 40% of cases among different tumor areas, and MET amplification in 25-50%. Cytoplasmic MET staining and positivity for vimentin predicted poor survival (p = 0.042 and 0.047, respectively).

CONCLUSIONS

MET status is highly heterogeneous among different nsNSCLC tumor areas, hindering adequate patient selection for MET-targeted therapies. MET cytoplasmic staining and vimentin might represent surrogate markers for MET activation.

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.

MET Exon 14 Skipping in Non-Small Cell Lung Cancer

BACKGROUND

Non-small cell lung cancers (NSCLCs) harboring specific genetic alterations can be highly sensitive to targeted therapies.

MATERIALS AND METHODS

We performed a targeted rearrangement assay on 54 NSCLCs across all stages that were from patients who were never smokers and did not have driver mutations. Because MET exon 14 skipping was the most frequent alteration found, we surveyed the results for MET exon 14 skipping at Massachusetts General Hospital (MGH) since the inclusion of this alteration into our current molecular profiling panel.

RESULTS

In a cohort of 54 never-smokers with lung cancers that were wild-type for known driver mutations, MET exon 14 skipping was the most frequently recurring alteration, occurring in 10 cancers (19%). Clinical testing at MGH via our next-generation sequencing (NGS) and NGS-rearrangement panels showed an additional 16 cases of MET exon 14 skipping, for an overall estimated frequency of 5.6%. A clinical case of a patient with MET exon 14 skipping treated with the MET inhibitor crizotinib is also described.

CONCLUSION

MET exon 14 skipping is a targetable gene alteration found in NSCLC. Patients with these alterations may respond well to MET inhibition.

IMPLICATIONS FOR PRACTICE

MET exon 14 skipping occurs with an approximately 5% frequency in NSCLC and is seen in both squamous and adenocarcinoma histology. Patients whose cancers have MET exon 14 skipping can respond well to MET inhibitors. Molecular testing for MET exon 14 skipping should be performed on all lung cancers because this is a targetable alteration.

MET Exon 14 Alterations in Lung Cancer: Exon Skipping Extends Half-Life

MET exon 14 alterations are a diverse group of mutations, many of which disrupt splice acceptor or donor sites leading to exon 14 skipping, impaired receptor degradation, and oncogenic transformation. These alterations are clinically targetable with MET-directed therapy. Clin Cancer Res; 22(12); 2832-4. ©2016 AACRSee related article by Tong et al., p. 3048.

Understanding and Targeting MET Signaling in Solid Tumors - Are We There Yet?

The MET signaling pathway plays an important role in normal physiology and its deregulation has proved critical for development of numerous solid tumors. Different technologies have been used to investigate the genomic and proteomic status of MET in cancer patients and its association with disease prognosis. Moreover, with the development of targeted therapeutic drugs, there is an urgent need to identify potential biomarkers for selection of patients who are more likely to derive benefit from these agents. Unfortunately, the variety of technical platforms and analysis criteria for diagnosis has brought confusion to the field and a lack of agreement in the evaluation of MET status as a prognostic or predictive marker for targeted therapy agents. We review the molecular mechanisms involved in the deregulation of the MET signaling pathway in solid tumors, the different technologies used for diagnosis, and the main factors that affect the outcome, emphasizing the urge for completing analytical and clinical validation of these tests. We also review the current clinical studies with MET targeted agents, which mostly focus on lung cancer.

Novel MET/TIE2/VEGFR2 inhibitor altiratinib inhibits tumor growth and invasiveness in bevacizumab-resistant glioblastoma mouse models

BACKGROUND

Glioblastoma highly expresses the proto-oncogene MET in the setting of resistance to bevacizumab. MET engagement by hepatocyte growth factor (HGF) results in receptor dimerization and autophosphorylation mediating tumor growth, invasion, and metastasis. Evasive revascularization and the recruitment of TIE2-expressing macrophages (TEMs) are also triggered by anti-VEGF therapy.

METHODS

We investigated the activity of altiratinib (a novel balanced inhibitor of MET/TIE2/VEGFR2) against human glioblastoma stem cell lines in vitro and in vivo using xenograft mouse models. The biological activity of altiratinib was assessed in vitro by testing the expression of HGF-stimulated MET phosphorylation as well as cell viability after altiratinib treatment. Tumor volume, stem cell and mesenchymal marker levels, microvessel density, and TIE2-expressing monocyte infiltration were evaluated in vivo following treatment with a control, bevacizumab alone, bevacizumab combined with altiratinib, or altiratinib alone.

RESULTS

In vitro, HGF-stimulated MET phosphorylation was completely suppressed by altiratinib in GSC17 and GSC267, and altiratinib markedly inhibited cell viability in several glioblastoma stem cell lines. More importantly, in multiple xenograft mouse models, altiratinib combined with bevacizumab dramatically reduced tumor volume, invasiveness, mesenchymal marker expression, microvessel density, and TIE2-expressing monocyte infiltration compared with bevacizumab alone. Furthermore, in the GSC17 xenograft model, altiratinib combined with bevacizumab significantly prolonged survival compared with bevacizumab alone.

CONCLUSIONS

Together, these data suggest that altiratinib may suppress tumor growth, invasiveness, angiogenesis, and myeloid cell infiltration in glioblastoma. Thus, altiratinib administered alone or in combination with bevacizumab may overcome resistance to bevacizumab and prolong survival in patients with glioblastoma.

MET Exon 14 Mutations in Non-Small-Cell Lung Cancer Are Associated With Advanced Age and Stage-Dependent MET Genomic Amplification and c-Met Overexpression

PURPOSE

Non-small-cell lung cancers (NSCLCs) harboring mutations in MET exon 14 and its flanking introns may respond to c-Met inhibitors. We sought to describe the clinical, pathologic, and genomic characteristics of patients with cancer with MET exon 14 mutations.

PATIENTS AND METHODS

We interrogated next-generation sequencing results from 6,376 cancers to identify those harboring MET exon 14 mutations. Clinical characteristics of MET exon 14 mutated NSCLCs were compared with those of NSCLCs with activating mutations in KRAS and EGFR. Co-occurring genomic mutations and copy number alterations were identified. c-Met immunohistochemistry and real-time polymerase chain reaction to detect exon 14 skipping were performed where sufficient tissue was available.

RESULTS

MET exon 14 mutations were identified in 28 of 933 nonsquamous NSCLCs (3.0%) and were not seen in other cancer types in this study. Patients with MET exon 14-mutated NSCLC were significantly older (median age, 72.5 years) than patients with EGFR-mutant (median age, 61 years; P < .001) or KRAS-mutant NSCLC (median age, 65 years; P < .001). Among patients with MET exon 14 mutations, 68% were women, and 36% were never-smokers. Stage IV MET exon 14-mutated NSCLCs were significantly more likely to have concurrent MET genomic amplification (mean ratio of MET to chromosome 7, 4.3) and strong c-Met immunohistochemical expression (mean H score, 253) than stage IA to IIIB MET exon 14-mutated NSCLCs (mean ratio of MET to chromosome 7, 1.4; P = .007; mean H score, 155; P = .002) and stage IV MET exon 14-wild-type NSCLCs (mean ratio of MET to chromosome 7, 1.2; P < .001; mean H score, 142; P < .001). A patient whose lung cancer harbored a MET exon 14 mutation with concurrent genomic amplification of the mutated MET allele experienced a major partial response to the c-Met inhibitor crizotinib.

CONCLUSION

MET exon 14 mutations represent a clinically unique molecular subtype of NSCLC. Prospective clinical trials with c-Met inhibitors will be necessary to validate MET exon 14 mutations as an important therapeutic target in NSCLC.

Personalized Therapy of Non-small Cell Lung Cancer (NSCLC)

Lung cancer remains the most common cause of cancer related deaths in both men and women in the United States and non-small cell lung cancer (NSCLC) accounts for over 85 % of all lung cancers. Survival of these patients has not significantly altered in over 30 years. This chapter initially discusses the clinical presentation of lung cancer patients. Most patients diagnosed with lung cancer due to symptoms have advanced stage cancer. Once diagnosed, lung cancer patients need imaging studies to assess the stage of the disease before decisions regarding therapy are finalized. The most important prognostic factors are stage of the disease and performance status and these factors also determine therapy. The chapter subsequently discusses management of each stage of the disease and the impact of several pathologic, clinical factors in personalizing therapy for each individual patient. Transition from chemotherapy for every patient to a more personalized approach based on histology and molecular markers has occurred in the management of advanced stage NSCLC. It is expected that such a personalized approach will extend to all stages of NSCLC and will likely improve the outcomes of all NSCLC patients.

Small molecule inhibitor of c-Met (PHA665752) suppresses the growth of ovarian cancer cells and reverses cisplatin resistance

c-Met as a tyrosine-kinase receptor plays a major role in tumorigenesis, invasion, and metastatic spread of human tumors, including ovarian cancer. Expressing high levels of c-Met proteins is often associated with resistance to chemotherapy and an adverse prognosis. In this study, we have determined the effect of PHA665752, a small molecule inhibitor of c-Met proteins, with and without cisplatin and the role of c-Met in several ovarian cancer cell lines having high c-Met expression. The methyl thiazolyl tetrazolium (MTT) assay was used to detect cell proliferation, and apoptosis was evaluated by flow cytometry. Western blotting was carried out to determine protein expression levels. Gene silencing was used to detect the influence of c-Met gene silence on the resistance to cisplatin. Compared to more sensitive ovarian cancer cell lines SKOV3 and 3AO, we found that the expression of c-Met was significantly increased in SKOV3(DDP), OVCAR3, and OV-90 ovarian cancer cell lines, which were resistant to cisplatin. Our data indicated that cisplatin sustained activated phosphor-Met in SKOV3(DDP), OVCAR3, and OV-90 cell lines. We also observed a significant transient activation of c-Met phosphorylation in SKOV3 and 3AO cells. Treatment with PHA665752 inhibited c-Met expression inhibited cell growth, induced apoptosis, and enhanced cisplatin-induced proliferation inhibition and apoptosis in c-Met over-expressed cell lines. In addition, blocking c-Met expression with small interfering RNA (siRNA) overcame the resistance of cancer cells to cisplatin. Thus, blocking c-Met expression presents a promising therapeutic approach for ovarian cancer.

Mutations Preventing Regulated Exon Skipping in MET Cause Osteofibrous Dysplasia

The periosteum contributes to bone repair and maintenance of cortical bone mass. In contrast to the understanding of bone development within the epiphyseal growth plate, factors that regulate periosteal osteogenesis have not been studied as intensively. Osteofibrous dysplasia (OFD) is a congenital disorder of osteogenesis and is typically sporadic and characterized by radiolucent lesions affecting the cortical bone immediately under the periosteum of the tibia and fibula. We identified germline mutations in MET, encoding a receptor tyrosine kinase, that segregate with an autosomal-dominant form of OFD in three families and a mutation in a fourth affected subject from a simplex family and with bilateral disease. Mutations identified in all families with dominant inheritance and in the one simplex subject with bilateral disease abolished the splice inclusion of exon 14 in MET transcripts, which resulted in a MET receptor (MET(Δ14)) lacking a cytoplasmic juxtamembrane domain. Splice exclusion of this domain occurs during normal embryonic development, and forced induction of this exon-exclusion event retarded osteoblastic differentiation in vitro and inhibited bone-matrix mineralization. In an additional subject with unilateral OFD, we identified a somatic MET mutation, also affecting exon 14, that substituted a tyrosine residue critical for MET receptor turnover and, as in the case of the MET(Δ14) mutations, had a stabilizing effect on the mature protein. Taken together, these data show that aberrant MET regulation via the juxtamembrane domain subverts core MET receptor functions that regulate osteogenesis within cortical diaphyseal bone.

Functional consequence of the MET-T1010I polymorphism in breast cancer

Major breast cancer predisposition genes, only account for approximately 30% of high-risk breast cancer families and only explain 15% of breast cancer familial relative risk. The HGF growth factor receptor MET is potentially functionally altered due to an uncommon germline single nucleotide polymorphism (SNP), MET-T1010I, in many cancer lineages including breast cancer where the MET-T1010I SNP is present in 2% of patients with metastatic breast cancer. Expression of MET-T1010I in the context of mammary epithelium increases colony formation, cell migration and invasion in-vitro and tumor growth and invasion in-vivo. A selective effect of MET-T1010I as compared to wild type MET on cell invasion both in-vitro and in-vivo suggests that the MET-T1010I SNP may alter tumor pathophysiology and should be considered as a potential biomarker when implementing MET targeted clinical trials.

[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.

CRISPR/Cas9: molecular tool for gene therapy to target genome and epigenome in the treatment of lung cancer

Although varied drugs and therapies have been developed for lung cancer treatment, in the past 5 years overall survival rates have not improved much. It has also been reported that lung cancer is diagnosed in most of the patients when it is already in the advanced stages with heterogeneous tumors where single therapy is mostly ineffective. A combination of therapies are being administered and specific genes in specific tissues are targeted while protecting normal cell, but most of the therapies face drawbacks for the development of resistance against them and tumor progression. Therefore, therapeutic implications for various therapies need to be complemented by divergent strategies. This review frames utilization of CRISPR/Cas9 for molecular targeted gene therapy leading to long-term repression and activation or inhibition of molecular targets linked to lung cancer, avoiding the cycles of therapy.

siRNA delivered by EGFR-specific scFv sensitizes EGFR-TKI-resistant human lung cancer cells

The overexpression of epidermal growth factor receptor (EGFR) is closely associated with a poor outcome in non-small cell lung cancer (NSCLC), and EGFR is an ideal biomarker for the targeted therapy of NSCLC. Although patients with EGFR-activating mutations respond to EGFR tyrosine kinase inhibitors (EGFR-TKIs), they eventually acquire resistance, which typically results from a secondary EGFR mutation or the activation of other signaling pathways. Novel approaches to overcome or prevent EGFR-TKI resistance are clinically important. In this study, we developed an EGFR-scFv-arginine nonamer peptide fusion protein, s-9R, as an siRNA carrier. Here, we show that s-9R effectively and specifically delivers EGFR-siRNAs, KRAS-siRNA and MET-siRNA into NSCLC cells and silences the expression of target genes. The sensitivity of NSCLC cells to gefitinib was restored after treatment with the s-9R/siRNA complex, and the apoptosis rates of the treated cells were significantly higher than those of the control groups. Furthermore, the co-administration of s-9R/siRNA and gefitinib successfully suppressed the progression of H1975 xenograft tumors and extended the life span of tumor-bearing nude mice. Collectively, the results of this study provide not only a new scFv derivative for delivering siRNA into EGFR-overexpressing, TKI-resistant NSCLC cells but also a novel method for overcoming TKI resistance.