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

Design, synthesis and biological evaluation of thienopyridine derivatives as c-Met kinase inhibitors

With cabozantinib as the precursor, a novel small molecule inhibitors of c-Met kinase with thieno [2,3-b] pyridine as the scaffold were designed, synthesized and evaluated for their biological activity against A549, Hela and MCF-7 cell lines. The in vitro activities of 16 compounds were tested by MTT method with cabozantinib as control drug. Most compounds had moderate to strong inhibitory activities on cells. Among them, compound 10 had the strongest inhibitory activity, which was superior to the lead compound cabozantinib. Its IC50 values for A549, Hela and MCF-7 cells were 0.005, 2.833 and 13.581 μM, respectively. The colony formation assay demonstrated that compound 10 significantly inhibited the colony formation of A549 cells and suppressed their growth in a concentration-dependent manner. The wound healing assay showed that compound 10 could effectively inhibit the migration of cancer cells compared to a blank control group. The AO/EB assay demonstrated that compound 10 possesses the capability to effectively trigger apoptosis in a concentration-dependent manner. The elementary structure-activity relationship, molecular docking and pharmacokinetics studies revealed the significance of thieno [2,3-b] pyridine derivatives in anti-tumor activity.

Combined inhibition of MET and VEGF enhances therapeutic efficacy of EGFR TKIs in EGFR-mutant non-small cell lung cancer with concomitant aberrant MET activation

BACKGROUND

Aberrant activation of mesenchymal epithelial transition (MET) has been considered to mediate primary and acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC). However, mechanisms underlying this process are not wholly clear and the effective therapeutic strategy remains to be determined.

METHODS

The gefitinib-resistant NSCLC cell lines were induced by concentration increase method in vitro. Western blot and qPCR were used to investigate the relationship between MET and vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) signaling pathway. Double luciferase reporter gene and co-immunoprecipitation were used to further reveal the regulation mechanism between MET and VEGF/VEGFR2. The effect of combined inhibition of MET and VEGF/VEGFR2 signaling pathway on the therapeutic sensitivity of EGFR-TKI in gefitinib resistant cell lines with MET aberration was verified ex vivo and in vivo.

RESULTS

We successfully obtained two gefitinib-resistant NSCLC cell lines with EGFR mutation and abnormal activation of MET. We observed that MET formed a positive feedback loop with the VEGF/VEGFR2 signaling, leading to persistent downstream signaling activation. Specifically, MET up-regulated VEGFR2 expression in a MAPK/ERK/ETS1-dependent manner, while VEGF promoted physical interaction between VEGFR2 and MET, thereby facilitating MET phosphorylation. A MET inhibitor, crizotinib, combined with an anti-VEGF antibody, bevacizumab, enhanced the sensitivity of NSCLC cells to gefitinib and synergistically inhibited the activation of downstream signaling in vitro. Dual inhibition of MET and VEGF combined with EGFR TKIs markedly restrained tumor growth in both human NSCLC xenograft models and in an EGFR/MET co-altered case.

CONCLUSIONS

Our work reveals a positive feedback loop between MET and VEGF/VEGFR2, resulting in continuous downstream signal activation. Combined inhibition of MET and VEGF/VEGFR2 signaling pathway may be beneficial for reversing EGFR TKIs resistance.

Genomic instability in congenital lung malformations in children

PURPOSE

To study the biological relationship between congenital lung malformations (CLMs) and malignancy.

METHODS

Biopsies of 12 CPAMs, 6 intralobar sequestrations and 2 extralobar sequestrations were analyzed through whole-genome sequencing. Blood samples from 10 patients were used to confirm or exclude somatic mosaicism. Putative somatic Single Nucleotide Variants (SNVs) were called for each malformed sample with a Panel of Normals built with control DNA samples extracted from blood. The variants were subsequently confirmed by Sanger sequencing and searched, whenever possible, in the blood samples of patients.

RESULTS

All CLMs but one presented a signature of genomic instability by means of multiple clusters of cells with gene mutations. Seven tumor transformation-related SNVs were detected in 6/20 congenital lung malformations. Four very rare in the general population SNVs were found in a region previously linked to lung cancer in 5p15.33, upstream of TERT oncogene. Furthermore, we identified missense genetic variants, whose tumorigenic role is well known, in the RET, FANCA and MET genes.

CONCLUSIONS

Genomic instability in 95% of CLMs and genetic variants linked to tumor development in 30% of them, regardless of histopathology, are predisposing factors to malignancy, that combined with exposure to carcinogens, might trigger the development of malignancy and explain the association between CLMs and lung cancer.

Savolitinib: A Promising Targeting Agent for Cancer

Savolitinib is a highly selective small molecule inhibitor of the mesenchymal epithelial transition factor (MET) tyrosine kinase, primarily developed for the treatment of non-small cell lung cancer (NSCLC) with MET mutations. It is also being investigated as a treatment for breast, head and neck, colorectal, gastric, pancreatic, and other gastrointestinal cancers. In both preclinical and clinical studies, it has demonstrated efficacy in lung, kidney, and stomach cancers. Savolitinib is an oral anti-cancer medication taken as a 600 mg dose once daily. It can be used as a monotherapy in patients with non-small cell lung cancer with MET mutations and in combination with epidermal growth factor receptor (EGFR) inhibitors for patients who have developed resistance to them. Furthermore, savolitinib has shown positive results in gastric cancer treatment, particularly in combination with docetaxel. As a result, this review aims to validate its efficacy in NSCLC and suggests its potential application in other gastrointestinal cancers, such as pancreatic cancer, based on related research in gastric and renal cancer.

Targeting MET Amplification: Opportunities and Obstacles in Therapeutic Approaches

The MET gene plays a vital role in cellular proliferation, earning it recognition as a principal oncogene. Therapies that target MET amplification have demonstrated promising results both in preclinical models and in specific clinical cases. A significant obstacle to these therapies is the ability to distinguish between focal amplification and polysomy, a task for which simple MET copy number measurement proves insufficient. To effectively differentiate between the two, it is crucial to utilize comparative measures, including in situ hybridization (ISH) with the centromere or next generation sequencing (NGS) with adjacent genes. Despite the promising potential of MET amplification treatment, the judicious selection of patients is paramount to maximize therapeutic efficacy. The effectiveness of MET inhibitors can fluctuate depending on the extent of MET amplification. Future research must seek to establish the ideal threshold value for MET amplification, identify the most efficacious combination therapies, and innovate new targeted treatments for patients exhibiting MET amplification.

Targeting the cMET pathway to enhance immunotherapeutic approaches for mUM patients

The liver is the most preferential initial site of metastasis for uveal melanoma (mUM), and this preference is associated with rapid mortality in mUM patients. Despite the significant clinical benefits of Immune checkpoint inhibitors (ICIs) in metastatic cutaneous melanoma patients, ICIs have shown little to no benefit in mUM patients. A potential reason for this inefficiency of ICI could be partly devoted to the involvement of the liver itself, thanks to its rich source of growth factors and immunosuppressive microenvironment. Uveal melanoma cells show increased expression of a transmembrane protein called cMET, which is known as the sole receptor for the Hepatocyte growth factor (HGF). Hyperactivation of cMET by HGF contributes to mUM development, and the liver, being the major source of HGF, may partially explain the metastasis of uveal melanoma cells to the liver. In addition, cMET/HGF signaling has also been shown to mediate resistance to ICI treatment, directly and indirectly, involving tumor and immune cell populations. Therefore, targeting the cMET/HGF interaction may enhance the efficacy of immunotherapeutic regimes for mUM patients. Hence in this minireview, we will discuss the rationale for combining cMET inhibitors/antibodies with leading immune checkpoint inhibitors for treating mUM. We will also briefly highlight the challenges and opportunities in targeting cMET in mUM.

SH005S7 Overcomes Primary and Acquired Resistance of Non-Small Cell Lung Cancer by Combined MET/EGFR/HER3 Inhibition

In this study, we have examined the anticancer effects of SH005S7 on MET-amplified and (HCC827GR) NSCLC cells and their primary HCC827 cells. In vitro, first of all, cell viability and colony formation assay confirmed the growth inhibitory effects of SH005S7 on both cells. Second, SH005S7 inactivated EGFR-related multiple cell signaling, which was associated with a marked decrease in the constitutive phosphorylation of EGFR, HER3, MET, AKT, and ERK. Third, SH005S7 attenuated the anchorage-independent cell growth. Fourth, SH005S7 blocked invasive and metastatic capability by downregulation of mesenchymal markers—vimentin, snail, and MMP-9. Fifth, BrdU assay confirmed the cell cycle arrest of SH005S7 on these cells. When administered orally to nude mice xenografically transplanted human NSCLC, SH005S7 inhibited the growth of tumor and did not cause hepatotoxicity and nephrotoxicity in animals. Immunohistochemical and Western blot analyses of tissue showed that the suppression of growth correlated with inhibition of proliferation (Ki-67, PCNA), invasiveness (vimentin, snail), and angiogenesis (CD31) marker and decrement in the constitutive and phosphorylation of EGFR, HER3, MET, AKT, and ERK. Additionally, SH005S7 had immune stimulatory effects by TNF-α cytokine release on macrophage, without cell cytotoxicity. Overall, our results suggest that SH005S7 can inhibit the growth of MET-amplified and gefitinib-resistant NSCLC cells through the suppression of EGFR-related multiple targets linked to overcome gefitinib resistance.

Targeting un-MET needs in advanced non-small cell lung cancer

Lung cancer classification has been radically transformed in recent years as genomic profiling has identified multiple novel therapeutic targets including MET exon 14 (METex14) alterations and MET amplification. Utilizing targeted therapies in patients with molecularly-defined NSCLC leads to remarkable objective response rates and improved progression-free survival. However, acquired resistance is inevitable. Several recent phase II trials have confirmed that METex14 NSCLC can be treated effectively with MET kinase inhibitors, such as crizotinib, capmatinib, tepotinib, and savolitinib. However, response rates for many MET TKIs are modest relative to the activity of targeted therapy in other oncogene-driven lung cancers, where ORRs are more consistently greater than 60%. In spite of significant gains in the field of MET inhibition in NSCLC, challenges remain: the landscape of resistance mechanisms to MET TKIs is not yet well characterized, and there may be intrinsic and acquired resistance mechanisms that require further characterization to enable increased MET TKI activity. In this review, we overview MET pathway dysregulation in lung cancer, methods of detection in the clinic, recent clinical trial data, and discuss current mechanisms of TKI resistance, exploring emerging strategies to overcome resistance.

Beyond epidermal growth factor receptor: MET amplification as a general resistance driver to targeted therapy in oncogene-driven non-small-cell lung cancer

The rapidly changing treatment paradigm for patients with metastatic oncogene-driven lung cancer continues to evolve, and consequently our understanding of the landscape of resistance must also advance. MET amplification is an established and frequent driver of resistance in EGFR-mutant non-small-cell lung cancer (NSCLC). Recently, the combination of MET proto-oncogene (MET) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has shown promise in overcoming this molecularly defined resistance in clinical trials, and this combination strategy is being pursued in ongoing trials. Emerging data also demonstrate MET amplification as a resistance driver to TKI-treated ALK-, RET-, and ROS-1-fusion NSCLC, consistently at the range of 15%, while the resistance profiling data are maturing for other molecular targets. In this review, we discuss MET amplification as a driver of acquired resistance in well-defined molecular subsets of NSCLC, explore the biology behind this mechanism of resistance, and summarize the recently published clinical data, including the proposed combination strategies in the clinic achieving success in overcoming acquired MET amplification-dependent resistance.

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Understanding mechanisms of resistance in oncogene-driven lung cancer is crucial.

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MET amplification is a recurrent driver of resistance, across molecularly defined subsets of NSCLC.

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Overcoming this resistance in clinical trials, using combination strategies, is currently being pursued.

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We explore the biology behind this mechanism of resistance and summarize recent successes in the clinic.

Challenge and countermeasures for EGFR targeted therapy in non-small cell lung cancer

Lung cancer causes the highest mortality compared to other cancers in the world according to the latest WHO reports. Non-small cell lung cancer (NSCLC) contributes about 85% of total lung cancer cases. An extensive number of risk factors are attributed to the progression of lung cancer. Epidermal growth factor receptor (EGFR), one of the most frequently mutant driver genes, is closely involved in the development of lung cancer through regulation of the PI3K/AKT and MAPK pathways. As a representative of precision medicine, EGFR-tyrosine kinase inhibitors (TKIs) targeted therapy significantly relieves the development of activating mutant EGFR-driven NSCLC. However, treatment with TKIs facilitates the emergence of acquired resistance that continues to pose a significant hurdle with respect to EGFR targeted therapy. In this review, the development of current approved EGFR-TKIs as well as the related supporting clinical trials are summarized and discussed. Mechanisms of action and resistance were addressed respectively, which serve as important guides to understanding acquired resistance. We also explored the corresponding combination treatment options according to different resistance mechanisms. Future challenges include more comprehensive characterization of unclear resistance mechanisms in different populations and the development of more efficient and precision synthetic therapeutic strategies.

Beyond EGFR, ALK and ROS1: Current evidence and future perspectives on newly targetable oncogenic drivers in lung adenocarcinoma

Lung cancer is the leading cause of cancer death worldwide. In the past decade EGFR, ALK and ROS1 TKIs lead to an unprecedented survival improvement of oncogene-addicted NSCLC patients, with better toxicity profile compared to chemotherapy. In recent years the implementation of high-throughput sequencing platforms led to the identification of uncommon molecular alterations in oncogenic drivers, such as BRAF, MET, RET, HER2 and NTRK. Moreover, newly developed drugs have been found to be active against hard to target drivers, such as KRAS. Specific TKIs targeting these genomic alterations are currently in clinical development and showed impressive activity and survival improvement, leading to FDA-accelerated approval for some of them. However, virtually all patients develop resistance to TKIs by on-target or off-target mechanisms. Here we review the clinicopathological features, the emerging targeted therapies and mechanisms of resistance and strategies to overcome them of KRAS, BRAF, MET, RET, HER2 and NTRK-addicted advanced NSCLCs.

circMET promotes NSCLC cell proliferation, metastasis, and immune evasion by regulating the miR-145-5p/CXCL3 axis

In recent years, circular RNAs (circRNAs) have been increasingly reported to play a crucial role in the proliferation, migration, and invasion of non-small-cell lung cancer (NSCLC) cells. However, the circRNA MET (circMET) oncogenic mechanism that drives NSCLC development and progression remains largely unknown. In this study, the present results demonstrated that circMET expression was significantly higher in NSCLC tissues than in peritumoral tissues using quantitative real-time polymerase chain reaction. Notably, NSCLC patients with a large tumor diameter, poor differentiation and lymphatic metastasis had high RNA levels of circMET. Moreover, high circMET expression served as an independent risk factor for short overall survival (OS) and progression-free survival (PFS) in NSCLC patients. Next, we validated that circMET overexpression can enhance NSCLC cell proliferation, metastasis, and immune evasion in vitro. Mechanistically, our study uncovers that circMET acts as a miR-145-5p sponge to upregulate CXCL3 expression. Collectively, circMET regulates the miR-145-5p/CXCL3 axis and serves as a novel, promising diagnostic and prognostic biomarker in patients with NSCLC.

Proteasome Inhibitors Diminish c-Met Expression and Induce Cell Death in Non-Small Cell Lung Cancer Cells

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and accounts for 85% of all lung carcinomas. The hepatocyte growth factor receptor (c-Met) has been considered as a potential therapeutic target for NSCLC. Proteasome inhibition induces cell apoptosis and has been used as a novel therapeutic approach for treating diseases including NSCLC; however, the effects of different proteasome inhibitors on NSCLC have not been fully investigated. The aim of this study is to determine a precise strategy for treating NSCLC by targeting c-Met using different proteasome inhibitors. Three proteasome inhibitors, bortezomib, MG132, and ONX 0914, were used in this study. Bortezomib (50 nM) significantly reduced c-Met levels and cell viability in H1299 and H441 cells, while similar effects were observed in H460 and A549 cells when a higher concentration (∼100 nM) was used. Bortezomib decreased c-Met gene expression in H1299 and H441 cells, but it had no effect in A549 and H460 cells. MG-132 at a low concentration (0.5 μM) diminished c-Met levels in H441 cells, while neither a low nor a high concentration (∼20 μM) altered c-Met levels in A549 and H460 cells. A higher concentration of MG-132 (5 μM) was required for decreasing c-Met levels in H1299 cells. Furthermore, MG-132 induced cell death in all four cell types. Among all the four cell lines, H441 cells expressed higher levels of c-Met and appeared to be the most susceptible to MG-132. MG-132 decreased c-Met mRNA levels in both H1299 and H441 cells. ONX 0914 reduced c-Met levels in H460, H1299, and H441 cells but not in A549 cells. c-Met levels were decreased the most in H441 cells treated with ONX 0914. ONX 0914 did not alter cell viability in H441; however, it did induce cell death among H460, A549, and H1299 cells. This study reveals that different proteasome inhibitors produce varied inhibitory effects in NSCLS cell lines.

MET receptor in oncology: From biomarker to therapeutic target

First discovered in the 1984, the MET receptor tyrosine kinase (RTK) and its ligand hepatocyte growth factor or HGF (also known as scatter factor or SF) are implicated as key players in tumor cell migration, proliferation, and invasion in a variety of cancers. This pathway also plays a key role during embryogenesis in the development of muscular and nervous structures. High expression of the MET receptor has been shown to correlate with poor prognosis and resistance to therapy. MET exon 14 splicing variants, initially identified by us in lung cancer, is actionable through various tyrosine kinase inhibitors (TKIs). For this reason, this pathway is of interest as a therapeutic target. In this chapter we will be discussing the history of MET, the genetics of this RTK, and give some background on the receptor biology. Furthermore, we will discuss directed therapeutics, mechanisms of resistance, and the future of MET as a therapeutic target.

High-level gain of mesenchymal-epithelial transition factor (MET) copy number using next-generation sequencing as a predictive biomarker for MET inhibitor efficacy

Background

In clinical oncology, targeted next-generation sequencing (NGS) has become an integral part of the routine molecular diagnostics repertoire. However, a consensus is yet to be agreed on the optimal mesenchymal-epithelial transition factor (MET) copy number (CN) cut-off value based on NGS data that could predict the MET-amplified non-small cell lung cancer (NSCLC) patients who could benefit from MET tyrosine kinase inhibitor (TKI) therapy. In this study, we aimed to identify the criteria to define MET amplification derived from NGS data.

Methods

Sequencing data from matched plasma and tissue samples from 40 MET-amplified NSCLC patients were used to derive a normalization method, referred to as adjusted copy number (adCN). Clinical outcomes from an additional 18 MET TKI-treated NSCLC patients with solely MET-amplified cancers were analyzed to validate the adCN cut-offs.

Results

AdCN, calculated as the absolute CN generated from NGS relative to the maximum mutant allele fraction (maxMAF) per sample, was demonstrated to have a high correlation with MET CN in tissue and plasma samples (R²=0.73). Using a cut-off value of 5.5 and 13, tertile stratification of adCN was able to distinguish patients with high-level MET amplification. The MET TKI-treated patients with adCN >13, categorized as high-level amplification, had significantly longer progression-free survival (PFS) than those with adCN <13 (P=0.009), suggesting that adCN positively correlated with the response to MET TKI.

Conclusions

We derived a normalization method that could reflect the relative CN and distinguish MET-amplified NSCLC patients with high-level gene amplification who were sensitive to crizotinib, suggesting adCN could potentially serve as a predictive biomarker for MET TKI response.

Detection of serum protein and circulating mRNA of cMET, HGF EGF and EGFR levels in lung cancer patients to guide individualized therapy

BACKGROUND

Reseptor tyrosine kinases (cMET and EGFR) are important in lung cancer targeted therapy. We believe if we can use them as markers for clinicians to help decide the diagnosis of lung cancer. This parameter will be important in serum samples of patients with lung cancer diagnosis and treatment. The aim of this study is aimed to evaluate the clinical utility of serum protein and circulating mRNA of cMET and HGF in lung cancer patients. We also analyzed the correlation of mRNA expression with clinicopathologic parameters.

METHODS

We performed enzyme-linked immunosorbent assay (ELISA) to measure and compare serum protein and circulating mRNA of cMET and HGF levels in peripheral blood from 60 lung cancer patients and 40 healthy control group.

RESULTS

We found that both protein and gene expression levels of serum c-MET, HGF and EGFR were significantly higher in patients with lung cancer than control group. There was no association between HGF, cMET, EGF, EGFR (both protein and gene) expression levels with age, gender, smoking habit, COPD, pathological types or tumor size, stage, metastatic-non metastatic adenocarcinoma-squamous carcinoma, SCLC-NSCLC. As a result of ROC analysis, serum cMET (AUC: 0.892) and HGF protein (AUC: 0.784) were diagnosed in lung cancer patients (Fig. 1). The AUC values of serum EGF and EGFR proteins were calculated to be 0.631 and 0.692, respectively.

CONCLUSION

To our knowledge this is the first study comparing the levels of protein and mRNA in the serum material of HGF, c-MET, EGF and EGFR parameters in lung cancer patients' blood samples. Further prospective studies with more participants for better understanding of mechanism and effect for HGF and c-MET inhibitors in lung cancer will help us to identify of these biomarkers role for guiding us to sellect individualized itargeted therapies.

Luirink R, P. Geerke D, Op de Beeck K, Hermans C, Tiseo M, Van Schil P, Lardon F, Germonpré P, Rolfo C, Giovannetti E, J. Peters G, Pauwels P. The Role of c-Met as a Biomarker and Player in Innate and Acquired Resistance in Non-Small-Cell Lung Cancer: Two New Mutations Warrant Further Studies

The c-Met receptor is a therapeutically actionable target in non-small-cell lung cancer (NSCLC), with one approved drug and several agents in development. Most suitable biomarkers for patient selection include c-Met amplification and exon-14 skipping. Our retrospective study focused on the frequency of different c-Met aberrations (overexpression, amplification and mutations) in 153 primary, therapy-naïve resection samples and their paired metastases, from Biobank@UZA. Furthermore, we determined the correlation of c-Met expression with clinicopathological factors, Epidermal Growth Factor Receptor (EGFR)-status and TP53 mutations. Our results showed that c-Met expression levels in primary tumors were comparable to their respective metastases. Five different mutations were detected by deep sequencing: three (E168D, S203T, N375S) previously described and two never reported (I333T, G783E). I333T, a new mutation in the Sema(phorin) domain of c-Met, might influence the binding of antibodies targeting the HGF-binding domain, potentially causing innate resistance. E168D and S203T mutations showed a trend towards a correlation with high c-Met expression (p = 0.058). We found a significant correlation between c-MET expression, EGFR expression (p = 0.010) and EGFR mutations (p = 0.013), as well as a trend (p = 0.057) with regards to TP53 mutant activity. In conclusion this study demonstrated a strong correlation between EGFR mutations, TP53 and c-Met expression in therapy-naïve primary resection samples. Moreover, we found two new c-Met mutations that warrant further studies.

Genome-wide mutation profiling and related risk signature for prognosis of papillary renal cell carcinoma

Background

The papillary renal cell carcinoma (pRCC) is a rare subtype of renal cell carcinoma with limited investigation. Our study aimed to explore a robust signature to predict the prognosis of pRCC from the perspective of mutation profiles.

Methods

In this study, we downloaded the simple nucleotide variation data of 288 pRCC samples from The Cancer Genome Atlas (TCGA) database. "GenVisR" package was utilized to visualize gene mutation profiles in pRCC. The PPI network was conducted based on the STRING database and the modification was performed via Cytoscape software (Version 3.7.1). Top 50 mutant genes were selected and Cox regression method was conducted to identify the hub prognostic mutant signature in pRCC using "survival" package. Mutation Related Signature (MRS) risk score was established by multivariate Cox regression method. Receiver Operating Characteristic (ROC) curve drawn by "timeROC" was conducted to assess the predictive accuracy of overall survival (OS) and Kaplan-Meier analysis was then performed. Relationships between mutants and expression levels were compared by Wilcox rank-sum test. Function enrichment pathway analysis for mutated genes was performed by "org.Hs.eg.db", "clusterProfiler", "ggplot2" and "enrichplot" packages. Gene Set Enrichment Analysis was exploited using the MRS as the phenotypes, which worked based on the JAVA platform. All statistical analyses were achieved by R software (version 3.5.2). P value <0.05 was considered to be significant.

Results

The mutation landscape in waterfall plot revealed that a list of 49 genes that were mutated in more than 10 samples, of which 6 genes (TTN, MUC16, KMT2C, MET, OBSCN, LRP2) were mutated in more than 20 samples. Besides, non-synonymous was the most frequent mutation effect, and missense mutation was one of the most common mutation types in mutated genes across 248 samples. The AUC of MRS model consisted of 17 prognostic mutant signatures was 0.907 in 3-year OS prediction. Moreover, pRCC patients with high level of MRS showed the worse survival outcomes compared with that in low-level MRS group (P=0). In addition, correlation analysis indicated that 6 mutated genes (BAP1, OBSCN, NF2, SETD2, PBRM1, DNAH1) were significantly associated with corresponding expression levels. Last, functional enriched pathway analysis showed that these mutant genes were involved in multiple cancer-related crosstalk, including PI3K-AKT signaling pathway, JAK-STAT signaling pathway, extracellular matrix (ECM)-receptor interaction or cell cycle.

Conclusions

In summary, our study was the first attempt to explore the mutation-related signature for predicting survival outcomes of pRCC based on the high-throughput data, which might provide valuable information for further uncovering the molecular pathogenesis in pRCC.

Hepatocyte growth factor enhances the clearance of a multidrug-resistant Mycobacterium tuberculosis strain by high doses of conventional chemotherapy, preserving liver function

Tuberculosis (TB) is one of the deadliest infectious diseases in humankind history. Although, drug sensible TB is slowly decreasing, at present the rise of TB cases produced by multidrug-resistant (MDR) and extensively drug-resistant strains is a big challenge. Thus, looking for new therapeutic options against these MDR strains is mandatory. In the present work, we studied, in BALB/c mice infected with MDR strain, the therapeutic effect of supra-pharmacological doses of the conventional primary antibiotics rifampicin and isoniazid (administrated by gavage or intratracheal routes), in combination with recombinant human hepatocyte growth factor (HGF). This high dose of antibiotics administered for 3 months, overcome the resistant threshold of the MDR strain producing a significant reduction of pulmonary bacillary loads but induced liver damage, which was totally prevented by the administration of HGF. To address the long-term efficiency of this combined treatment, groups of animals after 1 month of treatment termination were immunosuppressed by glucocorticoid administration and, after 1 month, mice were euthanized, and the bacillary load was determined in lungs. In comparison with animals treated only with a high dose of antibiotics, animals that received the combined treatment showed significantly lower bacterial burdens. Thus, treatment of MDR-TB with very high doses of primary antibiotics particularly administrated by aerial route can produce a very good therapeutic effect, and its hepatic toxicity can be prevented by the administration of HGF, becoming in a new treatment modality for MDR-TB.

Non-canonical cMet regulation by vimentin mediates Plk1 inhibitor-induced apoptosis

To address the need for improved systemic therapy for non-small-cell lung cancer (NSCLC), we previously demonstrated that mesenchymal NSCLC was sensitive to polo-like kinase (Plk1) inhibitors, but the mechanisms of resistance in epithelial NSCLC remain unknown. Here, we show that cMet was differentially regulated in isogenic pairs of epithelial and mesenchymal cell lines. Plk1 inhibition inhibits cMet phosphorylation only in mesenchymal cells. Constitutively active cMet abrogates Plk1 inhibitor-induced apoptosis. Likewise, cMet silencing or inhibition enhances Plk1 inhibitor-induced apoptosis. Cells with acquired resistance to Plk1 inhibitors are more epithelial than their parental cells and maintain cMet activation after Plk1 inhibition. In four animal NSCLC models, mesenchymal tumors were more sensitive to Plk1 inhibition alone than were epithelial tumors. The combination of cMet and Plk1 inhibition led to regression of tumors that did not regrow when drug treatment was stopped. Plk1 inhibition did not affect HGF levels but did decrease vimentin phosphorylation, which regulates cMet phosphorylation via β1-integrin. This research defines a heretofore unknown mechanism of ligand-independent activation of cMet downstream of Plk1 and an effective combination therapy.

Mesenchymal–epithelial transition gene amplification and protein overexpression in stage IV pulmonary adenocarcinoma

Background

In non-small cell lung cancer (NSCLC), MET gene copy number gain, including gene amplification and chromosome 7 polysomy, is reportedly associated with patient prognosis. Although relationship between MET copy number gain and poor prognosis has been suggested in surgically resected non-small cell lung cancer, the clinical significance of MET copy number gain and protein overexpression in patients with advanced unresectable tumor is unclear.

Methods

We assessed MET copy number gain and protein expression using fluorescence in situ hybridization and immunohistochemistry in 88 patients with clinical stage IV pulmonary adenocarcinoma receiving chemotherapy, immunotherapy or palliative care.

Results

We found MET amplification, polysomy 7 and high MET protein expression in 10.2, 18.2 and 62.5% of 88 cases, respectively. Gene amplification and high protein expression were not significantly associated. A univariate analysis showed that MET amplification-positive patients had increased overall survival (HR 0.335, 95% CI: 0.119–0.945; P = 0.0388). Although it was not statistically significant in the multivariate analysis of the whole cohort, with the removal of patients who did not receive any treatment other than palliative care, MET amplification independently improved the overall survival (HR 0.178, 95% CI: 0.041–0.770; P = 0.0209). Chromosome 7 polysomy and high MET protein expression did not affect the overall survival.

Conclusions

Although MET amplification-positive tumor is considered aggressive, our results suggest that it has a more favorable prognosis than amplification-negative cases in stage IV pulmonary adenocarcinoma with medical treatment.

Simultaneous Monitoring of Cell-surface Receptor and Tumor-targeted Photodynamic Therapy via TdT-initiated Poly-G-Quadruplexes

Cancer cells contain a unique set of cell surface receptors that provide potential targets for tumor theranostics. Here, we propose an efficient approach to construct G-quadruplex-based aptamers that specifically recognize cell-surface receptors and monitor them in an amplified manner. This designed aptamer combined particular sequence for the c-Met on the cell surface and poly-G-quadruplexes structures that allow a rapid and amplified fluorescent readout upon the binding of thioflavin T (ThT). The poly-G-quadruplexes also function as a carrier for photosensitizers such as TMPyP4 in that, the aptamer further trigger the production of reactive oxygen species (ROS) to commit cells to death. This unique c-Met targeting aptamer enabled simultaneous monitoring of c-Met on the cell surface with ThT and photodynamic killing of these lung cancer cells with TMPyP4. This strategy is expected to enhance the development of tumor-targeted diagnosis and drug delivery.

Correlation of MET gene amplification and TP53 mutation with PD-L1 expression in non-small cell lung cancer

Background

The role of MET amplification in lung cancer, particularly in relation to checkpoint inhibition and EGFR WT, has not been fully explored. In this study, we correlated PD-L1 expression with MET amplification and EGFR, KRAS, or TP53 mutation in primary lung cancer.

Methods

In this retrospective study, tissue collected from 471 various tumors, including 397 lung cancers, was tested for MET amplification by FISH with a MET/centromere probe. PD-L1 expression was evaluated using clone SP142 and standard immunohistochemistry, and TP53, KRAS, and EGFR mutations were tested using next generation sequencing.

Results

Our results revealed that PD-L1 expression in non-small cell lung cancer is inversely correlated with EGFR mutation (P=0.0003), and positively correlated with TP53 mutation (P=0.0001) and MET amplification (P=0.004). Patients with TP53 mutations had significantly higher MET amplification (P=0.007), and were more likely (P=0.0002) to be EGFR wild type. There was no correlation between KRAS mutation and overall PD-L1 expression, but significant positive correlation between PD-L1 expression and KRAS with TP53 co-mutation (P=0.0002). A cut-off for the ratio of MET: centromere signal was determined as 1.5%, and 4% of lung cancer patients were identified as MET amplified.

Conclusions

This data suggests that in lung cancer both MET and TP53 play direct roles in regulating PD-L1 opposing EGFR. Moreover, KRAS and TP53 co-mutation may cooperate to drive PD-L1 expression in lung cancer. Adding MET or TP53 inhibitors to checkpoint inhibitors may be an attractive combination therapy in patients with lung cancer and MET amplification.

MET in Lung Cancer: Biomarker Selection Based on Scientific Rationale

MET or hepatocyte growth factor (HGF) receptor pathway signaling mediates wound healing and hepatic regeneration, with pivotal roles in embryonic, neuronal, and muscle development. However, dysregulation of MET signaling mediates proliferation, apoptosis, and migration and is implicated in a number of malignancies. In non-small cell lung cancer (NSCLC), aberrant MET signaling can occur through a number of mechanisms that collectively represent a significant proportion of patients. These include MET or HGF protein overexpression, MET gene amplification, MET gene mutation or fusion/rearrangement, or aberrations in downstream signaling or regulatory components. Responses to MET tyrosine kinase inhibitors have been documented in clinical trials in patients with MET-amplified or MET-overexpressing NSCLC, and case studies or case series have shown that MET mutation/deletion is a biomarker that is also predictive of response to these agents. However, other recent clinical data have highlighted an urgent need to elucidate optimal biomarkers based on genetic and/or protein diagnostics to correctly identify patients most likely to benefit in ongoing clinical trials of an array of MET-targeted therapies of differing class. The latest advances in the development of MET biomarkers in NSCLC have been reviewed, toward establishing appropriate MET biomarker selection based on a scientific rationale. Mol Cancer Ther; 16(4); 555-65. ©2017 AACR.

Double Trouble: A Case Series on Concomitant Genetic Aberrations in NSCLC

Several oncogenic drivers have been identified in non-small cell lung cancer. Targeted therapies for these aberrations have already been successfully developed and implemented in clinical practice. Owing to improved sensitivity in genetic testing, more and more tumors with multiple driver mutations are identified, resulting in dilemmas for treating physicians whether and which targeted therapy to use. In this case series, we provide an overview of patients with intrinsic double mutations in oncogenic drivers and their reported response to targeted therapies, with a focus on epidermal growth factor receptor, anaplastic lymphoma kinase, cMET, and Kirsten rat sarcoma viral oncogene. We also include an unpublished case report on a patient with an epidermal growth factor receptor L858R and cMET exon 14 skipping.

MET Tyrosine Kinase Inhibition Enhances the Antitumor Efficacy of an HGF Antibody

Receptor tyrosine kinase therapies have proven to be efficacious in specific cancer patient populations; however, a significant limitation of tyrosine kinase inhibitor (TKI) treatment is the emergence of resistance mechanisms leading to a transient, partial, or complete lack of response. Combination therapies using agents with synergistic activity have potential to improve response and reduce acquired resistance. Chemoreagent or TKI treatment can lead to increased expression of hepatocyte growth factor (HGF) and/or MET, and this effect correlates with increased metastasis and poor prognosis. Despite MET's role in resistance and cancer biology, MET TKI monotherapy has yielded disappointing clinical responses. In this study, we describe the biological activity of a selective, oral MET TKI with slow off-rate and its synergistic antitumor effects when combined with an anti-HGF antibody. We evaluated the combined action of simultaneously neutralizing HGF ligand and inhibiting MET kinase activity in two cancer xenograft models that exhibit autocrine HGF/MET activation. The combination therapy results in additive antitumor activity in KP4 pancreatic tumors and synergistic activity in U-87MG glioblastoma tumors. Pharmacodynamic characterization of biomarkers that correlate with combination synergy reveal that monotherapies induce an increase in the total MET protein, whereas combination therapy significantly reduces total MET protein levels and phosphorylation of 4E-BP1. These results hold promise that dual targeting of HGF and MET by combining extracellular ligand inhibitors with intracellular MET TKIs could be an effective intervention strategy for cancer patients who have acquired resistance that is dependent on total MET protein. Mol Cancer Ther; 16(7); 1269-78. ©2017 AACR.

Better to be alone than in bad company: The antagonistic effect of cisplatin and crizotinib combination therapy in non-small cell lung cancer

AIM

To investigate the potential benefit of combining the cMET inhibitor crizotinib and cisplatin we performed in vitro combination studies.

METHODS

We tested three different treatment schemes in four non-small cell lung cancer (NSCLC) cell lines with a different cMET/epidermal growth factor receptor genetic background by means of the sulforhodamine B assay and performed analysis with Calcusyn.

RESULTS

All treatment schemes showed an antagonistic effect in all cell lines, independent of the cMET status. Despite their different genetic backgrounds, all cell lines (EBC-1, HCC827, H1975 and LUDLU-1) showed antagonistic combination indexes ranging from 1.3-2.7. These results were independent of the treatment schedule.

CONCLUSION

These results discourage further efforts to combine cMET inhibition with cisplatin chemotherapy in NSCLC.

EGFR gene deregulation mechanisms in lung adenocarcinoma: A molecular review

For the last two decades, evolution in molecular biology has expanded our knowledge in decoding a broad spectrum of genomic imbalances that progressively lead normal cells to a neoplastic state and finally to complete malignant transformation. Concerning oncogenes and signaling transduction pathways mediated by them, identification of specific gene alterations remains a critical process for handling patients by applying targeted therapeutic regimens. The epidermal growth factor receptor (EGFR) signaling pathway plays a crucial role in regulating cell proliferation, differentiation and apoptosis in normal cells. EGFR mutations and amplification represent the gene's main deregulation mechanisms in cancers of different histo-genetic origin. Furthermore, intra-cancer molecular heterogeneity due to clonal rise and expansion mainly explains the variable resistance to novel anti-EGFR monoclonal antibody (mAb), and also tyrosine kinase inhibitors (TKIs). According to recently published 2015 WHO new classification, lung cancer is the leading cause of death related to cancer and its incidence is still on the increase worldwide. The majority of patients suffering from lung cancer are diagnosed with epithelial tumors (adenocarcinoma predominantly and squamous cell carcinoma represent ∼85% of all pathologically defined lung cancer cases). In those patients, EGFR-activating somatic mutations in exons 18/19/20/21 modify patients' sensitivity (i.e. exon 21 L858R, exon 19 LREA deletion) or resistance (ie exon 20 T790M and/or insertion) to TKI mediated targeted therapeutic strategies. Additionally, the role of specific micro-RNAs that affect EGFR regulation is under investigation. In the current review, we focused on EGFR gene/protein structural and functional aspects and the corresponding alterations that occur mainly in lung adenocarcinoma to critically modify its molecular landscape.

cMET Exon 14 Skipping: From the Structure to the Clinic

The abnormal stimulation of the multiple signal transduction pathways downstream of the receptor tyrosine kinase mesenchymal-epithelial transition factor (cMET) promotes cellular transformation, tumor motility, and invasion. Therefore, cMET has been the focus of prognostic and therapeutic studies in different tumor types, including non-small cell lung cancer. In particular, several cMET inhibitors have been developed as innovative therapeutic candidates and are currently under investigation in clinical trials. However, one of the challenges in establishing effective targeted treatments against cMET remains the accurate identification of biomarkers for the selection of responsive subsets of patients. Recently, splice site mutations have been discovered in cMET that lead to the skipping of exon 14, impairing the breakdown of the receptor. Patients with NSCLC who are carrying this splice variant typically overexpress the cMET receptor and show a response to small molecule inhibitors of cMET. Here, we review the main differences at the structural level between the wild-type and the splice variants of cMET and their influence on cMET signaling. We clarify the reason why this variant responds to small molecule inhibitors and their prognostic/predictive role.

Sequence-defined cMET/HGFR-targeted Polymers as Gene Delivery Vehicles for the Theranostic Sodium Iodide Symporter (NIS) Gene

The sodium iodide symporter (NIS) as well-characterized theranostic gene represents an outstanding tool to target different cancer types allowing noninvasive imaging of functional NIS expression and therapeutic radioiodide application. Based on its overexpression on the surface of most cancer types, the cMET/hepatocyte growth factor receptor serves as ideal target for tumor-selective gene delivery. Sequence-defined polymers as nonviral gene delivery vehicles comprising polyethylene glycol (PEG) and cationic (oligoethanoamino) amide cores coupled with a cMET-binding peptide (cMBP2) were complexed with NIS-DNA and tested for receptor-specificity, transduction efficiency, and therapeutic efficacy in hepatocellular cancer cells HuH7. In vitro iodide uptake studies demonstrated high transduction efficiency and cMET-specificity of NIS-encoding polyplexes (cMBP2-PEG-Stp/NIS) compared to polyplexes without targeting ligand (Ala-PEG-Stp/NIS) and without coding DNA (cMBP2-PEG-Stp/Antisense-NIS). Tumor recruitment and vector biodistribution were investigated in vivo in a subcutaneous xenograft mouse model showing high tumor-selective iodide accumulation in cMBP2-PEG-Stp/NIS-treated mice (6.6 ± 1.6% ID/g (123)I, biological half-life 3 hours) by (123)I-scintigraphy. Therapy studies with three cycles of polyplexes and (131)I application resulted in significant delay in tumor growth and prolonged survival. These data demonstrate the enormous potential of cMET-targeted sequence-defined polymers combined with the unique theranostic function of NIS allowing for optimized transfection efficiency while eliminating toxicity.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.