Prognostic and predictive value of MET deregulation in non-small cell lung cancer

Oncogenic alterations in advanced NSCLC: a molecular super-highway

Lung cancer ranks among the most common cancers world-wide and is the first cancer-related cause of death. The classification of lung cancer has evolved tremendously over the past two decades. Today, non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma, comprises a multitude of molecular oncogenic subsets that change both the prognosis and management of disease.Since the first targeted oncogenic alteration identified in 2004, with the epidermal growth factor receptor (EGFR), there has been unprecedented progress in identifying and targeting new molecular alterations. Almost two decades of experience have allowed scientists to elucidate the biological function of oncogenic drivers and understand and often overcome the molecular basis of acquired resistance mechanisms. Today, targetable molecular alterations are identified in approximately 60% of lung adenocarcinoma patients in Western populations and 80% among Asian populations. Oncogenic drivers are largely enriched among non-smokers, east Asians, and younger patients, though each alteration has its own patient phenotype.The current landscape of druggable molecular targets includes EGFR, anaplastic lymphoma kinase (ALK), v-raf murine sarcoma viral oncogene homolog B (BRAF), ROS proto-oncogene 1 (ROS1), Kirstin rat sarcoma virus (KRAS), human epidermal receptor 2 (HER2), c-MET proto-oncogene (MET), neurotrophic receptor tyrosine kinase (NTRK), rearranged during transfection (RET), neuregulin 1 (NRG1). In addition to these known targets, others including Phosphoinositide 3-kinases (PI3K) and fibroblast growth factor receptor (FGFR) have garnered significant attention and are the subject of numerous ongoing trials.In this era of personalized, precision medicine, it is of paramount importance to identify known or potential oncogenic drivers in each patient. The development of targeted therapy is mirrored by diagnostic progress. Next generation sequencing offers high-throughput, speed and breadth to identify molecular alterations in entire genomes or targeted regions of DNA or RNA. It is the basis for the identification of the majority of current druggable alterations and offers a unique window into novel alterations, and de novo and acquired resistance mechanisms.In this review, we discuss the diagnostic approach in advanced NSCLC, focusing on current oncogenic driver alterations, through their pathophysiology, management, and future perspectives. We also explore the shortcomings and hurdles encountered in this rapidly evolving field.

The Efficacy and Safety of Treating Acquired MET Resistance Through Combinations of Parent and MET Tyrosine Kinase Inhibitors in Patients With Metastatic Oncogene-Driven NSCLC

Introduction

Acquired MET gene amplification, MET exon 14 skip mutations, or MET fusions can emerge as resistance mechanisms to tyrosine kinase inhibitors (TKIs) in patients with lung cancer. The efficacy and safety of combining MET TKIs (such as crizotinib, capmatinib, or tepotinib) with parent TKIs to target acquired MET resistance are not well characterized.

Methods

Multi-institutional retrospective chart review identified 83 patients with metastatic oncogene-driven NSCLC that were separated into the following two pairwise matched cohorts: (1) MET cohort (n = 41)-patients with acquired MET resistance continuing their parent TKI with a MET TKI added or (2) Chemotherapy cohort (n = 42)-patients without any actionable resistance continuing their parent TKI with a platinum-pemetrexed added. Clinicopathologic features, radiographic response (by means of Response Evaluation Criteria in Solid Tumors version 1.1), survival outcomes, adverse events (AEs) (by means of Common Terminology Criteria for Adverse Events version 5.0), and genomic data were collected. Survival outcomes were assessed using Kaplan-Meier methods. Multivariate modeling adjusted for lines of therapy, brain metastases, TP53 mutations, and oligometastatic disease.

Results

Within the MET cohort, median age was 56 years (range: 36-83 y). Most patients were never smokers (28 of 41, 68.3%). Baseline brain metastases were common (21 of 41, 51%). The most common oncogenes in the MET cohort were EGFR (30 of 41, 73.2%), ALK (seven of 41, 17.1%), and ROS1 (two of 41, 4.9%). Co-occurring TP53 mutations (32 of 41, 78%) were frequent. Acquired MET alterations included MET gene amplification (37 of 41, 90%), MET exon 14 mutations (two of 41, 5%), and MET gene fusions (two of 41, 5%). After multivariate adjustment, the objective response rate (ORR) was higher in the MET cohort versus the chemotherapy cohort (ORR: 69.2% versus 20%, p < 0.001). Within the MET cohort, MET gene copy number (≥10 versus 6-10) did not affect radiographic response (54.5% versus 68.4%, p = 0.698). There was no difference in ORR on the basis of MET TKI used (F [2, 36] = 0.021, p = 0.978). There was no difference in progression-free survival (5 versus 6 mo; hazard ratio = 0.64; 95% confidence interval: 0.34-1.23, p = 0.18) or overall survival (13 versus 11 mo; hazard ratio = 0.75; 95% confidence interval: 0.42-1.35, p = 0.34) between the MET and chemotherapy cohorts. In the MET cohort, dose reductions for MET TKI-related toxicities were common (17 of 41, 41.4%) but less frequent for parent TKIs (two of 41, 5%). Grade 3 AEs were not significant between crizotinib, capmatinib, and tepotinib (p = 0.3). The discontinuation rate of MET TKIs was 17% with no significant differences between MET TKIs (p = 0.315). Among pre- and post-treatment biopsies (n = 17) in the MET cohort, the most common next-generation sequencing findings were loss of MET gene amplification (15 of 17, 88.2%), MET on-target mutations (seven of 17, 41.2%), new Ras-Raf-MAPK alterations (three of 17, 17.6%), and EGFR gene amplification (two of 17, 11.7%).

Conclusions

The efficacy and safety of combining MET TKIs (crizotinib, capmatinib, or tepotinib) with parent TKIs for acquired MET resistance are efficacious. Radiographic response and AEs did not differ significantly on the basis of the underlying MET TKI used. Loss of MET gene amplification, development of MET on-target mutations, Ras-Raf-MAPK alterations, and EGFR gene amplification were molecular patterns found on progression with dual parent and MET TKI combinations.

A review of recent advances in the novel therapeutic targets and immunotherapy for lung cancer

Lung cancer is amongst the most pervasive malignancies having high mortality rates. It is broadly grouped into non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). The concept of personalized medicine has overshadowed the conventional chemotherapy given to all patients with lung cancer. The targeted therapy is given to a particular population having specific mutations to help in the better management of lung cancer. The targeting pathways for NSCLC include the epidermal growth factor receptor, vascular endothelial growth factor receptor, MET (Mesenchymal epithelial transition factor) oncogene, Kirsten rat sarcoma viral oncogene (KRAS), and anaplastic lymphoma kinase (ALK). SCLC targeting pathway includes Poly (ADP-ribose) polymerases (PARP) inhibitors, checkpoint kinase 1 (CHK 1) pathway, WEE1 pathway, Ataxia Telangiectasia and Rad3-related (ATR)/Ataxia telangiectasia mutated (ATM), and Delta-like canonical Notch ligand 3 (DLL-Immune checkpoint inhibitors like programmed cell death protein 1 (PD-1)/ programmed death-ligand 1 (PD-L1) inhibitors and Cytotoxic T-lymphocyte-associated antigen-4 (CTLA4) blockade are also utilized in the management of lung cancer. Many of the targeted therapies are still under development and require clinical trials to establish their safety and efficacy. This review summarizes the mechanism of molecular targets and immune-mediated targets, recently approved drugs, and their clinical trials for lung cancer.

Crizotinib attenuates cancer metastasis by inhibiting TGFβ signaling in non-small cell lung cancer cells

Crizotinib is a clinically approved tyrosine kinase inhibitor for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring EML4-ALK fusion. Crizotinib was originally developed as an inhibitor of MET (HGF receptor), which is involved in the metastatic cascade. However, little is known about whether crizotinib inhibits tumor metastasis in NSCLC cells. In this study, we found that crizotinib suppressed TGFβ signaling by blocking Smad phosphorylation in an ALK/MET/RON/ROS1-independent manner in NSCLC cells. Molecular docking and in vitro enzyme activity assays showed that crizotinib directly inhibited the kinase activity of TGFβ receptor I through a competitive inhibition mode. Cell tracking, scratch wound, and transwell migration assays showed that crizotinib simultaneously inhibited TGFβ- and HGF-mediated NSCLC cell migration and invasion. In addition, in vivo bioluminescence imaging analysis showed that crizotinib suppressed the metastatic capacity of NSCLC cells. Our results demonstrate that crizotinib attenuates cancer metastasis by inhibiting TGFβ signaling in NSCLC cells. Therefore, our findings will help to advance our understanding of the anticancer action of crizotinib and provide insight into future clinical investigations.

A Novel c-Mesenchymal-Epithelial Transition Factor Intergenic Fusion Response to Crizotinib in a Chinese Patient With Lung Adenocarcinoma: A Case Report

Background

The c-mesenchymal–epithelial transition factor (C-MET) is an oncogene encoding a tyrosine kinase receptor that plays an important role in tumor growth and metastasis. The National Comprehensive Cancer Network (NCCN) guidelines have approved carbatinib/crizotinib for advanced non-small cell lung cancer (NSCLC) patients with MET exon 14 skipping.

Methods

In June 2020, the Department of Respiratory and Critical Care Medicine of Peking University People’s Hospital admitted a 72-year-old male patient with lung adenocarcinoma (LADC) with a history of interstitial lung disease secondary to antineutrophil cytoplasmic antibody-associated vasculitis. Genetic examination by next-generation sequencing showed an intergenic fusion of MET, and crizotinib was administered on August 14, 2020. Follow-up showed that tumor volume was significantly reduced. However, crizotinib was discontinued in November 2020 because of the patient’s worsening interstitial lung disease, and CT scans showed continued partial response (PR) for 5 months. In April 2021, right lower lobe mass progressed, and disease progression was considered.

Conclusion

This was the first case of a patient with LADC with MET intergenic fusion who significantly benefited from crizotinib. Even after crizotinib was discontinued for 5 months, the patient continued exhibiting PR, suggesting that MET intergenic fusion may have carcinogenic activity in LADC and was sensitive to crizotinib.

Targeting MET Amplification with Crizotinib in a Case of Sinonasal Undifferentiated Carcinoma

Comprehensive molecular testing of individual tumors has led to the identification of novel molecularly defined cancer therapies and treatment indications. Given low frequencies of many molecular alterations, efficacy of therapies used to target them are often undefined, especially in the context of rare malignancies. Here we describe the first reported case of MET amplification in sinonasal undifferentiated carcinoma (SNUC), a rare cancer with a poor prognosis. The patient was treated with crizotinib, a tyrosine kinase inhibitor that targets c-MET, and experienced a complete response. Our report demonstrates the potential of employing precision oncology approaches in SNUC and other rare cancers.

Phase I/II Study of Capmatinib Plus Erlotinib in Patients With MET-Positive Non-Small-Cell Lung Cancer

PURPOSE

MET dysregulation is an oncogenic driver in non-small-cell lung cancer (NSCLC), as well as a mechanism of TKI (tyrosine kinase inhibitor) resistance in patients with epidermal growth factor receptor (EGFR)-mutated disease. This study was conducted to determine safety and preliminary efficacy of the combination EGFR and MET inhibitors as a strategy to overcome and/or delay EGFR-TKI resistance.

METHODS

A standard 3 + 3 dose-escalation trial of capmatinib in combination with erlotinib in patients with MET-positive NSCLC was used. Eighteen patients in the dose-escalation cohort received 100-600 mg twice daily of capmatinib with 100-150 mg daily of erlotinib. There were two dose-expansion cohorts. Cohort A included 12 patients with EGFR-mutant tumors resistant to TKIs. Cohort B included five patients with EGFR wild-type tumors. The primary outcome was to assess safety and determine the recommended phase II dose (RP2D) of the combination.

RESULTS

The most common adverse events of any grade were rash (62.9%), fatigue (51%), and nausea (45.7%). Capmatinib exhibited nonlinear pharmacokinetics combined with erlotinib, while showing no significant drug interactions. The RP2D was 400 mg twice daily capmatinib tablets with 150 mg daily erlotinib. The overall response rate (ORR) and DCR in dose-expansion cohort A was 50% and 50%, respectively. In cohort B, the ORR and disease control rate were 75% and 75%.

CONCLUSION

Capmatinib in combination with erlotinib demonstrated safety profiles consistent with prior studies. We observed efficacy in specific patient populations. Continued evaluation of capmatinib plus EGFR-TKIs is warranted in patients with EGFR activating mutations.

An integrated approach to biomarker discovery reveals gene signatures highly predictive of cancer progression

Current cancer biomarkers present variability in their predictive power and demonstrate limited clinical efficacy, possibly due to the lack of functional relevance of biomarker genes to cancer progression. To address this challenge, a biomarker discovery pipeline was developed to integrate gene expression profiles from The Cancer Genome Atlas and essential survival gene datasets from The Cancer Dependency Map, the latter of which catalogs genes driving cancer progression. By applying this pipeline to lung adenocarcinoma, lung squamous cell carcinoma, and glioblastoma, genes highly associated with cancer progression were identified and designated as progression gene signatures (PGSs). Analysis of area under the receiver operating characteristics curve revealed that PGSs predicted patient survival more accurately than previously identified cancer biomarkers. Moreover, PGSs stratified patients with high risk for progressive disease indicated by worse prognostic outcomes, increased frequency of cancer progression, and poor responses to chemotherapy. The robust performance of these PGSs were recapitulated in four independent microarray datasets from Gene Expression Omnibus and were further verified in six freshly dissected tumors from glioblastoma patients. Our results demonstrate the power of an integrated approach to cancer biomarker discovery and the possibility of implementing PGSs into clinical biomarker tests.

Overview of current targeted therapy in gallbladder cancer

Gallbladder cancer (GBC) is rare, but is the most malignant type of biliary tract tumor. Unfortunately, only a small population of cancer patients is acceptable for the surgical resection, the current effective regimen; thus, the high mortality rate has been static for decades. To substantially circumvent the stagnant scenario, a number of therapeutic approaches owing to the creation of advanced technologic measures (e.g., next-generation sequencing, transcriptomics, proteomics) have been intensively innovated, which include targeted therapy, immunotherapy, and nanoparticle-based delivery systems. In the current review, we primarily focus on the targeted therapy capable of specifically inhibiting individual key molecules that govern aberrant signaling cascades in GBC. Global clinical trials of targeted therapy in GBC are updated and may offer great value for novel pathologic and therapeutic insights of this deadly disease, ultimately improving the efficacy of treatment.

Phase I trial of the MET inhibitor tepotinib in Japanese patients with solid tumors

OBJECTIVES

Tepotinib (MSC2156119J) is an oral, potent and highly selective small molecule mesenchymal-epithelial transition factor (MET) inhibitor for which the recommended Phase II dose of 500 mg once daily has been defined, based on the first-in-man trial conducted in the USA and Europe. We carried out a multicenter Phase I trial with a classic `3 + 3' design to determine the recommended Phase II dose in Japanese patients with solid tumors (NCT01832506).

METHODS

Patients aged ≥20 years with advanced solid tumors (refractory to standard therapy or for whom no effective standard therapy was available) received tepotinib at 215, 300 or 500 mg once daily in a 21-day cycle. Occurrence of dose-limiting toxicities during cycle 1 was used to determine the maximum tolerated dose. Efficacy, safety and pharmacokinetics were also evaluated to support the dose assessment.

RESULTS

Twelve patients were treated. Tepotinib was generally well tolerated with no observed dose-limiting toxicities; treatment-related adverse events were mainly grades 1-2. The tolerability profile of tepotinib was similar to that observed in non-Japanese populations. Pharmacokinetics in Japanese and Western patients was comparable. One patient with gastric cancer and one patient with urachal cancer had stable disease of ≥12 weeks in duration. The observed safety profile and pharmacokinetics are comparable with those in patients from the USA and Europe, and the recommended Phase II dose of tepotinib in Japanese patients was confirmed as 500 mg once daily.

CONCLUSIONS

These results, including initial signals of antitumor activity, support further development of tepotinib in Japanese patients with cancer.

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.

Targeting the MET-Signaling Pathway in Non-Small-Cell Lung Cancer: Evidence to Date

The c-MET proto-oncogene (MET) plays an important role in lung oncogenesis, affecting cancer-cell survival, growth and invasiveness. The MET receptor in non-small-cell lung cancer (NSCLC) is a potential therapeutic target. The development of high-output next-generation sequencing techniques has enabled better identification of anomalies in the MET pathway, like the MET exon-14 (METex14) mutation. Moreover, analyses of epidermal growth factor-receptor (EGFR) and mechanisms of resistance to tyrosine-kinase inhibitors (TKIs) demonstrated the importance of MET amplification as an escape mechanism in patients with TKI-treated EGFR-mutated NSCLCs. This review summarizes the laboratory findings on MET and its anomalies, trial results on METex14 alterations and MET amplification in non-EGFR mutated NSCLCs, and acquired resistance to TKI in EGFR-mutated NSCLCs. The outcomes of the first trials with anti-MET agents on non-selected NSCLC patients or those selected for MET overexpression were disappointing. Two situations seem the most promising today for the use of anti-MET agents to treat these patients: tumors harboring METex14 and those EGFR-sensitive mutation mutated under TKI-EGFR with a MET-amplification mechanism of resistance or EGFR-resistance mutation.

MET Oncogene in Non-Small Cell Lung Cancer: Mechanism of MET Dysregulation and Agents Targeting the HGF/c-Met Axis

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide and has a poor prognosis. Current treatments for advanced NSCLC included traditional chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The efficacy of targeted therapy relies on oncogene addiction. Mesenchymal-epithelial transition factor (MET) gene can encode unconventional receptor tyrosine kinases with pleiotropic functions, when signals are abnormally activated, it can initiate and maintain tumor transformation, promote cell proliferation, survival, tumor invasion and angiogenesis. Thus, it is a promising therapeutic target. Previous studies have shown that elevated levels of HGF and/or overexpression of c-Met are associated with poor prognosis in lung cancer. In preclinical and clinical trials, c-MET inhibitors have shown some antitumor activity in NSCLC. Although the efficacy results of MET inhibitors in Phase III clinical trials are disappointing, given the molecular heterogeneity of NSCLC, only subgroups of patients with MET gene alterations may benefit from c-MET inhibitors. The challenge for the future is to screen out the potential beneficiaries. To solve this problem, there is need for large data analysis for the detection methods and treatment effects, to establish standards that meet the MET activation status, and determine reliable thresholds to achieve effective patient stratification and clinical decision making. This article summarized the structure of the hepatocyte growth factor (HGF)/c-Met axis, the different mechanisms of MET addiction, as well as MET amplification as acquired resistance mechanism to epidermal growth factor receptor-tyrosine kinase inhibitors, the latest advances of MET inhibitors, and immuotherapy in the treatment of NSCLC with MET alterations.

Suppression of c-MET overcomes erlotinib resistance in tongue cancer cells

Background

Erlotinib is a commonly used molecular-targeted drug for the treatment of tongue cancer. However, the development of acquired resistance to erlotinib hampers its therapeutic use.

Materials and methods

To analyze the erlotinib resistance, long-term and short term survival assay were used to compare the resistance between parental and resistant tongue cancer cells. Flow cytometry, Hochest staining and western blot were used to analyze the apoptosis among the cells. Moreover, Transwell and wound healing assay were used to compare the invasion ability of the cells. To deeply explore the drug resistance in vivo, orthotopic tumor studies were applied. Finally, to explain the mechanism of c-met in erlotinib resistance, shRNA against c-met was used to down-regulate the expression of c-met. And SU11274 also used in orthotopic model.

Results

We established erlotinib-resistant human tongue cancer cell line by chronic exposure of TCA-8113 cells to increasing concentrations of erlotinib and determined the role of c-MET and EGFR in the development of acquired resistance. We found a significant increase in the phosphorylation of c-MET and an obvious decrease of the phosphorylation of EGFR in erlotinib-resistant cells. Our results also revealed that inhibition of c-MET alone with SU11274 exerted an inhibitory effect on the proliferation of erlotinib-resistant cells in the short term; however, it failed to sustain the inhibitory effect in the long term. Simultaneous inhibition of c-MET and EGFR significantly inhibited the proliferation of erlotinib-resistant cells in both a short and long period. Furthermore, we explored the underlying mechanism and found that treatment of erlotinib-resistant cells with SU11274 or shRNA against c-MET induced the phosphorylation of EGFR. Moreover, our results demonstrated that simultaneous inhibition of c-MET and EGFR significantly inhibited the migration and invasion of erlotinib-resistant cells.

Conclusion

Taken together, our results suggested that c-MET is involved in acquired drug resistance to erlotinib and that cotargeting of EGFR and c-MET could overcome acquired resistance to erlotinib and inhibit the invasion and metastasis of erlotinib-resistant cells.

Non-small cell lung cancer treatment (r)evolution: ten years of advances and more to come

Diagnostic and treatment algorithms in non-small cell lung cancer (NSCLC) are evolving at a never-before-seen pace. Histological subtyping to maximise treatment efficacy and avoid toxicity has marked the beginning of the revolution, opening the way to molecular characterisation to guide genomically driven treatments with targeted agents, led by Epidermal Growth Factor Receptor (EGFR) and Anaplastic Lymphoma Kinase (ALK) inhibitors. More recently, agents against the Program Death 1 receptor (PD-1) and ligand 1 (PD-L1) have entered the clinical arena, offering new hope to NSCLC patients, although several uncertainties remain to be elucidated. Here, we review the most clinically relevant advances in the diagnosis and treatment of NSCLC in the past decade.

Biology and clinical significance of circulating tumor cell subpopulations in lung cancer

By identifying and tracking genetic changes in primary tumors and metastases, patients can be stratified for the most efficient therapeutic regimen by screening for known biomarkers. However, retrieving tissues biopsies is not always feasible due to tumor location or risk to patient. Therefore, a liquid biopsies approach offers an appealing solution to an otherwise invasive procedure. The rapid growth of the liquid biopsy field has been aided by improvements in the sensitivity and specificity of enrichment assays for isolating circulating tumor cells (CTCs) from normal surrounding blood cells. Furthermore, the identification and molecular characterization of CTCs has been shown in numerous studies to be of diagnostic and prognostic relevance in breast, prostate and colon cancer patients. Despite these advancements, and the highly metastatic nature of lung cancer, it remains a challenge to detect CTCs in advanced non-small cell lung cancer (NSCLC). It may be that loss of epithelial features, in favor of a mesenchymal phenotype, and the highly heterogeneous nature of NSCLC CTCs contribute to their evasion from current detection methods. By identifying a broader spectrum of biomarkers that could better differentiate the various NSCLC CTCs subpopulations, it may be possible to not only improve detection rates but also to shed light on which CTC clones are likely to drive metastatic initiation. Here we review the biology of CTCs and describe a number of proteins and genetic targets which could potentially be utilized for the dissemination of heterogenic subpopulations of CTCs in NSCLC.

MET expression and copy number status in clear-cell renal cell carcinoma: prognostic value and potential predictive marker

Multiple targeted therapy for advanced clear-cell renal cell carcinoma (RCC) has substantially improved patient outcome, but complete remission is uncommon and many tumors eventually develop resistance. Mechanistic, preclinical, and early clinical data highlight c-Met / hepatocyte growth factor receptor as a promising target for RCC therapeutic agents.We have examined MET expression, frequency of MET gene copy gains and MET gene mutation in a large, hospital-based series of renal cell carcinomas with long-term follow-up information.Out of a total of 572 clear-cell RCC, only 17% were negative for MET expression whereas 32% showed high protein levels. High MET expression and MET copy number gains were associated with an aggressive phenotype and an unfavorable patient outcome. Elevated protein levels in absence of gene amplification were not attributed to mutations, based on results of targeted next-generation sequencing.Our data reveal that clear-cell RCC with MET upregulation show an aggressive behavior and MET copy number increase is evident in a substantial percentage of patients with high-grade carcinomas and metastatic disease. Diagnostic assessment of MET expression and amplification may be of predictive value to guide targeted therapy against MET signaling in patients with clear-cell RCC.

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.

Phase II study of erlotinib plus tivantinib (ARQ 197) in patients with locally advanced or metastatic EGFR mutation-positive non-small-cell lung cancer just after progression on EGFR-TKI, gefitinib or erlotinib

Background

Patients with epidermal growth factor receptor (EGFR) activation mutation-positive non-small-cell lung cancer (NSCLC) respond well to EGFR tyrosine kinase inhibitors (EGFR-TKIs), but eventually become resistant in most cases. The hepatocyte growth factor/c-Met (HGF/c-Met) pathway is reported as a poor prognostic factor in various cancers. As c-Met is involved in EGFR-TKI resistance, a c-Met inhibitor and EGFR-TKI combination may reverse the resistance. This study evaluated the efficacy and safety of a c-Met selective inhibitor, tivantinib (ARQ 197), in combination with erlotinib, in Japanese EGFR mutation-positive patients with NSCLC who progressed while on EGFR-TKIs.

Methods

This study enrolled 45 patients with NSCLC with acquired resistance to EGFR-TKIs, who were orally administered a daily combination of tivantinib/erlotinib. The primary end point was the overall response rate (ORR) and secondary end points included disease control rate, progression-free survival (PFS) and overall survival (OS). The patients underwent a mandatory second biopsy just after progression on EGFR-TKIs. The predictive biomarkers were extensively analysed using tumour and blood samples.

Results

The ORR was 6.7% (95% CI 1.4% to 18.3%), and the lower limit of 95% CI did not exceed the target of 5%. The median PFS (mPFS) and median OS (mOS) were 2.7 months (95% CI 1.4 to 4.2) and 18.0 months (95% CI 13.4 to 22.2), respectively. Both were longer in c-Met high patients (c-Met high vs low: mPFS 4.1 vs 1.4 months; mOS 20.7 vs 13.9 months). Partial response was observed in three patients, all of whom were c-Met and HGF high. The common adverse events and their frequencies were similar to those known to occur with tivantinib or erlotinib alone.

Conclusions

Although this study did not prove clinical benefit of tivantinib in patients with acquired resistance to EGFR-TKIs, activated HGF/c-Met signalling, a poor prognostic factor, may define a patient subset associated with longer survival by the tivantinib/erlotinib combination.

Trial registration number

NCT01580735.

Quantitative imaging for development of companion diagnostics to drugs targeting HGF/MET

The limited clinical success of anti-HGF/MET drugs can be attributed to the lack of predictive biomarkers that adequately select patients for treatment. We demonstrate here that quantitative digital imaging of formalin fixed paraffin embedded tissues stained by immunohistochemistry can be used to measure signals from weakly staining antibodies and provides new opportunities to develop assays for detection of MET receptor activity. To establish a biomarker panel of MET activation, we employed seven antibodies measuring protein expression in the HGF/MET pathway in 20 cases and up to 80 cores from 18 human cancer types. The antibodies bind to epitopes in the extra (EC)- and intracellular (IC) domains of MET (MET4^EC, SP44_MET^IC, D1C2_MET^IC), to MET-pY1234/pY1235, a marker of MET kinase activation, as well as to HGF, pSFK or pMAPK. Expression of HGF was determined in tumour cells (T_HGF) as well as in stroma surrounding cancer (St_HGF). Remarkably, MET4^EC correlated more strongly with pMET (r = 0.47) than SP44_MET^IC (r = 0.21) or D1C2_MET^IC (r = 0.08) across 18 cancer types. In addition, correlation coefficients of pMET and T_HGF (r = 0.38) and pMET and pSFK (r = 0.56) were high. Prediction models of MET activation reveal cancer-type specific differences in performance of MET4^EC, SP44_MET^IC and anti-HGF antibodies. Thus, we conclude that assays to predict the response to HGF/MET inhibitors require a cancer-type specific antibody selection and should be developed in those cancer types in which they are employed clinically.