MET tyrosine kinase inhibitor crizotinib (PF-02341066) shows differential antitumor effects in non-small cell lung cancer according to MET alterations

Mapping kinase domain resistance mechanisms for the MET receptor tyrosine kinase via deep mutational scanning

Mutations in the kinase and juxtamembrane domains of the MET Receptor Tyrosine Kinase are responsible for oncogenesis in various cancers and can drive resistance to MET-directed treatments. Determining the most effective inhibitor for each mutational profile is a major challenge for MET-driven cancer treatment in precision medicine. Here, we used a deep mutational scan (DMS) of ∼5,764 MET kinase domain variants to profile the growth of each mutation against a panel of 11 inhibitors that are reported to target the MET kinase domain. We identified common resistance sites across type I, type II, and type I ½ inhibitors, unveiled unique resistance and sensitizing mutations for each inhibitor, and validated non-cross-resistant sensitivities for type I and type II inhibitor pairs. We augment a protein language model with biophysical and chemical features to improve the predictive performance for inhibitor-treated datasets. Together, our study demonstrates a pooled experimental pipeline for identifying resistance mutations, provides a reference dictionary for mutations that are sensitized to specific therapies, and offers insights for future drug development.

TWIST1 is a critical downstream target of the HGF/MET pathway and is required for MET driven acquired resistance in oncogene driven lung cancer

MET amplification/mutations are important targetable oncogenic drivers in NSCLC, however, acquired resistance is inevitable and the majority of patients with targetable MET alterations fail to respond to MET tyrosine kinase inhibitors (TKIs). Furthermore, MET amplification is among the most common mediators of TKI resistance. As such, novel therapies to target MET pathway and overcome MET TKI resistance are clearly needed. Here we show that the epithelial-mesenchymal transition (EMT) transcription factor, TWIST1 is a key downstream mediator of HGF/MET induced resistance through suppression of p27 and targeting TWIST1 can overcome resistance. We found that TWIST1 is overexpressed at the time of TKI resistance in multiple MET-dependent TKI acquired resistance PDX models. We have shown for the first time that MET directly stabilized the TWIST protein leading to TKI resistance and that TWIST1 was required for MET-driven lung tumorigenesis as well as could induce MET TKI resistance when overexpressed. TWIST1 mediated MET TKI resistance through suppression of p27 expression and genetic or pharmacologic inhibition of TWIST1 overcame TKI resistance in vitro and in vivo. Our findings suggest that targeting TWIST1 may be an effective therapeutic strategy to overcome resistance in MET-driven NSCLC as well as in other oncogene driven subtypes in which MET amplification is the resistance mechanism.

Identification of biomarkers, pathways, and therapeutic targets for EGFR-TKI resistance in NSCLC

This study aimed to map the hub genes and potential pathways that might be involved in the molecular pathogenesis of EGFR-TKI resistance in NSCLC. We performed bioinformatics analysis to identify differentially expressed genes, their function, gene interactions, and pathway analysis between EGFR-TKI-sensitive and EGFR-TKI-resistant patient-derived xenotransplantation samples based on Gene Expression Omnibus database. Survival analysis was performed via the GEPIA database (GEO). The relationship between the key gene ITGAM and the therapeutic candidates was retrieved from DGIdb. A total of 1,302 differentially expressed genes were identified based on GEO. The PPI network highlighted 10 potential hub genes. Only ITGAM was linked to poor DSF in NSCLC patients. A total of 10 drugs were predicted to be potential therapeutics for NSCLC with EGFR-TKI resistance. This study indicates the hub genes related to EGFR-TKI resistance in NSCLC through bioinformatics technologies which can improve the understanding of the mechanisms of EGFR-TKI resistance and provide novel insights into therapeutics.

MET exon 14 skipping mutation is a hepatocyte growth factor (HGF)-dependent oncogenic driver in vitro and in humanised HGF knock-in mice

Exon skipping mutations of the MET receptor tyrosine kinase (METex14), increasingly reported in cancers, occur in 3-4% of non-small-cell lung cancer (NSCLC). Only 50% of patients have a beneficial response to treatment with MET-tyrosine kinase inhibitors (TKIs), underlying the need to understand the mechanism of METex14 oncogenicity and sensitivity to TKIs. Whether METex14 is a driver mutation and whether it requires hepatocyte growth factor (HGF) for its oncogenicity in a range of in vitro functions and in vivo has not been fully elucidated from previous preclinical models. Using CRISPR/Cas9, we developed a METex14/WT isogenic model in nontransformed human lung cells and report that the METex14 single alteration was sufficient to drive MET-dependent in vitro anchorage-independent survival and motility and in vivo tumorigenesis, sensitising tumours to MET-TKIs. However, we also show that human HGF (hHGF) is required, as demonstrated in vivo using a humanised HGF knock-in strain of mice and further detected in tumour cells of METex14 NSCLC patient samples. Our results also suggest that METex14 oncogenicity is not a consequence of an escape from degradation in our cell model. Thus, we developed a valuable model for preclinical studies and present results that have potential clinical implication.

Sunitinib resistance in renal cell carcinoma: From molecular mechanisms to predictive biomarkers

Currently, renal cell carcinoma (RCC) is the most prevalent type of kidney cancer. Targeted therapy has replaced radiation therapy and chemotherapy as the main treatment option for RCC due to the lack of significant efficacy with these conventional therapeutic regimens. Sunitinib, a drug used to treat gastrointestinal tumors and renal cell carcinoma, inhibits the tyrosine kinase activity of a number of receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-Kit, rearranged during transfection (RET) and fms-related receptor tyrosine kinase 3 (Flt3). Although sunitinib has been shown to be efficacious in the treatment of patients with advanced RCC, a significant number of patients have primary resistance to sunitinib or acquired drug resistance within the 6-15 months of therapy. Thus, in order to develop more efficacious and long-lasting treatment strategies for patients with advanced RCC, it will be crucial to ascertain how to overcome sunitinib resistance that is produced by various drug resistance mechanisms. In this review, we discuss: 1) molecular mechanisms of sunitinib resistance; 2) strategies to overcome sunitinib resistance and 3) potential predictive biomarkers of sunitinib resistance.

Ran GTPase and Its Importance in Cellular Signaling and Malignant Phenotype

Ran is a member of the Ras superfamily of proteins, which primarily regulates nucleocytoplasmic trafficking and mediates mitosis by regulating spindle formation and nuclear envelope (NE) reassembly. Therefore, Ran is an integral cell fate determinant. It has been demonstrated that aberrant Ran expression in cancer is a result of upstream dysregulation of the expression of various factors, such as osteopontin (OPN), and aberrant activation of various signaling pathways, including the extracellular-regulated kinase/mitogen-activated protein kinase (ERK/MEK) and phosphatidylinositol 3-kinase/Protein kinase B (PI3K/Akt) pathways. In vitro, Ran overexpression has severe effects on the cell phenotype, altering proliferation, adhesion, colony density, and invasion. Therefore, Ran overexpression has been identified in numerous types of cancer and has been shown to correlate with tumor grade and the degree of metastasis present in various cancers. The increased malignancy and invasiveness have been attributed to multiple mechanisms. Increased dependence on Ran for spindle formation and mitosis is a consequence of the upregulation of these pathways and the ensuing overexpression of Ran, which increases cellular dependence on Ran for survival. This increases the sensitivity of cells to changes in Ran concentration, with ablation being associated with aneuploidy, cell cycle arrest, and ultimately, cell death. It has also been demonstrated that Ran dysregulation influences nucleocytoplasmic transport, leading to transcription factor misallocation. Consequently, patients with tumors that overexpress Ran have been shown to have a higher malignancy rate and a shorter survival time compared to their counterparts.

Dual Role of Fibroblasts Educated by Tumour in Cancer Behavior and Therapeutic Perspectives

Tumours are complex systems with dynamic interactions between tumour cells, non-tumour cells, and extracellular components that comprise the tumour microenvironment (TME). The majority of TME's cells are cancer-associated fibroblasts (CAFs), which are crucial in extracellular matrix (ECM) construction, tumour metabolism, immunology, adaptive chemoresistance, and tumour cell motility. CAF subtypes have been identified based on the expression of protein markers. CAFs may act as promoters or suppressors in tumour cells depending on a variety of factors, including cancer stage. Indeed, CAFs have been shown to promote tumour growth, survival and spread, and secretome changes, but they can also slow tumourigenesis at an early stage through mechanisms that are still poorly understood. Stromal-cancer interactions are governed by a variety of soluble factors that determine the outcome of the tumourigenic process. Cancer cells release factors that enhance the ability of fibroblasts to secrete multiple tumour-promoting chemokines, acting on malignant cells to promote proliferation, migration, and invasion. This crosstalk between CAFs and tumour cells has given new prominence to the stromal cells, from being considered as mere physical support to becoming key players in the tumour process. Here, we focus on the concept of cancer as a non-healing wound and the relevance of chronic inflammation to tumour initiation. In addition, we review CAFs heterogeneous origins and markers together with the potential therapeutic implications of CAFs "re-education" and/or targeting tumour progression inhibition.

Patient attrition in Molecular Tumour Boards: a systematic review

BACKGROUND

Molecular Tumour Boards (MTBs) were created with the purpose of supporting clinical decision-making within precision medicine. Though in use globally, reporting on these meetings often focuses on the small percentages of patients that receive treatment via this process and are less likely to report on, and assess, patients who do not receive treatment.

METHODS

A literature review was performed to understand patient attrition within MTBs and barriers to patients receiving treatment. A total of 51 papers were reviewed spanning a 6-year period from 11 different countries.

RESULTS

In total, 20% of patients received treatment through the MTB process. Of those that did not receive treatment, the main reasons were no mutations identified (27%), no actionable mutations (22%) and clinical deterioration (15%). However, data were often incomplete due to inconsistent reporting of MTBs with only 55% reporting on patients having no mutations, 55% reporting on the presence of actionable mutations with no treatment options and 59% reporting on clinical deterioration.

DISCUSSION

As patient attrition in MTBs is an issue which is very rarely alluded to in reporting, more transparent reporting is needed to understand barriers to treatment and integration of new technologies is required to process increasing omic and treatment data.

Effective response to crizotinib of concurrent KIF5B-MET and MET-CDR2-rearranged non-small cell lung cancer: A case report

BACKGROUND

Due to the rarity of mesenchymal-epithelial transition factor (MET) fusions, the clinical efficacy of crizotinib has only been described in a few patients with MET fusions involving various fusion partners. Herein, we report the clinical response to crizotinib of a patient with advanced poorly differentiated non-small cell carcinoma (NSCLC) having concurrent MET fusions.

CASE SUMMARY

A 46-year-old woman was diagnosed with poorly differentiated NSCLC (T4N3M1). With no classic driver mutations, she was treated with two cycles of gemcitabine and cisplatin without clinical benefit. Targeted sequencing revealed the detection of two concurrent MET fusions, KIF5B-MET and novel MET-CDR2. Crizotinib was initiated at a dose of 250 mg twice daily. Within 4 wk of crizotinib therapy, repeat computed chromatography revealed a dramatic reduction in primary and metastatic lesions, assessed as partial response. She continued to benefit from crizotinib for 3 mo until disease progression and died within 1 mo despite receiving nivolumab therapy.

CONCLUSION

Crizotinib sensitivity was observed in an advanced poorly differentiated NSCLC patient with concurrent MET fusions KIF5B-MET and MET-CDR2. Crizotinib can serve as a therapeutic option for patients with MET fusions. In addition, our case also highlights the importance of comprehensive genomic profiling particularly in patients with no classic driver mutation for guiding alternative therapeutic decisions.

Clinical Experience with Apatinib and Camrelizumab in Advance Clear Cell Sarcoma: A Retrospective Study

Purpose

Advanced clear cell sarcoma (CCS) is a rare subtype of sarcoma with few effective treatments. Evidence shows that apatinib is efficacious and safe for CCS. This study aimed to assess the safety and efficacy of apatinib and/or camrelizumab (a PD-1 inhibitor) in treating advanced CCS.

Methods

We retrospectively reviewed 12 patients with advanced CCS who received apatinib and/or camrelizumab therapy between November 2018 and July 2021. Standard descriptive statistics were employed for continuous variables and categorical variables (number and percentage).

Results

Of the 12 CCS patients, 3 had a partial response (PR), and 4 had stable disease (SD). Among the 5 patients treated with apatinib monotherapy, 1 PR and 2 SD were found, and the addition or replacement of camrelizumab after progressive disease (PD) did not work. In the 4 patients who received apatinib plus camrelizumab combination therapy, 1 PR and 1 SD were found. All 3 patients who received camrelizumab first had PD, and 1 PR and 1 SD were found after adding apatinib. Grade 3 or 4 adverse events were significantly more common in the apatinib plus camrelizumab combination therapy than in the apatinib or camrelizumab monotherapy, and these included increased aspartate aminotransferase and increased alanine aminotransferase levels.

Conclusion

Apatinib has promising effectiveness for CCS. Camrelizumab efficacy for the treatment of clear cell sarcoma is inconclusive. The efficacy of apatinib and PD-1 inhibitors in CCS need to be further investigated in prospective clinical trials.

Predictive role of neutropenia under crizotinib treatment in ALK-rearranged nonsmall cell lung cancer patients: A single-institution retrospective analysis

Background

Anaplastic lymphoma kinase (ALK)-rearranged nonsmall cell lung cancer (NSCLC) represents a molecular subgroup with high sensitivity to ALK inhibitors. Tyrosine kinase inhibitor crizotinib, an anticancer drug acting as an ALK inhibitor, has shown remarkable response in ALK-positive NSCLC. The aim of our study is to explore the adverse events (AEs) of patients on crizotinib therapy and analyze the predictability of AEs for better survival or response on NSCLC patients.

Methods

The medical records of our ALK-positive metastatic NSCLC patients who applied between years 2013 and 2018 had been reviewed retrospectively. ALK positivity of all patients had been detected by fluorescence in situ hybridization and no other driver mutations were present. Patient demographics, performance status, smoking history, previous treatments, metastatic sites, and AEs were recorded for further analyses.

Results

Thirty-six ALK-positive metastatic NSCLC patients were included in the study. Median follow-up was 30.1 months. Median progression-free survival (PFS) for patients who developed hepatic, cardiac, or endocrine toxicities was similar when compared to patients who did not develop. Although there was a numeric median PFS difference between patients who did develop visual disorders (18.4 months) and did not develop visual disorders (15.5 month), this was not regarded as statistically significant. However, median PFS of the patients who developed neutropenia upon crizotinib treatment (31.9 months) was found to be more favorable than the patients with normal neutrophil counts (12.8 months) (P = 0.026).

Conclusion

Neutropenia under crizotinib treatment was found to be associated with improved PFS suggesting that neutropenia might be an important determinant in treatment and survival strategies.

AZD8055 enhances in vivo efficacy of afatinib in chordomas

Chordomas are primary bone tumors that arise in the cranial base, mobile spine, and sacrococcygeal region, affecting patients of all ages. Currently, there are no approved agents for chordoma patients. Here, we evaluated the anti-tumor efficacy of small molecule inhibitors that target oncogenic pathways in chordoma, as single agents and in combination, to identify novel therapeutic approaches with the greatest translational potential. A panel of small molecule compounds was screened in vivo against patient-derived xenograft (PDX) models of chordoma, and potentially synergistic combinations were further evaluated using chordoma cell lines and xenograft models. Among the tested agents, inhibitors of EGFR (BIBX 1382, erlotinib, and afatinib), c-MET (crizotinib), and mTOR (AZD8055) significantly inhibited tumor growth in vivo but did not induce tumor regression. Co-inhibition of EGFR and c-MET using erlotinib and crizotinib synergistically reduced cell viability in chordoma cell lines but did not result in enhanced in vivo activity. Co-inhibition of EGFR and mTOR pathways using afatinib and AZD8055 synergistically reduced cell viability in chordoma cell lines. Importantly, this dual inhibition completely suppressed tumor growth in vivo, showing improved tumor control. Together, these data demonstrate that individual inhibitors of EGFR, c-MET, and mTOR pathways suppress chordoma growth both in vitro and in vivo. mTOR inhibition increased the efficacy of EGFR inhibition on chordoma growth in several preclinical models. The insights gained from our study potentially provide a novel combination therapeutic strategy for patients with chordoma. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

QSAR, molecular docking and ADMET properties in silico studies of novel 4,5,6,7-tetrahydrobenzo[D]-thiazol-2-Yl derivatives derived from dimedone as potent anti-tumor agents through inhibition of C-Met receptor tyrosine kinase

A quantitative structure-activity relationship (QSAR) study is performed on 48 novel 4,5,6,7-tetrahydrobenzo[D]-thiazol-2 derivatives as anticancer agents capable of inhibiting c-Met receptor tyrosine kinase. The present study is conducted using multiple linear regression, multiple nonlinear regression and artificial neural networks. Three QSAR models are developed after partitioning the database into two sets (training and test) via the k-means method. The obtained values of the correlation coefficients by the three developed QSAR models are 0.90, 0.91 and 0.92, respectively. The resulting models are validated by using the external validation, leave-one-out cross-validation, Y-randomization test, and applicability domain methods. Moreover, we evaluated the drug-likeness properties of seven selected molecules based on their observed high activity to inhibit the c-Met receptor. The results of the evaluation showed that three of the seven compounds present drug-like characteristics. In order to identify the important active sites for the inhibition of the c-Met receptor responsible for the development of cancer cell lines, the crystallized form of the Crizotinib-c-Met complex (PDB code: 2WGJ) is used. These sites are used as references in the molecular docking test of the three selected molecules to identify the most suitable molecule for use as a new c-Met inhibitor. A comparative study is conducted based on the evaluation of the predicted properties of ADMET in silico between the candidate molecule and the Crizotinib inhibitor. The comparison results show that the selected molecule can be used as new anticancer drug candidates.

[Progress on Mechanism of MET Gene Mutation and Targeted Drugs in Non-small Cell Lung Cancer]

间质-上皮细胞转化因子（mesenchymal-epithelial transition factor, MET）基因是非小细胞肺癌（non-small cell lung cancer, NSCLC）的一种重要肿瘤驱动基因，针对MET 14外显子的跳跃突变的靶向治疗药物给患者带来新的希望。目前已经上市或者即将上市的MET抑制剂包括：克唑替尼、卡博替尼、沃利替尼和Tepotinib等。MET抑制剂的客观缓解率较高，并且安全性良好。但是，MET抑制剂的耐药不可避免，因此需要重视对于耐药机制的研究。肝细胞生长因子（hepatocyte growth factor, HGF）/MET信号通路抑制剂与其他药物的联合应用，对于抑制和逆转耐药可能发挥重要作用。

Lung Cancer with MET exon 14 Skipping Mutation: Genetic Feature, Current Treatments, and Future Challenges

MET exon 14 skipping mutation (MET∆ex14) is present about 3% of non-small cell lung cancers (NSCLCs). NSCLC patients with MET∆ex14 are characterized by an average age of over 70 years at diagnosis, a smoking history and a higher frequency in pleomorphic carcinoma and adenosquamous cell carcinoma than in adenocarcinoma. It has also been reported that NSCLCs with MET∆ex14 often have codriver alterations such as EGFR amplification (6–28%), FGFR1 alterations (5–17%), KRAS alterations (~8%), BRAF alterations (~21%), or PIK3CA mutation/amplification (~14%). In 2020, the approval of two MET-tyrosine kinase inhibitors (TKIs), capmatinib and tepotinib, for NSCLCs carrying MET∆ex14 dawned a new era for MET-targeted therapy. These drugs yielded progression-free survival of 5.4−12.4 months in clinical trials; however, it has also been reported that one-third to half of patients show inherent resistance to MET-TKIs. In addition, the emergence of acquired resistance to MET-TKIs is inevitable. In this review, we summarize the clinical and molecular characteristics of NSCLCs with MET∆ex14, the efficacy and safety of capmatinib and tepotinib, the inherent and acquired resistance mechanisms to MET-TKIs, and new treatment strategies for NSCLCs with MET∆ex14 in the near future.

Narrative review: mesenchymal-epithelial transition inhibitors-meeting their target

Genetic alterations in mesenchymal-epithelial transition (MET) are commonly found in solid tumors, especially in non-small cell lung cancer (NSCLC). However, agents targeting MET have not progressed until recently. Advancements in our understanding of the role of various MET aberrations in carcinogenesis have allowed MET-directed therapy to find its way to clinic use. Of all MET alterations, MET exon 14 skipping (METex14 skip⁺ or MET^∆14), stands out as a true oncogenic driver. Recently, MET tyrosine kinase inhibitors (TKI) targeting METex14 skipping were able to demonstrate significant improvement in clinical outcomes including response rate and progression free survival. Of these, capmatinib was granted accelerated approval by the FDA in May 2020 for patients with advanced NSCLC harboring METex14 skip alterations. Tepotinib, another TKI, has shown significant activity in a phase II trial and received breakthrough therapy designation from the FDA in September 2019. MET amplification (MET^Amp) and overexpression are usually a late phenomenon in tumorigenesis and aggravate malignant properties of transformed cells. Capmatinib and savolitinib have shown activity in patients with NSCLC with high levels of MET^Amp. Several other agents are being developed and under evaluation in clinical trials involving multiple tumor types. In addition to TKIs, MET overexpression is also an appealing target for development of antibody conjugated chemotherapy. Understanding the mechanisms of resistance to MET TKIs and alterations in anti-tumor immunity through MET inhibition are clinically relevant areas that need further exploration.

Emerging MET tyrosine kinase inhibitors for the treatment of non-small cell lung cancer

Introduction MET aberrations, including MET exon 14 skipping mutation and amplification, are present in ~5% of non-small cell lung cancer (NSCLC) cases, and these levels are comparable to the frequency of ALK fusion. MET amplification also occurs as an acquired resistance mechanism in EGFR-mutated NSCLC after EGFR tyrosine kinase inhibitors (TKI) treatment failure. Therefore, the development of therapies for activated MET is urgently needed. Areas covered This review summarizes (1) the mechanisms and frequencies of MET aberrations in NSCLC, (2) the efficacies and toxicities of MET-TKIs under clinical development and (3) the mechanisms of inherent and acquired resistance to MET-TKIs. Expert opinion Type Ia, Ib and II MET-TKIs are currently under clinical development, and phase I/II studies have shown the potent activities of tepotinib, capmatinib and savolitinib; in fact, tepotinib and capmatinib were approved for use by health authorities. However, inherent and acquired resistance through on- and off-target mechanisms has been detected, and strategies to overcome this resistance are being developed.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Antitumor activity and combined inhibitory effect of ceritinib with gemcitabine in pancreatic cancer

Pancreatic cancer (PC) is predominantly incurable and is primarily treated with gemcitabine, but drug resistance commonly develops. Thus, new medicines are needed. Ceritinib (LDK378) is a second-generation tyrosine kinase inhibitor of anaplastic lymphoma kinase (ALK) with antitumor activity in various cancers. However, studies involving ceritinib for the treatment of PC are inadequate. We analyzed the combined effects of ceritinib and gemcitabine on PC and their mechanism of action. Three PC cell lines were used to evaluate the antitumor effects of ceritinib combined with gemcitabine. We analyzed cell viability using CCK-8 assays, determined apoptosis levels through flow cytometry, and analyzed autophagy and cell signaling pathways by Western blotting and tissue array analysis with samples from xenograft models. Ceritinib strongly inhibited the proliferation of PC cells in a dose-dependent manner, induced apoptosis, and inhibited autophagy and cell migration by regulating relevant factors. Ceritinib in combination with gemcitabine exhibited significant growth inhibition and additive antitumor effects in vitro. In vivo, gemcitabine and ceritinib reduced tumor size by up to 30%. In our study, ALK was shown to be highly expressed in various PC cells and tissues. Ceritinib strongly inhibited the levels of activated ALK in PC cells with subsequent effects on the downstream mediators STAT3, AKT, and ERK. In addition, ceritinib inhibited tumor progression in xenograft models. Overall, our research shows that ceritinib inhibits the ALK signaling pathway, leading to cell growth/angiogenesis inhibition in PC and the induction of apoptosis. We recommend using ceritinib as a new treatment for PC.NEW & NOTEWORTHY These data proved that ceritinib inhibits the anaplastic lymphoma kinase signaling pathway, leading to cell growth/angiogenesis inhibition and the induction of apoptosis by inhibiting STAT3, AKT, and ERK pathway in pancreatic cancer (PC). We recommend using ceritinib as a new treatment for PC.

Mechanisms of suppression of cell growth by dual inhibition of ALK and MEK in ALK-positive non-small cell lung cancer

Anaplastic lymphoma kinase (ALK) rearrangement, a key oncogenic driver in a small subset of non-small cell lung cancers, confers sensitivity to ALK tyrosine kinase inhibitors (TKIs). Crizotinib, a first generation ALK-TKI, has superiority to standard chemotherapy with longer progression-free survival and higher objective response rate. However, clinical benefit is limited by development of resistance, typically within a year of therapy. In this study the combined effect of crizotinib and the MEK inhibitor selumetinib was investigated in both crizotinib naïve (H3122) and crizotinib resistant (CR-H3122) ALK-positive lung cancer cells. Results showed that combination treatment potently inhibited the growth of both H3122 and CR-H3122 cells, resulting from increased apoptosis and decreased cell proliferation as a consequence of suppressed downstream RAS/MAPK signalling. The drug combination also elicited a greater than 3-fold increase in Bim, a mediator of apoptosis, and p27, a cyclin dependent kinase inhibitor compared to crizotinib alone. The results support the hypothesis that combining MEK inhibitors with ALK inhibitor can overcome ALK inhibitor resistance, and identifies Bim, PARP and CDK1 as druggable targets for possible triple drug therapy.

FAK-Copy-Gain Is a Predictive Marker for Sensitivity to FAK Inhibition in Breast Cancer

BACKGROUND

Cancers with copy-gain drug-target genes are excellent candidates for targeted therapy. In order to search for new predictive marker genes, we investigated the correlation between sensitivity to targeted drugs and the copy gain of candidate target genes in NCI-60 cells.

METHODS

For eight candidate genes showing copy gains in NCI-60 cells identified in our previous study, sensitivity to corresponding target drugs was tested on cells showing copy gains of the candidate genes.

RESULTS

Breast cancer cells with Focal Adhesion Kinase (FAK)-copy-gain showed a significantly higher sensitivity to the target inhibitor, FAK inhibitor 14 (F14). In addition, treatment of F14 or FAK-knockdown showed a specific apoptotic effect only in breast cancer cells showing FAK-copy-gain. Expression-profiling analyses on inducible FAK shRNA-transfected cells showed that FAK/AKT signaling might be important to the apoptotic effect by target inhibition. An animal experiment employing a mouse xenograft model also showed a significant growth-inhibitory effect of F14 on breast cancer cells showing FAK-copy-gain, but not on those without FAK-copy-gain.

CONCLUSION

FAK-copy-gain may be a predictive marker for FAK inhibition therapy in breast cancer.

Sensitivity and Resistance of MET Exon 14 Mutations in Lung Cancer to Eight MET Tyrosine Kinase Inhibitors In Vitro

BACKGROUND

MNNG HOS transforming gene (MET) exon 14 mutations in lung cancer, including exon 14 skipping and point mutations, have been attracting the attention of thoracic oncologists as new therapeutic targets. Tumors with these mutations almost always acquire resistance, which also occurs in other oncogene-addicted lung cancers. However, the resistance mechanisms and treatment strategies are not fully understood.

METHODS

We generated Ba/F3 cells expressing MET exon 14 mutations by retroviral gene transfer. The sensitivities of these cells to eight MET-tyrosine kinase inhibitors (TKIs) were determined using a colorimetric assay. In addition, using N-ethyl-N-nitrosourea mutagenesis, we generated resistant clones, searched for secondary MET mutations, and then examined the sensitivities of these resistant cells to different TKIs.

RESULTS

Ba/F3 cells transfected with MET mutations grew in the absence of interleukin-3, indicating their oncogenic activity. These cells were sensitive to all MET-TKIs except tivantinib. We identified a variety of secondary mutations. D1228 and Y1230 were common sites for resistance mutations for type I TKIs, which bind the active form of MET, whereas L1195 and F1200 were common sites for type II TKIs, which bind the inactive form. In general, resistance mutations against type I were sensitive to type II, and vice versa.

CONCLUSIONS

MET-TKIs inhibited the growth of cells with MET exon 14 mutations. We also identified mutation sites specific for TKI types as resistance mechanisms and complementary activities between type I and type II inhibitors against those mutations. These finding should provide relevant clinical implication for treating patients with lung cancer harboring MET exon 14 mutations.

Characterization of Hypoxia-associated Molecular Features to Aid Hypoxia-Targeted Therapy

Tumor hypoxia is a major contributor to resistance to anti-cancer therapies. Given that the results of hypoxia-targeted therapy trials have been disappointing, a more personalized approach may be needed. Here we characterize multi-OMIC molecular features associated with tumor hypoxia and identify molecular alterations that correlate with both drug-resistant and drug-sensitive responses to anti-cancer drugs. Based on a well-established hypoxia gene expression signature, we classify about 10,000 tumor samples into hypoxia score-high and score-low groups across different cancer types from The Cancer Genome Atlas and demonstrate their prognostic associations. We then identify various types of molecular features associated with hypoxia status that correlate with drug resistance but, in some cases, also with drug sensitivity, contrasting the conventional view that hypoxia confers drug resistance. We further show that 110 out of 121 (90.9%) clinically actionable genes can be affected by hypoxia status and experimentally validate the predicted effects of hypoxia on the response to several drugs in cultured cells. Our study provides a comprehensive molecular-level understanding of tumor hypoxia and may have practical implications for clinical cancer therapy.

Cyclosporine A sensitizes lung cancer cells to crizotinib through inhibition of the Ca2+/calcineurin/Erk pathway

Background

Crizotinib has potent anti-tumor activity in patients with advanced MET-amplified non-small cell lung cancer (NSCLC). However, the therapeutic effect is still not satisfying. Thus, developing approaches that improve the efficacy of crizotinib remains a significant challenge.

Methods

MET-amplified NSCLC cell lines were treated with crizotinib and cyclosporine A (CsA). Cell viability was determined by MTS assay. The changes of apoptosis, cell cycle and calcineurin-Erk pathways were assessed by western blot. Xenograft mouse model, primary human NSCLC cells and hollow fiber assays were utilized to confirm the effects of CsA.

Findings

We demonstrated that CsA significantly increased the anti-tumor effect of crizotinib on multiple MET-amplified NSCLC cells in vitro and in vivo. Mechanistically, crizotinib treatment led to the activation of Ca²⁺-calcineurin (CaN)-Kinase suppressor of Ras 2 (KSR2) signaling, resulting in Erk1/2 activation and enhanced survival of cancer cells. CsA effectively blocked CaN-KSR2-Erk1/2 signaling, promoting crizotinib-induced apoptosis and G2/M arrest. Similarly, pharmacologic or genetic inhibition of Erk1/2 also enhanced crizotinib-induced growth inhibition in vitro. Xenograft studies further confirmed that CsA or Erk1/2 inhibitor PD98059 enhanced the anti-cancer activity of crizotinib through inhibition of CaN-Erk1/2 axis. The results were also validated by primary human NSCLC cells in vitro and hollow fiber assays in vivo.

Interpretation

This study provides preclinical evidences that combination therapy of CsA and crizotinib is a promising approach for targeted treatment of MET-amplified lung cancer patients.

Fund

This work was supported by the National Natural Science Foundation of China, the Key Projects of Natural Foundation of Zhejiang Province, the Ten thousand plan youth talent support program of Zhejiang Province, the Zhejiang Natural Sciences Foundation Grant, and the Zhejiang medical innovative discipline construction project-2016.

Efficacy and safety analysis of the German expanded access program of osimertinib in patients with advanced, T790M-positive non-small cell lung cancer

PURPOSE

Osimertinib, a third-generation irreversible mutant-selective inhibitor of EGFR kinase activity was clinically evaluated in the AURA trials, where it showed high clinical efficacy and a favorable toxicity profile in patients with acquired exon 20-EGFR pT790M mutation. We provide the clinical data of the German expanded access program that further characterizes the efficacy and safety of osimertinib in a heterogeneous patient population outside clinical trials.

METHODS

We performed a retrospective data analysis on patients who were included into the German osimertinib EAP.

RESULTS

Of 81 patients enrolled, 51 patients (62.9%) with sufficient case report form data were available for efficacy and safety analysis. Unconfirmed overall response rate was 80.0% with 2 patients (3.9%) achieving a complete remission and 37 patients (72.5%) having a partial remission. Disease control rate was 95.9% and only two patients showed refractory disease. Disease control rate did not correlate with clinical characteristics and was independent of number as well as type of the previous therapy line(s). Estimated progression-free survival was 10.1 months (95% CI 9.2-11.0 months). Osimertinib showed a favorable toxicity profile with no dose reductions in our observation period, even in patients with low performance status. Median survival from first diagnosis to data cut-off was 47.3 months (95% CI 43.3-51.9 months). Repeated tissue/liquid biopsy of three patients in our cohort who showed disease progression revealed an amplification of MET.

CONCLUSIONS

We confirm safety and efficacy of osimertinib with high response rates among all subgroups, including patients with poor performance status and multiple prior therapy lines. Amplification of MET might mediate acquired resistance to osimertinib.

Met Receptor Tyrosine Kinase and Chemoprevention of Oral Cancer

Background

We have previously shown that gene expression profiles of oral leukoplakia (OL) may improve the prediction of oral cancer (OC) risk. To identify new targets for prevention, we performed a systematic survey of transcripts associated with an increased risk of oral cancer and overexpressed in OC vs normal mucosa (NM).

Methods

We used gene expression profiles of 86 patients with OL and available outcomes from a chemoprevention trial of OC and NM. MET expression was evaluated using immunohistochemistry in 120 OL patients, and its association with OC development was tested in multivariable analysis. Sensitivity to pharmacological Met inhibition was tested invitro in premalignant and OC cell lines (n = 33) and invivo using the 4-NQO model of oral chemoprevention (n = 20 mice per group). All statistical tests were two-sided.

Results

The overlap of 693 transcripts associated with an increased risk of OC with 163 transcripts overexpressed in OC compared with NM led to the identification of 23 overlapping transcripts, including MET. MET overexpression in OL was associated with a hazard ratio of 3.84 (95% confidence interval = 1.59 to 9.27, P = .003) of developing OC. Met activation was found in OC and preneoplastic cell lines. Crizotinib activity in preneoplastic and OC cell lines was comparable. ARQ 197 was more active in preneoplastic compared with OC cell lines. In the 4-NQO model, squamous cell carcinoma, dysplasia, and hyperkeratosis were observed in 75.0%, 15.0%, and 10.0% in the control group, and in 25.0%, 70.0%, and 5.0% in the crizotinib group (P < .001).

Conclusion

Together, these data suggest that MET activation may represent an early driver in oral premalignancy and a target for chemoprevention of OC.

MET amplification assessed using optimized FISH reporting criteria predicts early distant metastasis in patients with non-small cell lung cancer

To investigate the prognostic impact of MET copy number (MET-CN) in patients with non-small cell lung cancer (NSCLC), we retrospectively reviewed clinical and pathologic data of NSCLC patients whose tumors were assessed for MET-CN using fluorescence in situ hybridization (FISH). We correlated MET-CN status with patient overall survival (OS) and optimized MET-FISH reporting criteria. The study group included 384 patients with NSCLC of which 88% were adenocarcinoma and 55.7% of patients had distant metastases. There were 170 patients with stages I-III and 214 patients with stage IV disease. Based on the MET-CN and MET/CEP7 ratio the patients were classified into 3 categories: MET-amplification (METamp): MET/CEP7 ≥ 2 or MET-CN ≥ 5; MET-CN-gain (METcng): MET-CN ≥ 4 to < 5; and MET-negative (METneg): MET-CN < 4. METamp was associated with high fatality (P=.036) and stage IV tumors (P=.038). In patients with stages I-III NSCLC, patients in the METamp category had the shortest OS (P=.015) and more often developed distant metastases within 1 year (P=.004). In patients with stage IV tumors, METamp did not further impact the OS. Patients in the METcng category had the longest OS (P=.053). Multivariate analysis confirmed METamp to be an independent high-risk factor (HR 3.26; P=.026) and predicted earlier progression to distant metastasis (HR 4.86; P=.001). In conclusion, we suggest that the MET-FISH criteria presented optimizes risk stratification by defining 3 categories of NSCLC patients. METamp is an independent risk factor predicting early distant metastasis and patients with METcng could represent a lower-risk group.

Establishment and phenotyping of disease model cells created by cell-resealing technique

Cell-based assays are growing in importance for screening drugs and investigating their mechanisms of action. Most of the assays use so-called “normal” cell strain because it is difficult to produce cell lines in which the disease conditions are reproduced. In this study, we used a cell-resealing technique, which reversibly permeabilizes the plasma membrane, to develop diabetic (Db) model hepatocytes into which cytosol from diabetic mouse liver had been introduced. Db model hepatocytes showed several disease-specific phenotypes, namely disturbance of insulin-induced repression of gluconeogenic gene expression and glucose secretion. Quantitative image analysis and principal component analysis revealed that the ratio of phosphorylated Akt (pAkt) to Akt was the best index to describe the difference between wild-type and Db model hepatocytes. By performing image-based drug screening, we found pioglitazone, a PPARγ agonist, increased the pAkt/Akt ratio, which in turn ameliorated the insulin-induced transcriptional repression of the gluconeogenic gene phosphoenolpyruvate carboxykinase 1. The disease-specific model cells coupled with image-based quantitative analysis should be useful for drug development, enabling the reconstitution of disease conditions at the cellular level and the discovery of disease-specific markers.

Cancer associated fibroblasts: An essential role in the tumor microenvironment

Fibroblasts in the tumor stroma are well recognized as having an indispensable role in carcinogenesis, including in the initiation of epithelial tumor formation. The association between cancer cells and fibroblasts has been highlighted in several previous studies. Regulation factors released from cancer-associated fibroblasts (CAFs) into the tumor microenvironment have essential roles, including the support of tumor growth, angiogenesis, metastasis and therapy resistance. A mutual interaction between tumor-induced fibroblast activation, and fibroblast-induced tumor proliferation and metastasis occurs, thus CAFs act as tumor supporters. Previous studies have reported that by developing fibroblast-targeting drugs, it may be possible to interrupt the interaction between fibroblasts and the tumor, thus resulting in the suppression of tumor growth, and metastasis. The present review focused on the reciprocal feedback loop between fibroblasts and cancer cells, and evaluated the potential application of anti-CAF agents in the treatment of cancer.

Overall survival in EGFR mutated non-small-cell lung cancer patients treated with afatinib after EGFR TKI and resistant mechanisms upon disease progression

PURPOSE

To determine survival in afatinib-treated patients after treatment with first-generation EGFR tyrosine kinase inhibitors (TKIs) and to study resistance mechanisms in afatinib-resistant tumors.

METHODS

Characteristics and survival of patients treated with afatinib after resistance to erlotinib or gefitinib in two large Dutch centers were collected. Whole exome sequencing (WES) and pathway analysis was performed on available pre- and post-afatinib tumor biopsies and normal tissue.

RESULTS

A total of 38 patients were treated with afatinib. T790M mutations were identified in 22/29 (76%) pre-afatinib treatment tumor samples. No difference in median progression-free-survival (2.8 months (95% CI 2.3-3.3) and 2.7 months (95% CI 0.9-4.6), p = 0.55) and median overall-survival (8.8 months (95% CI 4.2-13.4) and 3.6 months (95% CI 2.3-5.0), p = 0.14) were observed in T790M+ patients compared to T790M- mutations. Somatic mutations in TP53, ADAMTS2, CNN2 and multiple genes in the Wnt and PI3K-AKT pathway were observed in post-afatinib tumors of six afatinib-responding and in one non-responding patient. No new EGFR mutations were found in the post-afatinib samples of the six responding patients. Further analyses of post-afatinib progressive tumors revealed 28 resistant specific mutations in six genes (HLA-DRB1, AQP7, FAM198A, SEC31A, CNTLN, and ESX1) in three afatinib responding patients. No known EGFR-TKI resistant-associated copy number gains were acquired in the post-afatinib samples.

CONCLUSION

No differences in survival were observed in patients with EGFR-T790M treated with afatinib compared to those without T790M. Tumors from patients who had progressive disease during afatinib treatment were enriched for mutations in genes involved in Wnt and PI3K-AKT pathways.

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.

A "Prozone-Like" Effect Influences the Efficacy of the Monoclonal Antibody ABT-700 against the Hepatocyte Growth Factor Receptor

ABT-700 is a therapeutic antibody against the hepatocyte growth factor receptor (MET). At doses or regimens that lead to exposures exceeding optimum in vivo, the efficacy of ABT-700 is unexpectedly reduced. We hypothesized that this reduction in efficacy was due to a "prozone-like" effect in vivo. A prozone-like effect, which is a reduction in efficacy beyond optimum exposure, is caused due a mechanism similar to the generation of false negative flocculation tests by excessive antibody titres. In vitro, we demonstrate that at higher ABT-700 concentrations, this "prozone-like" effect is mediated by a progressive conversion from bivalent to ineffective monovalent binding of the antibody. In vivo, the efficacy of ABT-700 is dependent on an optimum range of exposure as well. Our data suggest that the "prozone-like" effect is operative and independent of target expression. ABT-700 dose, regimen, exposure, and tumor burden are interdependent variables influencing the "prozone-like" effect and mediating and in vivo efficacy. By optimization of dosage and regimen we demonstrate that the "prozone-like" effect can be alleviated and ABT-700 efficacy at varying tumor loads can be further extended in combination with cisplatin. Our results suggest that optimization of exposure taking tumor burden into account may alleviate "prozone-like" effects without compromising efficacy.

The MET/AXL/FGFR Inhibitor S49076 Impairs Aurora B Activity and Improves the Antitumor Efficacy of Radiotherapy

Several therapeutic agents targeting HGF/MET signaling are under clinical development as single agents or in combination, notably with anti-EGFR therapies in non-small cell lung cancer (NSCLC). However, despite increasing data supporting a link between MET, irradiation, and cancer progression, no data regarding the combination of MET-targeting agents and radiotherapy are available from the clinic. S49076 is an oral ATP-competitive inhibitor of MET, AXL, and FGFR1-3 receptors that is currently in phase I/II clinical trials in combination with gefitinib in NSCLC patients whose tumors show resistance to EGFR inhibitors. Here, we studied the impact of S49076 on MET signaling, cell proliferation, and clonogenic survival in MET-dependent (GTL16 and U87-MG) and MET-independent (H441, H460, and A549) cells. Our data show that S49076 exerts its cytotoxic activity at low doses on MET-dependent cells through MET inhibition, whereas it inhibits growth of MET-independent cells at higher but clinically relevant doses by targeting Aurora B. Furthermore, we found that S49076 improves the antitumor efficacy of radiotherapy in both MET-dependent and MET-independent cell lines in vitro and in subcutaneous and orthotopic tumor models in vivo In conclusion, our study demonstrates that S49076 has dual antitumor activity and can be used in combination with radiotherapy for the treatment of both MET-dependent and MET-independent tumors. These results support the evaluation of combined treatment of S49076 with radiation in clinical trials without patient selection based on the tumor MET dependency status. Mol Cancer Ther; 16(10); 2107-19. ©2017 AACR.

EGFR Mediates Responses to Small-Molecule Drugs Targeting Oncogenic Fusion Kinases

Oncogenic kinase fusions of ALK, ROS1, RET, and NTRK1 act as drivers in human lung and other cancers. Residual tumor burden following treatment of ALK or ROS1⁺ lung cancer patients with oncogene-targeted therapy ultimately enables the emergence of drug-resistant clones, limiting the long-term effectiveness of these therapies. To determine the signaling mechanisms underlying incomplete tumor cell killing in oncogene-addicted cancer cells, we investigated the role of EGFR signaling in drug-naïve cancer cells harboring these oncogene fusions. We defined three distinct roles for EGFR in the response to oncogene-specific therapies. First, EGF-mediated activation of EGFR blunted fusion kinase inhibitor binding and restored fusion kinase signaling complexes. Second, fusion kinase inhibition shifted adaptor protein binding from the fusion oncoprotein to EGFR. Third, EGFR enabled bypass signaling to critical downstream pathways such as MAPK. While evidence of EGFR-mediated bypass signaling has been reported after ALK and ROS1 blockade, our results extended this effect to RET and NTRK1 blockade and uncovered the other additional mechanisms in gene fusion-positive lung cancer cells, mouse models, and human clinical specimens before the onset of acquired drug resistance. Collectively, our findings show how EGFR signaling can provide a critical adaptive survival mechanism that allows cancer cells to evade oncogene-specific inhibitors, providing a rationale to cotarget EGFR to reduce the risks of developing drug resistance. Cancer Res; 77(13); 3551-63. ©2017 AACR.

Chemical inhibitors of c-Met receptor tyrosine kinase stimulate osteoblast differentiation and bone regeneration

The c-Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), have been recently introduced to negatively regulate bone morphogenetic protein (BMP)-induced osteogenesis. However, the effect of chemical inhibitors of c-Met receptor on osteoblast differentiation process has not been examined, especially the applicability of c-Met chemical inhibitors on in vivo bone regeneration. In this study, we demonstrated that chemical inhibitors of c-Met receptor tyrosine kinase, SYN1143 and SGX523, could potentiate the differentiation of precursor cells to osteoblasts and stimulate regeneration in calvarial bone defects of mice. Treatment with SYN1143 or SGX523 inhibited HGF-induced c-Met phosphorylation in MC3T3-E1 and C3H10T1/2 cells. Cell proliferation of MC3T3-E1 or C3H10T1/2 was not significantly affected by the concentrations of these inhibitors. Co-treatment with chemical inhibitor of c-Met and osteogenic inducing media enhanced osteoblast-specific genes expression and calcium nodule formation accompanied by increased Runx2 expression via c-Met receptor-dependent but Erk-Smad signaling independent pathway. Notably, the administration of these c-Met inhibitors significantly repaired critical-sized calvarial bone defects. Collectively, our results suggest that chemical inhibitors of c-Met receptor tyrosine kinase might be used as novel therapeutics to induce bone regeneration.

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.

Screening for ROS1 gene rearrangements in non-small-cell lung cancers using immunohistochemistry with FISH confirmation is an effective method to identify this rare target

AIMS

To assess the prevalence of ROS1 rearrangements in a retrospective and prospective diagnostic Australian cohort and evaluate the effectiveness of immunohistochemical screening.

METHODS AND RESULTS

A retrospective cohort of 278 early stage lung adenocarcinomas and an additional 104 prospective non-small-cell lung cancer (NSCLC) cases referred for routine molecular testing were evaluated. ROS1 immunohistochemistry (IHC) was performed (D4D6 clone, Cell Signaling Technology) on all cases as well as fluorescence in-situ hybridization (FISH) using the ZytoVision and Abbott Molecular ROS1 FISH probes, with ≥15% of cells with split signals considered positive for rearrangement. Eighty-eight cases (32%) from the retrospective cohort showed staining by ROS1 IHC, and one case (0.4%) showed ROS1 rearrangement by FISH. Nineteen of the prospective diagnostic cases showed ROS1 IHC staining, 12 (12%) cases of which were confirmed as ROS1 rearranged by FISH. There were no ROS1 rearranged cases that showed no expression of ROS1 with IHC. The ROS1 rearranged cases in the prospective cohort were all EGFR wild-type and anaplastic lymphoma kinase (ALK) rearrangement-negative. The sensitivity of ROS1 IHC in the retrospective cohort was 100% and specificity was 76%.

CONCLUSIONS

ROS1 rearrangements are rare events in lung adenocarcinomas. Selection of cases for ROS1 FISH testing, by excluding EGFR/ALK-positive cases and use of IHC to screen for potentially positive cases, can be used to enrich for the likelihood of identifying a ROS1 rearranged lung cancer and prevent the need to undertake expensive and time-consuming FISH testing in all cases.

Omics Profiling in Precision Oncology

Cancer causes significant morbidity and mortality worldwide, and is the area most targeted in precision medicine. Recent development of high-throughput methods enables detailed omics analysis of the molecular mechanisms underpinning tumor biology. These studies have identified clinically actionable mutations, gene and protein expression patterns associated with prognosis, and provided further insights into the molecular mechanisms indicative of cancer biology and new therapeutics strategies such as immunotherapy. In this review, we summarize the techniques used for tumor omics analysis, recapitulate the key findings in cancer omics studies, and point to areas requiring further research on precision oncology.

MET-targeted therapy for gastric cancer: the importance of a biomarker-based strategy

The MET protooncogene encodes the receptor tyrosine kinase c-MET (MET). Aberrant activation of MET signaling occurs in a subset of advanced malignancies, including gastric cancer, and promotes tumor cell growth, survival, migration, and invasion as well as tumor angiogenesis, suggesting its potential importance as a therapeutic target. MET can be activated by two distinct pathways that are dependent on or independent of its ligand, hepatocyte growth factor (HGF), with the latter pathway having been attributed mostly to MET amplification in gastric cancer. Preclinical evidence has suggested that interruption of the HGF-MET axis either with antibodies to HGF or with MET tyrosine kinase inhibitors (TKIs) has antitumor effects in gastric cancer cells. Overexpression of MET occurs frequently in gastric cancer and has been proposed as a potential predictive biomarker for anti-MET therapy. However, several factors can trigger such MET upregulation in a manner independent of HGF, suggesting that gastric tumors with MET overexpression are not necessarily MET driven. On the other hand, gastric cancer cells with MET amplification are dependent on MET signaling for their survival and are thus vulnerable to MET TKI treatment. Given the low prevalence of MET amplification in gastric cancer (approximately 8 %), testing for this genetic change would substantially narrow the target population but it might constitute a better biomarker than MET overexpression for MET TKI therapy. We compare aberrant MET signaling dependent on the HGF-MET axis or on MET amplification as well as address clinical issues and challenges associated with the identification of appropriate biomarkers for MET-driven tumors.

Establishing proof of mechanism: Assessing target modulation in early-phase clinical trials

Since modulation of the putative target and the observed anti-tumor effects form the basis for the clinical development of a molecularly targeted therapy, early-phase clinical trials should be designed to demonstrate proof-of-mechanism in tissues of interest. In addition to establishing safety and the maximum tolerated dose, first-in-human clinical trials should be designed to demonstrate target modulation, define the proposed mechanism of action, and evaluate pharmacokinetic-pharmacodynamic relationships of a new anti-cancer agent. Assessing target modulation in paired tumor biopsies in patients with solid tumors presents multiple challenges, including procedural issues such as patient safety, ethical considerations, and logistics of sample handling and processing. In addition, the availability of qualified biomarker assay technologies, resources to conduct such studies, and real-time analysis of samples to detect inter-species differences that may affect the determination of optimal sampling time points must be taken into account. This article provides a discussion of the challenges that confront the practical application of pharmacodynamic studies in early-phase clinical trials of anti-cancer agents.

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.

Targeting the MET Pathway in Gastric and Oesophageal Cancers: Refining the Optimal Approach

Gastric and oesophageal cancers are a major cause of global cancer-related morbidity and mortality. Improvements in treatment for locoregional and metastatic gastric and oesophageal cancer have been incremental and the overall prognosis remains poor. Increasingly, molecular classification has identified recurrent, therapeutically relevant, somatic alterations in gastroesophageal malignancies. However, other than ERBB2 amplification, molecularly directed therapies have not translated to improved survival. Amplification of the receptor tyrosine kinase MET is found in about 5% of gastroesophageal cancers and represents an oncogenic driver and therapeutic target. Small series have shown activity of MET-directed tyrosine kinase inhibitors, but the clinical benefit of anti-MET antibodies has been disappointing. Here we discuss the MET pathway in gastroesophageal cancers, the clinical data for MET small molecule tyrosine kinase inhibitors, anti-MET antibodies and future clinical directions for targeting MET in gastric and oesophageal cancers. To our knowledge, this is the most comprehensive review of the clinical experience with MET-directed therapies in gastric and oesophageal cancers.

A Copula Based Approach for Design of Multivariate Random Forests for Drug Sensitivity Prediction

Modeling sensitivity to drugs based on genetic characterizations is a significant challenge in the area of systems medicine. Ensemble based approaches such as Random Forests have been shown to perform well in both individual sensitivity prediction studies and team science based prediction challenges. However, Random Forests generate a deterministic predictive model for each drug based on the genetic characterization of the cell lines and ignores the relationship between different drug sensitivities during model generation. This application motivates the need for generation of multivariate ensemble learning techniques that can increase prediction accuracy and improve variable importance ranking by incorporating the relationships between different output responses. In this article, we propose a novel cost criterion that captures the dissimilarity in the output response structure between the training data and node samples as the difference in the two empirical copulas. We illustrate that copulas are suitable for capturing the multivariate structure of output responses independent of the marginal distributions and the copula based multivariate random forest framework can provide higher accuracy prediction and improved variable selection. The proposed framework has been validated on genomics of drug sensitivity for cancer and cancer cell line encyclopedia database.

Relationships between Chromosome 7 Gain, MET Gene Copy Number Increase and MET Protein Overexpression in Chinese Papillary Renal Cell Carcinoma Patients

To investigate the relationships between Chromosome 7 gain, mesenchymal-epithelial transition factor (MET) gene copy number increase and MET protein overexpression in Chinese patients with papillary renal cell carcinoma (PRCC), immunohistochemistry (IHC), immunofluorescence (IF) and fluorescence in situ hybridization (FISH) were performed on 98 formalin-fixed, paraffin-embedded (FFPE) PRCC samples. Correlations between MET gene copy number increase, Chromosome 7 gain and MET protein overexpression were analyzed statistically. A highly significant correlation was observed between the percentage of tumor cells with MET gene copy number ≥3 and CEP7 copy number ≥3 (R² = 0.90, p<0.001) across two subtypes of PRCC. In addition, the percentage of tumor cells with MET gene copy number ≥3 was found to increase along with increases in MET IHC score. This correlation was further confirmed in those PRCC tumor cells with average MET gene copy number >5 using combined IF and FISH methodology. Overall, this study provides evidence that Chromosome 7 gain drives MET gene copy number increase in PRCC tumors, and appears to subsequently lead to an increase in MET protein overexpression in these tumor cells. This supports MET activation as a potential therapeutic target in sporadic PRCC.

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.