c-Met Activation Research Articles

Transcriptional upregulation of c-MET is associated with invasion and tumor budding in colorectal cancer.

c-MET and its ligand HGF are frequently overexpressed in colorectal cancer (CRC) and increased c-MET levels are found in CRC liver metastases. This study investigated the role of the HGF/c-MET axis in regulating migration/invasion in CRC, using pre-clinical models and clinical samples. Pre-clinically, we found marked upregulation of c-MET at both protein and mRNA levels in several invasive CRC cells. Down-regulation of c-MET using RNAi suppressed migration/invasion of parental and invasive CRC cells. Stimulation of CRC cells with rh-HGF or co-culture with HGF-expressing colonic myofibroblasts, resulted in significant increases in their migratory/invasive capacity. Importantly, HGF-induced c-MET activation promoted rapid downregulation of c-MET protein levels, while the MET transcript remained unaltered. Using RNA in situ hybridization (RNA ISH), we further showed that MET mRNA, but not protein levels, were significantly upregulated in tumor budding foci at the invasive front of a cohort of stage III CRC tumors (p < 0.001). Taken together, we show for the first time that transcriptional upregulation of MET is a key molecular event associated with CRC invasion and tumor budding. This data also indicates that RNA ISH, but not immunohistochemistry, provides a robust methodology to assess MET levels as a potential driving force of CRC tumor invasion and metastasis.

Development of a 3D Tissue Culture–Based High-Content Screening Platform That Uses Phenotypic Profiling to Discriminate Selective Inhibitors of Receptor Tyrosine Kinases

3D tissue cultures provide a more physiologically relevant context for the screening of compounds, compared with 2D cell cultures. Cells cultured in 3D hydrogels also show complex phenotypes, increasing the scope for phenotypic profiling. Here we describe a high-content screening platform that uses invasive human prostate cancer cells cultured in 3D in standard 384-well assay plates to study the activity of potential therapeutic small molecules and antibody biologics. Image analysis tools were developed to process 3D image data to measure over 800 phenotypic parameters. Multiparametric analysis was used to evaluate the effect of compounds on tissue morphology. We applied this screening platform to measure the activity and selectivity of inhibitors of the c-Met and epidermal growth factor (EGF) receptor (EGFR) tyrosine kinases in 3D cultured prostate carcinoma cells. c-Met and EGFR activity was quantified based on the phenotypic profiles induced by their respective ligands, hepatocyte growth factor and EGF. The screening method was applied to a novel collection of 80 putative inhibitors of c-Met and EGFR. Compounds were identified that induced phenotypic profiles indicative of selective inhibition of c-Met, EGFR, or bispecific inhibition of both targets. In conclusion, we describe a fully scalable high-content screening platform that uses phenotypic profiling to discriminate selective and nonselective (off-target) inhibitors in a physiologically relevant 3D cell culture setting.

Hepatocyte growth factor renders BRAF mutant human melanoma cell lines resistant to PLX4032 by downregulating the pro-apoptotic BH3-only proteins PUMA and BIM.

A large proportion of melanomas harbour the activating BRAFV600E mutation that renders these cells dependent on MAPK signalling for their survival. Although the highly specific and clinically approved BRAFV600E kinase inhibitor, PLX4032, induces apoptosis of melanoma cells bearing this mutation, the underlying molecular mechanisms are not fully understood. Here, we reveal that PLX4032-induced apoptosis depends on the induction of the pro-apoptotic BH3-only protein PUMA with a minor contribution of its relative BIM. Apoptosis could be significantly augmented when PLX4032 was combined with an inhibitor of the pro-survival protein BCL-XL, whereas neutralization of the pro-survival family member BCL-2 caused no additional cell death. Although the initial response to PLX4032 in melanoma patients is very potent, resistance to the drug eventually develops and relapse occurs. Several factors can cause melanoma cells to develop resistance to PLX4032; one of them is the activation of the receptor tyrosine kinase cMET on melanoma cells by its ligand, hepatocyte growth factor (HGF), provided by the tumour microenvironment or the cancer cells themselves. We found that HGF mediates resistance of cMET-expressing BRAF mutant melanoma cells to PLX4032-induced apoptosis through downregulation of PUMA and BIM rather than by increasing the expression of pro-survival BCL-2-like proteins. These results suggest that resistance to PLX4032 may be overcome by specifically increasing the levels of PUMA and BIM in melanoma cells through alternative signalling cascades or by blocking pro-survival BCL-2 family members with suitable BH3 mimetic compounds.

CARP-1 functional mimetics are novel inhibitors of drug-resistant triple negative breast cancers.

Doxorubicin and Cisplatin are the frontline therapeutics for treatment of the triple negative breast cancers (TNBCs). Emergence of drug-resistance often contributes to failure of drugs and poor prognosis, and thus necessitates development of new and improved modalities to treat TNBCs. We generated and characterized chemotherapy-resistant TNBC cells following their culture in chronic presence of Doxorubicin or Cisplatin, and tested whether their viabilities were inhibited by a novel class of CARP- 1 functional mimetic (CFM) compounds. Analogs of parent compound CFM-4 were obtained through structure-activity based medicinal chemistry studies. CFM-4.16, a novel analog of CFM-4, caused superior inhibition of viability of TNBC cells when used in combination with doxorubicin. Doxorubicin and cisplatin inhibited viabilities of parental cells with GI50 dose of 0.02–0.1 μM and 1.65 μM, respectively. The GI50 dose of doxorubicin for doxorubicin-resistant TNBC cells was ≥ 10.0 μM. For Cisplatin-resistant cells, the GI50 dose of Cisplatin was ≥ 6–15.0 μM for MDA-MB-468 sublines and ≥ 150.0 μM for MDA-MB-231 sublines. CFM-4.16 inhibited viability of chemotherapy-resistant TNBC cells, in part by inhibiting oncogenic cMet activation and expression, stimulating CARP-1 expression, caspase-8 cleavage and apoptosis. CFM-4.16 pretreatment enhanced anti-TNBC efficacies of inhibitors of cMET (Tevatinib) or cSrc (Dasatinib). CFM-4.16 suppressed growth of resistant TNBC cells in soft agar as well as in three-dimensional suspension cultures derived from enriched, stem-like cells. Finally, a nanolipid formulation of CFM-4.16 in combination with doxorubicin had superior efficacy in inhibiting TNBC xenograft growth. Our findings collectively demonstrate therapeutic potential of CFM-4.16 for parental and drug-resistant TNBCs.

FRMD6 inhibits human glioblastoma growth and progression by negatively regulating activity of receptor tyrosine kinases.

FRMD6 is an Ezrin/Radixin/Moesin (ERM) family protein and a human homologue of Drosophila expanded (ex). Ex functions in parallel of Drosophila merlin at upstream of the Hippo signaling pathway that controls proliferation, apoptosis, tissue regeneration, and tumorigenesis. Even though the core kinase cascade (MST1/2-Lats1/2-YAP/TAZ) of the Hippo pathway has been well established, its upstream regulators are not well understood. Merlin promotes activation of the Hippo pathway. However, the effect of FRMD6 on the Hippo pathway is controversial. Little is known about how FRMD6 functions and the potential role of FRMD in gliomagenesis and glioblastoma (GBM) progression. We demonstrate for the first time that FRMD6 is down-regulated in human GBM cells and tissues and that increased FRMD6 expression inhibits whereas FRMD6 knockdown promotes GBM cell proliferation/invasion in vitro and GBM growth/progression in vivo. Furthermore, we demonstrate that unlike increased expression of merlin, which enhances the stress induced activation of the Hippo pathway, increased FRMD6 expression displays little effect on the pathway. In contrast, we show that FRMD6 inhibits activation of a couple of receptor tyrosine kinases (RTKs) including c-Met and PDGFR and their downstream Erk and AKT kinases. Moreover, we show that expression of constitutively active c-Met, the TPR-Met fusion protein, largely reverses the anti-GBM effect of FRMD6 in vivo, suggesting that FRMD6 functions at least partially through inhibiting activity of RTKs especially c-Met. These results establish a novel function of FRMD6 in inhibiting human GBM growth and progression and uncover a novel mechanism by which FRMD6 exerts its anti-GBM activity.

Activation of the c-Met Pathway Mobilizes an Inflammatory Network in the Brain Microenvironment to Promote Brain Metastasis of Breast Cancer.

Brain metastasis is one of the chief causes of mortality in breast cancer patients, but the mechanisms that drive this process remain poorly understood. Here, we report that brain metastatic cells expressing high levels of c-Met promote the metastatic process via inflammatory cytokine upregulation and vascular reprogramming. Activated c-Met signaling promoted adhesion of tumor cells to brain endothelial cells and enhanced neovascularization by inducing the secretion of IL8 and CXCL1. Additionally, stimulation of IL1β secretion by activation of c-Met induced tumor-associated astrocytes to secrete the c-Met ligand HGF. Thus, a feed-forward mechanism of cytokine release initiated and sustained by c-Met fed a vicious cycle that generated a favorable microenvironment for metastatic cells. Reinforcing our results, we found that pterostilbene, a compound that penetrates the blood-brain barrier, could suppress brain metastasis by targeting c-Met signaling. These findings suggest a potential utility of this natural compound for chemoprevention. Cancer Res; 76(17); 4970-80. ©2016 AACR.

The novel c-Met inhibitor capmatinib mitigates diethylnitrosamine acute liver injury in mice

The receptor tyrosine kinase mesenchymal-epithelial transition factor (c-Met) sits at the interface between controlled cellular division of organogenesis and uncontrolled cellular division of carcinogenesis. c-Met contribution to the initial phases of liver injury and inflammation is still not resolved. Herein, we investigated the selective pharmacological intervention of c-Met by capmatinib (formerly known as INC280) in the diethylnitrosamine (DEN) acute liver injury model in mice. c-Met inhibition by capmatinib reduced DEN-induced elevation of the pro-inflammatory cytokines TNF-α, IL-1β, IL-17A, IL-23(p19/40) and IFN-γ, which correlated well with serum markers of hepatocellular injury (ALT, AST and LDH). The protective effects possessed by capmatinib were mainly mediated by inhibiting inflammatory cells infiltration to the liver. However, hematoxylin-eosin and bax-immunohistochemical stainings revealed that capmatinib (at a dose of 10, but not 5mg/kg) aggravated DEN-induced hepatocellular ballooning and apoptosis, respectively. These effects were concordant with hepatocellular overexpression of the amino acid transporter CD98. Such capmatinib effects arised mostly from exaggerating the elevation of the mutagenic lipid peroxide 4-HNE along with MDA that enhanced DEN-induced compensatory proliferation evidenced by PCNA expression. In conclusion, inhibition of c-Met activation by capmatinib may provide protection against liver injury, but may trigger undesirable elevation of the mutagenic 4-HNE.

Abstract 345: Olive oil-based oleocanthal and bioisosteres as c-Met inhibitors for the control of triple negative breast cancer

Abstract Breast cancer is the most commonly diagnosed cancer in women, claiming the lives of hundreds of thousands of women each year. Dysregulation of c Met correlates with aggressive proliferation, invasive character, and pathological motility, especially in triple negative breast cancer (TNBC). The Mediterranean diet is known to reduce the incidence of breast and colon malignancies. Extra-virgin olive oil (EVOO) represents a main ingredient in this diet. The EVOO-derived (-)-oleocanthal was shown to target the RTK c-Met. Oleocanthal selectively inhibited the proliferation, migration and invasion of several c-Met dependent breast and prostate tumor cell lines. Oleocanthal exerted potent in-vivo efficacy in an orthotopic athymic nude mouse breast cancer xenograft model much greater than its modest in-vitro potency. Several oleocanthal bioisosteres have been semisynthized of which the analog HVS have shown significant activity improvement against breast cancer in vitro and in vivo models. Selectivity profiling against a TKs panel, structurally related to c-Met, suggested the HVS has high selectivity to both Met and ABL1 kinases. Overexpression of ABL1 kinase is implicated in the progression of several solid tumors concomitantly with c-Met activation, including breast, colon, lung and other cancers. ABL1 interconnects oncogenic Met and p53 pathways and hence dual blockage of c-Met and ABL1 activation adds significant advantages over currently approved c-Met inhibitors and may justify its potent in vitro and in vivo activities. Therefore, the dual c-Met/ABL1 inhibitor HVS could not only be effective in slowing TNBC progression but also could prevent drug resistance. Detailed molecular and cellular mechanistic studies of oleocanthal and its bioisosteres indicate their potential for future use to control TNBC and other c-Met-dependent malignancies. This study was supported by NIH/NCI project 1R15CA167475-01. Citation Format: Hassan Y. Ebrahim, Mohamed M. Mohyeldin, Abu Bakar Siddique, Mohamed R. Akl, Mostafa Ibrahim, Khalid A. El Sayed. Olive oil-based oleocanthal and bioisosteres as c-Met inhibitors for the control of triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 345.

Abstract 905: Pterostilbene (PTER) suppresses breast cancer brain metastasis by targeting a c-Met mediated inflammation network

Abstract At the late stage of breast cancer, most patients develop metastatic lesions and the brain is one of the major metastatic sites. Brain metastasis profoundly affects the cognitive and sensory function as well as morbidity of patients, and the one year survival rate among these patients remains less than 20%. The result of our newly developed gene set enrichment analysis (GSEA)-based pathway screening indicates that c-Met pathway is highly activated among the patients who developed early brain metastasis. To identify a novel target of c-Met pathway in brain metastasis, we performed the microarray analysis in two brain metastatic cell lines with the expression of doxycycline-inducible sh-cMet. Our results indicate that a group of inflammatory cytokines including IL1b, IL8 and CXCL1 were significantly induced by c-Met activation. Furthermore, we found that IL1b was able to induce the secretion of HGF (hepatocyte growth factor) from tumor associated astrocytes (TAA) which in turn activates c-Met pathway in cancer cells. Our results of endothelial cell tube formation assays also strongly suggest that cMet-induced IL8 and the activation of its receptor, CXCL1, promote tumor angiogenesis which is essential for the metastatic growth of cancer cells. Natural compounds (NC) have been extensively studied for their anti-tumor effects. However, much less studies have been done on NC for the treatment/prevention of brain tumors mainly due to the obstacle of Blood-brain-barrier (BBB) permeability. To identify the NCs that can be used for treating brain metastasis, we performed pathway analysis which only focused on BBB-permeable NC. The results of GSEA indicate that Resveratrol-targeting genes were significantly enriched among those patients who developed brain metastasis compared to metastasis-free patients. Furthermore, we found that the one of derivatives of Resveratrol, Pterostilbene (PTER), showed significantly more potent activity than Resveratrol and suppressed brain metastasis in vitro and in vivo by targeting the c-Met oncogene. These findings suggest that TAA-mediated c-Met activation plays a key role in brain metastasis and that PTER is a potential therapeutic agent to treat brain metastasis by suppressing the c-Met expression. Citation Format: Fei Xing, Yin Liu, Sambad Sharma, Kerui Wu, Kounosuke Watabe. Pterostilbene (PTER) suppresses breast cancer brain metastasis by targeting a c-Met mediated inflammation network. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 905.

Abstract 4578: Quantification of protein complexes and post-translational modifications in colorectal cancer utilizing combinted MultiOmyxTM and PLA assay from a single FFPE slide

Abstract A comprehensive signaling pathway analysis is critical to characterize cancer pathogenesis, in which malignant cells evolve from nonmalignant cells, in heterogeneous tissues comprised of both healthy and pathological cells. Although significant advances in technologies have led to improved understanding of cancer biology, comprehensive profiling utilizing multiple biomarkers remains a technical challenge due to limited sample availability. GE Healthcare MultiOmyx multiplexed immunofluorescence (IF) assay overcomes this sample limitation and staining up to 60 protein biomarkers has been demonstrated in a single formalin-fixed, paraffin-embedded (FFPE) slide. In this study, proximity ligation assay (PLA) technology is adapted to expand MultiOmyx assay capabilities by enabling detection of protein-protein interactions (PPIs) and post-translational modification (PTMs) from a single FFPE slide. The MultiOmyx assay utilizes a pair of directly conjugated Cyanine dye-labeled (Cy3, Cy5) antibodies per round of staining. Each round of staining is imaged and followed by novel dye inactivation chemistry, enabling repeated rounds of staining. The PLA technology utilizes a pair of directly conjugated proximity probes to detect proteins of interest. Proximal binding of these probes lead to ligation and DNA amplification using rolling circle amplification (RCA). Amplified DNA is detected by hybridizing Cyanine dye-labeled oligonucleotides. Herein we report a comprehensive analysis of key receptor tyrosine kinases (RTKs) (HER1, HER2, HER3, cMET, others) along with their downstream signaling proteins (PI3K, phospho AKT, and phospho ERK1/2) in 10 colorectal cancer (CRC) samples using the standard MultiOmyx assay. A PLA-adapted MultiOmyx assay is utilized to detect dimerization partners (HER1:HER2, HER2:HER3, HER1:HER3) and RTK phosphorylation using separate antibodies against the RTK and the phosphorylation site. Protein IF staining revealed heterogeneous expression and activation across different samples. High EGFR and HER3 expression correlated with positive staining for AKT, through EGFR:HER3 dimer. High expression of EGFR correlated with positive staining for phospho Erk1/2, through EGFR:HER2 dimer. Additionally, intra-tumor heterogeneity was observed, with varied expression and activation of EGFR, HER2, HER3, and cMET. Current IHC and multiplexed IF assays measures the expression levels of individual proteins but overlook the measurement of PPIs and PTMs, which are crucial to understanding the biology of pathway signaling. The PLA-adapted MultiOmyx assay enables true comprehensive pathway signaling analysis at a single cell level by providing spatial context and quantitative analysis of protein expression, protein-protein interactions, and protein activations (phosphorylation). Citation Format: Qingyan Au, Flora Sahafi, Kathy Nguyen, Raghav Padmanabhan, Edward J. Moler, Nicholas Hoe. Quantification of protein complexes and post-translational modifications in colorectal cancer utilizing combinted MultiOmyxTM and PLA assay from a single FFPE slide. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4578.

Abstract 4663: Combination of c-Met inhibitor tepotinib (MSC2156119J) and a third-generation EGFR inhibitor can overcome double resistance mediated by EGFR T790M mutation and c-Met amplification in non-small cell lung cancer models

Abstract In clinical practice, acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) causes EGFR TKI treatment failure. Several resistance mechanisms have been identified; EGFR T790M mutation and aberrant activation of c-Met through c-Met gene amplification and/or HGF upregulation are the two most common mechanisms. We have previously shown that combining the highly selective c-Met inhibitor tepotinib with 1st or 2nd-generation EGFR TKIs overcomes gefitinib resistance caused only by c-MET amplification. Third-generation EGFR TKIs such as rociletinib have been developed specifically to overcome T790M-mediated resistance to EGFR TKIs. We hypothesized that combining a 3rd-generation EGFR TKI with tepotinib could overcome resistance to a 1st or 2nd-generation EGFR TKI (e.g. gefitinib) regardless of the mechanism of resistance. We assessed the efficacy of tepotinib and a Merck-synthesized version of rociletinib (MSR) as monotherapy or in combination in a NSCLC cell line xenograft model (HCC827-GR-T790M) with an EGFR del 19 mutation, c-Met amplification, and exogenous T790M expression, and in a patient-derived xenograft model (DFCI081) with an EGFR del 19 mutation and c-Met amplification, but not a T790M mutation. Single-agent tepotinib, erlotinib, and afatinib did not show antitumor activity in HCC827-GR-T790M xenografts and tumors progressed on treatment (median tumor volume [TV] changes &amp;gt;73%). The combinations of tepotinib + erlotinib and tepotinib + afatinib delayed tumor regrowth more than single-agent therapy, but were no more effective than single-agent MSR. In contrast, the combination of tepotinib + MSR had strong antitumor activity in this model with double resistance due to c-Met amplification and exogenous T790M expression, resulting in complete tumor regression (median TV change -97%). In the patient-derived xenograft model DFCI081, tumors progressed under single-agent therapy with the EGFR TKIs erlotinib, afatinib, and MSR, as expected given that this cell line expresses c-Met. In contrast, tepotinib induced complete tumor regression as monotherapy and when combined with each of the EGFR TKIs (median TV change -100%). Complete regression was maintained until the end of the 60-day observation period after treatment termination. These findings are compatible with the hypothesis that combining tepotinib with a 3rd-generation EGFR TKI to overcome double resistance to 1st and 2nd-generation TKIs mediated by T790M and c-Met in NSCLC is more effective than using either agent alone. Furthermore, whereas EGFR TKIs were not effective in tumor models showing c-Met amplification and EGFR del 19 mutation but not T790M mutation, ie resistance is c-Met mediated, tepotinib monotherapy induced complete tumor regression. Citation Format: Manja Friese-Hamim, Giuseppe Locatelli, Friedhelm Bladt. Combination of c-Met inhibitor tepotinib (MSC2156119J) and a third-generation EGFR inhibitor can overcome double resistance mediated by EGFR T790M mutation and c-Met amplification in non-small cell lung cancer models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4663.

Abstract 924: Upregulation of the MET transcript is consistently associated with invasion and tumor budding in colorectal cancer

Abstract Background: The c-MET proto-oncogene is frequently overexpressed (50-60%), amplified (1-3%), and mutated (1-3%) in colorectal cancer (CRC). Hepatocyte growth factor (HGF)-dependent and independent activation of c-MET has been associated with increased survival and resistance to targeted therapies. This study aimed to investigate the role of the HGF/c-MET axis in regulating migration/invasion in CRC, using pre-clinical models and clinical samples. Methods: In order to model CRC tumour cell invasion, we have generated invasive CRC subpopulations using Boyden Invasion chambers. To model the CRC microenvironment, we have used a range of co-culture techniques with CRC cells and colon fibroblasts. Migration/invasion was determined using xCELLigence System (Roche). c-MET expression in parental and invasive cell lines was measured using Western blotting and qRT-PCR. c-MET expression in CRC FFPE tissues was measured using IHC and RNAScope®. Results: We identified marked upregulated expression of c-MET at both the protein and transcript levels in our invasive CRC cell line models. Importantly, both parental and invasive subpopulations were found to be inherently dependent on c-MET for migration, as RNAi against c-MET abrogated migration/invasion in both parental and invasive models. We also demonstrated that stimulation of CRC cells with rh-HGF resulted in increased CRC cell migration/invasion. In addition, co-culture of CRC cells with colonic myofibroblasts, resulted in marked increases in migratory and invasive capacity, and this was dependent on HGF/c-MET signaling. Interestingly, stimulation with myofibroblast conditioned medium or HGF promotes rapid degradation of c-MET at the protein level, followed by recycling, while MET transcript remains unaltered, illustrating a dynamic expression of c-MET protein in response to activation. We further showed that MET is transcriptionally upregulated in tumour budding foci at the invasive front of a cohort of stage III CRC tumors. Intriguingly, c-MET protein levels do not correlate with the transcript, most likely due to a similar protein degradation process observed in our aforementioned in vitro models. Conclusions: We show for the first time a key role for transcriptional upregulation of MET as a molecular driver of tumour invasion, both in vitro and in stage III CRC tumours. Citation Format: Conor Bradley, Philip Dunne, Stephen McQuaid, Victoria Bingham, Mark Lawler, Manuel Salto-Tellez, Patrick Johnston, Sandra Van Schaeybroeck. Upregulation of the MET transcript is consistently associated with invasion and tumor budding in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 924.

Abstract 4825: A rationale for treatment of colorectal cancer with mitomycin C and crizotinib

Abstract Colorectal cancer (CRC) is the third leading cause of cancer-related death in men and women in the United States. Microsatellite instability (MSI) is found in approximately 15% of sporadic colorectal cancers and in the majority of Lynch syndrome patients. MSI has been correlated to deficiency in the mismatch repair (MMR) genes and therefore MSI-High tumors exhibit higher mutation rates then non-MSI-High tumors. We recently reported on 26 MSI-High and 558 non-MSI-High CRCs that were profiled at Caris Life Sciences (Shagisultanova et al., 2015 ASCO Annual Meeting Abstract No. e14684 “Association of increase in BRCA2 gene mutations in microsatellite instable (MSI-H) colorectal cancer (CRC) with increased c-MET expression.”). Immunohistochemistry and genomic analyses were performed in the BRCA-mutant versus BRCA wild-type MSI-High tumors. BRCA2 mutations were highly enriched (50%) in MSI-High CRC. MSI-High tumors with BRCA2 frameshift mutations had high c-MET expression. c-MET overexpression is known to be associated with aggressive metastatic CRC. We hypothesized there may be a synergistic drug interaction between drugs that are used to treat BRCA2-deficient tumors and c-MET inhibitors. We further hypothesized there may be a mechanistic link between BRCA2-deficiency, double-strand breaks following DNA damage, and c-MET overexpression. Mitomycin C (MMC) is an anti-cancer chemotherapeutic agent, which causes DNA damage by inducing double strand breaks (DSBs) through DNA cross-linking. Tumors deficient in genes encoding for proteins involved in DNA repair such as BRCA2 show hypersensitivity to MMC. Crizotinib is a small molecule inhibitor of c-MET and ALK receptor tyrosine kinases. In the present studies, we tested CRC cell lines for sensitivity to MMC plus crizotinib. CRC cell lines treated with MMC activated a DNA damage response as measured by up-regulation of ã-H2AX. Upon BRCA2 siRNA-mediated knockdown colorectal cancer cells became more sensitive to MMC shown by cleaved-PARP as a measure of apoptosis. Crizotinib inhibited the activation of c-MET in CRC cell lines treated with Hepatocyte Growth Factor (HGF). The combination treatment of colorectal cancer cells with crizotinib and MMC led to increased apoptosis (cleaved-PARP) compared to each drug alone. Combination treatment with increasing concentrations of both drugs in a CellTiter-Glo Cell Viability assay demonstrated a synergistic effect. However, we found no evidence for c-MET upregulation upon effective BRCA2 knockdown in the absence or presence of DNA damage. Although there is no mechanistic link between BRCA2 mutation and c-MET overexpression, c-MET is frequently overexpressed in CRC in general and BRCA2 is frequently mutated in CRC especially in MSI-High cases. The combination of crizotinib with MMC appeared synergistic regardless of whether CRC cell lines were MSI-High or non-MSI-High. Our results prompt the clinical testing of the combination of MMC and crizotinib in advanced CRC. Citation Format: Avital Lev, Elena Shagisultanova, Safoora Deihimi, David T. Dicker, Joanne Xui, Wafik S. El-Deiry. A rationale for treatment of colorectal cancer with mitomycin C and crizotinib. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4825.

Abstract 5045: Overexpression of ABC transporters through HGF/c-MET activation results in anti-cancer drug resistance in SCLC

Abstract Upregulation of hepatocyte growth factor (HGF)/c-MET pathway causes drug resistance to anti-cancer agents such as epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors in non-small lung cancer (NSCLC) with EGFR mutation and cytotoxic agents in small cell lung cancer (SCLC), but the roles and mechanisms of c-MET in drug-resistant cancer cells are not clarified. We studied to reveal the role of c-MET overexpression in the resistant lung cancer cell lines and to demonstrate whether MET-inhibition could restore drug sensitivity in anti-cancer drug resistant cell lines via ABC transporters down-regulation. In this study we used the 7-ethyl-10-hydroxycamptothesin (SN-38)-resistant cell line (PC-6/SN-38) that was derived from the human SCLC cell line PC-6. We compared the expression levels of the purposed genes by quantitative real-time PCR (qRT-PCR) and western blotting (WB). MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) assay was used to measure cell viability of the resistant cells compared with the parental cells. Inhibition of c-MET activation was performed by c-MET inhibitors, PHA665752 and Crizotinib or small interfering RNA against c-MET. We found MET inhibitors (4 or 8μM) reduced cell growth and restored drug sensitivity (2μM) of resistant cells, PC-6/SN38, compared to parental cells. To reveal the mechanisms of c-MET in drug resistance we examined ATP-binding cassette (ABC) transporters expression in PC-6/SN-38 compared to the parental cells by qRT-PCR, and found the mRNA level of ABCG2, which effluxes SN-38 as substrate, in PC-6/SN-38 cells was extremely increased and another ABC transporters that do not efflux SN-38 were not. Recently we reported PC-6/SN-38 cells had c-MET overexpression, and c-MET inhibition in resistant cells such PC-6/SN-38 resulted in restoration drug resistance. Based on this report we examined c-MET inhibition by c-MET inhibitor and small interfering RNA against c-MET in PC-6/SN38, and qRT-PCR and WB were performed to investigate alteration of ABCG2 expression, and found both two c-MET inhibition reduced ABCG2 expression. In addition, to demonstrate c-MET upregulation in resistant cells is addicted to the ligand HGF, PC-6 cells were incubated with HGF treated for 3 weeks and made PC-6/HGF, then continued to incubate with HGF and SN-38 was added two times in a week. Although c-MET expression is equal in PC-6 and PC-6/HGF, after SN-38 treatment c-MET was overexpressed. Furthermore, serum HGF level in SCLC patients correlated with clinical course. We demonstrated upregulation of ABC transporters via HGF/c-MET signaling activation might be one of the mechanisms of acquired resistance to cytotoxic anticancer agents in lung cancer cells. Decreased ABC transporters expression through inhibition of c-MET activation might overcome drug resistance to cytotoxic agents. Citation Format: Yoshitaka Yagi, Hiroaki Ozasa, Takahiro Tsuji, Yuichi Sakamori, Takeshi Nomizo, Hiroki Nagai, Young Hak Kim, Ken Maeno, Tetsuya Oguri, Michiaki Mishima. Overexpression of ABC transporters through HGF/c-MET activation results in anti-cancer drug resistance in SCLC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5045.

Abstract 747: Paracrine c-MET/HGF HCC PDX: evaluation of a biologics targeting c-MET

Abstract The interaction between the c-MET tyrosine kinase receptor (RTK) on the surface of cancer cells with its ligand, hepatocyte growth factor (HGF) secreted from surrounding tumor stroma, results in paracrine signal transduction in cancer cells to promote growth, invasion, angiogenesis and metastases. c-MET gene amplification/over-expression, or activating mutations, frequently function as oncogenic driver in several types of cancers. c-MET is thus considered a key target(1) for both TKIs or biologics. However, lack of suitable animal models has represented an obstacle for the development of new cMET inhibitors. While patient derived xenografts (PDXs) mirror patients’ histopathological/genetic profiles(2-6), they usually lose human stroma, the source of HGF; moreover the HGF originated from murine stroma is incapable of triggering a paracrine signaling because of lack of cross reactivity with the human c-MET. Some PDX grow independent of paracrine mechanisms because of their constitutive c-MET activation by the presence of activating mutations, gene amplification or autocrine signaling, and can be used to evaluate the efficacy of TKIs(5, 7, 8). However they are not suitable to assess biologics, e.g. antibodies disrupting receptor-ligand interaction. Alternatively it is possible to grow tumors in hu-HGF-transgenic immunocompromised mice (humanization) where an artificial paracrine signaling is created. Interestingly, we have identified a unique HCC-PDX, LI0801, which maintains human stroma throughout passages, as demonstrated by immunochemistry staining for human vimentine and human HGF, both markers of stromal components(7, 8). The mechanisms of human stroma maintenance in this PDXremain unclear. We showed that LI0801 responds to different TKIs(7, 8). In addition we evaluated the efficacy of an anti-human c-MET monoclonal antibody in reducing tumor burden in LI0801, and we were able to demonstrate great tumor response to anti-human c-MET antibody, which is significantly more effective than crizotinib. To the best of our knowledge, LI0801 is the first paracrine c-MET PDX reported, and represents an important model to study paracrine cMET/HGF signaling and to evaluate new c-MET inhibitors, both TKIs, and biologics.

Discovery and optimization of a series of imidazo[4,5-b]pyrazine derivatives as highly potent and exquisitely selective inhibitors of the mesenchymal–epithelial transition factor (c-Met) protein kinase

Aberrant c-Met activation has been implicated in multiple tumor oncogenic processes and drug resistance. In this study, a series of imidazo[4,5-b]pyrazine derivatives was designed and synthesized, and their inhibitory activities were evaluated in vitro. Structure–activity relationship (SAR) was investigated systematically and docking analysis was performed to elucidate the binding mode, leading to the identification of the most promising compound 1D-2 which exhibited significant inhibitory effect on both enzymatic (IC50=1.45nM) and cellular (IC50=24.7nM in H1993 cell line) assays, as well as exquisite selectivity and satisfactory metabolic stability in human and rat liver microsomes.

A novel antagonist anti-cMet antibody with antitumor activities targeting both ligand-dependent and ligand-independent c-Met receptors.

c-Met is a prototypic member of a sub-family of RTKs. Inappropriate c-Met activation plays a crucial role in tumor formation, proliferation and metastasis. Using a key c-Met dimerization assay, a set of 12 murine whole IgG1 monoclonal antibodies was selected and a lead candidate, m224G11, was humanized by CDR-grafting and engineered to generate a divalent full antagonist humanized IgG1 antibody, hz224G11. Neither m224G11 nor hz224G11 bind to the murine c-Met receptor. Their antitumor activity was investigated in vitro in a set of experiments consistent with the reported pleiotropic effects mediated by c-Met and, in vivo, using several human tumor xenograft models. Both m224G11 and hz224G11 exhibited nanomolar affinities for the receptor and inhibited HGF binding, c-Met phosphorylation, and receptor dimerization in a similar fashion, resulting in a profound inhibition of all c-Met functions in vitro. These effects were presumably responsible for the inhibition of c-Met's major functions including cell proliferation, migration, invasion scattering, morphogenesis and angiogenesis. In addition to these in vitro properties, hz224G11 dramatically inhibits the growth of autocrine, partially autophosphorylated and c-Met amplified cell lines in vivo. Pharmacological studies performed on Hs746T gastric cancer xenografts demonstrate that hz224G11 strongly downregulates c-Met expression and phosphorylation. It also decreases the tumor mitotic index (Ki67) and induces apoptosis. Taken together, the in vitro and in vivo data suggest that hz224G11 is a promising candidate for the treatment of tumors. This antibody, now known as ABT-700 and currently in Phase I clinical trials, may provide a novel therapeutic approach to c-Met-expressing cancers.

Tolerability, efficacy and recommended phase II dose (RP2D) of tepotinib plus gefitinib in Asian patients with c-Met-positive/EGFR-mutant NSCLC: Phase Ib data.

e20501Background: Patients (pts) with NSCLC treated with EGFR inhibitors (EGFRi) ultimately develop resistance, often through c-Met activation. Dual EGFR and c-Met inhibition is therefore a rationa...

GEOMETRY duo-1: A phase (Ph) Ib/II, multicenter trial of oral cMET inhibitor capmatinib (INC280) ± erlotinib vs platinum + pemetrexed in adult patients (pts) with epidermal growth factor receptor (EGFR)-mutated, cMET-amplified, locally advanced/metastatic non-small cell lung cancer (NSCLC) with acquired resistance to prior EGFR tyrosine kinase inhibitor (TKI) therapy.

TPS9109Background: Despite high overall response rates (ORR) to EGFR TKIs, most pts with EGFR-mutated NSCLC develop acquired resistance; secondary activation of cMET as gene amplification, occurs i...

C-MET overexpression as a resistance biomarker to epidermal growth factor receptor tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer.

e20660Background: Multiple mechanisms of C-MET activation have been reported in non-small cell lung cancer (NSCLC) including amplification and mutation. C-MET protein overexpression also occurs in ...