High c-Met Expression Research Articles

Preclinical rationale for combination of crizotinib with mitomycin C for the treatment of advanced colorectal cancer

ABSTRACTColorectal cancer (CRC) is a leading cause of cancer-related deaths in the United States. We analyzed 26 MSI-High and 558 non-MSI-High CRC tumors. BRCA2 mutations were highly enriched (50%) in MSI-High CRC. Immunohistochemistry showed that BRCA2-mutated MSI-High CRC had high c-MET (64%) expression compared with BRCA-WT (17%). We hypothesized a mechanistic link between BRCA2-deficiency and c-MET overexpression and synergistic interaction between drugs that treat BRCA-deficient tumors (mitomycin C (MMC) or PARP inhibitors) and c-MET inhibitors (crizotinib). We tested CRC cell lines for sensitivity to MMC plus crizotinib or other drug combinations including PARP-inhibitors. Combined treatment of tumor cells with crizotinib and MMC led to increased apoptosis as compared with each drug alone. Additionally, combination treatment with increasing concentrations of both drugs demonstrated a synergistic anti-cancer effect (CI = 0.006–0.74). However, we found no evidence for c-MET upregulation upon effective BRCA2 knockdown in tumor cells −/+DNA damage. Although we found no mechanistic link between BRCA2 deficiency and c-MET overexpression, c-MET is frequently overexpressed in CRC and BRCA2 is mutated especially in MSI-H CRC. The combination of crizotinib with MMC appeared synergistic regardless of MSI or BRCA2 status. Using an in-vivo CRC xenograft model we found reduced tumor growth with combined crizotinib and MMC therapy (p = 0.0088). Our preclinical results support clinical testing of the combination of MMC and crizotinib in advanced CRC. Targeting cell survival mediated by c-MET in combination with targeting DNA repair may be a reasonable strategy for therapy development in CRC or other cancers.

684P - Targeting c-met and DNA double-strand break (DSB) repair pathways for BRCA-mutated gastric carcinomas

Background: In the present study, we underline the importance of combining c-Met Inhibitor (Inh.) and DSB repair Inhibitor (PARP Inh.) with the goal of accomplishing a synergistic therapeutic strategy in BRCA-mutated gastric carcinomas. Methods: Firstly, to verify whether c-Met affects tumor response to PARP Inh., AGS (low c-Met expression) and Hs746T (high c-Met expression) cell lines, were subjected to knockdown c-Met expression, in the presence of PARP Inh. (NU1025). Subsequently, we examined the correlation between BRCA1/2 and c-Met. We knocked down BRCA1/2 expression in AGS and Hs746T cells and treated them with PARP Inh. Next, we examined the effects of combining c-Met Inh. (SU11274) and PARP Inh. (NU1025), measured by MTT, clonogenic cell survival and Annexin, assays. We also evaluated the effect of combining PARP Inh. and c-Met Inh. in AGS/Hs746T xenograft tumor models. AGS/Hs746T -pcDNA3 and AGS/Hs746T -siBRCA cells were injected into SCID mice. Tumor sizes were measured every 3 days. DNA damage was assessed by γ-H2AX staining. Results: Silence of Met expression promoted Hs746T cells more sensitive to PARP Inh. to similar levels as the AGS cells, as indicated by decreased cell viability. Silence of BRCA1/2 expression sensitized only AGS cells, signifying that increased expression of c-Met renders cells resistant to PARP Inh. in the context of inactivating BRCA1/2. Combining c-Met Inh. and PARP Inh. suppressed cell growth and clonogenicity and enhanced apoptosis in both AGS and Hs746T cells. The dual inhibition was demonstrated to be even more successful when cells were knockdown for BRCA1/2. Also, co-inhibition treatment substantially reduced tumor growth to AGS/Hs746T -pcDNA3 and more even effectively to AGS/Hs746T –siBRCA1/2 xenograft models, compared to either Inh. alone. DNA damage was higher in AGS/Hs746T –siBRCA1/2 compare to AGS/Hs746T -pcDNA3 xenograft models. Conclusions: BRCA deficiency renders gastric tumor cells sensitive to PARP inhibition. In addition, treatment with c-Met Inh. enhanced Hs746T sensitivity to the PARP Inh. Our data demonstrate that dual Met/PARP inhibition is synergistic providing an effective therapeutic strategy in BRCA-mutated gastric carcinomas. Legal entity responsible for the study: M.V. Karamouzis Funding: None Disclosure: All authors have declared no conflicts of interest.

Correlation between c-Met and ALDH1 contributes to the survival and tumor-sphere formation of ALDH1 positive breast cancer stem cells and predicts poor clinical outcome in breast cancer

c-Met is a receptor-type tyrosine kinase, which is involved in a wide range of cellular responses such as proliferation, motility, migration and invasion. It has been reported to be overexpressed in various cancers. However, the role of c-Met in breast cancer stem cells (CSCs) still remains unclear. We herein, show that c-Met expression is significantly elevated in Basal-like type of breast cancer in comparison with other subtypes. High expression of c-Met strongly correlated with the expression of two CSC markers, ALDH1A3 and CD133 in breast cancers. In addition, breast cancers at tumor stage III-IV expressing both c-Methigh and ALDH1A3high had poor prognosis. Furthermore, treatment with c-Met inhibitors (Crizotinib, Foretinib, PHA-665752 and Tivantinib) in MDA-MB157 cells with high c-Met protein expression resulted in significant suppression in cell viability, contrary to MDA-MB468 cells with low c-Met protein expression. These c-Met inhibitors also suppressed cell viability and tumor-sphere formation of ALDH1high breast cancer cells with high c-Met expression. These results suggest that c-Met in ALDH1 positive CSCs seems to play an important role in breast cancer repopulation. Therefore, we conclude that c-Met is a potential therapeutic target in ALDH1 positive breast CSCs.

PD-L1 and c-MET expression and survival in patients with small cell lung cancer.

BackgroundBlocking the binding between the PD-1 and PD-L1 has been reported to produce antitumor responses. The MET/HGF axis appears to be another signaling pathway frequently altered in small cell lung cancer (SCLC). Our study was aimed to investigate the expression and prognostic roles of PD-L1 and c-MET in SCLC.MethodsThe expression levels of PD-L1 and c-MET were evaluated by immunohistochemical analysis in 83 SCLC specimens. Survival analysis was performed using the Kaplan-Meier method.ResultsOf the SCLC specimens, 51.8% and 25.3% exhibited positivity for PD-L1 and c-MET, respectively. Higher PD-L1 expression in tumor specimens was significantly correlated with a limited disease (LD) stage, normal levels of serum lactate dehydrogenase (LDH) and neuron-specific enolase (NSE). No association was found between the levels of c-MET and PD-L1 expression or between c-MET expression and other clinical characteristics. SCLC patients with PD-L1-positive tumors showed significantly longer overall survival (OS) than patients with PD-L1-negative tumors (17.0 vs 9.0, p=0.018). Conversely, those with positive c-MET expression exhibited a shorter OS trend (12.0 vs 15.0, p=0.186). However, sub-analysis of LD-stage patients revealed longer OS among the c-MET-negative group (25.0 vs 14.0; p=0.011). The OS of patients with positivity for both PD-L1 and c-MET showed no significant difference compared with other patients (p=0.17). According to multivariate analyses, neither PD-L1 nor c-MET immunoreactivity was a prognostic factor.ConclusionExpression of PD-L1 was correlated with LD stage and might serve as a prognostic for better OS in SCLC patients. In LD-stage patients, high c-MET expression might be predictive of a poor outcome.

Correlation of c-MET Expression with PD-L1 Expression in Metastatic Clear Cell Renal Cell Carcinoma Treated by Sunitinib First-Line Therapy.

Clear cell renal cell carcinoma (ccRCC) is highly metastatic. Cabozantinib, an anti-angiogenic tyrosine kinase inhibitor that targets c-MET, provided interesting results in metastatic ccRCC treatment. To understand better the role of c-MET in ccRCC, we assessed its status in a population of patients with metastatic ccRCC. For this purpose, tumor samples were analyzed for c-MET expression by immunohistochemistry (IHC), for c-MET copy number alterations by fluorescence in situ hybridization (FISH), and for c-MET mutations by next generation sequencing (NGS) in a retrospective cohort of 90 primary ccRCC of patients with metastases treated by first-line sunitinib. The expression of c-MET was correlated with pathological, immunohistochemical (VEGFA, CAIX, PD-L1), clinical, and molecular criteria (VHL status) by univariate and multivariate analyses and to clinical outcome using Kaplan-Meier curves compared by log-rank test. Of ccRCC, 31.1% had low c-MET expression (absent to weak intensity by IHC) versus 68.9% with high expression (moderate to strong intensity). High expression of c-MET was associated with a gain in FISH analysis (p=0.0284) without amplification. No mutations were detected in NGS. Moreover, high c-MET expression was associated with lymph node metastases (p=0.004), sarcomatoid component (p=0.029), VEGFA (p=0.037), and PD-L1 (p=0.001) overexpression, the only factor that remained independently associated (p<0.001) after logistic regression. No difference was observed in clinical outcomes. This study is the first to analyse c-MET status in metastatic ccRCC. The high expression of c-MET in the majority of ccRCC and its independent association with PD-L1 expression, may suggest a potential benefit from combining c-MET inhibitors and targeted immunotherapy.

Differential expression of c-Met between primary and metastatic sites in clear-cell renal cell carcinoma (ccRCC) and its association with PD-L1 expression.

4573 Background: Preclinical models show that c-Met promotes survival of renal cancer cells through the regulation of programmed death-ligand 1 (PD-L1). The relationship between c-Met and PD-L1 in human ccRCC is not well characterized. We compared c-Met expression between primary and metastatic sites in ccRCC tissues and evaluated the association with PD-L1 expression. Methods: Pairedprimary and metastatic samples from 45 ccRCC patients were included. Areas with predominant and highest Fuhrman nuclear grade (FNG) were selected. c-Met expression was evaluated by IHC using an anti-Met monoclonal antibody (MET4 Ab, VARI) and calculated by a combined score (CS, 0-300) as: intensity of c-Met staining (0-3) x % of positive cells (0-100). PD-L1 expression was previously assessed by IHC (PMID: 26014095). c-Met expression (average c-Met CS) between paired primary and metastatic samples were compared using Wilcoxon signed-rank test. Associations of c-Met expression with PD-L1 expression (+/-) and other clinical features were assessed with Wilcoxon rank-sum tests. Results: Our cohort included 45 primary ccRCCs and 54 corresponding metastases. c-Met expression was higher in metastatic sites compared to primary (c-Met CS: 55 vs. 28, p=0.0003) and was numerically-greater in PD-L1+ vs. PD-L1- tumors. Higher c-Met expression was associated with higher FNG and T-stage in both primary and metastatic sites (Table). Conclusions: Higher c-Met expression in metastases compared to paired primary tumors in our cohort of ccRCC suggests that testing for biomarkers of response to c-Met inhibitors should be conducted in metastases. Although the observation of higher c-Met expression in PD-L1+ tumors requires further investigation, it supports exploring these targets in combination trials. [Table: see text]

The characteristics of c-MET and HER2 expression in gastric carcinoma and its correlation with clinical-pathological parameters.

e15566 Background: The aim of this study was to determine whether overexpression of c-MET or HER2 had an effect on the clinical-pathological parameters and / or the prognosis of gastric carcinoma, as well as a direct correlation among those parameters. Methods: 134 gastric resectates were archived between 2007-2012 and retrospectively examined for c-MET and HER2 expression via immunohistochemistry (IHC). The HER2 status IHC2 + was additionally verified by means of Chromogenic in situ hybridization (CISH). Statistical data analysis was performed on the basis of the parameters acquired in the prospective multicentre observation study QCGC'07 / 09. Results: A total of 71 patients (53%) were found to express c-MET low and 63 patients (47%) expressed c-MET high, 122 patients (91%) were found to be HER2 negative and 12 persons (9%) were HER2 positive. C-MET high was significantly more pronounced in the Lauren intestinal type (63.8%, p = 0.001) and moderately to poorly differentiated tumour tissue (G2 50.9%, G3 43.9%, p = 0.038) as well es tissue with lymph vessel infiltration (L1 59.1%, p = 0.039). HER2 showed no significant effect on the clinical-pathological parameters. The median overall survival was shown to be shortened for the c-MET high-expressing (c-MET low 56 months, SD: ± 24.67; 95% CI: 7.65-104.36 vs. c-MET high 32 months, SD: ± (median-OS HER2 negative 38 months, SD: ± 14.11, 95% CI: 10.35-65, p = 0.839), and HER2 negative, 65, median-OS HER2 positive not reached, p = 0.305) patients. 8/134 resectates (5.97%, p = 0.135) were high and positive in both expression patterns, showing no significant difference to the OS (p = 0.393). Conclusions: In our studies, c-MET high or HER2 negative expression was associated with a poorer OS. However, no direct correlation between HER2 and c-MET could be demonstrated

Hepatocyte Growth Factor/c-Met Signaling in Head and Neck Cancer and Implications for Treatment

Aberrant signaling of the hepatocyte growth factor (HGF)/c-Met pathway has been identified as a promoter of tumorigenesis in several tumor types including head and neck squamous cell carcinoma (HNSCC). Despite a relatively low c-Met mutation frequency, overexpression of HGF and its receptor c-Met has been observed in more than 80% of HNSCC tumors, with preclinical and clinical studies linking overexpression with cellular proliferation, invasion, migration, and poor prognosis. c-Met is activated by HGF through a paracrine mechanism to promote cellular morphogenesis enabling cells to acquire mesenchymal phenotypes in part through the epithelial-mesenchymal transition, contributing to metastasis. The HGF/c-Met pathway may also act as a resistance mechanism against epidermal growth factor receptor (EGFR) inhibition in advanced HNSCC. Furthermore, with the identification of a biologically distinct subset of HNSCC tumors acquired from human papillomavirus (HPV) infection that generally portends a good prognosis, high expression of HGF or c-Met in HPV-negative tumors has been associated with worse prognosis. Dysregulated HGF/c-Met signaling results in an aggressive HNSCC phenotype which has led to clinical investigations for targeted inhibition of this pathway. In this review, HGF/c-Met signaling, pathway alterations, associations with clinical outcomes, and preclinical and clinical therapeutic strategies for targeting HGF/c-Met signaling in HNSCC are discussed.

The role of c-Met in prognosis and clinicopathology of renal cell carcinoma: Results from a single-centre study and systematic review

Background and objectivesThe c-Met proto-oncogene pathway plays an important role in the progression of various cancers. However, the effect of the c-Met pathway on renal cell carcinoma (RCC) remains controversial. We decided to clarify the role of c-Met in prognosis and clinicopathology of RCC. MethodsA total of 10 pairs of tumour and adjacent tissues were obtained from patients with primary RCC between 2013 and 2014 and tissue microarrays to assess c-Met expression in tumour tissues from 90 patients with RCC by Western blot and immunohistochemical staining. We also presented a meta-analysis to explore the correlation between c-Met and pathological grade and stage of RCC. The two-tailed Pearson’s χ2 and Fischer exact tests were used to compare categorical variables. Multivariate analysis was performed using the multivariate Cox proportional hazards model. ResultsC-Met protein levels were increased in 8 of 10 RCC tissue samples compared with their adjacent normal tissue and c-Met expression levels were positively associated with a high nuclear grade (P = 0.008) and pT stage (P = 0.002). Multivariate analysis showed that a high expression of c-Met was an independent predictor of disease-specific survival (P = 0.017). A meta-analysis found that increased c-Met expression in RCC tissues was closely correlated with high tumour grade (P<0.001) and high pT stage (P = 0.001). Most importantly, c-Met expression was significantly correlated with disease-specific survival (P<0.001). ConclusionsBecause c-Met is strongly associated with pathological grade, stage and disease-specific survival, c-Met levels may have potential to predict patient prognosis and to guide clinical diagnosis and treatment.

Biological predictors of radiosensitivity in head and neck squamous cell carcinoma.

The aim of this study is to investigate the influence of prognostic biomarkers on radiosensitivity and survival of advanced head and neck squamous cell carcinomas treated by primary (chemo)radiation. The clinicopathological data and immunohistochemical staining of p16, c-Met, survivin, PD-1, and PD-L1 of 82 primarily (chemo)irradiated patients with head and neck squamous cell carcinoma were analyzed. Associations with local and locoregional radiation response, overall survival (OS), disease-free (DFS), and disease-specific survival (DSS) were assessed. Complete tumor response was associated with increased patient age (p=0.007), N0-status (p=0.022), M0-status (p=0.007), and p16-positivity (p=0.022). High PD-L1 was associated with M0-status (p=0.026) and indicated tumor response to irradiation (p=0.057); survivin expression showed higher rates of response failure (p=0.073). Low PD-1 was associated with increased T-stage (p=0.029) and local recurrence (p=0.014). High PD-1 was strongly correlated with PD-L1-positive tumor infiltrating lymphocytes (p<0.001). Low PD-L1 showed a significant correlation with high c-Met expression (p=0.01). Significant predictors for unfavorable univariate survival were incomplete tumor response (DSS, p<0.001), single radiotherapy (DSS, p=0.002), M1-status (DSS, p<0.001), decreased radiation dose (DSS, p=0.014), high survivin (DSS, p=0.045), and high c-Met (OS, p<0.05). Survivin and c-Met also showed prognostic significance in multivariate survival analysis. P16 and PD-L1 indicate radiosensitivity, whereas survivin and c-Met implicate radioresistance in primarily (chemo)irradiated head and neck squamous cell carcinomas. The role of the PD-1/PD-L1 immune checkpoints in radiation response and survival merits further investigation. The findings may improve patient-specific therapy according to individual tumor characteristics.

Correlation of c-Met Expression and Outcome in Patients With Renal Cell Carcinoma Treated With Sunitinib.

Treatment of patients with metastatic renal cell carcinoma (mRCC) has improved substantially since the introduction of targeted therapies, but no predictive biomarkers are available. The proto-oncogene c-Met is involved in tumor angiogenesis, development, and metastasis. The main objective was to evaluate c-Met expression in sunitinib-treated patients with mRCC, including patients with bone metastases. c-Met expression was analyzed from 137 formalin-fixed paraffin-embedded tumor samples using a validated immunostaining protocol. Patients with low c-Met expression (n= 78) had longer progression-free survival (PFS) (median 14.3 vs. 6.5 months; P< .001) and overall survival (OS) (median 32.1 vs. 20.1 months; P= .049) than those with high expression. High c-Met expression was an independent predictor of unfavorable PFS in a Cox proportional hazards model adjusted for the Heng risk criteria (HR 1.60 [1.09-2.35]; P= .016). In a subgroup of patients with no bone metastases (n= 106), low c-Met expression was associated with a both longer OS (unadjusted HR 0.63 [95% CI, 0.42-0.95]; P=.034) and PFS (unadjusted HR 0.47 [95% CI, 0.31-0.71]; P< .001). High c-Met expression was associated with poor survival in patients with mRCC treated with sunitinib. Interestingly, the prognostic role may vary based on the location of metastases.

C-Met in chromophobe renal cell carcinoma.

c-Met plays a role as a prognostic marker in clear cell renal cell carcinoma. In addition, recently the tyrosine kinase inhibitor cabozantinib targeting c-Met was approved for the treatment of advanced renal cell carcinoma (RCC). In contrast to clear cell RCC, little is known about c-Met expression patterns in rarer RCC subtypes. The aim of this study was to evaluate the prevalence, distribution and prognostic impact of c-Met expression on chromophobe (ch)RCC. Patients who underwent renal surgery due to chRCC were retrospectively evaluated. Tumor specimens were analyzed for c-Met expression by immunohistochemistry. Expression data were associated with clinicopathological parameters including patient survival. Eighty-one chRCC patients were eligible for analysis. Twenty-four (29.6%) patients showed a high c-Met expression (c-Methigh, staining intensity higher than median). Our results showed an association between c-Methigh expression and the existence of lymph node metastasis (p=0.007). No further significant clinicopathological associations with c-Met were identified, also regarding c-Met expression and overall survival. In conclusion, to our knowledge this is the first study evaluating the prognostic impact of c-Met in a considerably large cohort of chRCC. High c-Met expression is associated with the occurrence of lymph node metastasis. This indicates that c-Met might be implicated into metastatic progression in chRCC.

EGFR family and cMet expression profiles and prognostic significance in esophagogastric adenocarcinoma.

Targeted therapy with anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody in patients with HER2 overexpressed esophagogastric adenocarcinoma (EGA) improves survival; however, the effect is transient due to the development of resistance. Some studies suggest that cMet overexpression provides cross talk for epidermal growth factor receptor (EGFR) and HER2 inhibition. We sought to characterize the expression profile of the EGFR family and cMet receptors in untreated, resected EGA. This retrospective analysis included all sequential patients with esophageal or gastroesophageal junction (GEJ) adenocarcinoma who underwent primary resection, without neoadjuvant therapy or HER2 inhibition, with adequate tissue, at the University of Florida from 2001 to 2011. Central blinded immunohistochemistry (IHC) was performed on tumor specimens with EGFR, HER2, HER3, HER4 and cMet expression scored as low (0, 1+) or high (2+, 3+). Demographic and tumor characteristics were compared using Fisher exact test. Kaplan-Meier curves and univariate analysis compared survival among different receptors. Total 52 patients were included in the study with median age 66 years. High expression of EGFR (73%), HER2 (40%), HER3 (75%), HER4 (35%) and cMet (69%) was detected among the study group. HER3 and HER4 co-expression was found in 18 (35%) cases. Pan expression of all four EGFR family members with cMet was noted in only 17% of cases. On univariate analysis, tumor stage and depth correlated with survival, while cMet + HER3 +/- EGFR receptor co-expression trended towards a worse survival. EGFR family and cMet are frequently co-expressed in treatment naïve resected EGA or GEJ tumors. Although our data do not significantly show receptor status as a prognostic factor, the co-expression profiles support for further investigation to improve targeting of this signal transduction axis.

In vivo targeting of c-Met using a non-standard macrocyclic peptide in gastric carcinoma

Development of c-Met targeting probes based on specifically designed peptides with high affinity and stability could help enhance diagnostic efficacy and therapeutic effects in c-Met positive cancers. The Random non-standard Peptides Integrated Discovery (RaPID) system for synthesizing natural product-like macrocyclic peptides via in vitro translation-based selection has recently emerged to overcome the shortcomings of traditional peptide synthesis. Here, we developed non-standard macrocyclic peptides specific to c-Met, and examined the cancer-targeting efficiency of fluorescein-labeled (FL) anti-c-Met peptides, referred to as aML5-FL and aMD4-FL, both in vitro and in vivo. The aML5-FL effectively targeted SNU-638 gastric cancer cells with high c-Met expression, compared to the aMD4-FL due to its high affinity. After intravenous administration of aML5-FL in a tumor xenograft mouse model, FL signal intensity in the extracted SNU-638 tumors was higher than that in SNU-216 tumors. This study provides preclinical data for the usefulness of novel non-standard macrocyclic peptides developed by the RaPID system for specific biomarker imaging.

C-Met as a potential novel prognostic marker in squamous cell carcinoma and adenocarcinoma of esophagus: evidence from a meta-analysis.

INTRODUCTIONː The prognostic value of c-Met in patients with esophageal cancer (EC) remains inconsistent and controversial. Our study aims to clarify the correlation between c-Met overexpression and clinical outcome in EC patients. EVIDENCE ACQUISITIONː We performed a comprehensive search of EMBASE, PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Chinese Biomedical Database (CBM) (from inception to May 1, 2016) for published literature regarding the potential association between c-Met overexpression and clinical outcome in EC patients. A fixed-effects or random-effects model according to heterogeneity was applied to calculate the pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for overall survival (OS), disease-free survival (DFS) and disease-specific survival (DSS). EVIDENCE SYNTHESISː Nine eligible studies totaling 1062 patients were identified in this meta-analysis. C-Met overexpression was significantly associated with shorter OS (HR: 2.04, 95% CI: 1.66-2.52, P<0.001) and DSS (HR: 3.03, 95% CI: 2.04-4.48, P<0.001) in patients with EC. However, no significant relationship between high expression of c-Met and DFS that was found (HR: 1.81, 95% CI: 0.77-4.26, P=0.176). For OS, similar associations were demonstrated in either esophageal squamous cell carcinoma (ESCC) (HR: 2.17, 95% CI: 1.62-2.90, P<0.001) or esophageal adenocarcinoma (EAC) (HR: 1.92, 95% CI: 1.42-2.59, P<0.001). Additionally, further subgroup analyses according to publication year, ethnicity, the sample size, and statistical methodology all revealed a significant association between high expression of c-Met and OS in patients with EC. CONCLUSIONSː The current evidence indicated that c-Met overexpression is significantly associated with a poorer prognosis in EC. C-Met may serve as a potential novel prognostic biomarker for EC patients.

Human papillomavirus oncoprotein E6 upregulates c-Met through p53 downregulation

PurposeHuman papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) carries a distinct clinical behaviour. c-Met oncogene is an important driver for tumour progression and its relationship with HPV in OPSCC was explored in the present study. Experimental designKnockdown of HPV oncogene E6 or p53 alone and in combination was performed to examine their effects on c-Met expression by Western blot and quantitative real-time polymerase chain reaction. The effects of c-Met inhibition on cell proliferation, migration, and colony formation were examined in HPV-positive head and neck squamous cell carcinoma (HNSCC) cells. Retrospectively collected OPSCC patient specimens (N = 78) were stained for c-Met by immunohistochemistry and the staining levels were correlated with HPV status and patient outcomes. ResultsE6 knockdown decreased c-Met protein and mRNA expression in HPV-positive HNSCC cells, which was partially abolished by the elimination of p53. Reducing c-Met decreased cell proliferation, migration, and colony formation in HPV-positive HNSCC cells. In OPSCC patient samples, high c-Met expression was associated with HPV-positive status (OR = 4.11, 95%CI: 1.16–14.55, P = 0.028) and tumour stage (OR = 0.27, 95%CI: 0.08–0.93, P = 0.039) by multivariable analysis. In T3/T4 stage patients, high c-Met expression was associated with HPV positivity and low p53 levels, supporting an axis of E6-p53-c-Met regulation. Furthermore, high c-Met expression was marginally associated with poor disease-free survival in HPV-positive patients. ConclusionsOur results suggest that c-Met may serve as a novel target for treating HPV-associated OPSCC. The data also demonstrate that HPV E6 upregulates c-Met expression partially through p53 downregulation.

Combined CD44, c-MET, and EGFR expression in p16-positive and p16-negative head and neck squamous cell carcinomas.

To examine the association between CD44 and c-MET expression in relation to p16 and EGFR in patients with head and neck squamous cell carcinoma (HNSCC). Immunohistochemical staining of CD44, p16, EGFR, and c-MET was performed on 105 locally advanced HNSCC patients treated with chemoradiation. CD44 expression was correlated with c-MET, EGFR, and p16, locoregional control (LRC), distant metastases (DM), disease-free survival (DFS) and overall survival (OS). High CD44 expression was present in 33% of patients and was associated with non-oropharynx primaries (P < 0.001), high c-MET expression (P < 0.001), p16-negative (P < 0.001) and EGFR-positive tumors (P < 0.001). Fifty-seven percent of CD44 high expressing tumors had high c-MET expression compared to 21% of CD44 low expressing tumors (P < 0.001). High CD44 expression predicted for worse LRC (HR: 2.44; 95% CI: 1.16-5.13; P = 0.018), DFS (HR: 2.61; 95% CI: 1.46-4.67; P = 0.001), and OS (HR: 2.52; 95% CI: 1.30-4.92; P = 0.007) but not DM (P = 0.57) on univariate analysis. Patients with both high CD44 and c-MET expression had a poor prognosis with a 2-year DFS of 30% compared to 70% in the rest of the cohort (P = 0.003). On multivariable analysis, after adjusting for site, T-stage, smoking history, and EGFR status, high c-MET (P = 0.039) and negative p16 status (P = 0.034) predicted for worse DFS, while high CD44 expression did not (P = 0.43). High CD44 expression is associated with high c-MET expression, p16-negative tumors, and EGFR-positive tumors. The combination of these markers predicts for poor prognosis in HNSCC patients treated with chemoradiation.

Abstract 2242: cMET in non-small cell lung cancer: pieces of the puzzle

Abstract A rapidly growing domain in present-day oncology is the development of targeted therapies, including several cMET inhibitors against non-small cell lung cancer (NSCLC). Nowadays, cMET amplification is used as a standard biomarker for patient selection, however there is no clear cut-off value to determine amplification, nor is there a real consensus about the way to test this. More recently, splicing variants of cMET, which skip exon 14, are gaining importance since it has been shown that patients harboring this mutation can respond to cMET directed targeted therapy. In this study, we explored the occurrence of cMET aberrations and their correlation with cMET expression in a population of 155 primary EGFR-TKI naive NSCLC tumors. Since cMET is considered as important in metastatic behavior, we also investigated the correlation of cMET expression and amplification between the primary tumor and metastases. Finally, given the link between the EGFR and cMET pathways, the EGFR status was also studied. Samples were collected at the Antwerp University Hospital and the Onze-Lieve-Vrouw Hospital Aalst. The expression of EGFR and cMET was determined by immunohistochemistry (Ventana, clones 3C6 and SP66 respectively), while cMET amplification was examined by in situ hybridization (Ventana, MET DNP and CEN7 DIG probes). EGFR mutations and cMET splice site mutations were detected by Sanger sequencing. Significant correlations were tested using the Chi2 and kappa test (SPSS 23). In 146/155 tumors cMET expression could be determined; 73/146 samples showed high (2+ or 3+ score) cMET expression and 4/118 samples showed amplification (ratio ≥ 2). No significant correlations could be determined between cMET expression and histological subtype of NSCLC (p = 0.065), differentiation degree (p = 0.468) and cMET amplification (p = 0.214). However, a significant correlation was found between cMET expression, EGFR expression (p = 0.015) and EGFR mutations (p = 0.029). Splice site mutation regions were sequenced in 87/155 samples, all of which were wild-type. When comparing cMET amplification between the primary tumor and the corresponding metastases (n = 40), only one sample showed amplification in the metastases and not in the primary tumor. Hence, cMET expression showed a significant correlation between primary tumors and their metastases (kappa = 0.003). The overall results of our study are in agreement with earlier data. Moreover, we showed that overall expression levels of cMET in primary tumors and metastases are very similar despite large intratumor heterogeneity. In conclusion, this study shows that high cMET expression in most NSCLC samples does not originate from presently known genetic cMET aberrations. High cMET expression is likely to be caused by temporary changes in transcription and translation, influenced by EGFR-signaling, miRNAs or other regulatory mechanisms. Citation Format: Nele Van Der Steen, Vanessa Deschoolmeester, Filip Lardon, Christian Rolfo, Elisa Giovannetti, Godefridus J. Peters, Patrick Pauwels. cMET in non-small cell lung cancer: pieces of the puzzle. [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 2242.

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.

High c-MET expression defines a subset of pancreatic adenocarcinoma patients with poor prognosis following surgical resection: Exploration of mechanisms driving c-MET overexpression, transcriptomic analyses, and in vitro effects of c-MET inhibitors

High c-MET expression defines a subset of pancreatic adenocarcinoma patients with poor prognosis following surgical resection: Exploration of mechanisms driving c-MET overexpression, transcriptomic analyses, and in vitro effects of c-MET inhibitors