c-Met inhibitors

Orthogonal MET analysis in a population-representative stage II-III colon cancer cohort: prognostic and potential therapeutic implications

Clinical trials for MET inhibitors have demonstrated limited success for their use in colon cancer (CC). However, clinical efficacy may be obscured by a lack of standardisation in MET assessment for patient stratification. In this study, we aimed to determine the molecular context in which MET is deregulated in CC using a series of genomic and proteomic tests to define MET expression and identify patient subgroups that should be considered in future studies with MET-targeted agents. To this aim, orthogonal expression analysis of MET was conducted in a population-representative cohort of stage II/III CC patients (n = 240) diagnosed in Northern Ireland from 2004 to 2008. Targeted sequencing was used to determine the relative incidence of MET R970C and MET T992I mutations within the cohort. MET amplification was assessed using dual-colour dual-hapten brightfield in situ hybridisation (DDISH). Expression of transcribed MET and c-MET protein within the cohort was assessed using digital image analysis on MET RNA in situ hybridisation (ISH) and c-MET immunohistochemistry (IHC) stained slides. We found that less than 2% of the stage II/III CC patient population assessed demonstrated a genetic MET aberration. Determination of a high MET RNA-ISH/low c-MET IHC protein subgroup was found to be associated with poor 5-year cancer-specific outcomes compared to patients with concordant MET RNA-ISH and c-MET IHC protein expression (HR 2.12 [95%CI: 1.27-3.68]). The MET RNA-ISH/c-MET IHC protein biomarker paradigm identified in this study demonstrates that subtyping of MET expression may be required to identify MET-addicted malignancies in CC patients who will truly benefit from MET inhibition.

Angiogenesis in the progression from liver fibrosis to cirrhosis and hepatocelluar carcinoma

Introduction: Persistent inflammation and hypoxia are strong stimulus for pathological angiogenesis and vascular remodeling, and are also the most important elements resulting in liver fibrosis. Sustained inflammatory process stimulates fibrosis to the end-point of cirrhosis and sinusoidal portal hypertension is an important feature of cirrhosis. Neovascularization plays a pivotal role in collateral circulation formation of portal vein, mesenteric congestion, and high perfusion. Imbalance of hepatic artery and portal vein blood flow leads to the increase of hepatic artery inflow, which is beneficial to the formation of nodules. Angiogenesis contributes to progression from liver fibrosis to cirrhosis and hepatocellular carcinoma (HCC) and anti-angiogenesis therapy can improve liver fibrosis, reduce portal pressure, and prolong overall survival of patients with HCC. Areas covers: This paper will try to address the difference of the morphological characteristics and mechanisms of neovascularization in the process from liver fibrosis to cirrhosis and HCC and further compare the different efficacy of anti-angiogenesis therapy in these three stages. Expert opinion: More in-depth understanding of the role of angiogenesis factors and the relationship between angiogenesis and other aspects of the pathogenesis and transformation may be the key to enabling future progress in the treatment of patients with liver fibrosis, cirrhosis, and HCC.

Retracted Article: RNA-sequencing identified miR-3681 as a negative regulator in the proliferation and migration of cervical cancer cells via the posttranscriptional suppression of HGFR

In this study, RNA-sequencing was used to investigate the differentially expressed miRNAs between cervical cancer tissues and matched adjacent non-tumor tissues. Five miRNAs were sharply downregulated in the cancer tissue, including miR-199a, miR-22, miR-615, miR-3681-3p (miR-3681), and miR-1193. Among them, miR-3681 was uncharacterized. The results from qPCR analysis showed that miR-3681 expression was decreased in patients with cervical cancer compared with the control, and decreased in the human cervical cancer cell lines SiHa, HeLa, C4-1, C-33A and Caski, compared with the normal human cervical epithelial cell line HCerEpic. Then, different concentrations of miR-3681 mimic and miR-3681 inhibitor were respectively transfected into the human cervical cancer cell line C-33A, and the expression of miR-3681, cell proliferation, cell apoptosis and cell migration were measured after 48 h. The results showed that the miR-3681 mimic increased the miR-3681 level, suppressed cell proliferation and migration, and induced cell apoptosis in a dose-dependent manner. In contrast, the miR-3681 inhibitor decreased the miR-3681 level, promoted cell proliferation and migration, and inhibited cell apoptosis in a dose-dependent manner. Moreover, bioinformatics analysis showed that there was a miR-3681 binding site in the mRNA 3'UTR of HGFR, which was robustly upregulated in cervical cancer cell lines compared with HCerEpic cells. In addition, luciferase activity analysis demonstrated that miR-3681 could directly target HGFR, which promoted the proliferation and migration of C-33A cells via activation of the PI3K/Akt pathway in a dose-dependent manner. Furthermore, our results showed that knockdown of HGFR could antagonize the promotion of anti-miR-3681 on the activation of the PI3K/Akt pathway and cell proliferation and migration. In conclusion, MiR-3681 was identified as a negative regulator in the proliferation and migration of cervical cancer cells. This function is associated with the posttranscriptional suppression of HGFR and the deactivation of the PI3K/Akt pathway.

Discovery of an Indirubin Derivative as a Novel c-Met Kinase Inhibitor with In Vitro Anti-Tumor Effects

The c-Met protein is a receptor tyrosine kinase involved in cell growth, proliferation, survival, and angiogenesis of several human tumors. Overexpression of c-Met has been found in gastric cancers and correlated with a poor prognosis. Indirubin is the active component of Danggui Longhui Wan, which is a traditional Chinese antileukemic recipe. In the present study, we tested the anti-cancer effects of an indirubin derivative, LDD-1937, on human gastric cancer cells SNU-638. When we performed the in vitro kinase assay against the c-Met activity, LDD-1937 inhibited the activity of c-Met. This result was confirmed by immunoblot and immunofluorescence of phosphorylated c-Met. Immunoblot analysis showed that LDD-1937 decreased the expression of the Erk1/2, STAT3, STAT5, and Akt, downstream proteins of c-Met. In addition, LDD-1937 reduced the cell viability and suppressed colony formation and migration of SNU-638 cells. Furthermore, LDD-1937 induced G₂/M phase arrest in the SNU-638 cells by decreasing the expression levels of cyclin B1 and CDC2. Cleaved-PARP, an apoptosis-related protein, was up-regulated in cells treated with LDD-1937. Overall, this study suggests that LDD-1937 may be a novel small-molecule with therapeutic potential for selectively inhibiting c-Met and c-Met downstream pathways in human gastric cancers overexpressing c-Met.

Safety and Tolerability of c-MET Inhibitors in Cancer

The role of aberrant hepatocyte growth factor receptor (c-MET, also known as tyrosine-protein kinase MET)/hepatocyte growth factor (HGF) signaling in cancer progression and invasion has been extensively studied. c-MET inhibitors have shown promising pre-clinical and early phase clinical trial anti-tumor activity in several tumor types, although results of most phase III trials with these agents have been negative. To date, two small molecule c-MET inhibitors, cabozantinib and crizotinib, have been approved by regulatory authorities for the treatment of selected cancer types, but several novel c-MET inhibitors (either monoclonal antibodies or small molecule c-MET tyrosine kinase inhibitors) and treatment combinations are currently under study in different settings. Here we provide an overview of the mechanism of action and rationale of c-MET inhibition in cancer, the efficacy of approved agents, and novel promising c-MET-inhibitors and novel targeted combination strategies under development in different cancer types, with a focus on the safety profile and tolerability of these compounds.

Design, synthesis and molecular modeling studies of new series of antitumor 1,2,4-triazines with potential c-Met kinase inhibitory activity

The receptor tyrosine kinase c-Met is an attractive target for therapeutic treatment of cancers nowadays. Herein we describe the design and synthesis of a novel series of 1,2,4-triazine derivatives based on our lead NCI 748494/1, possessing different N-linkers to aromatic and heterocyclic rings. In addition, a molecular hybrid series combining the 1,2,4-triazine scaffold to the well-known anticancer drug 6-mercaptopurine (6-MP) was synthesized in order to explore its "double-drug" antitumor effect. The synthesized compounds were evaluated for their in vitro antitumor activity against three c-Met addicted cancer cell lines (A549, HT-29 and MKN-45). Most compounds showed moderate to excellent antitumor activity. Compound 3d showed potent inhibitory activity more than reference Foretinib, BMS-777607 and NCI 748494/1 with IC₅₀ values in the range 0.01-0.31 µM against the cancer cell lines. The calculated IC₅₀ of 3d against c-Met kinase was found to be 2.71 µM, which is more potent than NCI 748494/1 (IC₅₀ = 31.70 µM). Docking studies were performed to identify the binding mode of 3d with c-Met kinase domain in comparison to moderate and weak derivatives. The present study clearly demonstrates that 1,2,4-triazine ring exhibits promising antitumor activity and the double-drug optimization strategy led to identifying 3d as a potent c-Met kinase inhibitor suitable for further development.

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

Colorectal 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.

DCLK1 is correlated with MET and ERK5 expression, and associated with prognosis in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer for which more effective treatments are needed. In this study, strong to moderate staining of MET and ERK5 was detected in 67.1 and 48% of the analyzed 73 human mesothelioma tumors, and significant correlation of MET and ERK5 expression was identified (P<0.05). We evaluated the doublecortin-like kinase 1 (DCLK1) expression in human mesothelioma tumors. Our results showed that 50.7% of the immunohistochemistry analyzed human mesothelioma tumors have strong to moderate staining of DCLK1, and its expression is significantly correlated with MET or ERK5 expression (P<0.05). Also, the upregulation of DCLK1 is correlated with poor prognosis in MPM patients (P=0.0235). To investigate whether DCLK1 is downstream of MET/ERK5 signaling in human mesothelioma, the effect of DCLK1 expression was analyzed after treatments with either the MET inhibitor XL184 or the ERK5 inhibitor XMD8-92 in human mesothelioma cell lines. Our results showed that the MET inhibitor XL184 reduced the expression of phospho‑ERK5 and DCLK1 expression in human mesothelioma cell lines. In addition, the ERK5 inhibitor XMD8-92 reduced the expression of phospho-ERK5 and DCLK1 expression in human mesothelioma cell lines. Furthermore, XML184 and XMD8-92 treatment impaired invasion and tumor sphere formation ability of H290 mesothelioma cells. These results suggest that DCLK1 is regulated by MET/ERK5 signaling in human mesothelioma, and the MET/ERK5/DCLK1 signaling cascade could be further developed into a promising therapeutic target against mesothelioma.

C-MET overexpression and amplification in gliomas

We investigated c-Met overexpression and MET gene amplification in gliomas to determine their incidence and prognostic significance. c-Met immunohistochemistry and MET gene fluorescence in situ hybridization were carried out on tissue microarrays from 250 patients with gliomas (137 grade IV GBMs and 113 grade II and III diffuse gliomas). Clinicopathological features of these cases were reviewed. c-Met overexpression and MET gene amplification were detected in 13.1% and 5.1% of the GBMs, respectively. All the MET-amplified cases showed c-Met overexpression, but MET amplification was not always concordant with c-Met overexpression. None of grade II and III gliomas demonstrated c-Met overexpression or MET gene amplification. Mean survival of the GBM patients with MET amplification was not significantly different from patients without MET amplification (P=0.155). However, GBM patients with c-Met overexpression survived longer than patients without c-Met overexpression (P=0.035). Although MET amplification was not related to poor GBM prognosis, it is partially associated with the aggressiveness of gliomas, as MET amplification was found only in grade IV, not in grade II and III gliomas. We suggest that MET inhibitor therapy may be beneficial in about 5% GBMs, which was the incidence of MET gene amplification found in the patients included in this study.

SU11274 suppresses proliferation and motility of pancreatic cancer cells

Mesenchymal-epithelial transition factor (c-Met) is associated with the proliferation and motility of cancer cells. c-Met expression has been detected in surgical pancreatic cancer specimens, and its overexpression is associated with a poor prognosis. SU11274 is a specific inhibitor of c-Met. In the present study, the cell proliferation and motility of pancreatic cancer cells treated with SU11274 was investigated. The PANC-1, MIA-Paca2, NOR-P1, PK-45H, PK-1 and PK-59 pancreatic cancer cell lines were used. The expression of c-Met and cyclin D1 was analyzed by quantitative polymerase chain reaction. In addition, a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt assay was performed to assess cell proliferation, and a scratch assay was performed to assess cell motility. c-Met expression was higher in PANC-1, PK-45H, PK-1 and PK-59 cell lines compared with that in normal pancreatic tissue. Following treatment with 30 µM SU11274, the proliferation of MIA-Paca2 and PK-45H cells was suppressed to 19.8±10.7% (P<0.05) and 45.8±14.8% (P<0.05) of the control level, respectively. Furthermore, cyclin D1 expression was downregulated to 43.7±17.9% (P<0.05) and 53.2±18.6% (P<0.05) of the control level in the MIA-Paca2 and PK-45H cell lines, respectively, following treatment with 30 µM SU11274. In addition, cell motility was reduced to 1.0±0.3% in MIA-Paca2 (P<0.05) and 14.7±3.5% in PK-45H (P<0.05) following treatment with 30 µM SU11274, compared with the motility of untreated cells. These results indicated that SU11274 suppresses the proliferation of pancreatic cancer cells via the downregulation of cyclin D1. The present study also demonstrated that cell motility was suppressed by treatment with SU11274.

Phase 1 trial of tivantinib in combination with sorafenib in adult patients with advanced solid tumors

PURPOSE

This phase I study evaluated the safety, tolerability, maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of tivantinib combined with sorafenib in patients with advanced solid tumors.

MATERIALS AND METHODS

A standard 3 + 3 dose escalation design was used. At the RP2D, expansion cohorts in 5 tumor types could be enrolled. Pharmacogenetic and pharmacodynamic analysis were performed.

RESULTS

Eighty-seven patients received the study treatment. The combination had no unexpected toxicities. The most common treatment-related adverse events (AE) were rash (40 %), diarrhea (38 %), and anorexia (33 %). The RP2D was tivantinib 360 mg BID and sorafenib 400 mg BID for all cancer histologies, except in hepatocellular carcinoma (HCC) patients tivantinib was 240 mg BID plus sorafenib 400 mg BID. The overall response rate was 12 % in all patients, 26 % in melanoma, 15 % in renal cell carcinoma (RCC), 10 % in HCC, and 0 % in other patients. Disease control rate (CR, PR and SD ≥8 weeks) was 58 % in all patients, 90 % in RCC, 65 % in HCC, 63 % in melanoma, 40 % in breast cancer, and 8 % in NSCLC patients.

CONCLUSIONS

The combination treatment could be administered at full standard single-agent doses in all patients except those with HCC, where tivantinib was lowered to 240 mg BID. Preliminary evidence of anticancer activity was observed in patients with RCC, HCC, and melanoma, including patients refractory to sorafenib and/or other anti-VEGF pathway therapies. The combination treatment has therapeutic potential in treating a variety of solid tumors.

Co-culture of hepatocellular carcinoma cells and human umbilical endothelial cells damaged by SU11274

Mesenchymal-epithelial transition factor (c-Met) is a receptor that binds to the hepatocyte growth factor and is upregulated in hepatocellular carcinoma (HCC). The anti-tumor effects of (3Z)-N-(3-chlorophenyl)-3-({3,5-dimethyl-4-[(4- methyl-piperazin-1-yl)carbonyl]-1H-pyrrol-2-yl}methylene)-N-me- thyl-2-oxo-2,3-dihydro-1H-indole-5-sulfonamide (SU11274), a c-Met inhibitor, were investigated in the present study. HCC cells (HLE, HLF, PLC/PRL/5, Hep3B, Huh-6 and HepG2) and human umbilical vein endothelial cells (HUVECs) were used. Quantitative polymerase chain reaction was performed to detect the expression level of c-Met in HCC and HUVECs, and cyclin D1 in HCC. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-car-boxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt assay was performed to assess the proliferation of the HCC cells and HUVECs cultured with SU11274. Co-culture of HLF or PLC/PRL/5 cells and HUVECs was established as an in vitro model of HCC tissues. The expression levels of c-Met in HLE, HLF, PLC/PRL/5, Hep3B, Huh-6 and HepG2, adult healthy liver and HUVECs were 4.43±0.50, 1.61±0.18, 3.70±0.08, 0.81±0.18, 6.60±1.29, 1.06±0.35, 1.00±0.09 and 88.8±17.3 (mean ± standard deviation), respectively. SU11274 (30 μM) suppressed the proliferation of HLF, PLC/PRL/5 and HUVECs to 11.0±9.4, 46.5±30.7 and 29.4±5.0%, respectively. SU11274 (30 μM) decreased the expression levels of cyclin D1 in HLF and PLC/PRL/5 cells to 45.1±11.6 and 30.1±10.3%, respectively. SU11274, at a concentration of 30 μM damaged the morphology of the co-cultures of HLF or PLC/PRL/5 cells with HUVECs and all the cells died. c-Met is highly expressed in HUVECs and HCC cells, but not in Hep3B. At a 30-μM concentration, SU11274 suppresses the proliferation of HLF, PLC/PRL/5 and HUVECs. SU11274 (30 μM) damages the co-cultures of HLF or PLC/PRL/5 cells with HUVECs.

The role of Wnt signaling pathway in carcinogenesis and implications for anticancer therapeutics

The Wnt proteins are a family of 19 secreted glycoproteins that occupy crucial roles in the regulation of processes such as cell survival, proliferation, migration and polarity, cell fate specification, body axis patterning and self-renewal in stem cells. The canonical pathway has been implicated in a variety of cancers. As such, it is only fair to conclude that therapies targeting the Wnt pathway may play an essential role in the future of anticancer therapeutics, both alone or in conjunction with traditional therapies.