Biophysical and structural characterization of the impacts of MET phosphorylation on tepotinib binding

The receptor tyrosine kinase MET is activated by hepatocyte growth factor binding, followed by phosphorylation of the intracellular kinase domain (KD) mainly within the activation loop (A-loop) on Y1234 and Y1235. Dysregulation of MET can lead to both tumor growth and metastatic progression of cancer cells. Tepotinib is a highly selective, potent type Ib MET inhibitor and approved for treatment of non-small cell lung cancer harboring METex14 skipping alterations. Tepotinib binds to the ATP site of unphosphorylated MET with critical π-stacking contacts to Y1230 of the A-loop, resulting in a high residence time. In our study, we combined protein crystallography, biophysical methods (surface plasmon resonance, differential scanning fluorimetry), and mass spectrometry to clarify the impacts of A-loop conformation on tepotinib binding using different recombinant MET KD protein variants. We solved the first crystal structures of MET mutants Y1235D, Y1234E/1235E, and F1200I in complex with tepotinib. Our biophysical and structural data indicated a linkage between reduced residence times for tepotinib and modulation of A-loop conformation either by mutation (Y1235D), by affecting the overall Y1234/Y1235 phosphorylation status (L1195V and F1200I) or by disturbing critical π-stacking interactions with tepotinib (Y1230C). We corroborated these data with target engagement studies by fluorescence cross-correlation spectroscopy using KD constructs in cell lysates or full-length receptors from solubilized cellular membranes as WT or activated mutants (Y1235D and Y1234E/1235E). Collectively, our results provide further insight into the MET A-loop structural determinants that affect the binding of the selective inhibitor tepotinib.

The Preclinical Pharmacology of Tepotinib-A Highly Selective MET Inhibitor with Activity in Tumors Harboring MET Alterations

The mesenchymal-epithelial transition factor (MET) proto-oncogene encodes the MET receptor tyrosine kinase. MET aberrations drive tumorigenesis in several cancer types through a variety of molecular mechanisms, including MET mutations, gene amplification, rearrangement, and overexpression. Therefore, MET is a therapeutic target and the selective type Ib MET inhibitor, tepotinib, was designed to potently inhibit MET kinase activity. In vitro, tepotinib inhibits MET in a concentration-dependent manner irrespective of the mode of MET activation, and in vivo, tepotinib exhibits marked, dose-dependent antitumor activity in MET-dependent tumor models of various cancer indications. Tepotinib penetrates the blood-brain barrier and demonstrates strong antitumor activity in subcutaneous and orthotopic brain metastasis models, in-line with clinical activity observed in patients. MET amplification is an established mechanism of resistance to EGFR tyrosine kinase inhibitors (TKI), and preclinical studies show that tepotinib in combination with EGFR TKIs can overcome this resistance. Tepotinib is currently approved for the treatment of adult patients with advanced or metastatic non-small cell lung cancer harboring MET exon 14 skipping alterations. This review focuses on the pharmacology of tepotinib in preclinical cancer models harboring MET alterations and demonstrates that strong adherence to the principles of the Pharmacological Audit Trail may result in a successful discovery and development of a precision medicine.

The natural product berberine synergizes with osimertinib preferentially against MET-amplified osimertinib-resistant lung cancer via direct MET inhibition

Berberine is a natural product that has long been used in traditional Chinese medicine due to its antimicrobial, anti-inflammatory and metabolism-regulatory properties. Osimertinib is the first third-generation EGFR-tyrosine kinase inhibitor (TKI) approved for the treatment of non-small cell lung cancer (NSCLC) with activating EGFR mutations and those resistant to earlier generation EGFR-TKIs due to a T790M mutation. However, emergence of acquired resistance to osimertinib limits its long-term efficacy in the clinic. One known mechanism of acquired resistance to osimertinib and other EGFR-TKIs is MET (c-MET) gene amplification. Here, we report that berberine, when combined with osimertinib, synergistically and selectively decreased the survival of several MET-amplified osimertinib-resistant EGFR mutant NSCLC cell lines with enhanced induction of apoptosis likely through Bim elevation and Mcl-1 reduction. Importantly, this combination effectively enhanced suppressive effect on the growth of MET-amplified osimertinib-resistant xenografts in nude mice and was well tolerated. Molecular modeling showed that berberine was able to bind to the kinase domain of non-phosphorylated MET, occupy the front of the binding pocket, and interact with the activation loop, in a similar way as other known MET inhibitors do. MET kinase assay showed clear concentration-dependent inhibitory effects of berberine against MET activity, confirming its kinase inhibitory activity. These findings collectively suggest that berberine can act as a naturally-existing MET inhibitor to synergize with osimertinib in overcoming osimertinib acquired resistance caused by MET amplification.

Dictamnine, a novel c-Met inhibitor, suppresses the proliferation of lung cancer cells by downregulating the PI3K/AKT/mTOR and MAPK signaling pathways

Dictamnine (Dic), a naturally occurring small-molecule furoquinoline alkaloid isolated from the root bark of Dictamnus dasycarpus Turcz., is reported to display anticancer properties. However, little is known about the direct target proteins and anticancer mechanisms of Dic. In the current study, Dic was found to suppress the growth of lung cancer cells in vitro and in vivo, and to attenuate the activation of PI3K/AKT/mTOR and mitogen-activated protein kinase (MAPK) signaling pathways by inhibiting the phosphorylation and activation of receptor tyrosine kinase c-Met. Moreover, the binding of Dic to c-Met was confirmed by using cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) assay. Among all cancer cell lines tested, Dic inhibited the proliferation of c-Met-dependent EBC-1 cells with the greatest potency (IC50 = 2.811 μM). Notably, Dic was shown to synergistically improve the chemo-sensitivity of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant lung cancer cells to gefitinib and osimertinib. These results suggest that Dic is a c-Met inhibitor that can serve as a potential therapeutic agent in the treatment of lung cancer, especially against EGFR TKI-resistant and c-Met-dependent lung cancer.

CABOCOL-01 trial: a single-arm phase II study assessing safety and efficacy of Cabozantinib for advanced or metastatic cervical carcinoma after platinum treatment failure

BACKGROUND

Cervical cancer is the tenth diagnosed cancer in the world. Early-stage and locally recurrent disease may be cured with radical surgery or chemo-radiotherapy. However, if disease persists or recurs, options are limited and the prognosis is poor. In addition to chemotherapy, bevacizumab, an antiangiogenic agent, has recently demonstrated its efficacy in this setting. Cabozantinib is an oral small molecule tyrosine kinase inhibitor that exhibits potent inhibitory activity against several receptor tyrosine kinases that are known to influence tumor growth, metastasis, and angiogenesis. The main targets of Cabozantinib are VEGFR2, MET and AXL. It is currently approved for the treatment of metastatic renal cell carcinoma, hepatocellular carcinoma and medullary thyroid carcinoma. Given its angiogenic properties associated with growth factor receptors inhibition, Cabozantinib represents a potential active treatment in cervical carcinoma. In this context, we propose to assess the efficacy and safety of cabozantinib monotherapy in advanced/metastatic cervical carcinoma (CC) after failure to platinum-based regimen treatment.

METHODS

This study is a single-arm two-stage multicenter phase II aiming to simultaneously assess efficacy and safety of Cabozantinib among advanced/metastatic cervical carcinoma (CC) after failure to platinum-based regimen treatment. The main criterion will be based on both safety and clinical efficacy by conducting a Bryant-and-Day design. Safety endpoint is the proportion of patients with clinical gastro-intestinal (GI) perforation/fistula, GI-vaginal fistula and genito-urinary (GU) fistula events grade ≥ 2 (NCI CTCAE V.5.0) occurring up to one month after the end of treatment. Efficacy endpoint is the proportion of patients with disease control rate 3 months after Cabozantinib initiation. A patients' self-reported quality of life evaluation is also planned, as well as the investigation of nutritional outcomes. Cabozantinib will be administered at the daily dose of 60 mg given orally, without interruption until disease progression or discontinuation for any cause.

DISCUSSION

Cabozantinib is a promising drug for patients with advanced/metastatic cervical cancer where few therapeutics options are available after failure to platinum-based regimen metastatic CC. It appears challenging to assess the interest of Cabozantinib in this indication, taking into account the potential toxicity of the drug.

TRIAL REGISTRATION

NCT04205799 , registered "2019 12 19".

PROTOCOL VERSION

Version 3.1 dated from 2020 08 31.

Computational study on novel natural inhibitors targeting c-MET

This study was designed to select ideal lead compounds and preclinical drug candidates http://dict.youdao.com/w/eng/preclinical_drug_candidate/javascript:void (0); with inhibitory effect on c-MET from the drug library (ZINC database).A battery of computer-aided virtual techniques was used to identify possible inhibitors of c-MET. A total of 17,931 ligands were screened from the ZINC15 database. LibDock is applied for structure-based screening followed by absorption, distribution, metabolic, and excretion, and toxicity prediction. Molecular docking was conducted to confirm the binding affinity mechanism between the ligand and c-MET. Molecular dynamics simulations were used to assess the stability of ligand-c-MET complexes.Two new natural compounds ZINC000005879645 and ZINC000002528509 were found to bind to c-MET in the ZINC database, showing higher binding affinity. In addition, they were predicted to have lower rodent carcinogenicity, Ames mutagenicity, developmental toxicity potential, and high tolerance to cytochrome P4502D6. Molecular dynamics simulation shows that ZINC000005879645 and ZINC000002528509 have more favorable potential energies with c-MET, which could exist stably in the natural environment.This study suggests that ZINC000005879645 and ZINC000002528509 are ideal latent inhibitors of c-MET targeting. As drug candidates, these 2 compounds have low cytotoxicity and hepatotoxicity as well as important implications for the design and improvement of c-MET target drugs.

Novel Pyridine Bioisostere of Cabozantinib as a Potent c-Met Kinase Inhibitor: Synthesis and Anti-Tumor Activity against Hepatocellular Carcinoma

Two novel bioisosteres of cabozantinib, 3 and 4, were designed and synthesized. The benzene ring in the center of the cabozantinib structure was replaced by trimethylpyridine (3) and pyridine (4), respectively. Surprisingly, the two compounds showed extremely contrasting mesenchymal-epithelial transition factor (c-Met) inhibitory activities at 1 μM concentration (4% inhibition of 3 vs. 94% inhibition of 4). The IC₅₀ value of compound 4 was 4.9 nM, similar to that of cabozantinib (5.4 nM). A ligand-based docking study suggested that 4 includes the preferred conformation for the binding to c-Met in the conformational ensemble, but 3 does not. The anti-proliferative activity of compound 4 against hepatocellular carcinoma (Hep3B and Huh7) and non-small-cell lung cancer (A549 and H1299) cell lines was better than that of cabozantinib, whereas 3 did not show a significant anti-proliferative activity. Moreover, the tumor selectivity of compound 4 toward hepatocellular carcinoma cell lines was higher than that of cabozantinib. In the xenograft chick tumor model, compound 4 inhibited Hep3B tumor growth to a much greater extent than cabozantinib. The present study suggests that compound 4 may be a good therapeutic candidate against hepatocellular carcinoma.

Combinational blockade of MET and PD-L1 improves pancreatic cancer immunotherapeutic efficacy

BACKGROUND

Dysregulated expression and activation of receptor tyrosine kinases (RTKs) are associated with a range of human cancers. However, current RTK-targeting strategies exert little effect on pancreatic cancer, a highly malignant tumor with complex immune microenvironment. Given that immunotherapy for pancreatic cancer still remains challenging, this study aimed to elucidate the prognostic role of RTKs in pancreatic tumors with different immunological backgrounds and investigate their targeting potential in pancreatic cancer immunotherapy.

METHODS

Kaplan-Meier plotter was used to analyze the prognostic significance of each of the all-known RTKs to date in immune "hot" and "cold" pancreatic cancers. Gene Expression Profiling Interactive Analysis-2 was applied to assess the differential expression of RTKs between pancreatic tumors and normal pancreatic tissues, as well as its correlation with immune checkpoints (ICPs). One hundred and fifty in-house clinical tissue specimens of pancreatic cancer were collected for expression and correlation validation via immunohistochemical analysis. Two pancreatic cancer cell lines were used to demonstrate the regulatory effects of RTKs on ICPs by biochemistry and flow cytometry. Two in vivo models bearing pancreatic tumors were jointly applied to investigate the combinational regimen of RTK inhibition and immune checkpoint blockade for pancreatic cancer immunotherapy.

RESULTS

MET was identified as a pancreatic cancer-specific RTK, which is significantly associated with prognosis in both immune "hot" and "cold" pancreatic cancers. MET was observed to be highly upregulated in pancreatic cancer tissues, and positively correlated with PD-L1 levels. Elevated MET and PD-L1 expressions were closely associated with lymph node metastasis, tumor TNM stage, and overall survival in pancreatic cancer. Mechanistically, MET could interact with PD-L1, and maintain its expression level in multiple ways. MET deficiency was found to facilitate lymphocyte infiltration into pancreatic tumors. Finally, significant benefits of combining MET inhibition with PD-1/PD-L1 blockage were verified in both orthotopic and subcutaneous mouse models of pancreatic cancer.

CONCLUSIONS

This study systematically investigated the potential effectiveness of a novel pancreatic cancer immunotherapy targeting RTKs, and revealed the function of MET in PD-L1 regulation as well as the combined therapeutic efficacy of MET and PD-L1 in pancreatic cancer.

Inhibition of c-MET reverses radiation-induced malignant potential in pancreatic cancer

As a treatment option for PDAC, radiation therapy induces good local control. However, radiation also reportedly enhances the malignant potential (e.g., invasion and migration ability) in various cancers, thus increasing the risk of distant metastasis. It remains unclear how radiation induces malignant potential, and how such enhanced malignant potential can be suppressed. In the current study, we evaluated the sequential change of c-Met expression in pancreatic cancer cells following irradiation. We found that irradiation transiently induced c-Met expression in vitro. In an in vivo subcutaneous tumor mouse model, irradiation also enhanced downstream phosphorylated Met (p-Met). Furthermore, this enhancement of p-Met protein expression was suppressed by oral administration of the c-Met inhibitor INC280. Irradiated pancreatic cancer cells with enhanced c-Met expression exhibited higher malignant potential, including invasion and migration ability, compared with cells showing low c-Met expression. Pancreatic cancer cells that overexpressed c-met also showed enhanced malignant potential, which was reversed by c-Met inhibition. Additionally, c-Met inhibitor suppressed the metastatic potential in a liver metastasis mouse model using c-met-overexpressing cells. Overall, our present results revealed that irradiation could induce c-met expression in pancreatic cancer cells, leading to enhanced malignant potential (e.g., invasion and migration ability) and thus promoting distant metastasis. Moreover, a c-Met inhibitor could reverse this enhanced malignant potential.

The Level of Mesenchymal-Epithelial Transition Autophosphorylation is Correlated with Esophageal Squamous Cell Carcinoma Migration

Background

The MET receptor is a critical member of cancer-associated receptor tyrosine kinases and plays an important role in different biological activities, including differentiation, migration, and cell proliferation.

Methods

In this study, novel MET inhibitors were introduced and applied on esophageal squamous carcinoma cell line KYSE-30, and the level of proliferation and migration, as well as the activated form of MET receptor protein were assessed in the examined cells. The human KYSE-30 cell line was cultured according to ATCC recommendations. The mRNA level of the MET gene was measured in the examined cell line using the quantitative RT-PCR assay. Cytotoxicity evaluation test was performed at different concentrations of heterocyclic anti-MET compounds (i.e. D1, D2, D5, D6, D7, and D8). Finally, the capability of these compounds in MET receptor inhibition was evaluated using the migration assay and Western blot. All experiments were performed in triplicate and repeated three times with similar results.

Results

Cell growth and proliferation were significantly inhibited (p ≤ 0.05) by all the above-mentioned compounds. Moreover, the majority of compounds significantly prevented the cell migration (p ≤ 0.05) and inhibited MET autophosphorylation. Interestingly, the level of phosphorylated MET was significantly correlated with KYSE-30 cell migration.

Conclusion

The obtained data introduced and confirmed the biological activities of the mentioned novel compounds in KYSE-30 cells and proposed that the therapeutic inhibition of MET with these compounds may be a powerful approach for inhibiting cancer cell migration and proliferation although some structural optimizations are needed to improve their inhibitory functions.

Feed-forward activation of STAT3 signaling limits the efficacy of c-Met inhibitors in esophageal squamous cell carcinoma (ESCC) treatment

c-Hepatocyte growth factor receptor (Met) inhibitors have demonstrated clinical benefits in some types of solid tumors. However, the efficacy of c-Met inhibitors in esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, we discovered that c-Met inhibitors induced "Signal Transducer and Activator of Transcription (STAT3)-addiction" in ESCC cells, and the feedback activation of STAT3 in ESCC cells limits the tumor response to c-Met inhibition. Mechanistically, c-Met inhibition increased the autocrine of several cytokines, including CCL2, interleukin 8, or leukemia inhibitory factor, and facilitated the interactions between the receptors of these cytokines and Janus Kinase1/2 (JAK1/2) to resultantly activate JAKs/STAT3 signaling. Pharmacological inhibition of c-Met together with cytokines/JAKs/STAT3 axis enhanced cancer cells regression in vitro. Importantly, combined c-Met and STAT3 inhibitors synergistically suppressed tumor growth and promoted the apoptosis of tumor cells without producing systematic toxicity. These findings suggest that inhibition of the STAT3 feedback loop may augment the response to c-Met inhibitors via the STAT3-mediated oncogene addiction in ESCC cells.

The Molecular Characteristics of Non-Clear Cell Renal Cell Carcinoma: What's the Story Morning Glory?

Non-clear cell renal cell carcinomas are a miscellaneous group of tumors that include different histological subtypes, each one characterized by peculiarity in terms of genetic alteration, clinical behavior, prognosis, and treatment response. Because of their low incidence and poor enrollment in clinical trials, alongside their heterogeneity, additional efforts are required to better unveil the pathogenetic mechanisms and, consequently, to improve the treatment algorithm. Nowadays, tyrosine kinase inhibitors, mTOR and MET inhibitors, and even cisplatin-based chemotherapy and immunotherapy are potential weapons that are still under evaluation in this setting. Various biomarkers have been evaluated for detecting progression and monitoring renal cell carcinoma, but more studies are necessary to improve this field. In this review, we provide an overview on the molecular characteristics of this group of tumors and the recently published trials, giving an insight into what might become the future therapeutic standard in this complex world of non-clear cell kidney cancers.

A challenging frontier - the genomics and therapeutics of nonclear cell renal cell carcinoma

PURPOSE OF REVIEW

As molecular profiling of renal cell carcinoma (RCC) continues to elucidate novel targets for nonclear cell histologies, understanding the landscape of these targets is of utmost importance. In this review, we highlight the genomic landscape of nonclear cell RCC and its implications for current and future systemic therapies.

RECENT FINDINGS

Several genomic studies have described the mutational burden among nonclear cell histologies. These studies have highlighted the importance of MET in papillary RCC and led to several clinical trials evaluating the efficacy of MET inhibitors for papillary RCC. The success of immune checkpoint inhibitors, such as ipilimumab and nivolumab, in clear cell RCC has led to ongoing trials evaluating these novel therapeutics in nonclear cell RCC.

SUMMARY

Genomic profiling has allowed for the evaluation of novel targets for nonclear cell RCC. This evolving therapeutic landscape is being explored in promising, ongoing trials that have the potential for changing how nonclear cell RCC is managed.

Targeted therapy in Xp11 translocation renal cell carcinoma

BACKGROUND

Translocation renal cell carcinoma (TRCC) is a rare form of RCC affecting mostly children and young adults with the occurrence of only 1-5% of all renal cell carcinomas. These carcinomas are associated with different translocations on a short arm of chromosome X in the region 11.2, which results in genetic modification of the p arm containing the transcription factor E3 gene.

METHODS

Herein we report a case of a patient who was dia-gnosed with TRCC with c-Met overexpression and was treated with multiple targeted therapy agents and immunotherapy.

CASE

A 28-year old woman without a significant past medical history underwent left sided total nephrectomy for TRCC. Seven months later, she developed systemic relapse and was treated with multiple lines of targeted therapy including sunitinib, everolimus, sorafenib, crizotinib, and pazopanib as well as with anti-PD-L1 antibody nivolumab, with stable disease as a best response. The most pronounced disease stabilization was achieved with sorafenib, which lasted 18 months. The patient died 81 months after initial dia-gnosis and 74 months from the dia-gnosis of metastatic disease.

CONCLUSION

Improved survival observed in our patient could be related to the effectivity of tyrosine-kinase inhibitors, but notm-TOR inhibitors, even though disease stabilisation was observed as a best response. Identification of new treatment targets are warranted in this rare disease.

Targeted Therapy Approaches for MET Abnormalities in Non-Small Cell Lung Cancer

The tyrosine kinase receptor mesenchymal epithelial transition (MET) is a proto-oncogene that, through the activation of the MET-hepatocyte growth factor (HGF) pathway, encodes a variety of biological processes, including cell development, proliferation, invasion, and migration. Abnormal activation of the MET pathway, occurring through MET protein overexpression, and gene amplification or mutation, can contribute to oncogenesis and has been implicated in non-small cell lung cancer (NSCLC). Though it is associated with poor clinical outcome in NSCLCs, MET overexpression and its role as a therapeutic target remains somewhat elusive due to discrepancies in its occurrence. Unlike MET overexpression, MET amplification has demonstrated a stronger potential as a biomarker for therapeutic treatment, with clinical data indicating a compelling connection between a high MET gene copy number and a high response rate to targeted therapies. However, MET exon 14 skipping mutations, occurring in 3%-4 % of lung adenocarcinomas, are of particular interest, as tumors harboring these mutations have shown a significant response to MET inhibitors. Following the discovery of MET as a potential therapeutic target, extensive clinical studies have proposed three approaches to targeting MET: (1) MET tyrosine kinase inhibitors (TKIs), including crizotinib, capmatinib, tepotinib, savolinitib, and cabozantinib; (2) MET or HGF monoclonal antibodies, including emibetuzumab and ficlatuzumab; and (3) MET or HGF antibody drug conjugates, including telisotuzumab. Herein, we discuss the relevant clinical trials, particularly focusing on the efficacy as well as the safety and tolerability of the treatment options, in the promising field of targeting MET in NSCLC.

Targeted inhibition of c-MET by podophyllotoxin promotes caspase-dependent apoptosis and suppresses cell growth in gefitinib-resistant non-small cell lung cancer cells

BACKGROUND

Lung cancer has the highest incidence and cancer-related mortality of all cancers worldwide. Its treatment is focused on molecular targeted therapy. c-MET plays an important role in the development and metastasis of various human cancers and has been identified as an attractive potential anti-cancer target. Podophyllotoxin (PPT), an aryltetralin lignan isolated from the rhizomes of Podophyllum species, has several pharmacological activities that include anti-viral and anti-cancer effects. However, the mechanism of the anti-cancer effects of PPT on gefitinib-sensitive (HCC827) or -resistant (MET-amplified HCC827GR) non-small cell lung cancer (NSCLC) cells remains unexplored.

PURPOSE

In the present study, we investigated the underlying mechanisms of PPT-induced apoptosis in NSCLC cells and found that the inhibition of c-MET kinase activity contributed to PPT-induced cell death.

METHODS

The regulation of c-MET by PPT was examined by pull-down assay, ATP-competitive binding assay, kinase activity assay, molecular docking simulation, and Western blot analysis. The cell growth inhibitory effects of PPT on NSCLC cells were assessed using the MTT assay, soft agar assay, and flow cytometry analysis.

RESULTS

PPT could directly interact with c-MET and inhibit kinase activity, which further induced the apoptosis of HCC827GR cells. In contrast, PPT did not significantly affect EGFR kinase activity. PPT significantly inhibited the cell viability of HCC827GR cells, whereas the PPT-treated HCC827 cells showed a cell viability of more than 80%. PPT dose-dependently induced G2/M cell cycle arrest, as shown by the downregulation of cyclin B1 and cdc2, and upregulation of p27 expression in HCC827GR cells. Furthermore, PPT treatment induced Bad expression and downregulation of Mcl-1, survivin, and Bcl-xl expression, subsequently activating multi-caspases. PPT thereby induced caspase-dependent apoptosis in HCC827GR cells.

CONCLUSION

These results suggest the potential of PPT as a c-MET inhibitor to overcome tyrosine kinase inhibitor resistance in lung cancer.

MET and RON receptor tyrosine kinases in colorectal adenocarcinoma: molecular features as drug targets and antibody-drug conjugates for therapy

Advanced colorectal adenocarcinoma (CRAC), featured by distinctive histopathological appearance, distant organ metastasis, acquired chemoresistance, and tumorigenic stemness is a group of heterogeneous cancers with unique genetic signatures and malignant phenotypes. Treatment of CRAC is a daunting task for oncologists. Currently, various strategies including molecular targeting using therapeutic monoclonal antibodies, small molecule kinase inhibitors and immunoregulatory checkpoint therapy have been applied to combat this deadly disease. However, these therapeutic modalities and approaches achieve only limited success. Thus, there is a pharmaceutical need to discover new targets and develop novel therapeutics for CRAC therapy. MET and RON receptor tyrosine kinases have been implicated in CRAC pathogenesis. Clinical studies have revealed that aberrant MET and/or RON expression and signaling are critical in regulating CRAC progression and malignant phenotypes. Increased MET and/or RON expression also has prognostic value for CRAC progression and patient survival. These features provide the rationale to target MET and RON for clinical CRAC intervention. At present, the use of small molecule kinase inhibitors targeting MET for CRAC treatment has achieved significant progress with several approvals for clinical application. Nevertheless, antibody-based biotherapeutics, although under clinical trials for more than 8 years, have made very little progress. In this review, we discuss the importance of MET and/or RON in CRAC tumorigenesis and development of anti-MET, anti-RON, and MET and RON-dual targeting antibody-drug conjugates for clinical application. The findings from both preclinical studies and clinical trials highlight the potential of this novel type of biotherapeutics for CRAC therapy in the future.

Quinoline-Based Molecules Targeting c-Met, EGF, and VEGF Receptors and the Proteins Involved in Related Carcinogenic Pathways

The quinoline ring system has long been known as a versatile nucleus in the design and synthesis of biologically active compounds. Currently, more than one hundred quinoline compounds have been approved in therapy as antimicrobial, local anaesthetic, antipsychotic, and anticancer drugs. In drug discovery, indeed, over the last few years, an increase in the publication of papers and patents about quinoline derivatives possessing antiproliferative properties has been observed. This trend can be justified by the versatility and accessibility of the quinoline scaffold, from which new derivatives can be easily designed and synthesized. Within the numerous quinoline small molecules developed as antiproliferative drugs, this review is focused on compounds effective on c-Met, VEGF (vascular endothelial growth factor), and EGF (epidermal growth factor) receptors, pivotal targets for the activation of important carcinogenic pathways (Ras/Raf/MEK and PI3K/AkT/mTOR). These signalling cascades are closely connected and regulate the survival processes in the cell, such as proliferation, apoptosis, differentiation, and angiogenesis. The antiproliferative biological data of remarkable quinoline compounds have been analysed, confirming the pivotal importance of this ring system in the efficacy of several approved drugs. Furthermore, in view of an SAR (structure-activity relationship) study, the most recurrent ligand–protein interactions of the reviewed molecules are summarized.

Tepotinib in Non-Small-Cell Lung Cancer with MET Exon 14 Skipping Mutations

BACKGROUND

A splice-site mutation that results in a loss of transcription of exon 14 in the oncogenic driver MET occurs in 3 to 4% of patients with non-small-cell lung cancer (NSCLC). We evaluated the efficacy and safety of tepotinib, a highly selective MET inhibitor, in this patient population.

METHODS

In this open-label, phase 2 study, we administered tepotinib (at a dose of 500 mg) once daily in patients with advanced or metastatic NSCLC with a confirmed MET exon 14 skipping mutation. The primary end point was the objective response by independent review among patients who had undergone at least 9 months of follow-up. The response was also analyzed according to whether the presence of a MET exon 14 skipping mutation was detected on liquid biopsy or tissue biopsy.

RESULTS

As of January 1, 2020, a total of 152 patients had received tepotinib, and 99 patients had been followed for at least 9 months. The response rate by independent review was 46% (95% confidence interval [CI], 36 to 57), with a median duration of response of 11.1 months (95% CI, 7.2 to could not be estimated) in the combined-biopsy group. The response rate was 48% (95% CI, 36 to 61) among 66 patients in the liquid-biopsy group and 50% (95% CI, 37 to 63) among 60 patients in the tissue-biopsy group; 27 patients had positive results according to both methods. The investigator-assessed response rate was 56% (95% CI, 45 to 66) and was similar regardless of the previous therapy received for advanced or metastatic disease. Adverse events of grade 3 or higher that were considered by investigators to be related to tepotinib therapy were reported in 28% of the patients, including peripheral edema in 7%. Adverse events led to permanent discontinuation of tepotinib in 11% of the patients. A molecular response, as measured in circulating free DNA, was observed in 67% of the patients with matched liquid-biopsy samples at baseline and during treatment.

CONCLUSIONS

Among patients with advanced NSCLC with a confirmed MET exon 14 skipping mutation, the use of tepotinib was associated with a partial response in approximately half the patients. Peripheral edema was the main toxic effect of grade 3 or higher. (Funded by Merck [Darmstadt, Germany]; VISION ClinicalTrials.gov number, NCT02864992.).

Capmatinib in MET Exon 14-Mutated or MET-Amplified Non-Small-Cell Lung Cancer

BACKGROUND

Among patients with non-small-cell lung cancer (NSCLC), MET exon 14 skipping mutations occur in 3 to 4% and MET amplifications occur in 1 to 6%. Capmatinib, a selective inhibitor of the MET receptor, has shown activity in cancer models with various types of MET activation.

METHODS

We conducted a multiple-cohort, phase 2 study evaluating capmatinib in patients with MET-dysregulated advanced NSCLC. Patients were assigned to cohorts on the basis of previous lines of therapy and MET status (MET exon 14 skipping mutation or MET amplification according to gene copy number in tumor tissue). Patients received capmatinib (400-mg tablet) twice daily. The primary end point was overall response (complete or partial response), and the key secondary end point was response duration; both end points were assessed by an independent review committee whose members were unaware of the cohort assignments.

RESULTS

A total of 364 patients were assigned to the cohorts. Among patients with NSCLC with a MET exon 14 skipping mutation, overall response was observed in 41% (95% confidence interval [CI], 29 to 53) of 69 patients who had received one or two lines of therapy previously and in 68% (95% CI, 48 to 84) of 28 patients who had not received treatment previously; the median duration of response was 9.7 months (95% CI, 5.6 to 13.0) and 12.6 months (95% CI, 5.6 to could not be estimated), respectively. Limited efficacy was observed in previously treated patients with MET amplification who had a gene copy number of less than 10 (overall response in 7 to 12% of patients). Among patients with MET amplification and a gene copy number of 10 or higher, overall response was observed in 29% (95% CI, 19 to 41) of previously treated patients and in 40% (95% CI, 16 to 68) of those who had not received treatment previously. The most frequently reported adverse events were peripheral edema (in 51%) and nausea (in 45%); these events were mostly of grade 1 or 2.

CONCLUSIONS

Capmatinib showed substantial antitumor activity in patients with advanced NSCLC with a MET exon 14 skipping mutation, particularly in those not treated previously. The efficacy in MET-amplified advanced NSCLC was higher in tumors with a high gene copy number than in those with a low gene copy number. Low-grade peripheral edema and nausea were the main toxic effects. (Funded by Novartis Pharmaceuticals; GEOMETRY mono-1 ClinicalTrials.gov number, NCT02414139.).

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

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

Tepotinib Inhibits the Epithelial-Mesenchymal Transition and Tumor Growth of Gastric Cancers by Increasing GSK3β, E-Cadherin, and Mucin 5AC and 6 Levels

Aberrant expression of mucins (MUCs) can promote the epithelial–mesenchymal transition (EMT), which leads to enhanced tumorigenesis. Carcinogenesis-related pathways involving c-MET and β-catenin are associated with MUCs. In this study, we characterized the expression of EMT-relevant proteins including MET, β-catenin, and E-cadherin in human gastric cancer (GC) cell lines, and further characterized the differential susceptibility of these cell lines compared with the c-MET inhibitor tepotinib. We assessed the antitumor activity of tepotinib in GC cell lines. The effects of tepotinib on cell viability, apoptotic cell death, EMT, and c-MET and β-catenin signaling were evaluated by 3-(4,5 dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium (MTS), flow cytometry, Western blotting, and qRT-PCR. The antitumor efficacy was assessed in MKN45 xenograft mice. Tepotinib treatment induced apoptosis in c-MET-amplified SNU620, MKN45, and KATO III cells, but had no effect on c-MET-reduced MKN28 or AGS cells. Tepotinib treatment also significantly reduced the protein levels of phosphorylated and total c-MET, phosphorylated and total ERK, β-catenin, and c-MYC in SNU620 and MKN45 cells. In contrast, this drug was only slightly active against KATO III cells. Notably, tepotinib significantly reduced the expression of EMT-promoting genes such as MMP7, COX-2, WNT1, MUC5B, and c-MYC in c-MET-amplified GC cells and increased the expression of EMT-suppressing genes such as MUC5AC, MUC6, GSK3β, and E-cadherin. In a mouse model, tepotinib exhibited good antitumor growth activity along with increased E-cadherin and decreased phosphorylated c-MET (phospho-c-MET) protein levels. Collectively, these results suggest that tepotinib suppresses tumor growth and migration by negatively regulating c-MET-induced EMT. These findings provide new insights into the mechanism by which MUC5AC and MUC6 contribute to GC progression.

Suppression of c-Met-Overexpressing Tumors by a Novel c-Met/CD3 Bispecific Antibody

INTRODUCTION

Overexpression of c-Met, or hepatocyte growth factor (HGF) receptor, is commonly observed in tumor biopsies and often associated with poor patient survival, which makes HGF/c-Met pathway an attractive molecular target for cancer therapy. A number of antibody-based therapeutic strategies have been explored to block c-Met or HGF in cancers; however, clinical efficacy has been very limited, indicating that blockade of c-Met signal alone is not sufficient. Thus, an alternative approach is to develop an immunotherapy strategy for c-Met-overexpressing cancers. c-Met/CD3 bispecific antibody (BsAb) could bridge CD3-positive T lymphocytes and tumor cells to result in potent tumor cell killing.

MATERIALS AND METHODS

A bispecific antibody, BS001, which binds both c-Met and CD3, was generated using a novel BsAb platform. Western blotting and T cells-mediated killing assays were utilized to evaluate the BsAb's effects on cell proliferation, survival and signal transduction in tumor cells. Subcutaneous tumor mouse models were used to analyze the in vivo anti-tumor effects of the bispecific antibody and its combination therapy with PD-L1 antibody.

RESULTS

BS001 showed potent T-cell mediated tumor cells killing in vitro. Furthermore, BS001 inhibited phosphorylation of c-Met and downstream signal transduction in tumor cells. In A549 lung cancer xenograft model, BS001 inhibited tumor growth and increased the proportion of activated CD56+ tumor infiltrating lymphocytes. In vivo combination therapy of BS001 with Atezolizumab (an anti-programmed cell death protein1-ligand (PD-L1) antibody) showed more potent tumor inhibition than monotherapies. Similarly, in SKOV3 xenograft model, BS001 showed a significant efficacy in tumor growth inhibition and tumor recurrence was not observed in more than half of mice treated with a combination of BS001 and Pembrolizumab.

CONCLUSION

c-Met/CD3 bispecific antibody BS001 exhibited potent anti-tumor activities in vitro and in vivo, which was achieved through two distinguished mechanisms: through antibody-mediated tumor cell killing by T cells and through inhibition of c-Met signal transduction.

c-MET inhibition: novel treatment for sporadic and MEN1-associated GEP NETs

Gastroenteropancreatic neuroendocrine tumors (GEP NETs) comprise a heterogenous and diverse group of neoplasms arising from a common neuroendocrine cell origin. The majority of these tumors occur sporadically while ~20% manifest within the context of hereditary syndromes. Germline MEN1 mutations cause a syndrome with an increased susceptibility to multifocal primary GEP NETs. In addition, somatic MEN1 mutations also occur in these sporadic lesions. MEN1 alterations are the most frequent somatic mutation found in pancreatic neuroendocrine tumors. In this review, we explore the implication of the loss of the MEN1-encoded protein menin as a key pathogenic driver in subsets of GEP NETs with downstream consequences including upregulation of the oncogenic receptor c-MET (hepatocyte growth factor receptor). Furthermore, the review will summarize the data related to the clinical presentation, therapeutic standards, and outcomes of these tumors in both sporadic and germline MEN1 mutation-associated contexts. Finally, we present the data on c-MET expression in GEP NETs, clinical trials using c-MET inhibitors and provide an overview of the molecular mechanisms by which c-MET inhibition in these lesions represents a potential precision-medicine targeted approach.

Efficacy of Savolitinib vs Sunitinib in Patients With MET-Driven Papillary Renal Cell Carcinoma: The SAVOIR Phase 3 Randomized Clinical Trial

Importance

Papillary renal cell carcinoma (PRCC) is the most common type of non-clear cell RCC. Because some cases of PRCC are MET-driven, MET inhibition could be a targeted treatment approach. In previous studies, savolitinib (AZD6094, HMPL-504, volitinib), a highly selective MET-tyrosine kinase inhibitor, demonstrated antitumor activity in this patient group.

Objective

To determine whether savolitinib is a better treatment option for this patient population, vs standard of care, sunitinib.

Design, Setting, and Participants

The SAVOIR phase 3, open-label, randomized clinical trial was a multicenter study carried out in 32 centers in 7 countries between July 2017 and the data cutoff in August 2019. Overall, 360 to 450 patients were to be screened to randomize approximately 180 patients. Patients were adults with MET-driven (centrally confirmed), metastatic PRCC, with 1 or more measurable lesions. Exclusion criteria included prior receipt of sunitinib or MET inhibitor treatment. Overall, 254 patients were screened.

Interventions

Patients received 600 mg of savolitinib orally once daily (qd), or 50 mg of sunitinib orally qd for 4 weeks, followed by 2 weeks without treatment.

Main Outcomes and Measures

The primary end point was progression-free survival (PFS, assessed by investigator and confirmed by blinded independent central review). Secondary end points included overall survival (OS), objective response rate (ORR), duration of response, and safety/tolerability.

Results

At data cutoff, 60 patients were randomized (savolitinib n = 33; sunitinib n = 27); most patients had chromosome 7 gain (savolitinib, 30 [91%]; sunitinib, 26 [96%]) and no prior therapy (savolitinib, 28 [85%]; sunitinib, 25 [93%]). For savolitinib and sunitinib, 4 (12%) and 10 (37%) patients were women, and the median (range) age was 60 (23-78) and 65 (31-77) years, respectively. Following availability of external data on PFS with sunitinib in patients with MET-driven disease, study enrollment was closed. Progression-free survival, OS, and ORR were numerically greater with savolitinib vs sunitinib. Median PFS was not statistically different between the 2 groups: 7.0 months (95% CI, 2.8-not calculated) for savolitinib and 5.6 months (95% CI, 4.1-6.9) for sunitinib (hazard ratio [HR], 0.71; 95% CI, 0.37-1.36; P = .31). For savolitinib and sunitinib respectively, grade 3 or higher adverse events (AEs) were reported in 14 (42%) and 22 (81%) of patients and AE-related dose modifications in 10 (30%) and 20 (74%). After discontinuation, 12 (36%) and 5 (19%) of patients on savolitinib and sunitinib respectively, received subsequent anticancer therapy.

Conclusions and Relevance

Although patient numbers and follow-up were limited, savolitinib demonstrated encouraging efficacy vs sunitinib, with fewer grade 3 or higher AEs and dose modifications. Further investigation of savolitinib as a treatment option for MET-driven PRCC is warranted.

Trial Registration

ClinicalTrials.gov Identifier: NCT03091192.

MET receptor in oncology: From biomarker to therapeutic target

First discovered in the 1984, the MET receptor tyrosine kinase (RTK) and its ligand hepatocyte growth factor or HGF (also known as scatter factor or SF) are implicated as key players in tumor cell migration, proliferation, and invasion in a variety of cancers. This pathway also plays a key role during embryogenesis in the development of muscular and nervous structures. High expression of the MET receptor has been shown to correlate with poor prognosis and resistance to therapy. MET exon 14 splicing variants, initially identified by us in lung cancer, is actionable through various tyrosine kinase inhibitors (TKIs). For this reason, this pathway is of interest as a therapeutic target. In this chapter we will be discussing the history of MET, the genetics of this RTK, and give some background on the receptor biology. Furthermore, we will discuss directed therapeutics, mechanisms of resistance, and the future of MET as a therapeutic target.

Research Progress of Small Molecule VEGFR/c-Met Inhibitors as Anticancer Agents (2016-Present)

Vascular endothelial growth factor receptor 2 (VEGFR-2) binds to VEGFR-A, VEGFR-C and VEGFR-D and participates in the formation of tumor blood vessels, mediates the proliferation of endothelial cells, enhances microvascular permeability, and blocks apoptosis. Blocking or downregulating the signal transduction of VEGFR is the main way to discover new drugs for many human angiogenesis-dependent malignancies. Mesenchymal epithelial transfer factor tyrosine kinase (c-Met) is a high affinity receptor for hepatocyte growth factor (HGF). Abnormal c-Met signaling plays an important role in the formation, invasion and metastasis of human tumors. Therefore, the HGF/c-Met signaling pathway has become a significant target for cancer treatment. Related studies have shown that the conduction of the VEGFR and c-Met signaling pathways has a synergistic effect in inducing angiogenesis and inhibiting tumor growth. In recent years, multi-target small molecule inhibitors have become a research hotspot, among which the research of VEGFR and c-Met dual-target small molecule inhibitors has become more and more extensive. In this review, we comprehensively summarize the chemical structures and biological characteristics of novel VEGFR/c-Met dual-target small-molecule inhibitors in the past five years.

A phase 1b study of the MET inhibitor capmatinib combined with cetuximab in patients with MET-positive colorectal cancer who had progressed following anti-EGFR monoclonal antibody treatment

Background Overcoming resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) in patients with KRAS wildtype (WT) metastatic colorectal cancer (mCRC) could help meet the needs of patients with limited treatment options. Methods In this phase 1b study, patients with N/KRAS WT, MET-positive mCRC who had progressed following anti-EGFR mAb treatment received escalating oral doses of capmatinib (150, 300, and 400 mg) twice daily plus weekly intravenous cetuximab (at the approved dose). The primary objective was to establish a recommended dose for expansion (RDE) of capmatinib in combination with cetuximab. Safety, preliminary activity, pharmacokinetics, and pharmacodynamics were also explored. Results Thirteen patients were enrolled. No patients experienced a dose-limiting toxicity at investigated doses; the RDE was established as capmatinib 400 mg twice daily plus cetuximab. All patients experienced adverse events (AEs) suspected to be related to the study treatment. Five patients (38.5%) reported study-drug-related AEs of grade 3/4 in severity. No patients achieved a complete or partial response according to RECIST v1.1; however, tumor shrinkage of 29-44% was observed in 4 patients. Conclusions Capmatinib plus cetuximab was well tolerated. Preliminary signs of activity were observed. Further investigation is warranted to obtain efficacy data and refine predictive biomarkers of response. Clinical trial registration NCT02205398.

Discovery of N-substituted-3-phenyl-1,6-naphthyridinone derivatives bearing quinoline moiety as selective type II c-Met kinase inhibitors against VEGFR-2

New N-substituted-3-phenyl-1,6-naphthyridinone derivatives are designed and synthesized, based on structural modification of our previously reported compound 3. Extensive enzyme-based SAR studies and PK evaluation led to the discovery of compound 4r, with comparable c-Met potency to that of Cabozantinib and high VEGFR-2 selectivity, while Cabozantinib displayed no VEGFR-2 selectivity. More importantly, at oral doses of 45 mg/kg (Q.D.), compound 4r exhibits significant tumor growth inhibition (93%) in a U-87MG human gliobastoma xenograft model. The promising selectivity against VEGFR-2 and excellent tumor growth inhibition of compound 4r suggest that it could be used as a new lead molecule for further discovery of selective type II c-Met inhibitors.

Rational targeting of immunosuppressive neutrophils in cancer

Neutrophils, the most abundant circulating leukocytes in human, play an indispensable role in the innate immune response to microbial infections. However, the contribution of tumor-associated neutrophils (TANs) to cancer progression and tumor immunity has been a matter of debate for decades. A higher neutrophil-to-lymphocyte ratio is associated with adverse overall survival in many solid tumors. Preclinical evidence exists to support both anti-tumor and pro-tumor activities of TANs, and TANs employ diverse mechanisms to influence tumor progression and metastasis. Here, we focus our review on the immunosuppressive mechanism of TANs and highlight how neutrophils can operate to dampen both innate and adaptive immunity to promote tumorigenesis. Here we discuss the intriguing and sometimes controversial connection between TANs and granulocytic/polymorphonuclear myeloid-derived suppressor cells (G/PMN-MDSCs). The molecular mechanisms underlying neutrophils' role in immunosuppression provide potential therapeutic targets for cancer treatment, either as monotherapies or as a part of combinatorial regimens. Therefore, we also highlight a number of neutrophil-targeting approaches that may improve the efficacy of current anticancer therapies, especially cancer immunotherapy. Currently interest is surging in the understanding and targeting of immunosuppressive neutrophils, with the goal of developing novel therapeutic strategies in the battle against cancer.

Targeting c-Met in triple negative breast cancer: preclinical studies using the c-Met inhibitor, Cpd A

Introduction Triple negative breast cancer (TNBC) represents a heterogeneous subtype of breast cancer that carries a poorer prognosis. There remains a need to identify novel drivers of TNBC, which may represent targets to treat the disease. c-Met overexpression is linked with decreased survival and is associated with the basal subtype of breast cancer. Cpd A, a kinase inhibitor selective/specific for Met kinase has demonstrated preclinical anti-cancer efficacy in TNBC. We aimed to assess the anti-cancer efficacy of Cpd A when combined with Src kinase, ErbB-family or hepatocyte growth factor (HGF) inhibitors in TNBC cell lines. Methods We determined the anti-proliferative effects of Cpd A, rilotumumab, neratinib and saracatinib tested alone and in combination in a panel of TNBC cells by acid phosphatase assays. We performed reverse phase protein array analysis of c-Met and IGF1Rβ expression and phosphorylation of c-Met (Y1234/1235) in TNBC cells and correlated their expression/phosphorylation with Cpd A sensitivity. We examined the impact of Cpd A, neratinib and saracatinib tested alone and in combination on invasive potential and colony formation.Results TNBC cells are not inherently sensitive to Cpd A, and neither c-Met expression nor phosphorylation are biomarkers of sensitivity to Cpd A. Cpd A enhanced the anti-proliferative effects of neratinib in vitro; however, this effect was limited to cell lines with innate sensitivity to Cpd A. Cpd A had limited anti-invasive effects but it reduced colony formation in the TNBC cell line panel.Conclusions Despite Cpd A having a potential role in reducing cancer cell metastasis, identification of strong predictive biomarkers of c-Met sensitivity would be essential to the development of a c-Met targeted treatment for an appropriately selected cohort of TNBC patients.

The c-Met inhibitor capmatinib alleviates acetaminophen-induced hepatotoxicity

Acetaminophen (APAP)-induced hepatotoxicity comes among the most frequent humans' toxicities caused by drugs. So far, therapeutic interventions for such type of drug-induced toxicity are still limited. In the current study, we examined the influence of capmatinib (Cap), a novel c-Met inhibitor, on APAP-induced hepatotoxicity in mice when administered 2 h prior, 2 h post and 4 h post APAP-challenge. The results revealed that Cap administration significantly attenuated APAP-induced liver injury when administered only 2 h prior and post APAP-administration. Cap hepatoprotective effect was mediated by lowering the excessive formation of lipid peroxidation and nitrosative stress products caused by APAP. Besides, Cap attenuated APAP-induced overproduction and release of proinflammatory mediators like TNF-α, IL-1β, IL-17A, IL-6, and MCP-1. Cap treatment also led to avoidance of APAP-subsequent repair by abating APAP-induced elevation of hepatic IL-22 and PCNA expressions. In conclusion, c-Met receptor inhibition may be a potential strategy for alleviating APAP-hepatotoxicity, especially when administered in the early phase of intoxication.

Open-label, single-center, phase I trial to investigate the mass balance and absolute bioavailability of the highly selective oral MET inhibitor tepotinib in healthy volunteers

Tepotinib (MSC2156119J) is an oral, potent, highly selective MET inhibitor. This open-label, phase I study in healthy volunteers (EudraCT 2013-003226-86) investigated its mass balance (part A) and absolute bioavailability (part B). In part A, six participants received tepotinib orally (498 mg spiked with 2.67 MBq [¹⁴C]-tepotinib). Blood, plasma, urine, and feces were collected up to day 25 or until excretion of radioactivity was <1% of the administered dose. In part B, six participants received 500 mg tepotinib orally as a film-coated tablet, followed by an intravenous [¹⁴C]-tepotinib tracer dose (53–54 kBq) 4 h later. Blood samples were collected until day 14. In part A, a median of 92.5% (range, 87.1–96.9%) of the [¹⁴C]-tepotinib dose was recovered in excreta. Radioactivity was mainly excreted via feces (median, 78.7%; range, 69.4–82.5%). Urinary excretion was a minor route of elimination (median, 14.4% [8.8–17.7%]). Parent compound was the main constituent in excreta (45% [feces] and 7% [urine] of the radioactive dose). M506 was the only major metabolite. In part B, absolute bioavailability was 72% (range, 62–81%) after oral administration of 500 mg tablets (the dose and formulation used in phase II trials). In conclusion, tepotinib and its metabolites are mainly excreted via feces; parent drug is the major eliminated constituent. Oral bioavailability of tepotinib is high, supporting the use of the current tablet formulation in clinical trials. Tepotinib was well tolerated in this study with healthy volunteers.

Activation of the HGF/c-MET axis promotes lenvatinib resistance in hepatocellular carcinoma cells with high c-MET expression

Lenvatinib is a long-awaited alternative to sorafenib for the first-line targeted therapy of patients with advanced hepatocellular carcinoma (HCC). However, resistance to lenvatinib has also become a major obstacle to improving the prognosis of HCC patients. The underlying molecular mechanisms contributing to lenvatinib resistance in HCC are largely unknown. HGF/c-MET axis activation is related to tumor progression and several hallmarks of cancer and is considered as the key contributor to drug resistance. In the present study, we focused on the role of the HGF/c-MET axis in mediating lenvatinib resistance in HCC cells. We showed that HGF reduced the antiproliferative, proapoptotic, and anti-invasive effects of lenvatinib on HCC cells with high c-MET expression but did not significantly affect HCC cells with low c-MET expression. The c-MET inhibitor PHA-665752 rescued HCC cells from HGF-induced lenvatinib resistance. Furthermore, HGF/c-MET activated the downstream PI3K/AKT and MAPK/ERK pathways and promoted epithelial-mesenchymal transition (EMT) in HCC cells. Collectively, our results suggested that combining lenvatinib treatment with a c-MET inhibitor may improve its systemic therapeutic efficacy in HCC patients with high c-MET expression.

Synthesis of triazolotriazine derivatives as c-Met inhibitors

Receptor tyrosine kinase c-Met is an important antitumor drug target. Triazolotriazine analogues 2-10 were prepared efficiently and evaluated the enzymatic and cellular c-Met activities. Brief structure-activity relationships of triazolotriazine core and CF₂-quinoline part were investigated, leading to the discovery of compound 8 with nanomolar enzymatic c-Met activity, and subnanomolar MKN45 and EBC-1 cellular potencies. The proposed binding model of 8 and c-Met unraveled that two canonical hydrogen bonds and a π-π stacking interaction formed between the inhibitor and the ATP binding site of c-Met kinase domain, which accounted for its potent c-Met activities.

Discovery of 1,6-naphthyridinone-based MET kinase inhibitor bearing quinoline moiety as promising antitumor drug candidate

A series of 1,6-naphthyridinone-based MET kinase inhibitors bearing quinoline moiety in block A were designed and synthesized based on the structures of Cabozantinib and our reported compound IV. Extensive SAR and DMPK studies led to the identification of 20j, a potent and orally bioavailable MET kinase inhibitor with favorable kinase selectivity. More importantly, 20j exhibited statistically significant tumor growth inhibition (Tumor growth inhibition/TGI of 131%, 4/6 partial regression/PR) in the U-87 MG xeograft model, which is superior to that of Cabozantinib (TGI of 97%, 2/6 PR), and significantly better than that of compound IV (TGI of 15%, 0/6 PR) at the same dose (12.5 mg/kg). Combined with favorable in vitro potency, kinase selectivity, pharmacokinetic profile and in vivo efficacy, the promising antitumor drug candidate 20j has subsequently advanced into preclinical research.

Licochalcone D Induces ROS-Dependent Apoptosis in Gefitinib-Sensitive or Resistant Lung Cancer Cells by Targeting EGFR and MET

Licochalcone D (LCD), a flavonoid isolated from a Chinese medicinal plant Glycyrrhiza inflata, has a variety of pharmacological activities. However, the anti-cancer effects of LCD on non-small cell lung cancer (NSCLC) have not been investigated yet. The amplification of MET (hepatocyte growth factor receptor) compensates for the inhibition of epidermal growth factor receptor (EGFR) activity due to tyrosine kinase inhibitor (TKI), leading to TKI resistance. Therefore, EGFR and MET can be attractive targets for lung cancer. We investigated the anti-proliferative and apoptotic effects of LCD in lung cancer cells HCC827 (gefitinib-sensitive) and HCC827GR (gefitinib-resistant) through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, pull-down/kinase assay, cell cycle analysis, Annexin-V/7-ADD staining, reactive oxygen species (ROS) assay, mitochondrial membrane potential (MMP) assay, multi-caspase assay, and Western blot analysis. The results showed that LCD inhibited phosphorylation and the kinase activity of EGFR and MET. In addition, the predicted pose of LCD was competitively located at the ATP binding site. LCD suppressed lung cancer cells growth by blocking cell cycle progression at the G2/M transition and inducing apoptosis. LCD also induced caspases activation and poly (ADP-ribose) polymerase (PARP) cleavage, thus displaying features of apoptotic signals. These results provide evidence that LCD has anti-tumor effects by inhibiting EGFR and MET activities and inducing ROS-dependent apoptosis in NSCLC, suggesting that LCD has the potential to treat lung cancer.

Novel Peptide CM 7 Targeted c-Met with Antitumor Activity

Anomalous changes of the cell mesenchymal–epithelial transition factor (c-Met) receptor tyrosine kinase signaling pathway play an important role in the occurrence and development of human cancers, including gastric cancer. In this study, we designed and synthesized a novel peptide (CM 7) targeting the tyrosine kinase receptor c-Met, that can inhibit c-Met-mediated signaling in MKN-45 and U87 cells. Its affinity to human c-Met protein or c-Met-positive cells was determined, which showed specific binding to c-Met with high affinity. Its biological activities against MKN-45 c-Met-positive cells were evaluated in vitro and in vivo. As a result, peptide CM 7 exhibited moderate regulation of c-Met-mediated cell proliferation, migration, invasion, and scattering. The inhibitory effect of peptide CM 7 on tumor growth in vivo was investigated by establishing a xenograft mouse model using MKN-45 cells, and the growth inhibition rate of tumor masses for peptide CM 7 was 62%. Based on our data, CM 7 could be a promising therapeutic peptide for c-Met-dependent cancer patients.

Design, Synthesis, and Biological Evaluation of Pyridineamide Derivatives Containing a 1,2,3-Triazole Fragment as Type II c-Met Inhibitors

A series of 4-(pyridin-4-yloxy)benzamide derivatives containing a 1,2,3-triazole fragment were designed, synthesized, and their inhibitory activity against A549, HeLa, and MCF-7 cancer cell lines was evaluated. Most compounds exhibited moderate to potent antitumor activity against the three cell lines. Among them, the promising compound B26 showed stronger inhibitory activity than Golvatinib, with IC₅₀ values of 3.22, 4.33, and 5.82 μM against A549, HeLa, and MCF-7 cell lines, respectively. The structure–activity relationships (SARs) demonstrated that the modification of the terminal benzene ring with a single electron-withdrawing substituent (fluorine atom) and the introduction of a pyridine amide chain with a strong hydrophilic group (morpholine) to the hinge region greatly improved the antitumor activity. Meanwhile, the optimal compound B26 showed potent biological activity in some pharmacological experiments in vitro, such as cell morphology study, dose-dependent test, kinase activity assay, and cell cycle experiment. Finally, the molecular docking simulation was performed to further explore the binding mode of compound B26 with c-Met.

Novel Crizotinib-GnRH Conjugates Revealed the Significance of Lysosomal Trapping in GnRH-Based Drug Delivery Systems

Several promising anti-cancer drug–GnRH (gonadotropin-releasing hormone) conjugates have been developed in the last two decades, although none of them have been approved for clinical use yet. Crizotinib is an effective multi-target kinase inhibitor, approved against anaplastic lymphoma kinase (ALK)- or ROS proto-oncogene 1 (ROS-1)-positive non-small cell lung carcinoma (NSCLC); however, its application is accompanied by serious side effects. In order to deliver crizotinib selectively into the tumor cells, we synthesized novel crizotinib analogues and conjugated them to a [d-Lys⁶]–GnRH-I targeting peptide. Our most prominent crizotinib–GnRH conjugates, the amide-bond-containing [d-Lys⁶(crizotinib*)]–GnRH-I and the ester-bond-containing [d-Lys⁶(MJ55*)]–GnRH-I, were able to bind to GnRH-receptor (GnRHR) and exert a potent c-Met kinase inhibitory effect. The efficacy of compounds was tested on the MET-amplified and GnRHR-expressing EBC-1 NSCLC cells. In vitro pharmacological profiling led to the conclusion that that crizotinib–GnRH conjugates are transported directly into lysosomes, where the membrane permeability of crizotinib is diminished. As a consequence of GnRHR-mediated endocytosis, GnRH-conjugated crizotinib bypasses its molecular targets—the ATP-binding site of RTKs— and is sequestered in the lysosomes. These results explained the lower efficacy of crizotinib–GnRH conjugates in EBC-1 cells, and led to the conclusion that drug escape from the lysosomes is a major challenge in the development of clinically relevant anti-cancer drug–GnRH conjugates.

Design, synthesis, and biological evaluation of 4-phenoxyquinoline derivatives as potent c-Met kinase inhibitor

A series of novel 4-phenoxyquinoline derivatives containing 3-oxo-3,4-dihydro-quinoxaline moiety were synthesized and evaluated for their antiproliferative activity against five human cancer cell lines (A549, H460, HT-29, MKN-45 and U87MG) in vitro. Most of the tested compounds exhibited more potent inhibitory activities than the positive control foretinib. Compound 1b, 1s and 1t were further examined for their inhibitory activity against c-Met kinase. The most promising compound 1s (with c-Met IC₅₀ value of 1.42 nM) showed remarkable cytotoxicity against A549, H460, HT-29, MKN45 and U87MG cell lines with IC₅₀ values of 0.39 μM, 0.18 μM, 0.38 μM, 0.81 μM, respectively. Their preliminary structure-activity relationships (SARs) study indicated that the replacement of the aromatic ring with the cyclohexane improved their antiproliferative activity.

A Phase Ib/II Study of Ramucirumab in Combination with Emibetuzumab in Patients with Advanced Cancer

PURPOSE

Inhibition of the VEGFR-2 blocks angiogenesis and attenuates tumor growth, but cancers may evade this effect through activation of the hepatocyte growth factor receptor MET. Here we report results of the phase Ib/II study of ramucirumab, a monoclonal anti-VEGFR-2 antibody, plus the anti-MET mAb emibetuzumab.

PATIENTS AND METHODS

A 3+3 dose escalation of emibetuzumab plus ramucirumab (phase Ib) was followed by tumor-specific expansion cohorts. Primary objectives were to determine the recommended phase II dose and to evaluate antitumor activity. Secondary objectives included safety, pharmacokinetics, and immunogenicity. Tumoral MET expression was explored by immunohistochemistry (IHC).

RESULTS

A total of 97 patients with solid tumor [6 phase Ib, 16 gastric or gastroesophageal junction adenocarcinoma, 45 hepatocellular carcinoma (HCC), 15 renal cell carcinoma, and 15 non-small lung cancer] received emibetuzumab at 750 or 2,000 mg flat dosing plus ramucirumab at 8 mg/kg every 2 weeks. No dose-limiting toxicities were observed. Common adverse events were primarily mild or moderate and included fatigue (36.1%), peripheral edema (28.9%), and nausea (14.4%). Emibetuzumab exposures were similar as in previous studies with no apparent drug-drug interactions. Five partial responses (5.2%) were observed across all tumor types. The greatest antitumor activity was noted in HCC with a 6.7% overall response rate, 60% disease control rate, and 5.42 months (95% confidence interval, 1.64-8.12) progression-free survival (PFS). HCC with high MET expression showed improved PFS with approximately 3-fold increase in PFS (8.1 vs. 2.8 months) relative to low MET expression.

CONCLUSIONS

Ramucirumab plus emibetuzumab was safe and exhibited cytostatic antitumor activity. MET expression may help to select patients benefitting most from this combination treatment in select tumor types.

The repression and reciprocal interaction of DNA methyltransferase 1 and specificity protein 1 contributes to the inhibition of MET expression by the combination of Chinese herbal medicine FZKA decoction and erlotinib

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese herbal medicine Fuzheng Kang-Ai (FZKA) decoction obtained from Guangdong Kangmei Pharmaceutical Company, which contains 12 components with different types of constituents, has been used as part of the adjuvant treatment of lung cancer for decades. We previously showed that FZKA decoction enhances the growth inhibition of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant non-small cell lung cancer (NSCLC) cells by suppressing glycoprotein mucin 1 (MUC1) expression. However, the molecular mechanism underlying the therapeutic potential, particularly in sensitizing or/and enhancing the anti-lung cancer effect of EGFR-TKIs, remains unclear.

MATERIALS AND METHODS

Cell viability was measured using 3-(4, 5-diMEThylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and 5-ethynyl -2'-deoxyuridine (EdU) assays. Western blot analysis was performed to examine the protein expressions of DNA methyltransferase 1 (DNMT1), specificity protein 1 (SP1), and MET, an oncogene encoding for a trans-membrane tyrosine kinase receptor activated by the hepatocyte growth factor (HGF). The expression of MET mRNA was measured by quantitative real-time PCR (qRT-PCR). Exogenous expression of DNMT1 and SP1, and MET were carried out by transient transfection assays. The promoter activity of MET was tested using Dual-luciferase reporter assays. A nude mouse xenografted tumor model further evaluated the effect of the combination of FZKA decoction and erlotinib in vivo.

RESULTS

The combination of FZKA and erlotinib produced an even greater inhibition of NSCLC cell growth. FZKA decreased the expressions of DNMT1, SP1, and MET (c-MET) proteins, and the combination of FZKA and erlotinib demonstrated enhanced responses. Interestingly, there was a mutual regulation of DNMT1 and SP1. In addition, exogenously expressed DNMT1 and SP1 blocked the FZKA-inhibited c-MET expression. Moreover, excessive expressed MET neutralized FZKA-inhibited growth of NSCLC cells. FZKA decreased the mRNA and promoter activity of c-MET, which was not observed in cells with ectopic expressed DNMT1 gene. Similar findings were observed in vivo.

CONCLUSION

FZKA decreases MET gene expression through the repression and mutual regulation of DNMT1 and SP1 in vitro and in vivo. This leads to inhibit the growth of human lung cancer cells. The combination of FZKA and EGFR-TKI erlotinib exhibits synergy in this process. The regulatory loops among the DNMT1, SP1 and MET converge in the overall effects of FZKA and EGFR-TKI erlotinib. This in vitro and in vivo study clarifies an additional novel molecular mechanism underlying the anti-lung cancer effects in response to the combination of FZKA and erlotinib in gefitinib-resistant NSCLC cells.

SHR-A1403, a novel c-Met antibody-drug conjugate, exerts encouraging anti-tumor activity in c-Met-overexpressing models

Emerging evidence demonstrates that a c-Met antibody-drug conjugate (ADC) has superior efficacy and safety profiles compared with those of currently available small molecules or antibody inhibitors for the treatment of c-Met-overexpressing cancers. Here we described both the in vitro and in vivo efficacies of SHR-A1403, a novel c-Met ADC composed of a humanized IgG2 monoclonal antibody against c-Met conjugated to a novel cytotoxic microtubule inhibitor. SHR-A1403 showed high affinity to c-Met proteins derived from human or monkey and potent inhibitory effects in cancer cell lines with high c-Met protein expression. In mice bearing tumors derived from cancer cell lines or patient HCC tissues with confirmed c-Met overexpression, SHR-A1403 showed excellent anti-tumor efficacy. Antibody binding with c-Met contributed to SHR-A1403 endocytosis; the subsequent translocation to lysosomes and cytotoxicity of the released toxin are speculated to be predominant mechanisms underlying the anti-tumor activity of SHR-A1403. In conclusion, SHR-A1403 showed significant anti-tumor activity in cancer cell lines, xenograft mouse models and an HCC PDX model, which all have high c-Met levels. These data provide references for SHR-A1403 as a potential therapy for the treatment of cancers with c-Met overexpression.

Going After METex14 in NSCLC

Patients with non-small cell lung cancer harboring MET exon 14 skipping mutations have commonly been treated with the multikinase inhibitor crizotinib, but more MET-specific therapies are being developed. Two such agents, capmatinib and tepotinib, have demonstrated preliminary efficacy in ongoing phase II trials.

Virtual Screening Guided Design, Synthesis and Bioactivity Study of Benzisoselenazolones (BISAs) on Inhibition of c-Met and Its Downstream Signalling Pathways

c-Met is a transmembrane receptor tyrosine kinase and an important therapeutic target for anticancer drugs. In this study, we designed a small library containing 300 BISAs molecules that consisted of carbohydrates, amino acids, isothiourea, tetramethylthiourea, guanidine and heterocyclic groups and screened c-Met targeting compounds using docking and MM/GBSA. Guided by virtual screening, we synthesised a series of novel compounds and their activity on inhibition of the autophosphorylation of c-Met and its downstream signalling pathway proteins were evaluated. We found a panel of benzisoselenazolones (BISAs) obtained by introducing isothiourea, tetramethylthiourea and heterocyclic groups into the C-ring of Ebselen, including 7a, 7b, 8a, 8b and 12c (with IC50 values of less than 20 μM in MET gene amplified lung cancer cell line EBC-1), exhibited more potent antitumour activity than Ebselen by cell growth assay combined with in vitro biochemical assays. In addition, we also tested the antitumour activity of three cancer cell lines without MET gene amplification/activation, including DLD1, MDA-MB-231 and A549. The neuroblastoma SK-N-SH cells with HGF overexpression which activates MET signalling are sensitive to MET inhibitors. The results reveal that our compounds may be nonspecific multitarget kinase inhibitors, just like type-II small molecule inhibitors. Western blot analysis showed that these inhibitors inhibited autophosphorylation of c-MET, and its downstream signalling pathways, such as PI3K/AKT and MARK/ERK. Results suggest that bensoisoselenones can be used as a scaffold for the design of c-Met inhibiting drug leads, and this study opens up new possibilities for future antitumour drug design.

Incidence and risk of fatigue in cancer patients treated with MET inhibitors: A systematic review and meta-analysis

BACKGROUND

The N-methyl-N'-nitroso-guanidine human osteosarcoma transforming gene (MET) inhibitors show a surprising survival benefit in the treatment of numerous tumors especially in MET-high tumor. Besides their impressive efficacy, fatigue reduced by MET inhibitors is still the safety issue during treatment. Thus, an understanding of this risk in the context of expanding MET-inhibitors use is an important cost and patient safety issue.

METHODS

We searched PubMed, Embase, and the Cochrane Library databases for relevant studies up to October 2017. Eligibility criteria included phase II/III trials of MET inhibitors that reported adequate safety profiles of fatigue. The principal summary measures were incidence and relative risk (RR) of all-grade (grade 1-4) and high-grade (grade 3-4) fatigue, respectively. Random-effects model was applied to consider within-study and between-study variation.

RESULTS

A total of 5028 patients from 17 clinical trials were identified. The results revealed that the incidences of MET inhibitors-associated all-grade and high-grade fatigue were 41.9% and 9.6%, respectively. The RR of high-grade fatigue was (RR = 1.37; 95% confidence interval, 1.14-1.66; P = .0009), whereas the RR of all-grade fatigue was (RR = 1.02; 95% confidence interval, 0.91-1.15; P = .71).

CONCLUSION

Our meta-analysis has demonstrated that MET inhibitors-based treatment is associated with an increased risk of high-grade fatigue compared with control.

Bioengineering fluorescent virus-like particle/RNAi nanocomplexes act synergistically with temozolomide to eradicate brain tumors

The proof-of-concept strategy in this study based on biodegradable and biocompatible self-assembling fluorescent virus-like particle/RNAi nanocomplexes (VLP/RNAi) produced in Escherichia coli (E. coli) followed by surface modification with a cell-penetrating peptide (CPP) and an apolipoprotein E peptide (ApoEP) (dP@VLP/RNAi), which can cross the blood-brain barrier (BBB) to inhibit the DNA repair mechanism and act synergistically with temozolomide (TMZ) for promoting clinical chemotherapy has achieved good therapeutic effects towards malignant brain tumors. The synergistic value of this study's design was verified in intracranial mouse models of glioblastomas (GBMs). Intravenous administration of this formulation enhanced the curative efficacy of TMZ by downregulating the hepatocyte growth factor receptor (c-MET) gene in GBM U87 cells. Furthermore, upon gene-chemotherapy, the methylated DNA in GBM U87 cells was significantly enhanced by inhibiting the DNA repair mechanism, leading to significant brain tumor suppression. The results of this study could be critical for the design of RNAi-based genetic therapeutics for promoting chemotherapy against brain tumors.

MM-131, a bispecific anti-Met/EpCAM mAb, inhibits HGF-dependent and HGF-independent Met signaling through concurrent binding to EpCAM

Activation of the Met receptor tyrosine kinase, either by its ligand, hepatocyte growth factor (HGF), or via ligand-independent mechanisms, such as MET amplification or receptor overexpression, has been implicated in driving tumor proliferation, metastasis, and resistance to therapy. Clinical development of Met-targeted antibodies has been challenging, however, as bivalent antibodies exhibit agonistic properties, whereas monovalent antibodies lack potency and the capacity to down-regulate Met. Through computational modeling, we found that the potency of a monovalent antibody targeting Met could be dramatically improved by introducing a second binding site that recognizes an unrelated, highly expressed antigen on the tumor cell surface. Guided by this prediction, we engineered MM-131, a bispecific antibody that is monovalent for both Met and epithelial cell adhesion molecule (EpCAM). MM-131 is a purely antagonistic antibody that blocks ligand-dependent and ligand-independent Met signaling by inhibiting HGF binding to Met and inducing receptor down-regulation. Together, these mechanisms lead to inhibition of proliferation in Met-driven cancer cells, inhibition of HGF-mediated cancer cell migration, and inhibition of tumor growth in HGF-dependent and -independent mouse xenograft models. Consistent with its design, MM-131 is more potent in EpCAM-high cells than in EpCAM-low cells, and its potency decreases when EpCAM levels are reduced by RNAi. Evaluation of Met, EpCAM, and HGF levels in human tumor samples reveals that EpCAM is expressed at high levels in a wide range of Met-positive tumor types, suggesting a broad opportunity for clinical development of MM-131.