Expression and mutational analysis of MET in human solid cancers

AXL and SRC in clear cell renal cell carcinoma: absence of mutations, rare alternative splicing events, but association of protein expression with poor prognosis

Novel treatment options for metastatic renal cell carcinomas (RCC) include specific MET inhibitors, GAS6/AXL inhibitors, and SRC inhibitors. The interplay between c-MET, SRC, AXL expression, and their gene mutation patterns in different renal carcinoma subtypes is unclear. To improve the understanding of these signaling pathways, we analyzed c-MET, AXL, and SRC expression in 590 clear cell RCC (ccRCC) and 127 papillary RCC (pRCC) by immunohistochemistry and integrated sequencing data to investigate the frequency of MET, AXL, and SRC gene mutations, their expression levels, and the presence of splice variants. In TCGA and in Foundation Medicine, Inc. (FMI) datasets, AXL and SRC gene alterations were extremely rare (<2%) or absent in ccRCC (n = 531 and 2,781, respectively) and pRCC (n = 290 and 566, respectively). On the other hand, MET mutations or amplifications were found in 9.7% (TCGA) and 10.2% (FMI) of pRCC. We show that strong SRC staining intensity by immunohistochemistry is associated with high tumor stage, high grade, and shorter survival in ccRCC (p < 0.001 each). AXL expression correlates with high stage and grade in ccRCC (p < 0.001 each). Both SRC and AXL expression were independent prognostic parameters in multivariate analysis (p < 0.05). MET expression is associated with longer survival in pRCC (p < 0.05). Our TCGA data analysis aligns with SRC immunohistochemistry findings on tumor stage and shorter survival in ccRCC. TCGA expression data showed a moderate positive correlation between AXL and c-MET in pRCC. In addition, we identified alternative splicing events reported for AXL in pRCC, and MET and SRC in ccRCC, across various alternative splicing databases. In conclusion, we identified high SRC expression as a biomarker for poor prognosis of ccRCC. Our data demonstrate c-MET, AXL, and SRC signaling pathway interactions independent of c-MET, AXL, and SRC mutations in ccRCC.

MET tyrosine kinase inhibitors in combination with EGFR tyrosine kinase inhibitors in NSCLC patients with EGFR mutations and acquired MET alterations: a systematic review and meta-analysis

BACKGROUND

Acquired MET alterations is one of the resistance mechanisms to advanced NSCLC patients treated with EGFR tyrosine kinase inhibitors (TKIs). Several clinical trials combined MET-TKI (such as capmatinib, tepotinib, savolitinib) with EGFR-TKI to overcome MET alterations resistance. We performed this meta-analysis to determine the efficacy and safety of MET-TKI plus EGFR-TKI combined therapy in NSCLC patients.

METHODS

Pubmed, Embase and the Cochrane Library were searched for relevant studies up to August 19, 2024. Data of objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), median duration of response (mDOR) and adverse events were extracted from the publications and analyzed.

RESULTS

Six studies involving 562 patients were included in this meta-analysis. Our study showed a pooled ORR of 49.2% (95% confidence interval [CI] 0.402-0.582), a pooled DCR of 78.6% (95%CI 0.680-0.893), a mDOR of 6.85 months (95%CI 5.85-7.86), and a mPFS of 5.62 months (95%CI 4.74-6.50) in MET-TKI plus EGFR-TKI combination therapy for NSCLC patients with acquired MET-driven resistance after EGFR-TKI treatment. The pooled efficacy data suggested that combining MET-TKI with a third-generation EGFR-TKI was numerically superior to combining MET-TKI with a first-generation EGFR-TKI in patients who were T790M negative with MET-dependent resistance mechanism (ORR: 56.8% vs. 47.8%, p = 0.15; DCR: 81.6% vs. 75%, p = 0.57; mDOR: 9.08 vs. 7.00 months, p = 0.25; mPFS: 7.45 vs. 4.55 months, p = 0.05). The efficacy data of capmatinib plus EGFR-TKI, savolitinib plus EGFR-TKI and tepotinib plus EGFR-TKI (regardless of generation of EGFR-TKIs) was similar (ORR:47.7% vs. 50.7% vs. 48.8%, p = 0.96; DCR: 71.4% vs. 84.9% vs. 63.3%, p = 0.02; mDOR: NR vs. 8.4 vs. 8.01 months, p = 0.18; mPFS: 5.49 vs. 6.88 vs. 5.48 months, p = 0.56). Capmatinib subgroup seemed to demonstrate lower hepatotoxicity compared with savolitinib and tepotinib subgroups numerically (increased AST level: 12.8% vs. 18.8% vs. 17.4%, p = 0.66; increased ALT level: 14.2% vs. 17.6% vs. 20.1%, p = 0.91). And a lower occurrence rate of ≥ 3 grade TRAEs was observed in the capmatinib subgroup compared to the savolitinib or tepotinib subgroups (30.0% vs. 46.7% vs. 41.2%, p = 0.07).

CONCLUSION

The findings from this meta-analysis suggest that the combination of MET-TKI and EGFR-TKI represents a promising therapeutic approach for NSCLC patients who have acquired MET alterations following EGFR-TKI treatment. Notably, the combination of MET-TKI and a third-generation EGFR-TKI demonstrated enhanced survival benefits compared to the combination with a first-generation EGFR-TKI. Furthermore, different MET-TKIs based combination therapy did not display significant differences in efficacy, while capmatinib based combination therapy showed better safety profile and lower hepatotoxicity.

The Era of Antibody Drug Conjugates in Lung Cancer: Trick or Threat?

Antibody drug conjugates (ADCs) are a novel class of therapeutics that structurally are composed by an antibody directed to a tumor epitope connected via a linker to a cytotoxic payload, and that have shown significant antitumor activity across a range of malignancies including lung cancer. In this article we review the pharmacology and design of ADCs, as well as we describe the results of different studies evaluating ADCs in lung cancer directed to several targets including HER2, HER3, TROP2, MET, CEACAM5 and DLL3.

Recent advances in therapeutic strategies for non-small cell lung cancer

The development of targeted therapy with small-molecule tyrosine kinase inhibitors and immunotherapy with immune checkpoints inhibitors has ushered in the era of precision medicine in treating lung cancer, which remains the leading cause of cancer-related deaths worldwide. Both targeted therapy and immunotherapy have significantly improved the survival of patients with metastatic non-small-cell lung cancer (NSCLC). Additionally, recent groundbreaking studies have demonstrated their efficacy in both the perioperative setting and following concurrent chemoradiotherapy in early-stage NSCLC. Despite significant advancements in first-line treatment options, disease progression remains inevitable for most patients with advanced NSCLC, necessitating the exploration and optimization of subsequent therapeutic strategies. Emerging novel agents are expanding treatment options in the first-line setting and beyond. Recently, emerging bispecific antibodies have shown enhanced efficacy. For instance, amivantamab has been approved as a treatment for epidermal growth factor receptor (EGFR)-mutant NSCLC, including those with EGFR exon 20 insertion mutations. Additionally, antibody-drug conjugates (ADCs), including HER2-targeting trastuzumab deruxtecan, TROP2-targeting ADCs, HER3-targeting patritumab deruxtecan, and MET-targeting telisotuzumab vedotin, have demonstrated promising outcomes in several clinical trials. This review summarizes the recent advancements and challenges associated with the evolving NSCLC therapeutic landscape.

Cigarette smoke extract induces malignant transformation and DNA damage via c-MET phosphorylation in human bronchial epithelial cells

Cigarette smoke, a complex mixture produced by tobacco combustion, contains a variety of carcinogens and can trigger DNA damage. Overactivation of c-MET, a receptor tyrosine kinase, may cause cancer and cellular DNA damage, but the underlying mechanisms are unknown. In this work, we investigated the mechanisms of cigarette smoke extract (CSE) induced malignant transformation and DNA damage in human bronchial epithelial cells (BEAS-2B). The results demonstrated that CSE treatment led to up-regulated mRNA expression of genes associated with the c-MET signaling pathway, increased expression of the DNA damage sensor protein γ-H2AX, and uncontrolled proliferation in BEAS-2B cells. ATR, ATR, and CHK2, which are involved in DNA damage repair, as well as the phosphorylation of c-MET and a group of kinases (ATM, ATR, CHK1, CHK2) involved in the DNA damage response were all activated by CSE. In addition, CSE activation promotes the phosphorylation modification of ATR, CHK1 proteins associated with DNA damage repair. The addition of PHA665752, a specific inhibitor of c-MET, or knock-down with c-MET both attenuated DNA damage, while overexpression of c-MET exacerbated DNA damage. Thus, c-MET phosphorylation may be involved in CSE-induced DNA damage, providing a potential target for intervention in the prevention and treatment of smoking-induced lung diseases.

Unveiling the Role of HGF/c-Met Signaling in Non-Small Cell Lung Cancer Tumor Microenvironment

Non-small cell lung cancer (NSCLC) is characterized by several molecular alterations that contribute to its development and progression. These alterations include the epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), human epidermal growth factor receptor 2 (HER2), and mesenchymal-epithelial transition factor (c-MET). Among these, the hepatocyte growth factor (HGF)/c-MET signaling pathway plays a crucial role in NSCLC. In spite of this, the involvement of the HGF/c-MET signaling axis in remodeling the tumor microenvironment (TME) remains relatively unexplored. This review explores the biological functions of the HGF/c-MET signaling pathway in both normal and cancerous cells, examining its multifaceted roles in the NSCLC tumor microenvironment, including tumor cell proliferation, migration and invasion, angiogenesis, and immune evasion. Furthermore, we summarize the current progress and clinical applications of MET-targeted therapies in NSCLC and discuss future research directions, such as the development of novel MET inhibitors and the potential of combination immunotherapy.

Discovery of Pyrazolopyrazines as Selective, Potent, and Mutant-Active MET Inhibitors with Intracranial Efficacy

Mesenchymal-epithelial transition factor (MET) is a receptor tyrosine kinase that serves a critical function in numerous developmental, morphogenic, and proliferative signaling pathways. If dysregulated, MET has been shown to be involved in the development and survival of several cancers, including non-small cell lung cancer (NSCLC), renal cancer, and other epithelial tumors. Currently, the clinical efficacy of FDA approved MET inhibitors is limited by on-target acquired resistance, dose-limiting toxicities, and less than optimal efficacy against brain metastasis. Therefore, there is still an unmet medical need for the development of MET inhibitors to address these issues. Herein we report the application of structure-based design for the discovery and development of a novel class of brain-penetrant MET inhibitors with enhanced activity against clinically relevant mutations and improved selectivity. Compound 13 with a MET D1228N cell line IC50 value of 23 nM showed good efficacy in an intracranial tumor model and increased the median overall survival of the animals to 100% when dosed orally at 100 mg/kg daily for 21 days.

The rapidly changing field of predictive biomarkers of non-small cell lung cancer

Lung cancer is a leading cause of cancer-related death worldwide in both men and women, however mortality in the US and EU are recently declining in parallel with the gradual cut of smoking prevalence. Consequently, the relative frequency of adenocarcinoma increased while that of squamous and small cell carcinomas declined. During the last two decades a plethora of targeted drug therapies have appeared for the treatment of metastasizing non-small cell lung carcinomas (NSCLC). Personalized oncology aims to precisely match patients to treatments with the highest potential of success. Extensive research is done to introduce biomarkers which can predict the effectiveness of a specific targeted therapeutic approach. The EGFR signaling pathway includes several sufficient targets for the treatment of human cancers including NSCLC. Lung adenocarcinoma may harbor both activating and resistance mutations of the EGFR gene, and further, mutations of KRAS and BRAF oncogenes. Less frequent but targetable genetic alterations include ALK, ROS1, RET gene rearrangements, and various alterations of MET proto-oncogene. In addition, the importance of anti-tumor immunity and of tumor microenvironment has become evident recently. Accumulation of mutations generally trigger tumor specific immune defense, but immune protection may be upregulated as an aggressive feature. The blockade of immune checkpoints results in potential reactivation of tumor cell killing and induces significant tumor regression in various tumor types, such as lung carcinoma. Therapeutic responses to anti PD1-PD-L1 treatment may correlate with the expression of PD-L1 by tumor cells. Due to the wide range of diagnostic and predictive features in lung cancer a plenty of tests are required from a single small biopsy or cytology specimen, which is challenged by major issues of sample quantity and quality. Thus, the efficacy of biomarker testing should be warranted by standardized policy and optimal material usage. In this review we aim to discuss major targeted therapy-related biomarkers in NSCLC and testing possibilities comprehensively.

c-MET pathway in human malignancies and its targeting by natural compounds for cancer therapy

BACKGROUND

c-MET is a receptor tyrosine kinase which is classically activated by HGF to activate its downstream signaling cascades such as MAPK, PI3K/Akt/mTOR, and STAT3. The c-MET modulates cell proliferation, epithelial-mesenchymal transition (EMT), immune response, morphogenesis, apoptosis, and angiogenesis. The c-MET has been shown to serve a prominent role in embryogenesis and early development. The c-MET pathway is deregulated in a broad range of malignancies, due to overexpression of ligands or receptors, genomic amplification, and MET mutations. The link between the deregulation of c-MET signaling and tumor progression has been well-documented. Overexpression or overactivation of c-MET is associated with dismal clinical outcomes and acquired resistance to targeted therapies. Since c-MET activation results in the triggering of oncogenic pathways, abrogating the c-MET pathway is considered to be a pivotal strategy in cancer therapeutics. Herein, an analysis of role of the c-MET pathway in human cancers and its relevance in bone metastasis and therapeutic resistance has been undertaken. Also, an attempt has been made to summarize the inhibitory activity of selected natural compounds towards c-MET signaling in cancers.

METHODS

The publications related to c-MET pathway in malignancies and its natural compound modulators were obtained from databases such as PubMed, Scopus, and Google Scholar and summarized based on PRISMA guidelines. Some of the keywords used for extracting relevant literature are c-MET, natural compound inhibitors of c-MET, c-MET in liver cancer, c-MET in breast cancer, c-MET in lung cancer, c-MET in pancreatic cancer, c-MET in head and neck cancer, c-MET in bone metastasis, c-MET in therapeutic resistance, and combination of c-MET inhibitors and chemotherapeutic agents. The chemical structure of natural compounds was verified in PubChem database.

RESULTS

The search yielded 3935 publications, of which 195 reference publications were used for our analysis. Clinical trials were referenced using ClinicalTrials.gov identifier. The c-MET pathway has been recognized as a prominent target to combat the growth, metastasis, and chemotherapeutic resistance in cancers. The key role of the c-MET in bone metastasis as well as therapeutic resistance has been elaborated. Also, suppressive effect of selected natural compounds on the c-MET pathway in clinical/preclinical studies has been discussed.

MET alterations in advanced non-small cell lung cancer

Precision medicine has helped identify several tumor molecular aberrations to be treated with targeted therapies. These therapies showed substantial improvement in efficacy without excessive toxicity in patients with specific oncogenic drivers with advanced cancers. In metastatic lung cancers, the implementation of broad platforms for molecular tumor sequencing has helped oncology providers identify oncogenic drivers linked with better outcomes when treated upfront with targeted therapies. Mesenchymal-epithelial transition factor (MET) alterations are present in up to 60% of non-small cell lung cancer and are associated with a poor prognosis. Capmatinib and tepotinib are currently the only two approved targeted therapies by the U.S. Food and Drug Administration (FDA) for patients with MET exon 14 skipping mutation. Several agents are being developed to tackle an unmet need in patients with MET alterations. Some of these agents are being used in combination with EGFR targeted therapy to mitigate resistance to EGFR inhibitor. These agents are poised to provide new hope for these patients.

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

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

Fully automated radiolabeling of [68Ga]Ga-EMP100 targeting c-MET for PET-CT clinical imaging

BACKGROUND

c-MET is a transmembrane receptor involved in many biological processes and contributes to cell proliferation and migration during cancer invasion process. Its expression is measured by immunehistochemistry on tissue biopsy in clinic, although this technique has its limitations. PET-CT could allow in vivo mapping of lesions expressing c-MET, providing whole-body detection. A number of radiopharmaceuticals are under development for this purpose but are not yet in routine clinical use. EMP100 is a cyclic oligopeptide bound to a DOTA chelator, with nanomolar affinity for c-MET. The aim of this project was to develop an automated method for radiolabelling the radiopharmaceutical [68Ga]Ga-EMP100.

RESULTS

The main results showed an optimal pH range between 3.25 and 3.75 for the complexation reaction and a stabilisation of the temperature at 90 °C, resulting in an almost complete incorporation of gallium-68 after 10 min of heating. In these experiments, 90 µg of EMP-100 peptide were initially used and then lower amounts (30, 50, 75 µg) were explored to determine the minimum required for sufficient synthesis yield. Radiolysis impurities were identified by radio-HPLC and ascorbic acid and ethanol were used to improve the purity of the compound. Three batches of [68Ga]Ga-EMP100 were then prepared according to the optimised parameters and all met the established specifications. Finally, the stability of [68Ga]Ga-EMP100 was assessed at room temperature over 3 h with satisfactory results in terms of appearance, pH, radiochemical purity and sterility.

CONCLUSIONS

For the automated synthesis of [68Ga]Ga-EMP100, the parameters of pH, temperature, precursor peptide content and the use of adjuvants for impurity management were efficiently optimised, resulting in the production of three compliant and stable batches according to the principles of good manufacturing practice. [68Ga]Ga-EMP100 was successfully synthesised and is now available for clinical development in PET-CT imaging.

Molecular Basis and Natural History of Medullary Thyroid Cancer: It is (Almost) All in the RET

Medullary thyroid cancer (MTC) is a rare disease, which can be either sporadic (roughly 75% of cases) or genetically determined (multiple endocrine neoplasia type 2, due to REarranged during Transfection RET germline mutations, 25% of cases). Interestingly, RET pathogenic variants (mainly M918T) have also been reported in aggressive forms of sporadic MTC, suggesting the importance of RET signalling pathways in the pathogenesis of MTC. The initial theory of RET codon-related MTC aggressiveness has been recently questioned by studies suggesting that this would only define the age at disease onset rather than the aggressiveness of MTC. Other factors might however impact the natural history of the disease, such as RET polymorphisms, epigenetic factors, environmental factors, MET (mesenchymal-epithelial transition) alterations, or even other genetic alterations such as RAS family (HRAS, KRAS, NRAS) genetic alterations. This review will detail the molecular bases of MTC, focusing on RET pathways, and the potential mechanisms that explain the phenotypic intra- and interfamilial heterogeneity.

Tyrosine kinase signaling-independent MET-targeting with CAR-T cells

BACKGROUND

Recent progress in cancer immunotherapy encourages the expansion of chimeric antigen receptor (CAR) T cell therapy in solid tumors including hepatocellular carcinoma (HCC). Overexpression of MET receptor tyrosine kinase is common in HCC; however, MET inhibitors are effective only when MET is in an active form, making patient stratification difficult. Specific MET-targeting CAR-T cells hold the promise of targeting HCC with MET overexpression regardless of signaling pathway activity.

METHODS

MET-specific CARs with CD28ζ or 4-1BBζ as co-stimulation domains were constructed. MET-CAR-T cells derived from healthy subjects (HS) and HCC patients were evaluated for their killing activity and cytokine release against HCC cells with various MET activations in vitro, and for their tumor growth inhibition in orthotopic xenograft models in vivo.

RESULTS

MET-CAR.CD28ζ and MET-CAR.4-1BBζ T cells derived from both HS and HCC patients specifically killed MET-positive HCC cells. When stimulated with MET-positive HCC cells in vitro, MET-CAR.CD28ζ T cells demonstrated a higher level of cytokine release and expression of programmed cell death protein 1 (PD-1) than MET-CAR.4-1BBζ T cells. When analyzed in vivo, MET-CAR.CD28ζ T cells more effectively inhibited HCC orthotopic tumor growth in mice when compared to MET-CAR.4-1BBζ T cells.

CONCLUSION

We generated and characterized MET-specific CAR-T cells for targeting HCC with MET overexpression regardless of MET activation. Compared with MET-CAR.4-1BBζ, MET-CAR.CD28ζ T cells showed a higher anti-HCC potency but also a higher level of T cell exhaustion. While MET-CAR.CD28ζ is preferred for further development, overcoming the exhaustion of MET-CAR-T cells is necessary to improve their therapeutic efficacy in vivo.

Discovery of novel cMET-targeting antibody Fab drug conjugates as potential treatment for solid tumors with highly expressed cMET

BACKGROUND

Solid tumors are becoming prevalent affecting both old and young populations. Numerous solid tumors are associated with high cMET expression. The complexity of solid tumors combined with the highly interconnected nature of the cMET/HGF pathway with other cellular pathways make the pursuit of finding an effective treatment extremely challenging. The current standard of care for these malignancies is mostly small molecule-based chemotherapy. Antibody-based therapeutics as well as antibody drug conjugates are promising emerging classes against cMET-overexpressing solid tumors.

RESEARCH DESIGN AND METHODS

In this study, we described the design, synthesis, in vitro and in vivo characterization of cMET-targeting Fab drug conjugates (FDCs) as an alternative therapeutic strategy. The format is comprised of a Fab conjugated to a potent cytotoxic drug via a cleavable linker employing lysine-based and cysteine-based conjugation chemistries.

RESULTS

We found that the FDCs have potent anti-tumor efficacies in cancer cells with elevated overexpression of cMET. Moreover, they demonstrated a remarkable anti-tumor effect in a human gastric xenograft mouse model.

CONCLUSIONS

The FDC format has the potential to overcome some of the challenges presented by the other classes of therapeutics. This study highlights the promise of antibody fragment-based drug conjugate formats for the treatment of solid tumors.

The role of m6A methylation in therapy resistance in cancer

Cancer therapy resistance is the main cause of cancer treatment failure. The mechanism of therapy resistance is a hot topic in epigenetics. As one of the most common RNA modifications, N6-methyladenosine (m6A) is involved in various processes of RNA metabolism, such as stability, splicing, transcription, translation, and degradation. A large number of studies have shown that m6A RNA methylation regulates the proliferation and invasion of cancer cells, but the role of m6A in cancer therapy resistance is unclear. In this review, we summarized the research progress related to the role of m6A in regulating therapy resistance in cancers.

Overview of Molecular Detection Technologies for MET in Lung Cancer

MET tyrosine kinase receptor pathway activation has become an important actionable target in solid tumors. Aberrations in the MET proto-oncogene, including MET overexpression, the activation of MET mutations, MET mutations that lead to MET exon 14 skipping, MET gene amplifications, and MET fusions, are known to be primary and secondary oncogenic drivers in cancer; these aberrations have evolved as predictive biomarkers in clinical diagnostics. Thus, the detection of all known MET aberrations in daily clinical care is essential. In this review, current molecular technologies for the detection of the different MET aberrations are highlighted, including the benefits and drawbacks. In the future, another focus will be on the standardization of detection technologies for the delivery of reliable, quick, and affordable tests in clinical molecular diagnostics.

Antibody-Drug Conjugates for Lung Cancer: Payloads and Progress

Antibody Drug Conjugates (ADCs) are a novel class of therapeutic that structurally comprise an antibody directed at a tumor epitope connected via a linker to a cytotoxic payload that have shown significant antitumor activity across a range of malignancies including lung cancer. In this article we review the pharmacology of ADCs, describe results of trials with ADCs directed at targets in lung cancer including Trophoblast cell-surface antigen 2(TROP2), HER3, MET, Carcinoembryonic antigen-related cell adhesion molecular 5(CECAM-5) and HER2. Trastuzumab Deruxtecan (also known as DS-8201a or T-DXd) an ADC directed at HER2 recently became the first ADC to receive FDA approval in lung cancer, on the basis of its activity in tumors with HER2 mutations, demonstrated in the Destiny-Lung01 and Lung02 trials.

MET alterations in advanced non-small cell lung cancer

Targeting the MET pathway in advanced NSCLC has been of particular interest due to its role as both a primary oncogenic driver and secondary oncogenic driver of acquired resistance. Activation of the MET pathway can occur through several mechanisms, which can complicate the diagnostic and treatment approach. Recently, several MET-directed therapies have been developed with promising results. In this narrative review, we summarize the biology and mechanism of MET as a clinically relevant driver mutation, distinct MET alterations including diagnostic challenges, significance in the setting of acquired resistance, and novel treatment strategies in advanced NSCLC.

Phase Ib Study of Telisotuzumab Vedotin in Combination With Erlotinib in Patients With c-Met Protein-Expressing Non-Small-Cell Lung Cancer

PURPOSE

Overexpression of c-Met protein and epidermal growth factor receptor (EGFR) mutations can co-occur in non-small-cell lung cancer (NSCLC), providing strong rationale for dual targeting. Telisotuzumab vedotin (Teliso-V), a first-in-class antibody-drug conjugate targeting c-Met, has shown a tolerable safety profile and antitumor activity as monotherapy. Herein, we report the results of a phase Ib study (ClinicalTrials.gov identifier: NCT02099058) evaluating Teliso-V plus erlotinib, an EGFR tyrosine kinase inhibitor (TKI), in patients with c-Met-positive (+) NSCLC.

PATIENTS AND METHODS

This study evaluated Teliso-V (2.7 mg/kg once every 21 days) plus erlotinib (150 mg once daily) in adult patients (age ≥ 18 years) with c-Met+ NSCLC. Later enrollment required presence of an EGFR-activating mutation (EGFR-M+) and progression on a prior EGFR TKI. End points included safety, pharmacokinetics, objective response rate (ORR), and progression-free survival (PFS). The efficacy-evaluable population consisted of c-Met+ patients (confirmed histology [H]-score ≥ 150) who had at least one postbaseline scan; c-Met+ patients with H-scores ≥ 225 were classified as c-Met high.

RESULTS

As of January 2020, 42 patients were enrolled (N = 36 efficacy-evaluable). Neuropathies were the most common any-grade adverse events reported, with 24 of 42 patients (57%) experiencing at least one event. The pharmacokinetic profile of Teliso-V plus erlotinib was similar to Teliso-V monotherapy. Median PFS for all efficacy-evaluable patients was 5.9 months (95% CI, 2.8 to not reached). ORR for EGFR-M+ patients (n = 28) was 32.1%. Of EGFR-M+ patients, those who were c-Met high (n = 15) had an ORR of 52.6%. Median PFS was 6.8 months for non-T790M+ and for those whose T790M status was unknown, versus 3.7 months for T790M+.

CONCLUSION

Teliso-V plus erlotinib showed encouraging antitumor activity and acceptable toxicity in EGFR TKI-pretreated patients with EGFR-M+, c-Met+ NSCLC.

Molecular and Biological Investigation of Isolated Marine Fungal Metabolites as Anticancer Agents: A Multi-Target Approach

Cancer is the leading cause of death globally, with an increasing number of cases being annually reported. Nature-derived metabolites have been widely studied for their potential programmed necrosis, cytotoxicity, and anti-proliferation leading to enrichment for the modern medicine, particularly within the last couple of decades. At a more rapid pace, the concept of multi-target agents has evolved from being an innovative approach into a regular drug development procedure for hampering the multi-fashioned pathophysiology and high-resistance nature of cancer cells. With the advent of the Red Sea Penicillium chrysogenum strain S003-isolated indole-based alkaloids, we thoroughly investigated the molecular aspects for three major metabolites: meleagrin (MEL), roquefortine C (ROC), and isoroquefortine C (ISO) against three cancer-associated biological targets Cdc-25A, PTP-1B, and c-Met kinase. The study presented, for the first time, the detailed molecular insights and near-physiological affinity for these marine indole alkaloids against the assign targets through molecular docking-coupled all-atom dynamic simulation analysis. Findings highlighted the superiority of MEL's binding affinity/stability being quite in concordance with the in vitro anticancer activity profile conducted via sulforhodamine B bioassay on different cancerous cell lines reaching down to low micromolar or even nanomolar potencies. The advent of lengthy structural topologies via the metabolites' extended tetracyclic cores and aromatic imidazole arm permitted multi-pocket accommodation addressing the selectivity concerns. Additionally, the presence decorating polar functionalities on the core hydrophobic tetracyclic ring contributed compound's pharmacodynamic preferentiality. Introducing ionizable functionality with more lipophilic characters was highlighted to improve binding affinities which was also in concordance with the conducted drug-likeness/pharmacokinetic profiling for obtaining a balanced pharmacokinetic/dynamic profile. Our study adds to the knowledge regarding drug development and optimization of marine-isolated indole-based alkaloids for future iterative synthesis and pre-clinical investigations as multi-target anticancer agents.

An In silico Approach towards Finding the Cancer-Causing Mutations in Human MET Gene

Mesenchymal-epithelial transition (MET) factor is a proto-oncogene encoding tyrosine kinase receptor with hepatocyte growth factor (HGF) or scatter factor (SF). It is found on the human chromosome number 7 and regulates the diverse cellular mechanisms of the human body. The impact of mutations occurring in the MET gene is demonstrated by their detrimental effects on normal cellular functions. These mutations can change the structure and function of MET leading to different diseases such as lung cancer, neck cancer, colorectal cancer, and many other complex syndromes. Hence, the current study focused on finding deleterious non-synonymous single nucleotide polymorphisms (nsSNPs) and their subsequent impact on the protein's structure and functions, which may contribute to the emergence of cancers. These nsSNPs were first identified utilizing computational tools like SIFT, PROVEAN, PANTHER-PSEP, PolyPhen-2, I-Mutant 2.0, and MUpro. A total of 45359 SNPs of MET gene were accumulated from the database of dbSNP, and among them, 1306 SNPs were identified as non-synonymous or missense variants. Out of all 1306 nsSNPs, 18 were found to be the most deleterious. Moreover, these nsSNPs exhibited substantial effects on structure, binding affinity with ligand, phylogenetic conservation, secondary structure, and post-translational modification sites of MET, which were evaluated using MutPred2, RaptorX, ConSurf, PSIPRED, and MusiteDeep, respectively. Also, these deleterious nsSNPs were accompanied by changes in properties of MET like residue charge, size, and hydrophobicity. These findings along with the docking results are indicating the potency of the identified SNPs to alter the structure and function of the protein, which may lead to the development of cancers. Nonetheless, Genome-wide association study (GWAS) studies and experimental research are required to confirm the analysis of these nsSNPs.

Management and Treatment of Non-small Cell Lung Cancer with MET Alteration and Mechanisms of Resistance

OPINION STATEMENT

MET-driven tumors are a heterogenous group of non-small cell lung cancers (NSCLC) with activating mutations. Pathologic activation of MET can be achieved with increased number of gene copies overexpression, or decreased protein degradation through several mechanisms, including mutations, amplifications, or fusions. Besides its role as primary driver, MET activation might also mediate resistance to kinase inhibitors in NSCLC with various other actionable alterations. While checkpoint inhibitors have modest efficacy in MET-driven tumors, several approaches of targeted blockade are available. Among them the most promising are small tyrosine kinase inhibitors, antibody-drug conjugates, and bispecific antibodies. Unfortunately, resistance is virtually inevitable. Resistance to small kinase inhibitors might be mediated by kinase domain mutations or activation of shunting cascades. Various resistance mechanisms might be present in one patient, making it overcoming an unresolved problem.

MET-targeted therapies for the treatment of non-small-cell lung cancer: A systematic review and meta-analysis

BACKGROUND

Dysregulation of the mesenchymal epithelial transition (MET) pathway contributes to poor clinical outcomes in patients with non-small cell lung cancer (NSCLC). Numerous clinical trials are currently investigating several therapies based on modulation of the MET pathway.

OBJECTIVES

This study aimed to systematically evaluate the activity and safety of MET inhibitors in patients with NSCLC.

METHODS

We searched PubMed, Embase, and the Cochrane Library from inception to June 02, 2022. The objective response rate (ORR) and disease control rate (DCR) were extracted as the main outcomes and pooled using the weighted mean proportion with fixed- or random-effects models in cases of significant heterogeneity (I 2>50%). Safety analysis was performed based on adverse events reported in all studies.

RESULTS

Eleven studies (882 patients) were included in the meta-analysis. The pooled ORR was 28.1% (95% confidence interval [CI], 0.223-0.354), while the pooled DCR was 69.1% (95% CI, 0.631-0.756). ORRs were higher for tepotinib (44.7% [95% CI, 0.365-0.530]) and savolitinib (42.9% [95% CI, 0.311-0.553]) than for other types of MET inhibitors. Patients with NSCLC with exon 14 skipping exhibited higher ORRs (39.3% (95% CI, 0.296-0.522)) and DCRs (77.8% (95% CI, 0.714-0.847)) than those with MET protein overexpression or amplification. Intracranial response rate and intracranial disease control rates were 40.1% (95% CI, 0.289-0.556) and 95.4% (95% CI, 0.892-0.100), respectively. Adverse events were mild (grade 1 to 2) in 87.2% of patients. Common adverse events above grade 3 included lower extremity edema (3.5% [95% CI, 0.027-0.044]), alanine aminotransferase (ALT) elevation (2.4% [95% CI, 0.014-0.033]), and lipase elevation (2.2% [95% CI, 0.016-0.031]).

CONCLUSION

MET inhibitors, which exhibited a satisfactory safety profile in the current study, may become a new standard of care for addressing MET dysregulation in patients with advanced or metastatic NSCLC, and even in those with brain metastases, particularly tepotinib, savolitinib and capmatinib. Further randomized trials are required to establish standard predictive biomarkers for MET therapies and to compare the effects of different MET inhibitors in NSCLC with MET dysregulation.

MiR-23b-3p suppresses epithelial-mesenchymal transition, migration, and invasion of hepatocellular carcinoma cells by targeting c-MET

BACKGROUND

Aberrant expression of c-MET is known to be associated with tumor recurrence and metastasis by promoting cell proliferation, epithelial-mesenchymal transition (EMT), and migration in hepatocellular carcinoma (HCC). Recently, miR-23b-3p has been identified as a tumor suppressor, but detailed role of miR-23b-3p in HCC is still unclear. Our study aimed to investigate how miR-23b-3p is associated with the malignant potential of HCC cells.

METHODS

HCC tissues and their adjacent non-tumor tissues were acquired from 30 patients with HCC. Expression of EMT- or stemness-related genes were examined in the two HCC cell lines. Migration of HCC cells was analyzed using transwell and wound healing assays.

RESULTS

c-MET was overexpressed in HCC tissues compared to the adjacent non-tumor tissues. c-MET knockdown inhibited EMT and reduced migration and invasion of HCC cells. Furthermore, c-MET was a target of miR-23b-3p, and miR-23b-3p expression was decreased in HCC tissues compared to non-tumor tissues. Treatment of miR-23b-3p inhibitor in HCC cells promoted EMT, cell migration, and invasion. In contrast, miR-23b-3p overexpression suppressed EMT, cell migration, and invasion, concomitantly reducing c-MET expression. Transfection of miR-23b-3p inhibitor with concomitant c-MET knockdown mitigated the effects of miR-23b-3p inhibitor on EMT in HCC cells. In addition, transforming growth factor beta1 (TGF-β1) stimulation after miR-23b-3p overexpression induced neither the mesenchymal phenotype nor migratory property of HCC cells.

CONCLUSION

In this study, we confirmed that miR-23b-3p downregulation significantly increased EMT, migration, and invasion of HCC cells. In addition, c-MET was confirmed to be a target of miR-23b-3p in HCC cells and regulated the functional effects of miR-23b-3p. These results suggest that miR-23b-3p can be used as a prognostic biomarker and candidate target for HCC treatment.

Early Feasibility Assessment: A Method for Accurately Predicting Biotherapeutic Dosing to Inform Early Drug Discovery Decisions

The application of model-informed drug discovery and development (MID3) approaches in the early stages of drug discovery can help determine feasibility of drugging a target, prioritize between targets, or define optimal drug properties for a target product profile (TPP). However, applying MID3 in early discovery can be challenging due to the lack of pharmacokinetic (PK) and pharmacodynamic (PD) data at this stage. Early Feasibility Assessment (EFA) is the application of mechanistic PKPD models, built from first principles, and parameterized by data that is readily available early in drug discovery to make effective dose predictions. This manuscript demonstrates the ability of EFA to make accurate predictions of clinical effective doses for nine approved biotherapeutics and outlines the potential of extending this approach to novel therapeutics to impact early drug discovery decisions.

Met inhibitors in the treatment of lung cancer: the evidence to date

INTRODUCTION

: The hepatocyte growth factor (HGF) receptor MET is an oncogenic driver in a subpopulation of Non-small Lung Cancer Cells (NSCLC) at the primary tumor stage or in acquired resistance to treatment with tumor-targeting tyrosine kinase inhibitors (TKIs).

AREAS COVERED

This article summarizes the mechanisms leading to overexpression and activation of MET by amplification and mutations including exon 14 aberrations. Furthermore, the methods to detect and categorize MET as a tumor driver and the selective TKIs for patient treatment are discussed.

EXPERT OPINION

: Activating mutations and rearrangements of kinases in NSCLC are the target of successful therapeutic intervention. However, MET activation involves a number of complex alterations including gene amplification, prevention of degradation by METex14 exon skipping and a host of gene mutations. A high-level of MET expression is the precondition for tumor responses to TKIs and the confirmation of MET-dependent tumor progression is difficult in primary lesions and in tumors exhibiting resistance to mutated EGFR-directed therapy in absence of standardized and concordant assays of MET amplification.

Imaging Endocytosis Dynamics in Health and Disease

Endocytosis is a critical process for cell growth and viability. It mediates nutrient uptake, guarantees plasma membrane homeostasis, and generates intracellular signaling cascades. Moreover, it plays an important role in dead cell clearance and defense against external microbes. Finally, endocytosis is an important cellular route for the delivery of nanomedicines for therapeutic treatments. Thus, it is not surprising that both environmental and genetic perturbation of endocytosis have been associated with several human conditions such as cancer, neurological disorders, and virus infections, among others. Over the last decades, a lot of research has been focused on developing advanced imaging methods to monitor endocytosis events with high resolution in living cells and tissues. These include fluorescence imaging, electron microscopy, and correlative and super-resolution microscopy. In this review, we outline the major endocytic pathways and briefly discuss how defects in the molecular machinery of these pathways lead to disease. We then discuss the current imaging methodologies used to study endocytosis in different contexts, highlighting strengths and weaknesses.

CircTMTC1 contributes to nasopharyngeal carcinoma progression through targeting miR-495-MET-eIF4G1 translational regulation axis

Nasopharyngeal carcinoma (NPC) is the most common primary malignancy arising from the epithelial cells of nasopharynx. CircTMTC1 is upregulated in NPC patients, but its role and molecular mechanism in NPC are unknown. Normal nasopharyngeal epithelium and tumor tissues were collected. The expression of circTMTC1, miR-495, MET/eIF4G1 pathway-related molecules were examined. Colony formation and transwell assays were used to assess cell proliferation, migration, and invasion. Cell apoptosis was analyzed by annexin V and propidium iodide (PI) staining. Gene interaction was examined by RNA immunoprecipitation (RIP) and luciferase activity assays. Subcutaneous and intravenous xenograft mouse models were established to analyze NPC growth and metastasis in vivo. CircTMTC1 was highly expressed and miR-495 was downregulated in NPC, which were associated with poor prognosis of NPC. Both circTMTC1 knockdown and miR-495 overexpression inhibited NPC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) and promoted cell apoptosis. CircTMTC1 directly targeted miR-495 to promote the expression of its downstream target gene MET. miR-495 knockdown enhanced the expression of c-Myc, Cyclin D1, and survivin and accelerated NPC cell proliferation, migration, invasion, and EMT through targeting MET and activating the MET-eIF4G1 axis. CircTMTC1 silence inhibited NPC growth and lung metastasis by targeting the miR-495-MET-eIF4G1 translational regulation axis in vivo. CircTMTC1 accelerates NPC progression through targeting miR-495 and consequently activating the MET-eIF4G1 translational regulation axis, suggesting potential therapeutic targets for NPC treatment.

Discovery of small-molecule fluorescent probes for C-Met

C-mesenchymal-epithelia transition factor (c-Met) is highly expressed in various solid tumors such as gastric cancer, liver cancer, and lung cancer, playing a pivotal role in the growth, maintenance, and development of different tumor cells. In this study, three small-molecule fluorescent probes (5, 11, 16) targeting c-Met were developed, and their design strategies were also initially explored. In general, the fluorescence properties of the probes themselves could meet the imaging requirements, and they have shown sufficient inhibitory activities against c-Met, especially probe 16, reflecting the targeting and acceptance. Also, fluorescence polarization assays and flow cytometry analysis verified the binding between the probes and c-Met. Cell imaging confirmed that these probes could be used to label c-Met on living cells. It is of positive significance for the development of c-Met kinase inhibitors and tumor pathology research.

The Emerging Role of c-Met in Carcinogenesis and Clinical Implications as a Possible Therapeutic Target

Background

c-MET is a receptor tyrosine kinase receptor (RTK) for the hepatocyte growth factor (HGF). The binding of HGF to c-MET regulates several cellular functions: differentiation, proliferation, epithelial cell motility, angiogenesis, and epithelial-mesenchymal transition (EMT). Moreover, it is known to be involved in carcinogenesis. Comprehension of HGF-c-MET signaling pathway might have important clinical consequences allowing to predict prognosis, response to treatment, and survival rates based on its expression and dysregulation. Discussion. c-MET represents a useful molecular target for novel engineered drugs. Several clinical trials are underway for various solid tumors and the development of new specific monoclonal antibodies depends on the recent knowledge about the definite c-MET role in each different malignance. Recent clinical trials based on c-MET molecular targets result in good safety profile and represent a promising therapeutic strategy for solid cancers, in monotherapy or in combination with other target drugs.

Conclusion

The list of cell surface receptors crosslinking with the c-MET signaling is constantly growing, highlighting the importance of this pathway for personalized target therapy. Research on the combination of c-MET inhibitors with other drugs will hopefully lead to discovery of new effective treatment options.

Recent advances in lung cancer genomics: Application in targeted therapy

Genomic characterization of lung cancer has not only improved our understanding of disease biology and carcinogenesis but also revealed several therapeutic opportunities. Targeting tumor dependencies on specific genomic alterations (oncogene addiction) has accelerated the therapeutic developments and significantly improved the outcomes even in advanced stage of disease. Identification of genomic alterations predicting response to specific targeted treatment is the key to success for this "personalized treatment" approach. Availability of multiple choices of therapeutic options for specific genomic alterations highlight the importance of optimum sequencing of drugs. Multiplex gene testing has become mandatory in view of constantly increasing number of therapeutic targets and effective treatment options. Influence of genomic characteristics on response to immunotherapy further makes comprehensive genomic profiling necessary before therapeutic decision making. A comprehensive elucidation of resistance mechanisms and directed treatments have made the continuum of care possible and transformed this deadly disease into a chronic condition. Liquid biopsy-based approach has made the dynamic monitoring of disease possible and enabled treatment optimizations accordingly. Current lung cancer management is the perfect example of "precision-medicine" in clinical oncology.

Correlation of c-MET expression with clinical characteristics and the prognosis of colorectal cancer

Background

The proto-oncogene c-MET (mesenchymal-epithelial transition factor gene) plays a critical role in cellular proliferation, survival, migration, and invasion in cancers. The aim of this study is to explore the relationship between c-MET expression and the clinicopathological characteristics of colorectal cancer (CRC) patients.

Methods

A total of 337 enrolled patients were collected in present study. Here, the c-MET and EGFR expression were detected by immunohistochemistry (IHC). The mutational statuses of KRAS in exons 2, 3, and 4, NRAS in exons 2, 3, and 4, and BRAF in exon 15 from formalin-fixed sections were detected by direct DNA sequencing.

Results

Our results showed that high c-MET expression was significantly associated with tumor perineural invasion (P=0.007) and gender (P=0.016). High level c-MET expression (c-MET-high) in the primary tumors was observed in 68.2% of patients. In the 337 enrolled patients, 43.2% of patients had KRAS mutations, 3.3% of patients had NRAS mutations, and 4.7% of patients had BRAF mutations. However, KRAS, NRAS, and BRAF gene mutations had no association with c-MET protein levels in primary tumors. Additionally, c-MET protein expression had a strong correlation with EGFR expression (P=0.002). The survival time was not significantly longer for patients with c-MET-high primary tumors than for those with c-MET-low primary tumors.

Conclusions

c-MET immunohistochemistry was significantly higher in primary tumors with perineural invasion, female gender, and EGFR high expression. However, c-MET-high in the primary tumors was not significantly associated with longer survival compared with c-MET-low tumors. Further studies are required to investigate c-MET as potential molecular marker of progression and to test the possibility of its incorporation as a new therapeutic target.

MET Amplification and Efficacy of Nivolumab in Patients With NSCLC

Introduction

MET amplification is an important genetic alteration in NSCLC. Unlike in patients with EGFR and ALK alterations, the efficacy of immune checkpoint inhibitors in patients with MET-amplified NSCLC remains unknown.

Methods

An exploratory analysis of a prospective, multi-institutional cohort comprising 200 patients with advanced or recurrent NSCLC treated with nivolumab monotherapy was performed, and MET amplification was defined as a MET-to-CEP7 ratio of greater than or equal to 2 using fluorescent in situ hybridization. High-level and low-level MET gains were also defined as MET signals ≥10/nuclei and 10> MET signals ≥5/nuclei, respectively. Overall response rates (ORRs) and survival outcomes were evaluated on the basis of the MET gene copy number status.

Results

Among 175 patients eligible for analysis, MET amplification was detected in 13 tumors (7.4%). Four (2.3%) high-level and 14 (8.0%) low-level MET gains were also detected. There were no considerable differences in ORRs in accordance with the MET gene copy number status. Similarly, no significant differences in both progression-free survival (PFS) and overall survival (OS) were observed between patients with and without MET-amplified NSCLC (log-rank, p = 0.813 for PFS, and p = 0.855 for OS). Among 101 adenocarcinomas, ORRs in patients with high-level and low-level MET gains (50.0% for both, p = 0.049) were significantly higher than those without MET gains (17.6%), yet survival outcomes for both PFS and OS did not improve.

Conclusions

MET amplification was not associated with greater benefit of nivolumab treatment in patients with NSCLC. Further studies are warranted to prioritize immune checkpoint inhibitors in the treatment regimen for patients with MET amplification.

Mesenchymal-Epithelial Transition Exon 14 Skipping Mutation and Amplification in 5,008 Patients With Lung Cancer

Background

Lung cancer is a major health concern worldwide because of its increasing incidence and mortality. This study aimed to clarify the association between mesenchymal-epithelial transition (MET) genomic alterations and clinical characteristics of lung cancer.

Method

We collected data from 5,008 patients with lung cancer diagnosed and treated between January 2017 and July 2021 at the Affiliated Hospital of Qingdao University. Genomic alterations in the MET gene, including the exon 14 skipping mutation and amplification, were detected using amplification refractory mutation system-polymerase chain reaction (2,057 cases) and next-generation sequencing (2,951 cases). Clinical characteristics such as age, sex, tumor location, tumor stage, smoking, pleural invasion, and histology were statistically analyzed for MET exon 14 skipping mutation and amplification. The DNA splicing sites causing the MET exon 14 skipping mutation at the mRNA level were also investigated.

Results

The incidence of the MET exon 14 skipping mutation was 0.90% (41/4,564) in adenocarcinoma, 1.02% (3/294) in squamous cell carcinoma, and 8.33% (1/12) in sarcomatoid carcinoma specimens. It was more frequently observed in patients over 60 years of age than the MET exon 14 skipping mutation wildtype. The MET exon 14 skipping mutation co-occurred with epidermal growth factor receptor (EGFR) L858R, EGFR 19-Del, and BRAF V600E mutations. At the DNA level, single nucleotide mutation and small fragment deletion (1-38 base pairs) upstream and downstream of MET exon 14 led to MET exon 14 skipping mutation at the mRNA level. MET amplification occurred in 0.78% (21/2,676) adenocarcinoma and 1.07% (2/187) squamous cell carcinoma specimens and was significantly associated with advanced tumor stages (III + IV) compared to the MET amplification wildtype. MET amplification primarily co-occurred with the EGFR mutation.

Conclusions

Our study found that MET genomic alterations were statistically related to age and tumor stage and co-existed with mutations of other oncogenic driver genes, such as EGFR and BRAF. Moreover, various splicing site changes at the DNA level led to the exon 14 skipping mutation at the mRNA level. Further studies are required to clarify the association between MET genomic alterations and prognosis.

Protein Phosphatase 2A as a Therapeutic Target in Small Cell Lung Cancer

Protein phosphatase 2A (PP2A), a serine/threonine phosphatase involved in the regulation of apoptosis, proliferation, and DNA-damage response, is overexpressed in many cancers, including small cell lung cancer (SCLC). Here we report that LB100, a small molecule inhibitor of PP2A, when combined with platinum-based chemotherapy, synergistically elicited an antitumor response both in vitro and in vivo with no apparent toxicity. Using inductively coupled plasma mass spectrometry, we determined quantitatively that sensitization via LB100 was mediated by increased uptake of carboplatin in SCLC cells. Treatment with LB100 alone or in combination resulted in inhibition of cell viability in two-dimensional culture and three-dimensional spheroid models of SCLC, reduced glucose uptake, and attenuated mitochondrial and glycolytic ATP production. Combining LB100 with atezolizumab increased the capacity of T cells to infiltrate and kill tumor spheroids, and combining LB100 with carboplatin caused hyperphosphorylation of the DNA repair marker γH2AX and enhanced apoptosis while attenuating MET signaling and invasion through an endothelial cell monolayer. Taken together, these data highlight the translational potential of inhibiting PP2A with LB100 in combination with platinum-based chemotherapy and immunotherapy in SCLC.

Development of metastatic poorly differentiated thyroid cancer from a sub-centimeter papillary thyroid carcinoma in a young patient with a germline MET mutation - association or random chance?

Background

Thyroid cancer dedifferentiation is an unusual observation among young patients and is poorly understood, although a recent correlation to DICER1 gene mutations has been proposed.

Case presentation

A 28-year old patient presented with a sub-centimeter cytology-verified primary papillary thyroid carcinoma (PTC) and a synchronous lateral lymph node metastasis. Following surgery, histopathology confirmed a 9 mm oxyphilic PTC and a synchronous metastasis of poorly differentiated thyroid carcinoma (PDTC). Extensive molecular examinations of both lesions revealed wildtype DICER1 sequences, but identified a somatic ETV6-NTRK3 gene fusion and a MET germline variant (c.1076G > A, p.Arg359Gln). MET is an established oncogene known to be overexpressed in thyroid cancer, and this specific alteration was not reported as a single nucleotide polymorphism (SNP), suggestive of a mutation. Both the primary PTC and the metastatic PDTC displayed strong MET immunoreactivity. A validation cohort of 50 PTCs from young patients were analyzed using quantitative real-time PCR, revealing significantly higher MET gene expression in tumors than normal thyroid controls, a finding which was particularly pronounced in BRAF V600E mutated cases. No additional tumors apart from the index case harbored the p.Arg359Gln MET mutation. Transfecting PTC cell lines MDA-T32 and MDA-T41 with a p.Arg359Gln MET plasmid construct revealed no obvious effects on cellular migratory or invasive properties, whereas overexpression of wildtype MET stimulated invasion.

Conclusions

The question of whether the observed MET mutation in any way influenced the dedifferentiation of a primary PTC into a PDTC metastasis remains to be established. Moreover, our data corroborate earlier studies, indicating that MET is aberrantly expressed in PTC and may influence the invasive behavior of these tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13044-021-00110-4.

N6-methyladenosine methyltransferases: functions, regulation, and clinical potential

N6-methyladenosine (m6A) has emerged as an abundant modification throughout the transcriptome with widespread functions in protein-coding and noncoding RNAs. It affects the fates of modified RNAs, including their stability, splicing, and/or translation, and thus plays important roles in posttranscriptional regulation. To date, m6A methyltransferases have been reported to execute m6A deposition on distinct RNAs by their own or forming different complexes with additional partner proteins. In this review, we summarize the function of these m6A methyltransferases or complexes in regulating the key genes and pathways of cancer biology. We also highlight the progress in the use of m6A methyltransferases in mediating therapy resistance, including chemotherapy, targeted therapy, immunotherapy and radiotherapy. Finally, we discuss the current approaches and clinical potential of m6A methyltransferase-targeting strategies.

HGF/c-MET pathway in cancer: from molecular characterization to clinical evidence

This review provides a comprehensive landscape of HGF/c-MET (hepatocyte growth factor (HGF) /mesenchymal-epithelial transition factor (c-MET)) signaling pathway in cancers. First, we generalize the compelling influence of HGF/c-MET pathway on multiple cellular processes. Then, we present the genomic characterization of HGF/c-MET pathway in carcinogenesis. Furthermore, we extensively illustrate the malignant biological behaviors of HGF/c-MET pathway in cancers, in which hyperactive HGF/c-MET signaling is considered as a hallmark. In addition, we investigate the current clinical trials of HGF/c-MET-targeted therapy in cancers. We find that although HGF/c-MET-targeted therapy has led to breakthroughs in certain cancers, monotherapy of targeting HGF/c-MET has failed to demonstrate significant clinical efficacy in most cancers. With the advantage of the combinations of HGF/c-MET-targeted therapy, the exploration of more options of combinational targeted therapy in cancers may be the major challenge in the future.

Higher cMET dependence of sacral compared to clival chordoma cells: contributing to a better understanding of cMET in chordoma

Chordomas are rare slow growing, malignant bone tumors of the axial skeleton with no approved medical treatment. As the majority of chordomas express cMET and its ligand, HGF, and crosstalks between EGFR and MET-signaling exist, we aimed to explore cMET activity in chordoma cell lines and clinical samples. We investigated nine chordoma patients and four chordoma cell lines for cMET expression. Two clival and two sacral chordoma cell lines were tested for chromosomal abnormalities of the MET gene locus; we studied the influence of HGF on the autocrine secretion and migration behavior, as well as protein expression and phosphorylation. Two MET/ALK inhibitors were investigated for their effects on cell viability, cell cycle, cyclin alterations, apoptosis, and downstream signaling pathways. Moderate and strong expression of membrane and cytoplasmic cMET in chordoma patients and cell lines used, as well as concentration-dependent increase in phospho cMET expression after HGF stimulation in all four chordoma cell lines was shown. U-CH2, MUG-Chor1, and UM-Chor1 are polysomic for MET. Chordoma cell lines secreted EGF, VEGF, IL-6, and MMP9 upon HGF-stimulation. Sacral cell lines showed a distinct HGF-induced migration. Both inhibitors dose-dependently inhibited cell growth, induce apoptosis and cell-cycle arrest, and suppress downstream pathways. Heterogeneous responses obtained in our in vitro setting indicate that cMET inhibitors alone or in combination with other drugs might particularly benefit patients with sacral chordomas.

Translational pharmacokinetic-pharmacodynamic modeling of preclinical and clinical data of the oral MET inhibitor tepotinib to determine the recommended phase II dose

Tepotinib is a highly selective and potent MET inhibitor in development for the treatment of patients with solid tumors. Given the favorable tolerability and safety profiles up to the maximum tested dose in the first‐in‐human (FIH) trial, an efficacy‐driven translational modeling approach was proposed to establish the recommended phase II dose (RP2D). To study the in vivo pharmacokinetics (PKs)/target inhibition/tumor growth inhibition relationship, a subcutaneous KP‐4 pancreatic cell‐line xenograft model in mice with sensitivity to MET pathway inhibition was selected as a surrogate tumor model. Further clinical PK and target inhibition data (derived from predose and postdose paired tumor biopsies) from a FIH study were integrated with the longitudinal PKs and target inhibition profiles from the mouse xenograft study to establish a translational PK/pharmacodynamic (PD) model. Preclinical data showed that tumor regression with tepotinib treatment in KP‐4 xenograft tumors corresponded to 95% target inhibition. We therefore concluded that a PD criterion of sustained, near‐to‐complete (>95%) phospho‐MET inhibition in tumors should be targeted for tepotinib to be effective. Simulations of dose‐dependent target inhibition profiles in human tumors that exceeded the PD threshold in more than 90% of patients established an RP2D of tepotinib 500 mg once daily. This translational mathematical modeling approach supports an efficacy‐driven rationale for tepotinib phase II dose selection of 500 mg once daily. Tepotinib at this dose has obtained regulatory approval for the treatment of patients with non‐small cell lung cancer harboring MET exon 14 skipping.

A narrative review of MET inhibitors in non-small cell lung cancer with MET exon 14 skipping mutations

Treatment of advanced non-small cell lung cancer (NSCLC) has radically improved in the last years due to development and clinical approval of highly effective agents including immune checkpoint inhibitors (ICIs) and oncogene-directed therapies. Molecular profiling of lung cancer samples for activated oncogenes, including epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), c-ros oncogene 1 (ROS1) and BRAF, is routinely performed to select the most appropriate up-front treatment. However, the identification of new therapeutic targets remains a high priority. Recently, MET exon 14 skipping mutations have emerged as novel actionable oncogenic alterations in NSCLC, sensitive to MET inhibition. In this review we discuss: (I) MET gene and MET receptor structure and signaling pathway; (II) MET exon 14 alterations; (III) current data on MET inhibitors, mainly focusing on selective MET tyrosine kinase inhibitors (TKIs), in the treatment of NSCLC with MET exon 14 skipping mutations. We identified the references for this review through a literature search of papers about MET, MET exon 14 skipping mutations, and MET inhibitors, published up to September 2020, by using PubMed, Scopus and Web of Science databases. We also searched on websites of main international cancer congresses (ASCO, ESMO, IASLC) for ongoing studies presented as abstracts. MET exon 14 skipping mutations have been associated with clinical activity of selective MET inhibitors, including capmatinib, that has recently received approval by FDA for clinical use in this subgroup of NSCLC patients. A large number of trials are testing MET inhibitors, also in combinatorial therapeutic strategies, in MET exon 14-altered NSCLC. Results from these trials are eagerly awaited to definitively establish the role and setting for use of these agents in NSCLC patients.

Radiolabeled Peptide Probes for Liver Cancer Imaging

Liver cancer/Hepatocellular Carcinoma (HCC) is a leading cause of cancer death and represents an important cause of mortality worldwide. Several biomarkers are overexpressed in liver cancer, such as Glypican 3 (GPC3) and Epidermal Growth Factor Receptor (EGFR). These biomarkers play important roles in the progression of tumors and could serve as imaging and therapeutic targets for this disease. Peptides with adequate stability, receptor binding properties, and biokinetic behavior have been intensively studied for liver cancer imaging. A great variety of them have been radiolabeled with clinically relevant radionuclides for liver cancer diagnosis, and many are promising imaging and therapeutic candidates for clinical translation. Herein, we summarize the advancement of radiolabeled peptides for the targeted imaging of liver cancer.

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.

Genomic and clinical characteristics of MET exon14 alterations in a large cohort of Chinese cancer patients revealed distinct features and a novel resistance mechanism for crizotinib

Background: Alterations in MET exon 14 (METex14) and its flanking intronic regions have been identified in a variety of cancers. Patients with METex14 alterations often benefit from MET inhibitors such as crizotinib. Given the unique mutation profiles of Chinese lung cancer patients, it is necessary to investigate the prevalence of METex14 alterations in a large cohort of cancer patients. Patients and methods: Cases carrying METex14 alterations were screened from 26,391 Chinese cancer patients by next-generation sequencing (NGS), and the clinicopathologic and molecular characteristics were reviewed. Results: Compared to Western population (~3%), the frequency of METex14 alterations is much lower in Chinese cancer patients (0.7%, n=184) and lung cancer patients (1.1%, n=175). Seventy-eight distinct METex14 alterations, including several novel alteration types were detected. Concurrent MET copy gain and non-exon14 MET mutations were also found. EGFR copy gain (11%) and mutations (8%), KRAS (5%) and PIK3CA (5%), appeared in a mutually exclusive pattern. Female patients contain much less TP53 mutations than male patients (65% vs. 24%, FDR = 0.01). Co-amplification of CDK4 and MDM2, CDK6 and EGFR were identified, which indicated cell cycle dysregulation and EGFR alteration are important co-occurring features in patients with METex 14 alteration. Of 9 tissue specimens having PD-L1 immunohistochemistry (IHC) results, 5 of them (55.5%) were found PD-L1 positive, which is comparable to other types of tumor. In 14 crizotinib-treated patients, the median progression free survival (mPFS) was 7 months. Upon resistance to crizotinib, two patients acquired secondary mutations in MET and one patient acquired BRAF p.K601E that can be a novel resistance mechanism. Conclusion: Chinese cancer patients have a relatively lower frequency of METex14 alterations compared to Western patients. Patients with METex14 alterations showed distinct molecular characteristics and the representative case study showed responses to MET tyrosine kinase inhibitor (TKI).

Co-stimulatory and co-inhibitory immune markers in solid tumors with MET alterations

The implication of MET alterations in solid tumors and the immune microenvironment remains elusive. Formalin-fixed, paraffin-embedded samples of 21 patients with solid tumors harboring MET alterations were used for immunohistochemical staining. Extracted RNA was analyzed with the NanoString nCounter human PanCancer immune profiling panel (NanoString Technologies, Inc., WA, USA). Patients were diagnosed with lung (n = 10), breast (n = 5), genitourinary (n = 3) or colorectal cancer (n = 3). Eleven had a MET missense mutation, four had an exon 14 splice site mutation and six had MET amplification. CD6, CCL19, CD40LG, XCR1, MAGEA1, ATM and CCL19 genes were significantly differentially expressed in MET-altered cancers. MET alterations may have a role in various solid tumors as potential therapeutic targets and combination therapy candidates with immune checkpoint inhibitors.

MET is a receptor for growth signals that keeps cells alive and healthy. However, some tumors have changes in MET that allow for uncontrollable cell growth. Patients with MET-altered tumors may benefit from treatments targeting this gene, but eventually they become resistant to the treatments. Thus, there is a need to identify additional therapies for this patient population. The authors tested immune gene expression in tumors with MET alterations to determine if these patients would benefit from a new class of treatments called immunotherapies and found that patients with and without MET changes had differences in immune gene expression.