Sensitivity and Resistance of MET Exon 14 Mutations in Lung Cancer to Eight MET Tyrosine Kinase Inhibitors In Vitro

Metastatic Non-Small Cell Lung Cancer Mimicking Metaplastic Breast Cancer: A Case Report

NGS used to diagnose and treat NSCLC patient with initial concern for metaplastic breast cancer.

Phase 2 trial of crizotinib in Japanese patients with advanced NSCLC harboring a MET gene alteration: a Co-MET study

BACKGROUND

MET exon 14 skipping mutations occur in 3-4% and MET high amplifications occur in < 1% of patients with non-small-cell lung cancer (NSCLC). Crizotinib, a selective ATP-competitive small-molecule inhibitor of c-Met, ALK, and ROS1 tyrosine kinases, has shown activity in cancer models with various types of MET activation.

METHODS

The Co-MET study is a single-arm phase 2 trial to assess the safety and efficacy of crizotinib in MET inhibitor-naïve patients with advanced NSCLC harboring MET exon 14 skipping mutation (cohort 1) or high MET gene copy number of ≥ 7 (cohort 2). The primary endpoint was the objective response rate (ORR) per RECIST v1.1 by independent radiology review in cohort 1. The key secondary endpoints were the duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

A total of 28 patients (23 in cohort 1 and 5 in cohort 2) were enrolled between March 2018 and February 2020. The primary endpoint was met as the ORR (90% confidence interval: CI) in cohort 1 was 38.1% (20.6-58.3). Median DoR, PFS, and OS (95% CI) were 7.6 (1.9-NE), 5.7 (2.1-11.3), 9.1 (4.0-19.9) months, respectively, in cohort 1. ORR in cohort 2 was 40.0% (18.9-92.4). The safety signals were generally consistent with the known safety profile of crizotinib.

CONCLUSIONS

Crizotinib showed a clinical activity similar to that of tepotinib and capmatinib in patients with NSCLC harboring MET exon 14 skipping mutations.

CLINICAL TRIAL INFORMATION

UMIN000031623.

Conserved regulatory motifs in the juxtamembrane domain and kinase N-lobe revealed through deep mutational scanning of the MET receptor tyrosine kinase domain

MET is a receptor tyrosine kinase (RTK) responsible for initiating signaling pathways involved in development and wound repair. MET activation relies on ligand binding to the extracellular receptor, which prompts dimerization, intracellular phosphorylation, and recruitment of associated signaling proteins. Mutations, which are predominantly observed clinically in the intracellular juxtamembrane and kinase domains, can disrupt typical MET regulatory mechanisms. Understanding how juxtamembrane variants, such as exon 14 skipping (METΔEx14), and rare kinase domain mutations can increase signaling, often leading to cancer, remains a challenge. Here, we perform a parallel deep mutational scan (DMS) of the MET intracellular kinase domain in two fusion protein backgrounds: wild type and METΔEx14. Our comparative approach has revealed a critical hydrophobic interaction between a juxtamembrane segment and the kinase αC-helix, pointing to potential differences in regulatory mechanisms between MET and other RTKs. Additionally, we have uncovered a β5 motif that acts as a structural pivot for the kinase domain in MET and other TAM family of kinases. We also describe a number of previously unknown activating mutations, aiding the effort to annotate driver, passenger, and drug resistance mutations in the MET kinase domain.

Clinicopathological features, prognostic factor analysis, and survival nomogram of patients with double primary cancers involving lung cancer

BACKGROUND

Although the incidence of double primary cancers (DPCs) involving lung cancer is rising, they have not been studied sufficiently. This study retrospectively analyzed the clinicopathological and prognostic characteristics of DPC patients with lung cancer and developed a survival nomogram to predict the individual OS rates.

METHODS

We included 103 DPC patients with lung cancer from Shengjing Hospital between 2016 and 2021. Based on the 6-month cancer occurrence interval, the cases were categorized as synchronous DPCs (sDPCs) or metachronous DPCs (mDPCs). Furthermore, the mDPCs were subdivided based on whether the lung cancer occurred first (LCF cohort) or the other cancer occurred first (OCF cohort).

RESULTS

Among the patients, 35 (33.98%) and 68 (66.02%) had sDPCs and mDPCs, respectively. In the mDPCs cohort, 18 (26.47%) belonged to the LCF cohort and 50 (73.53%) to the OCF cohort. The most frequent primary cancer sites were the breast (27.18%), colorectum (22.33%), and urinary system (18.45%). Independent risk factors for progression-free survival were Stage IV lung cancer (p = 0.008) and failure to undergo radical lung cancer surgery (p = 0.028). The risk factors for OS included squamous carcinoma (p = 0.048), Stage IV lung cancer (p = 0.001), single cancer resection plus drug therapy (p < 0.001), drug therapy alone (p = 0.002), failure to undergo radical lung cancer surgery (p = 0.014), and chemotherapy (p = 0.042). The median OS was 37 months, with 3- and 5-year rates of 50.9% and 35.9%, respectively.

CONCLUSION

DPCs involving lung cancer account for 1.11% of cases. The breast, colorectum, and urinary system were the most common extra-pulmonary sites, and mDPCs were more frequent than sDPCs. Radical lung cancer surgery significantly affects prognosis, and drug therapy alone may be preferable when only one tumor is operable. The developed nomogram can accurately predict individual 3-year and 5-year OS rates.

TWIST1 is a critical downstream target of the HGF/MET pathway and is required for MET driven acquired resistance in oncogene driven lung cancer

MET amplification/mutations are important targetable oncogenic drivers in NSCLC, however, acquired resistance is inevitable and the majority of patients with targetable MET alterations fail to respond to MET tyrosine kinase inhibitors (TKIs). Furthermore, MET amplification is among the most common mediators of TKI resistance. As such, novel therapies to target MET pathway and overcome MET TKI resistance are clearly needed. Here we show that the epithelial-mesenchymal transition (EMT) transcription factor, TWIST1 is a key downstream mediator of HGF/MET induced resistance through suppression of p27 and targeting TWIST1 can overcome resistance. We found that TWIST1 is overexpressed at the time of TKI resistance in multiple MET-dependent TKI acquired resistance PDX models. We have shown for the first time that MET directly stabilized the TWIST protein leading to TKI resistance and that TWIST1 was required for MET-driven lung tumorigenesis as well as could induce MET TKI resistance when overexpressed. TWIST1 mediated MET TKI resistance through suppression of p27 expression and genetic or pharmacologic inhibition of TWIST1 overcame TKI resistance in vitro and in vivo. Our findings suggest that targeting TWIST1 may be an effective therapeutic strategy to overcome resistance in MET-driven NSCLC as well as in other oncogene driven subtypes in which MET amplification is the resistance mechanism.

Recording and classifying MET receptor mutations in cancers

Tyrosine kinase inhibitors (TKI) directed against MET have been recently approved to treat advanced non-small cell lung cancer (NSCLC) harbouring activating MET mutations. This success is the consequence of a long characterization of MET mutations in cancers, which we propose to outline in this review. MET, a receptor tyrosine kinase (RTK), displays in a broad panel of cancers many deregulations liable to promote tumour progression. The first MET mutation was discovered in 1997, in hereditary papillary renal cancer (HPRC), providing the first direct link between MET mutations and cancer development. As in other RTKs, these mutations are located in the kinase domain, leading in most cases to ligand-independent MET activation. In 2014, novel MET mutations were identified in several advanced cancers, including lung cancers. These mutations alter splice sites of exon 14, causing in-frame exon 14 skipping and deletion of a regulatory domain. Because these mutations are not located in the kinase domain, they are original and their mode of action has yet to be fully elucidated. Less than five years after the discovery of such mutations, the efficacy of a MET TKI was evidenced in NSCLC patients displaying MET exon 14 skipping. Yet its use led to a resistance mechanism involving acquisition of novel and already characterized MET mutations. Furthermore, novel somatic MET mutations are constantly being discovered. The challenge is no longer to identify them but to characterize them in order to predict their transforming activity and their sensitivity or resistance to MET TKIs, in order to adapt treatment.

Phase II study investigating the efficacy and safety of glesatinib (MGCD265) in patients with advanced NSCLC containing MET activating alterations

OBJECTIVES

Dysregulated signaling by mesenchymal epithelial transition factor (MET) and heightened AXL activation are implicated in the pathogenesis of non-small cell lung cancer (NSCLC). Glesatinib (MGCD265) is an investigational, oral inhibitor of MET and AXL.

MATERIALS AND METHODS

This open-label, Phase II study investigated glesatinib (free-base suspension [FBS] capsule 1050 mg BID or spray-dried dispersion [SDD] tablet 750 mg BID) in patients with advanced, previously treated NSCLC across four cohorts grouped according to presence of MET activating mutations or amplification in tumor or ctDNA. The primary endpoint was objective response rate (ORR).

RESULTS

Sixty-eight patients were enrolled: n = 28 and n = 8 with MET exon 14 skipping mutations in tumor tissue and ctDNA, respectively, and n = 20 and n = 12 with MET gene amplification in tumor tissue and ctDNA, respectively. Overall, ORR was 11.8 %, median progression-free survival was 4.0 months, and median overall survival was 7.0 months. Among patients with MET activating mutations, ORR was 10.7 % with tumor testing and 25.0 % with ctDNA testing. For MET amplification, responses were observed only in patients enrolled by tumor testing (ORR 15.0 %). Diarrhea (82.4 %), nausea (50.0 %), increased alanine aminotransferase (41.2 %), fatigue (38.2 %), and increased aspartate aminotransferase (36.8 %) were the most frequent adverse events assessed as related to study medication. Glesatinib exposure was similar with the SDD tablet and FBS capsule formulations. The study was terminated early by the sponsor due to modest clinical activity.

CONCLUSIONS

Glesatinib had an acceptable safety profile in patients with advanced, pre-treated NSCLC with MET activating alterations. Modest clinical activity was observed, which likely reflects suboptimal drug bioavailability suggested by previously reported Phase I data, and pharmacodynamic findings of lower than anticipated increases in circulating soluble shed MET ectodomain (s-MET).

EGFR degraders in non-small-cell lung cancer: Breakthrough and unresolved issue

The epidermal growth factor receptor (EGFR) has been well validated as a therapeutic target for anticancer drug discovery. Osimertinib has become the first globally accessible third-generation EGFR inhibitor, representing one of the most advanced developments in non-small-cell lung cancer (NSCLC) therapy. However, a tertiary Cys797 to Ser797 (C797S) point mutation has hampered osimertinib treatment in patients with advanced EGFR-mutated NSCLC. Several classes of fourth-generation EGFR inhibitors were consequently discovered with the aim of overcoming the EGFRC797S mutation-mediated resistance. However, no clinical efficacy data of the fourth-generation EGFR inhibitors were reported to date, and EGFRC797S mutation-mediated resistance remains an "unmet clinical need." Proteolysis-targeting chimeric molecules (PROTACs) obtained from EGFR-TKIs have been developed to target drug resistance EGFR in NSCLC. Some PROTACs are from nature products. These degraders compared with EGFR inhibitors showed better efficiency in their cellular potency, inhibition, and toxicity profiles. In this review, we first introduce the structural properties of EGFR, the resistance, and mutations of EGFR, and then mainly focus on the recent advances of EGFR-targeting degraders along with its advantages and outstanding challenges.

From osimertinib to preemptive combinations

Here, I suggest that while first-line osimertinib extends median progression-free survival (PFS) in EGFR-mutant lung cancer compared to first-generation TKIs, it reduces individual PFS in 15-20% of patients compared to first-generation TKIs. Since detecting a single resistant cell before treatment is usually impossible, osimertinib must be used in all patients as a first-line treatment, raising median PFS overall but harming some. The simplest remedy is a preemptive combination (PC) of osimertinib and gefitinib. A comprehensive PC (osimertinib, afatinib/gefitinib, and capmatinib) could dramatically increase PFS for 80% of patients compared to osimertinib alone, without harming anyone. This article also explores PCs for MET-driven lung cancer.

Targeting MET in NSCLC: An Ever-Expanding Territory

MET protooncogene (MET) alterations are known driver oncogenes in NSCLC. Since the identification of MET as a potential therapeutic target, extensive clinical trials have been performed. As a result, MET-targeted therapies, including MET tyrosine kinase inhibitors, monoclonal antibodies, and MET antibody-drug conjugates now play important roles in the standard treatment of MET-altered NSCLC; they have considerably improved the outcomes of patients with tumors that harbor MET oncogenic drivers. Although clinical agents are currently available and numerous other options are in development, particular challenges in the field require attention. For example, the therapeutic efficacy of each drug remains unsatisfactory, and concomitantly, the resistance mechanisms are not fully understood. Thus, there is an urgent need for optimal drug sequencing and combinations, along with a thorough understanding of treatment resistance. In this review, we describe the current landscape of pertinent clinical trials focusing on MET-targeted strategies and discuss future developmental directions in this rapidly expanding field.

My battle with cancer. Part 1

In January 2023, diagnosed with numerous metastases of lung cancer in my brain, I felt that I must accomplish a mission. If everything happens for a reason, my cancer, in particular, I must find out how metastatic cancer can be treated with curative intent. This is my mission now, and the reason I was ever born. In January 2023, I understood the meaning of life, of my life. I was born to write this article. In this article, I argue that monotherapy with targeted drugs, even when used in sequence, cannot cure metastatic cancer. However, preemptive combinations of targeted drugs may, in theory, cure incurable cancer. Also, I share insights on various topics, including rapamycin, an anti-aging drug that can delay but not prevent cancer, through my personal journey.

The Treatment of a New Entity in Advanced Non-small Cell Lung Cancer: MET Exon 14 Skipping Mutation

BACKGROUND

MET (MET Proto-Oncogene, Receptor Tyrosine Kinase) exon 14 skipping mutation represents one of the most common MET alterations, accounting for approximately 1-3% of all mutations in advanced lung adenocarcinomas. While until 2020 no specific treatment was available for this subset of patients, as of today, three MET Tyrosine Kinase Inhibitors (TKIs) are currently approved in this setting, namely capmatinib, tepotinib and savolitinib.

OBJECTIVE

This article aims to provide an extensive overview of the current therapeutic standard of care for exon 14 skipped advanced Non-small Cell Lung Cancer (NSCLC) patients, alongside with mentions of the main future challenges and opportunities.

CONCLUSION

FDA-approved MET-TKIs currently represent the best option for treating exon 14 skipped advanced NSCLC patients, thanks to their excellent efficacy profile, alongside their manageable safety and tolerability. However, we currently lack specific agents to treat patients progressing on capmatinib or tepotinib, due to a limited understanding of the mechanisms underlying both on- and off-target resistance. In this respect, on-target mutations presently constitute the most explored ones from a mechanistic point of view, and type II MET-TKIs are currently under investigation as the most promising agents capable of overcoming the acquired resistance.

Tepotinib in patients with non-small cell lung cancer with high-level MET amplification detected by liquid biopsy: VISION Cohort B

High-level MET amplification (METamp) is a primary driver in ∼1%-2% of non-small cell lung cancers (NSCLCs). Cohort B of the phase 2 VISION trial evaluates tepotinib, an oral MET inhibitor, in patients with advanced NSCLC with high-level METamp who were enrolled by liquid biopsy. While the study was halted before the enrollment of the planned 60 patients, the results of 24 enrolled patients are presented here. The objective response rate (ORR) is 41.7% (95% confidence interval [CI], 22.1-63.4), and the median duration of response is 14.3 months (95% CI, 2.8-not estimable). In exploratory biomarker analyses, focal METamp, RB1 wild-type, MYC diploidy, low circulating tumor DNA (ctDNA) burden at baseline, and early molecular response are associated with better outcomes. Adverse events include edema (composite term; any grade: 58.3%; grade 3: 12.5%) and constipation (any grade: 41.7%; grade 3: 4.2%). Tepotinib provides antitumor activity in high-level METamp NSCLC (ClinicalTrials.gov: NCT02864992).

Targeting the hedgehog pathway in MET mutation cancers and its effects on cells associated with cancer development

The mutation of MET plays a crucial role in the initiation of cancer, while the Hedgehog (Hh) pathway also plays a significant role in cell differentiation and the maintenance of tumor stem cells. Conventional chemotherapy drugs are primarily designed to target the majority of cell populations within tumors rather than tumor stem cells. Consequently, after a brief period of remission, tumors often relapse. Moreover, the exclusive targeting of tumor stemness cell disregards the potential for other tumor cells to regain stemness and acquire drug resistance. As a result, current drugs that solely target the HGF/c-MET axis and the Hh pathway demonstrate only moderate efficacy in specific types of cancer. Mounting evidence indicates that these two pathways not only play important roles in cancer but also exert significant influence on the development of resistance to single-target therapies through the secretion of their own ligands. In this comprehensive review, we analyze and compare the potential impact of the Hh pathway on the tumor microenvironment (TME) in HGF/c-MET-driven tumor models, as well as the interplay between different cell types. Additionally, we further substantiate the potential and necessity of dual-pathway combination therapy as a critical target in MET addicted cancer treatment. Video Abstract.

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 development of amivantamab for the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) patients with sensitizing oncogenic driver mutations benefit from targeted therapies. Tyrosine kinase inhibitors are highly effective against classic sensitizing epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletions and exon 21 L858R point mutations. Conversely, EGFR exon 20 insertions (exon20ins) are resistant to the traditional EGFR tyrosine kinase inhibitors (TKIs). In May 2021, the US Federal Drug Administration (FDA) provided accelerated approval to amivantamab (Rybrevant) in adults with locally advanced or metastatic NSCLC with EGFR exon20ins after treatment with platinum-based chemotherapy. Amivantamab was the first EGFR/MET bispecific antibody to be approved specifically for EGFR exon20ins where there was an unmet need. Furthermore, amivantamab is being evaluated in additional settings such as post osimertinib in sensitizing EGFR mutations as well as in MET altered NSCLC. Here we discuss amivantamab in regard to its mechanism of action, preclinical and clinical data, and clinical impact for patients with EGFR exon20ins NSCLC and beyond.

RNA splicing alterations in lung cancer pathogenesis and therapy

RNA splicing alterations are widespread and play critical roles in cancer pathogenesis and therapy. Lung cancer is highly heterogeneous and causes the most cancer-related deaths worldwide. Large-scale multi-omics studies have not only characterized the mutational landscapes but also discovered a plethora of transcriptional and post-transcriptional changes in lung cancer. Such resources have greatly facilitated the development of new diagnostic markers and therapeutic options over the past two decades. Intriguingly, altered RNA splicing has emerged as an important molecular feature and therapeutic target of lung cancer. In this review, we provide a brief overview of splicing dysregulation in lung cancer and summarize the recent progress on key splicing events and splicing factors that contribute to lung cancer pathogenesis. Moreover, we describe the general strategies targeting splicing alterations in lung cancer and highlight the potential of combining splicing modulation with currently approved therapies to combat this deadly disease. This review provides new mechanistic and therapeutic insights into splicing dysregulation in cancer.

MET in Non-Small-Cell Lung Cancer (NSCLC): Cross 'a Long and Winding Road' Looking for a Target

Non-Small-Cell Lung Cancer (NSCLC) can harbour different MET alterations, such as MET overexpression (MET OE), MET gene amplification (MET AMP), or MET gene mutations. Retrospective studies of surgical series of patients with MET-dysregulated NSCLC have shown worse clinical outcomes irrespective of the type of specific MET gene alteration. On the other hand, earlier attempts failed to identify the 'druggable' molecular gene driver until the discovery of MET exon 14 skipping mutations (METex14). METex14 are rare and amount to around 3% of all NSCLCs. Patients with METex14 NSCLC attain modest results when they are treated with immune checkpoint inhibitors (ICIs). New selective MET inhibitors (MET-Is) showed a long-lasting clinical benefit in patients with METex14 NSCLC and modest activity in patients with MET AMP NSCLC. Ongoing clinical trials are investigating new small molecule tyrosine kinase inhibitors, bispecific antibodies, or antibodies drug conjugate (ADCs). This review focuses on the prognostic role of MET, the summary of pivotal clinical trials of selective MET-Is with a focus on resistance mechanisms. The last section is addressed to future developments and challenges.

The Combined Therapy of Cabozantinib, Crizotinib, and Osimertinib in a Lung Cancer Patient with Acquired MET Amplification and Resistance Mutations

EGFR-mutant lung cancers develop a wide range of potential resistance alterations under therapy with the third-generation EGFR tyrosine kinase inhibitor osimertinib. MET amplification ranks among the most common acquired resistance alterations and is currently being investigated as a therapeutic target in several studies. Nevertheless, targeted therapy of MET might similarly result in acquired resistance by point mutations in MET, which further expands therapeutic and diagnostic challenges. Here, we report a 50-year-old male patient with EGFR-mutant lung adenocarcinoma and stepwise acquired resistance by a focal amplification of MET followed by D1246N (D1228N), D1246H (D1228H), and L1213V (L1195V) point mutations in MET, all detected by NGS. The patient successfully responded to the combined and sequential treatment of osimertinib, osimertinib/crizotinib, and third-line osimertinib/cabozantinib. This case highlights the importance of well-designed, sequential molecular diagnostic analyses and the personalized treatment of patients with acquired resistance.

BBT-176, a Novel Fourth-Generation Tyrosine Kinase Inhibitor for Osimertinib-Resistant EGFR Mutations in Non-Small Cell Lung Cancer

PURPOSE

Resistance to third-generation EGFR inhibitors including osimertinib arises in part from the C797S mutation in EGFR. Currently, no targeted treatment option is available for these patients. We have developed a new EGFR tyrosine kinase inhibitor (TKI), BBT-176, targeting the C797S mutation.

PATIENTS AND METHODS

Recombinant EGFR proteins and Ba/F3 cell lines, patient-derived cells, and patient-derived xenografts expressing mutant EGFRs were used to test the inhibitory potency and the anticancer efficacy of BBT-176 both in vitro and in vivo. Patient case data are also available from an ongoing phase I clinical trial (NCT04820023).

RESULTS

The half maximal inhibitory concentration (IC50) of BBT-176 against EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, and EGFR L858R/C797S proteins were measured at 4.36, 1.79, and 5.35 nmol/L, respectively (vs. 304.39, 124.82, and 573.72 nmol/L, for osimertinib). IC50 values of BBT-176 against Ba/F3 cells expressing EGFR 19Del/C797S, EGFR 19Del/T790M/C797S, EGFR L858R/C797S, and EGFR L858R/T790M/C797S were 42, 49, 183, and 202 nmol/L, respectively (vs. 869, 1,134, 2,799, and 2,685 nmol/L for osimertinib). N-ethyl-N-nitrosourea mutagenesis suggested that BBT-176 treatment does not introduce any secondary mutations in the EGFR gene but increases EGFR expression levels. Combined with the EGFR antibody cetuximab, BBT-176 effectively suppressed the growth of BBT-176-resistant clones. BBT-176 strongly inhibited the tumor growth, and in some conditions induced tumor regression in mouse models. In the clinical trial, two patients harboring EGFR 19Del/T790M/C797S in blood showed tumor shrinkage and radiologic improvements.

CONCLUSIONS

BBT-176 is a fourth-generation EGFR inhibitor showing promising preclinical activity against NSCLC resistant to current EGFR TKI, with early clinical efficacy and safety.

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.

Targeting MET in Non-Small Cell Lung Cancer (NSCLC): A New Old Story?

In recent years, we have seen the development and approval for clinical use of an increasing number of therapeutic agents against actionable oncogenic drivers in metastatic non-small cell lung cancer (NSCLC). Among them, selective inhibitors, including tyrosine kinase inhibitors (TKIs) and monoclonal antibodies targeting the mesenchymal-epithelial transition (MET) receptor, have been studied in patients with advanced NSCLC with MET deregulation, primarily due to exon 14 skipping mutations or MET amplification. Some MET TKIs, including capmatinib and tepotinib, have proven to be highly effective in this molecularly defined subgroup of patients and are already approved for clinical use. Other similar agents are being tested in early-stage clinical trials with promising antitumor activity. The purpose of this review is to provide an overview of MET signaling pathways, MET oncogenic alterations primarily focusing on exon 14 skipping mutations, and the laboratory techniques used to detect MET alterations. Furthermore, we will summarize the currently available clinical data and ongoing studies on MET inhibitors, as well as the mechanisms of resistance to MET TKIs and new potential strategies, including combinatorial approaches, to improve the clinical outcomes of MET exon 14-altered NSCLC patients.

Targeting MET: Discovery of Small Molecule Inhibitors as Non-Small Cell Lung Cancer Therapy

MET has been considered as a promising drug target for the treatment of MET-dependent diseases, particularly non-small cell lung cancer (NSCLC). Small molecule MET inhibitors with mainly three types of binding modes (Ia/Ib, II, and III) have been developed. In this Review, we provide an overview of the structural features, activation mechanism, and dysregulation pathway of MET and summarize progress on the development and discovery strategies utilized for MET inhibitors as well as mechanisms of acquired resistance to current approved inhibitors. The insights will accelerate discovery of new generation MET inhibitors to overcome clinical acquired resistance.

SYK-mediated epithelial cell state is associated with response to c-Met inhibitors in c-Met-overexpressing lung cancer

Genomic MET amplification and exon 14 skipping are currently clinically recognized biomarkers for stratifying subsets of non-small cell lung cancer (NSCLC) patients according to the predicted response to c-Met inhibitors (c-Metis), yet the overall clinical benefit of this strategy is quite limited. Notably, c-Met protein overexpression, which occurs in approximately 20-25% of NSCLC patients, has not yet been clearly defined as a clinically useful biomarker. An optimized strategy for accurately classifying patients with c-Met overexpression for decision-making regarding c-Meti treatment is lacking. Herein, we found that SYK regulates the plasticity of cells in an epithelial state and is associated with their sensitivity to c-Metis both in vitro and in vivo in PDX models with c-Met overexpression regardless of MET gene status. Furthermore, TGF-β1 treatment resulted in SYK transcriptional downregulation, increased Sp1-mediated transcription of FRA1, and restored the mesenchymal state, which conferred resistance to c-Metis. Clinically, a subpopulation of NSCLC patients with c-Met overexpression coupled with SYK overexpression exhibited a high response rate of 73.3% and longer progression-free survival with c-Meti treatment than other patients. SYK negativity coupled with TGF-β1 positivity conferred de novo and acquired resistance. In summary, SYK regulates cell plasticity toward a therapy-sensitive epithelial cell state. Furthermore, our findings showed that SYK overexpression can aid in precisely stratifying NSCLC patients with c-Met overexpression regardless of MET alterations and expand the population predicted to benefit from c-Met-targeted therapy.

Potent antitumor activity of ensartinib in MET exon 14 skipping-mutated non-small cell lung cancer

Met proto-oncogene exon 14 skipping (METex14) mutations are targetable driver genes in approximately 3% of non-small-cell lung cancers (NSCLCs). Ensartinib, a type Ia MET inhibitor, is a multi-kinase inhibitor that has been approved for ALK-positive NSCLCs. Ensartinib was administered for compassionate use (cohort 1) and in a phase II clinical trial (cohort 2) to patients with METex14 mutant NSCLCs, with ORR as a primary endpoint. Molecular simulation was conducted to evaluate ensartinib c-MET interaction, and cell lines, patient-derived organoids (PDOs), and xenograft models were used to test the effectiveness of ensartinib. Among 29 evaluable patients, the ORR and DCR of ensartinib were 67% and 94% in cohort 1, and 73% and 91% in cohort 2. The median DoR was 6.8 months and median PFS was 6.1 months in the total population. Rash was the most common drug-related adverse event, and peripheral edema of any grade was reported in only 9% patients. Molecular simulations indicated favorable binding of ensartinib to c-MET. The kinase assay demonstrated an IC₅₀ of 7.9 nM of ensartinib against METex14 protein. In vitro, Hs746T (METex14 mutation) and EBC-1 (MET amplification) cells were sensitive to ensartinib, with IC₅₀ of 31 and 44 nM, respectively. Ensartinib exhibited comparable inhibitory effects on cell migration as crizotinib and tepotinib in both cell types. In vivo, ensartinib suppressed the growth of Hs746T cells. Ensartinib also potently inhibited the viability of PDOs. Overall, Ensartinib exhibited substantial antitumor effects against METex14 mutant NSCLCs in preclinical and clinical trials, with relatively low peripheral edema rates.

Effect of capmatinib on the pharmacokinetics of substrates of CYP3A (midazolam) and CYP1A2 (caffeine) in patients with MET-dysregulated solid tumours

BACKGROUND

Preclinical studies showed that capmatinib reversibly inhibits cytochrome P450 (CYP) 3A4 and CYP1A2 in a time-dependent manner. In this study, we evaluated the effect of capmatinib on the exposure of sensitive substrates of CYP3A (midazolam) and CYP1A2 (caffeine) in patients with mesenchymal-epithelial transition (MET)-dysregulated solid tumours. Besides pharmacokinetics, we assessed treatment response and safety.

METHODS

This open-label, multicentre, single-sequence study consisted of a molecular prescreening period, a screening/baseline period of ≤28 days and a drug-drug interaction (DDI) phase of 12 days. On day 1 of the DDI phase, 37 patients received a single oral dose of midazolam 2.5 mg and caffeine 100 mg as a two-drug cocktail. Capmatinib 400 mg bid was administered from day 4 on a continuous dosing schedule. On day 9 of the DDI phase, patients were re-exposed to midazolam and caffeine. After the DDI phase, patients received capmatinib on continuous 21-day cycles until disease progression at the discretion of the investigator.

RESULTS

A 22% (90% confidence interval [CI] 7-38%) increase in the midazolam maximum plasma concentration (C_max ) was noted when administered with capmatinib, but this was deemed not clinically meaningful. Co-administration with capmatinib resulted in 134% (90% CI 108-163%) and 122% (90% CI 95-153%) increases in the caffeine area under the plasma concentration-time curve from time zero to infinity (AUC_inf ) and area under the plasma concentration-time curve from time zero to the last measurable point (AUC_last ), respectively, with no change in C_max . Adverse events were consistent with the known capmatinib safety profile. No new safety signals were reported in this study.

CONCLUSION

The data from this study demonstrated that capmatinib is a moderate CYP1A2 inhibitor. Capmatinib administration did not cause any clinically relevant changes in midazolam exposure.

Possible role of combined therapy targeting MET and pro-HGF activation for renal cell carcinoma: analysis by human HGF-producing SCID mice

MET is a high-affinity receptor tyrosine kinase of HGF (hepatocyte growth factor). HGF is secreted as an inactive single-chain precursor (pro-HGF), which requires proteolytic activation for conversion to an active form. HGF activator inhibitor (HAI)-2 is a transmembrane Kunitz-type serine protease inhibitor, which inhibits all pro-HGF-activating enzymes. In RCC, increased expression of MET and decreased expression of HAI-2 were reported to be poor prognostic factors. In the current study, we tried to inhibit the growth of RCC cells by dual inhibition of both MET phosphorylation and pro-HGF-activation using MET inhibitor and HAI-2 overexpression. A transgenic mouse model which expressed human HGF (HGF mouse) was used for in vivo analysis to evaluate the HGF/MET signaling axis accurately. Initially, doxycycline-induced HAI-2 overexpression RCC cells (786-O-HAI2) were prepared. The cells were cultured with pro-HGF, and inhibitory effect of MET inhibitor (SCC244) and HAI-2 was evaluated by phosphorylation of MET and cell proliferation. Next, the cells were subcutaneously implanted to HGF mice and the growth inhibition was determined by SCC244 and HAI-2. Single use of each inhibitor showed significant inhibition in MET phosphorylation, migration and proliferation of 786-O-HAI2 cells; however, the strongest effect was observed by combined use of both inhibitors. Although in vivo analysis also showed apparent downregulation of MET phosphorylation and growth inhibition in combined treatment, statistical significance was not observed compared with single use of MET inhibitor. Combined treatment with MET-TKI and HAI-2 suggested to consider as a candidate for new strong therapy for RCC.

A comprehensive overview of the relationship between RET gene and tumor occurrence

RET gene plays significant roles in the nervous system and many other tissues. Rearranged during transfection (RET) mutation is related to cell proliferation, invasion, and migration. Many invasive tumors (e.g., non-small cell lung cancer, thyroid cancer, and breast cancer) were found to have changes in RET. Recently, great efforts have been made against RET. Selpercatinib and pralsetinib, with encouraging efficacy, intracranial activity, and tolerability, were approved by the Food and Drug Administration (FDA) in 2020. The development of acquired resistance is inevitable, and a deeper exploration should be conducted. This article systematically reviewed RET gene and its biology as well as the oncogenic role in multiple cancers. Moreover, we also summarized recent advances in the treatment of RET and the mechanism of drug resistance.

Evaluation of the Pharmacokinetic Drug Interaction of Capmatinib With Itraconazole and Rifampicin and Potential Impact on Renal Transporters in Healthy Subjects

Capmatinib is a highly specific, potent, and selective mesenchymal-epithelial transition factor inhibitor predominantly eliminated by cytochrome P450 (CYP) 3A4 and aldehyde oxidase. Here, we investigated the effects of a strong CYP3A inhibitor (itraconazole) and a strong CYP3A inducer (rifampicin) on single-dose pharmacokinetics of capmatinib. In addition, serum creatinine and cystatin C were monitored to assess the potential inhibition of renal transporters by capmatinib. This was an open-label, 2-cohort (inhibition and induction), 2-period (capmatinib alone and inhibition/induction periods) study in healthy subjects. In the inhibition cohort, capmatinib (400 mg/day) was given alone, then with itraconazole (200 mg/day for 10 days, 5-day lead-in before coadministration). In the induction cohort, capmatinib (400 mg/day) was given alone, then with rifampicin (600 mg/day for 9 days, 5-day lead-in before coadministration). Fifty-three subjects (inhibition cohort, n = 27; induction cohort, n = 26) were enrolled. Coadministration of itraconazole resulted in an increase of capmatinib area under the plasma concentration-time curve from time 0 to infinity by 42% (geometric mean ratio [GMR], 1.42; 90%CI, 1.33-1.52) with no change in maximum plasma concentration (GMR, 1.03; 90%CI, 0.866-1.22). Coadministration of rifampicin resulted in a reduction of capmatinib area under the plasma concentration-time curve from time 0 to infinity by 66.5% (GMR, 0.335; 90%CI, 0.300-0.374) and a decrease in maximum plasma concentration by 55.9% (GMR, 0.441; 90%CI, 0.387-0.502). After a single dose of capmatinib, a transient increase in serum creatinine was observed with no change in serum cystatin C concentration during the 3-day monitoring period. In conclusion, coadministration of itraconazole or rifampicin resulted in clinically relevant changes in systemic exposure to capmatinib. The transient increase in serum creatinine without any increase in cystatin C suggests inhibition of renal transport by capmatinib.

Response and acquired resistance to MET inhibitors in de novo MET fusion-positive advanced non-small cell lung cancer

OBJECTIVES

De novo mesenchymal-to-epithelial transition (MET) gene fusions in non-small cell lung cancer (NSCLC) are a promising target for MET tyrosine kinase inhibitors (TKIs). We aimed to examine the response to targeted therapy with MET TKIs and resistance mechanisms in de novo MET fusion-positive NSCLC as these have not been comprehensively explored.

MATERIALS AND METHODS

We examined the MET fusions in 4,429 patients with advanced-stage NSCLC using targeted next-generation sequencing and validated the results using RT-PCR. We analyzed cellular models harboring MET fusions and established a patient-derived organoid (PDO) model.

RESULTS

We identified 13 (0.29 %, 13/4429) patients with de novo MET fusions and found EPHB4, THAP5, TNPO3, and DST as novel MET fusion partners. The most common concomitant gene with MET fusions was TP53 mutations. Among 12 patients receiving MET TKI treatment, two achieved stable disease, six achieved partial response, and four underwent progressive disease. An in vitro study showed that EPHB4-MET is a functional driver gene. MET inhibitors significantly inhibited the proliferation and phosphorylation of downstream STAT3, AKT, and ERK1/2 in EPHB4-MET overexpressing cells. Acquired MET D1228H/N or D1246N mutations were found in patients harboring MET fusions after acquiring resistance to MET TKIs. Tivantinib showed optimal suppression efficacy in a PDO model with an acquired MET D1228N mutation.

CONCLUSION

MET fusions occur in a rare subset of patients with NSCLC and represent a promising therapeutic target. MET secondary mutations D1228H/N or D1246N present the potential resistance mechanisms of MET inhibitors in patients with de novo MET fusions.

Response to Capmatinib in a MET Fusion-positive Cholangiocarcinoma

Cholangiocarcinoma is the second most common liver cancer after hepatocellular carcinoma. In case of metastatic or unresectable disease, the recommended first-line treatment is gemcitabine-based doublet, most commonly gemcitabine and cisplatin. There is no standard treatment for further lines. MET fusions are rare alterations described in many cancers. The efficacy of specific MET inhibitors is poorly studied. We present the case of a patient with chemotherapy-refractory metastatic cholangiocarcinoma harboring a CAPZA-2-MET fusion along with MET amplification who dramatically responded to capmatinib, a specific MET tyrosine kinase inhibitor.

Investigation of the prevalence and clinical implications of ERBB2 exon 16 skipping mutations in Chinese pan-cancer patients

Background

Although rare, ERBB2 exon 16 skipping mutations (ERBB2ΔEx16) have been implicated in resistance to anti-HER2 and anti-EGFR targeted agents. Our study investigated the prevalence and clinical significance of ERBB2ΔEx16 in Chinese pan-cancer patients.

Methods

We retrospectively screened 40996 patients, spanning 19 cancer types, who had available genomic profiles acquired with DNA-based next-generation sequencing (NGS). We characterized the clinical and molecular features of the ERBB2ΔEx16-positive patients. Furthermore, we also analyzed a pan-cancer dataset from the Cancer Genome Atlas (TCGA; n=8705).

Results

A total of 22 patients were detected with ERBB2ΔEx16, resulting in an overall prevalence rate of 0.054% (22/40996). Of them, 16 patients had lung cancer (LC; 0.05%, 16/30890), five patients had gastric cancer (GC; 0.35%, 5/1448), and one patient had ovarian cancer (0.12%, 1/826). Among the 16 LC patients, ERBB2ΔEx16 was detected in four treatment-naïve EGFR/ALK-negative patients and 12 EGFR-positive patients after the onset of resistance to EGFR tyrosine kinase inhibitors (TKIs). The treatment-naïve patients harbored no LC-associated oncogenic drivers except ERBB2 amplification, suggesting a potential oncogenic role for ERBB2ΔEx16. Consistently, ERBB2ΔEx16+ patients from TCGA data also carried no known drivers despite various concurrent alterations. In the 12 EGFR TKI-resistant LC patients, relative variant frequencies for ERBB2ΔEx16 were lower than in untreated patients, suggesting ERBB2ΔEx16 as secondary alterations following TKI treatment and thereby implicating ERBB2ΔEx16 in mediating therapeutic resistance.

Conclusions

Our study identified an overall ERBB2ΔEx16 prevalence rate of 0.054% and provided insights into the clinical implications of ERBB2ΔEx16 in Chinese pan-cancer patients.

Phase I Study Evaluating Glesatinib (MGCD265), An Inhibitor of MET and AXL, in Patients with Non-small Cell Lung Cancer and Other Advanced Solid Tumors

BACKGROUND

Heightened signaling by mesenchymal epithelial transition factor (MET) is implicated in tumorigenesis. Glesatinib is an investigational, oral inhibitor of MET and AXL.

OBJECTIVE

This phase I study determined the maximum tolerated dose (MTD), recommended phase II dose (RP2D), and safety profile of glesatinib in patients with advanced or unresectable solid tumors. Antitumor activity and pharmacokinetics (PK) were secondary objectives.

PATIENTS AND METHODS

Four formulations of glesatinib glycolate salt (capsule, unmicronized, micronized, and micronized version 2 [V2] tablets) and two free-base formulations (free-base suspension [FBS] capsule and spray-dried dispersion [SDD] tablet), developed to enhance drug exposure and optimize manufacturing processes, were evaluated in patients with genetically unselected advanced/unresectable solid tumors. MTD, based on dose-limiting toxicities (DLTs) observed during the first 21-day treatment cycle, was further evaluated in dose-expansion cohorts comprising patients with overexpression of MET and/or AXL, MET/AXL amplification, MET-activating mutations, or MET/AXL rearrangements for confirmation as the RP2D.

RESULTS

Glesatinib was evaluated across 27 dose-escalation cohorts (n = 108). Due to suboptimal exposure with glesatinib glycolate salt formulations in the initial cohorts, investigations subsequently focused on the FBS capsule and SDD tablet; for these formulations, MTD was identified as 1050 mg twice daily and 750 mg twice daily, respectively. An additional 71 patients received glesatinib in the FBS and SDD dose-expansion cohorts. At MTDs, the most frequent treatment-related adverse events were diarrhea (FBS, 83.3%; SDD, 75.0%), nausea (57.1%, 30.6%), vomiting (45.2%, 25.0%), increased alanine aminotransferase (45.2%, 30.6%), and increased aspartate aminotransferase (47.6%, 27.8%). Exploratory pharmacodynamic analyses indicated target engagement and inhibition of MET by glesatinib. Antitumor activity was observed with glesatinib FBS 1050 mg twice daily and SDD 750 mg twice daily in tumors harboring MET/AXL alteration or aberrant protein expression, particularly in patients with non--small cell lung cancer (NSCLC). In patients with NSCLC, the objective response rate was 25.9% in those with MET/AXL mutation or amplification and 30.0% in a subset with MET-activating mutations. All six partial responses occurred in patients with tumors carrying MET exon 14 deletion mutations.

CONCLUSIONS

The safety profile of single-agent glesatinib was acceptable. SDD 750 mg twice daily was selected as the preferred glesatinib formulation and dose based on clinical activity, safety, and PK data. Observations from this study led to initiation of a phase II study of glesatinib in patients with NSCLC stratified by type of MET alteration (NCT02544633).

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT00697632; June 2008.

Recent progress in targeted therapy for non-small cell lung cancer

The high morbidity and mortality of non-small cell lung cancer (NSCLC) have always been major threats to people's health. With the identification of carcinogenic drivers in non-small cell lung cancer and the clinical application of targeted drugs, the prognosis of non-small cell lung cancer patients has greatly improved. However, in a large number of non-small cell lung cancer cases, the carcinogenic driver is unknown. Identifying genetic alterations is critical for effective individualized therapy in NSCLC. Moreover, targeted drugs are difficult to apply in the clinic. Cancer drug resistance is an unavoidable obstacle limiting the efficacy and application of targeted drugs. This review describes the mechanisms of targeted-drug resistance and newly identified non-small cell lung cancer targets (e.g., KRAS G12C, NGRs, DDRs, CLIP1-LTK, PELP1, STK11/LKB1, NFE2L2/KEAP1, RICTOR, PTEN, RASGRF1, LINE-1, and SphK1). Research into these mechanisms and targets will drive individualized treatment of non-small cell lung cancer to generate better outcomes.

Resistance to MET inhibition in MET-dependent NSCLC and therapeutic activity after switching from type I to type II MET inhibitors

OBJECTIVES

Resistance to MET inhibition occurs inevitably in MET-dependent non-small cell lung cancer and the underlying mechanisms are insufficiently understood. We describe resistance mechanisms in patients with MET exon 14 skipping mutation (METΔ^ex14), MET amplification, and MET fusion and report treatment outcomes after switching therapy from type I to type II MET inhibitors.

MATERIALS AND METHODS

Pre- and post-treatment biopsies were analysed by NGS (next generation sequencing), digital droplet PCR (polymerase chain reaction), and FISH (fluorescense in situ hybridization). A patient-derived xenograft model was generated in one case.

RESULTS

Of 26 patients with MET tyrosine kinase inhibitor treatment, eight had paired pre- and post-treatment biopsies (Three with MET amplification, three with METΔ^ex14, two with MET fusions (KIF5B-MET and PRKAR2B-MET).) In six patients, mechanisms of resistance were detected, whereas in two cases, the cause of resistance remained unclear. We found off-target resistance mechanisms in four cases with KRAS mutations and HER2 amplifications appearing. Two patients exhibited second-site MET mutations (p.D1246N and p. Y1248H). Three patients received type I and type II MET tyrosine kinase inhibitors sequentially. In two cases, further progressive disease was seen hereafter. The patient with KIF5B-MET fusion received three different MET inhibitors and showed long-lasting stable disease and a repeated response after switching therapy, respectively.

CONCLUSION

Resistance to MET inhibition is heterogeneous with on- and off-target mechanisms occurring regardless of the initial MET aberration. Switching therapy between different types of kinase inhibitors can lead to repeated responses in cases with second-site mutations. Controlled clinical trials in this setting with larger patient numbers are needed, as evidence to date is limited to preclinical data and case series.

Mutations in the MET tyrosine kinase domain and resistance to tyrosine kinase inhibitors in non-small-cell lung cancer

BACKGROUND

The Mesenchymal epithelial transition factor (MET) gene encodes a receptor tyrosine kinase with pleiotropic functions in cancer. MET exon 14 skipping alterations and high-level MET amplification are oncogenic and targetable genetic changes in patients with non-small-cell lung cancer (NSCLC). Resistance to tyrosine kinase inhibitors (TKIs) has been a major challenge for targeted therapies that impairs their clinical efficacies.

METHODS

Eighty-six NSCLC patients were categorized into three cohorts based on the time of detecting MET tyrosine kinase domain (TKD) mutations (cohort 1: at baseline; cohort 2: after MET-TKI treatment; cohort 3: after EGFR-TKI treatment). Baseline and paired TKI treatment samples were analyzed by targeted next-generation sequencing.

RESULTS

MET TKD mutations were highly prevalent in METex14-positive NSCLC patients after MET-TKI treatment, including L1195V, D1228N/H/Y/E, Y1230C/H/N/S, and a double-mutant within codons D1228 and M1229. Missense mutations in MET TKD were also identified at baseline and in post-EGFR-TKI treatment samples, which showed different distribution patterns than those in post-MET-TKI treatment samples. Remarkably, H1094Y and L1195F, absent from MET-TKI-treated patients, were the predominant type of MET TKD mutations in patients after EGFR-TKI treatment. D1228H, which was not found in treatment-naïve patients, also accounted for 14.3% of all MET TKD mutations in EGFR-TKI-treated samples. Two patients with baseline EGFR-sensitizing mutations who acquired MET-V1092I or MET-H1094Y after first-line EGFR-TKI treatment experienced an overall improvement in their clinical symptoms, followed by targeted therapy with MET-TKIs.

CONCLUSIONS

MET TKD mutations were identified in both baseline and patients treated with TKIs. MET-H1094Y might play an oncogenic role in NSCLC and may confer acquired resistance to EGFR-TKIs. Preliminary data indicates that EGFR-mutated NSCLC patients who acquired MET-V1092I or MET-H1094Y may benefit from combinatorial therapy with EGFR-TKI and MET-TKI, providing insights into personalized medical treatment.

Molecular pathways, resistance mechanisms and targeted interventions in non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related mortality worldwide. The discovery of tyrosine kinase inhibitors effectively targeting EGFR mutations in lung cancer patients in 2004 represented the beginning of the precision medicine era for this refractory disease. This great progress benefits from the identification of driver gene mutations, and after that, conventional and new technologies such as NGS further illustrated part of the complex molecular pathways of NSCLC. More targetable driver gene mutation identification in NSCLC patients greatly promoted the development of targeted therapy and provided great help for patient outcomes including significantly improved survival time and quality of life. Herein, we review the literature and ongoing clinical trials of NSCLC targeted therapy to address the molecular pathways and targeted intervention progress in NSCLC. In addition, the mutations in EGFR gene, ALK rearrangements, and KRAS mutations in the main sections, and the less common molecular alterations in MET, HER2, BRAF, ROS1, RET, and NTRK are discussed. The main resistance mechanisms of each targeted oncogene are highlighted to demonstrate the current dilemma of targeted therapy in NSCLC. Moreover, we discuss potential therapies to overcome the challenges of drug resistance. In this review, we manage to display the current landscape of targetable therapeutic patterns in NSCLC in this era of precision medicine.

Landscape of Savolitinib Development for the Treatment of Non-Small Cell Lung Cancer with MET Alteration-A Narrative Review

Non-small cell lung cancer (NSCLC) is increasingly being treated with targeted therapies. Savolitinib (Orpathys^®) is highly selective mesenchymal epithelial transition (MET)-tyrosine kinase inhibitor (TKI), which is conditionally approved in China for advanced NSCLC with MET exon 14 skipping mutations (METex14). This article summarizes the clinical development of savolitinib, as a monotherapy in NSCLC with METex14 mutation and in combination with epidermal growth factor receptor (EGFR) inhibitor in post EGFR-TKI resistance NSCLC due to MET-based acquired resistance. Preclinical models demonstrated anti-tumor activities in MET-driven cancer cell line and xenograft tumor models. The Phase Ia/Ib study established an optimized, recommended phase II dose in Chinese NSCLC patients, while TATTON study of savolitinib plus osimertinib in patients with EGFR mutant, MET-amplified and TKI-progressed NSCLC showed beneficial efficacy with acceptable safety profile. In a pivotal phase II study, Chinese patients with pulmonary sarcomatoid carcinoma, brain metastasis and other NSCLC subtype positive for METex14 mutation showed notable responses and acceptable safety profile with savolitinib. Currently, results from ongoing clinical trials are eagerly anticipated to confirm the efficacious and safety benefits of savolitinib as monotherapy and in combination with EGFR-TKI in acquired resistance setting in advanced NSCLC and its subtypes with MET alterations.

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 Signaling Pathways, Resistance Mechanisms, and Opportunities for Target Therapies

The MET gene, known as MET proto-oncogene receptor tyrosine kinase, was first identified to induce tumor cell migration, invasion, and proliferation/survival through canonical RAS-CDC42-PAK-Rho kinase, RAS-MAPK, PI3K-AKT-mTOR, and β-catenin signaling pathways, and its driver mutations, such as MET gene amplification (METamp) and the exon 14 skipping alterations (METex14), activate cell transformation, cancer progression, and worse patient prognosis, principally in lung cancer through the overactivation of their own oncogenic and MET parallel signaling pathways. Because of this, MET driver alterations have become of interest in lung adenocarcinomas since the FDA approval of target therapies for METamp and METex14 in 2020. However, after using MET target therapies, tumor cells develop adaptative changes, favoring tumor resistance to drugs, the main current challenge to precision medicine. Here, we review a link between the resistance mechanism and MET signaling pathways, which is not only limited to MET. The resistance impacts MET parallel tyrosine kinase receptors and signals shared hubs. Therefore, this information could be relevant in the patient's mutational profile evaluation before the first target therapy prescription and follow-up to reduce the risk of drug resistance. However, to develop a resistance mechanism to a MET inhibitor, patients must have access to the drugs. For instance, none of the FDA approved MET inhibitors are registered as such in Chile and other developing countries. Constant cross-feeding between basic and clinical research will thus be required to meet future challenges imposed by the acquired resistance to targeted therapies.

Circulating tumour DNA biomarkers in savolitinib-treated patients with non-small cell lung cancer harbouring MET exon 14 skipping alterations: a post hoc analysis of a pivotal phase 2 study

Background

Savolitinib, a selective MET inhibitor, showed efficacy in patients with non-small cell lung cancer (NSCLC), including pulmonary sarcomatoid carcinoma (PSC), harbouring MET exon 14 skipping alteration (METex14).

Objective

To analyse post hoc, the association between circulating tumour DNA (ctDNA) biomarkers and clinical outcomes, including resistance, with savolitinib.

Design

A multicentre, single-arm, open-label phase 2 study.

Methods

All enrolled patients with baseline plasma samples were included. Outcomes were objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) by baseline METex14 and post-treatment clearance, coexisting gene alterations at baseline and disease progression.

Results

Among 66 patients with baseline ctDNA sequencing, 46 (70%) had detectable METex14. Frequent coexisting baseline gene alterations included TP53 and POT1 mutations. Patients with detectable baseline METex14 exhibited worse PFS [hazard ratio (HR), 1.77; 95% confidence interval (CI), 0.88-3.57; p = 0.108] and OS (HR, 3.26; 95% CI, 1.35-7.89; p = 0.006) than those without, despite showing a numerically higher ORR. Among 24 patients with baseline detectable METex14 and evaluable postbaseline samples, 13 achieved METex14 clearance post-treatment. Median time to first clearance was 1.3 months (range, 0.7-1.5). METex14 post-treatment clearance was associated with better ORR (92.3%; 95% CI, 64.0-99.8 versus 36.4%; 95% CI, 10.9-69.2; p = 0.0078), PFS (HR, 0.44; 95% CI, 0.2-1.3; p = 0.1225) and OS (HR, 0.31; 95% CI, 0.1-1.0; p = 0.0397) versus non-clearance. Among 22 patients with disease progression, 10 acquired pathway alterations (e.g. in RAS/RAF and PI3K/PTEN) alone or with secondary MET mutations (D1228H/N and Y1230C/H/S).

Conclusion

ctDNA biomarkers may allow for longitudinal monitoring of clinical outcomes with savolitinib in patients with METex14-positive PSC and other NSCLC subtypes. Specifically, undetectable baseline METex14 or post-treatment clearance may predict favourable clinical outcomes, while secondary MET mutations and other acquired gene alterations may explain resistance to savolitinib.

Registration

The trial was registered with ClinicalTrials.gov (NCT02897479) on 13 September 2016.

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.

Integrative genomic analysis of drug resistance in MET exon 14 skipping lung cancer using patient-derived xenograft models

Background

Non-small cell lung cancer (NSCLC) driven by MET exon 14 skipping (METex14) occurs in 3-4% of NSCLC cases and defines a subset of patients with distinct characteristics. While MET targeted therapy has led to strong clinical results in METex14 patients, acquired drug resistance seemed to be unavoidable during treatment. Limited information is available regarding acquired resistance during MET targeted therapy, nor has there been any report on such patient-derived xenografts (PDXs) model facilitating the research.

Methods

We describe a patient case harboring METex14 who exhibited drug resistance after treatment with crizotinib. Subcutaneous xenografts were generated from pretreatment and post-resistance patient specimens. PDX mice were then treated with MET inhibitors (crizotinib and tepotinib) and EGFR-MET bispecific antibodies (EMB-01 and amivantamab) to evaluate their drug response in vivo. DNA and RNA sequencing analysis was performed on patient tumor specimens and matching xenografts.

Results

PDXs preserved most of the histological and molecular profiles of the parental tumors. Drug resistance to MET targeted therapy was confirmed in PDX models through in vivo drug analysis. Newly acquired MET D1228H mutations and EGFR amplificated were detected in patient-resistant tumor specimens. Although the mutations were not detected in the PDX, EGFR overexpression was observed in RNA sequencing analysis indicating possible off-target resistance through the EGFR bypass signaling pathway. As expected, EGFR-MET bispecific antibodies overcome drug resistant in the PDX model.

Conclusions

We detected a novel MET splice site deletion mutation that could lead to METex14. We also established and characterized a pair of METex14 NSCLC PDXs, including the first crizotinib resistant METex14 PDX. And dual inhibition of MET and EGFR might be a therapeutic strategy for EGFR-driven drug resistance METex14 lung cancer.

Biomarker-Targeted Therapies in Non-Small Cell Lung Cancer: Current Status and Perspectives

Non-small-cell lung cancer (NSCLC) is one of the most common malignancies and the leading causes of cancer-related death worldwide. Despite many therapeutic advances in the past decade, NSCLC remains an incurable disease for the majority of patients. Molecular targeted therapies and immunotherapies have significantly improved the prognosis of NSCLC. However, the vast majority of advanced NSCLC develop resistance to current therapies and eventually progress. In this review, we discuss current and potential therapies for NSCLC, focusing on targeted therapies and immunotherapies. We highlight the future role of metabolic therapies and combination therapies in NSCLC.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

MET alterations in NSCLC—Current Perspectives and Future Challenges

Targeted therapies have revolutionized the treatment and improved the outcome for oncogene-driven NSCLC and an increasing number of oncogenic driver therapies have become available. For MET-dysregulated NSCLC (especially MET exon 14 skipping mutations and MET-amplifications, which is one of the most common bypass mechanisms of resistance in oncogene-addicted NSCLC), several anti-MET-targeted therapies have been approved recently (MET exon 14 skipping mutation) and multiple others are in development. In this narrative review, we summarize the role of MET as an oncogenic driver in NSCLC, discuss the different testing methods for exon 14 skipping mutations, gene amplification, and protein overexpression, and review the existing data and ongoing clinical trials regarding targeted therapies in MET-altered NSCLC. As immunotherapy with or without chemotherapy has become the standard of care for advanced NSCLC, immunotherapy data for MET-dysregulated NSCLC are put into perspective. Finally, we discuss future challenges in this rapidly evolving landscape.

Foretinib can overcome common on-target resistance mutations after capmatinib/tepotinib treatment in NSCLCs with MET exon 14 skipping mutation

Background

Capmatinib and tepotinib are guideline-recommended front-line treatments for non-small-cell lung cancer (NSCLC) patients with MET exon 14 skipping mutations (METex14). However, the emergence of acquired resistance to capmatinib/tepotinib is almost inevitable partially due to D1228X or Y1230X secondary mutations of the MET. In this study, we explored agents that are active against both D1228X and Y1230X MET to propose an ideal sequential treatment after capmatinib/tepotinib treatment failure in NSCLC patients with METex14.

Methods

The inhibitory effects of 300 drugs, including 33 MET-TKIs, were screened in Ba/F3 cells carrying METex14 plus MET D1228A/Y secondary mutations. The screen revealed four-candidate type II MET-TKIs (altiratinib, CEP-40783, foretinib and sitravatinib). Therefore, we performed further growth inhibitory assays using these four MET-TKIs plus cabozantinib and merestinib in Ba/F3 cells carrying MET D1228A/E/G/H/N/V/Y or Y1230C/D/H/N/S secondary mutations. We also performed analyses using Hs746t cell models carrying METex14 (with mutant allele amplification) with/without D1228X or Y1230X in vitro and in vivo to confirm the findings. Furthermore, molecular dynamics (MD) simulations were carried out to examine differences in binding between type II MET-TKIs.

Results

All 6 type II MET-TKIs were active against Y1230X secondary mutations. However, among these 6 agents, only foretinib showed potent activity against D1228X secondary mutations of the MET in the Ba/F3 cell and Hs746t in vitro model and Hs746t in vivo model, and CEP-40783 and altiratinib demonstrated some activity. MD analysis suggested that the long tail of foretinib plays an important role in binding D1228X MET through interaction with a residue at the solvent front (G1163). Tertiary G1163X mutations, together with L1195F/I and F1200I/L, occurred as acquired resistance mechanisms to the second-line treatment foretinib in Ba/F3 cell models.

Conclusions

The type II MET-TKI foretinib may be an appropriate second-line treatment for NSCLCs carrying METex14 after campatinib/tepotinib treatment failure by secondary mutations at residue D1228 or Y1230.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01299-z.

Spotlight on Tepotinib and Capmatinib for Non-Small Cell Lung Cancer with MET Exon 14 Skipping Mutation

Mesenchymal-epithelial transition (MET) receptor tyrosine kinase is overexpressed, amplified, or mutated in 1–20% of NSCLC. MET dysregulation is associated with a poor prognosis. Recently, development of targeted therapies against MET exon 14 mutations has demonstrated efficacy and tolerability in early trials. Here we focus on tepotinib and capmatinib in regards to molecular characteristics, early preclinical and clinical data, and the emerging role in future studies and clinical practice.