Characterization of MET exon 14 alteration and association with clinical outcomes of crizotinib in Chinese lung cancers

Exploring practical experience with different treatments in NSCLC patients with MET-deregulated: a retrospective analysis from the real world

BACKGROUND

Mesenchymal to epithelial transition factor (MET) dysregulation in non-small-cell-lung-cancer (NSCLC) is understudied, with scant data on treatment outcomes.

METHODS

We retrospectively examined 160 NSCLC patients: 125 with primary MET mutations (further classified into MET exon 14 (METex14) skipping mutations and primary MET amplifications) and 35 with secondary MET amplifications. Patients underwent varied treatments: Chemotherapy, Immune monotherapy, Crizotinib, or Savolitinib. Secondary MET amplification patients were grouped by treatment: Group A (Class Ib MET-TKI with third-generation EGFR-TKI), Group B (Crizotinib with first-generation EGFR-TKI), and Group C (Crizotinib alone). One hundred and thirty patients have completed the whole treatment process. Their data were included in the study's survival analysis (included 95 patients with primary MET mutations and 35 patients with secondary MET amplifications).

RESULTS

Among METex14 skipping mutations patients (n = 57), median progression free survival (PFS) was: Chemotherapy 7.64 m, Crizotinib 8.5 m, Savolitinib 9.3 m, and Immunotherapy 3.87 m. Targeted therapies and chemotherapy significantly outperformed Immunotherapy. Sub-group analysis indicated splice donor region mutations benefited more than those at the polypyrimidine tract (9.23 m vs. 4.03 m, P = 0.038). For primary MET amplifications (n = 38), PFS was: Chemotherapy 2.84 m, Crizotinib 3.80 m, Savolitinib 5.23 m, and Immunotherapy 3.30 m. Patients with copy number (CN) > 5 had longer PFS than CN ≤ 5 (5.17 m vs. 3.44 m, P = 0.039). In secondary MET amplifications (n = 35), Group A and B had similar PFS (6.77 m and 6.57 m) versus Group C (3.13 m). Dual-target therapy PFS showed no difference between CN ≤ 5 and CN > 5 (8.63 m vs. 6.27 m, P = 0.29).

CONCLUSION

NSCLC patients with METex14 skipping mutations benefit more from targeted therapies, especially those with splice donor mutations. MET amplification patients benefit universally from targeted therapies; primary MET amplifications show higher benefits with increased copy numbers. For secondary MET amplifications post-EGFR-TKI resistance, dual-target therapy surpasses Crizotinib monotherapy, independent of MET copy number.

Analytical and clinical validation of a NGS panel in detecting targetable variants from ctDNA of metastatic NSCLC patients

BACKGROUND

Circulating tumor DNA (ctDNA) has emerged as a promising biomarker for noninvasive cancer diagnostics, particularly in the context of metastatic non-small-cell lung cancer (NSCLC). Detecting targetable variants through ctDNA analysis offers the potential to guide treatment decisions, especially in cases where tissue samples are insufficient or unavailable.

METHOD

In this study, we developed and validated a next-generation sequencing panel targeting 101 cancer-related genes (101-test) to detect somatic variants in ctDNA from a large cohort of Chinese patients with metastatic NSCLC. The performance of the 101-test was assessed by evaluating its limit of detection (LOD), accuracy, and precision in identifying molecular variants. Additionally, the concordance between ctDNA and tissue samples for detecting targetable variants was analyzed in 904 patients.

RESULTS

The 101-test demonstrated a LOD of 0.38% for single-nucleotide variants (SNVs), 0.33% for insertions and deletions (InDels), and 0.33% for fusions. Sensitivity was 98.3% for SNVs, 100% for InDels, and 100% for fusions when compared to digital droplet PCR (ddPCR)/breakpoint PCR reference methods. The by-variant sensitivity for somatic variants was 97.5%, with a specificity of 99.9% between tumor-only and tumor-normal analyses. In a real-world cohort, the concordance between ctDNA and tissue samples for identifying targetable variants was 72.2% (457/633). Notably, the EGFR S768I variant, recently recommended by clinical guidelines, achieved an 80% concordance rate. Furthermore, 4.3% of patients (27/633) with targetable variants were identified exclusively through ctDNA testing.

CONCLUSION

The ctDNA-based 101-test is a highly sensitive and specific tool for detecting targetable variants in metastatic NSCLC, particularly in cases with insufficient tissue samples. The findings support the use of ctDNA testing as a reliable and complementary method to traditional tissue-based molecular analysis, enhancing the precision of treatment strategies for NSCLC patients.

Mutation of MET D1228N as an Acquired Potential Mechanism of Crizotinib Resistance in NSCLC with MET Y1003H Mutation

Mesenchymal-epithelial transition (MET) gene has been identified as a promising target for treatments. However, different sites of the MET mutation show different effects to MET inhibition. Here, we reported a non-small cell lung cancer (NSCLC) patient harboring MET Y1003H mutation who achieved a durable partial response to crizotinib with a PFS of 22.4 months. Furthermore, we report for the first time the identification of MET D1228N as a possible mechanism of acquired resistance to crizotinib in a patient with MET Y1003H mutation during disease progression.

MET Exon 14 Skipping in NSCLC: A Systematic Literature Review of Epidemiology, Clinical Characteristics, and Outcomes

INTRODUCTION

MET exon 14 (METex14) skipping is a rare oncogenic driver in non-small-cell lung cancer (NSCLC) for which targeted therapy with MET tyrosine kinase inhibitors (TKIs) was recently approved. Given the heterogeneity in published data of METex14 skipping NSCLC, we conducted a systematic literature review to evaluate its frequency, patient characteristics, and outcomes.

METHODS

On June 13, 2022 we conducted a systematic literature review of publications and conference abstracts reporting frequency, patient characteristics, or outcomes of patients with METex14 skipping NSCLC.

RESULTS

We included 139 studies reporting frequency or patient characteristics (350,997 patients), and 39 studies reporting clinical outcomes (3989 patients). Median METex14 skipping frequency was 2.0% in unselected patients with NSCLC, with minimal geographic variation. Median frequency was 2.4% in adenocarcinoma or nonsquamous subgroups, 12.0% in sarcomatoid, and 1.3% in squamous histology. Patients with METex14 skipping NSCLC were more likely to be elderly, have adenocarcinoma histology; there was no marked sex or smoking status distribution. In first line of treatment, median objective response rate ranged from 50.7% to 68.8% with targeted therapies (both values correspond to MET TKIs), was 33.3% with immunotherapy, and ranged from 23.1% to 27.0% with chemotherapy.

CONCLUSIONS

Patients with METex14 skipping are more likely to have certain characteristics, but no patient subgroup can be ruled out; thus, it is crucial to test all patients with NSCLC to identify suitable candidates for MET inhibitor therapy. MET TKIs appeared to result in higher efficacy outcomes, although no direct comparison with chemotherapy or immunotherapy regimens was found.

Targeted therapy for rare lung cancers: Status, challenges, and prospects

Lung cancer causes the most cancer-related deaths worldwide. In recent years, molecular and immunohistochemical techniques have rapidly developed, further inaugurating an era of personalized medicine for lung cancer. The rare subset of lung cancers accounts for approximately 10%, each displaying distinct clinical characteristics. Treatments for rare lung cancers are mainly based on evidence from common counterparts, which may lead to unsolid clinical benefits considering intertumoral heterogeneity. The increasing knowledge of molecular profiling of rare lung cancers has made targeting genetic alterations and immune checkpoints a powerful strategy. Additionally, cellular therapy has emerged as a promising way to target tumor cells. In this review, we first discuss the current status of targeted therapy and preclinical models for rare lung cancers, as well as provide mutational profiles by integrating the results of existing cohorts. Finally, we point out the challenges and future directions for developing targeted agents for rare lung cancer.

Optimized Detection of Unknown MET Exon 14 Skipping Mutations in Routine Testing for Patients With Non-Small-Cell Lung Cancer

PURPOSE

MET exon 14 (METex14) skipping is an actionable biomarker in non-small-cell lung cancer. However, MET variants are highly complex and diverse, and not all variants lead to exon 14 skipping. Assessing the skipping effect of unknown variants is still a key issue in molecular diagnosis.

MATERIALS AND METHODS

We retrospectively collected MET variants around exon 14 from 4,233 patients with non-small-cell lung cancer who underwent next-generation sequencing testing using DNA, as well as two published data sets.

RESULTS

Among the 4,233 patients, 44 unique variants including 29 novel variants (65.9%) were discovered from 53 patients. Notably, 31 samples (58.5%) failed RNA verification. Using RNA verification, nine novel skipping variants and five nonskipping variants were confirmed. We further used SpliceAI with the delta score cutoff of 0.315 to aid the classification of novel variants (sensitivity = 98.88% and specificity = 100%). When applied to the reported variants, we also found three wrongly classified nonskipping variants. Finally, an optimized knowledge-based interpretation procedure for clinical routine was built according to the mutation type and location, and five more skipping mutations from the 13 unknown variants were determined, which improved the population determination rate to 0.92%.

CONCLUSION

This study discovered more METex14 skipping variants and optimized an innovative approach that could be adapted for the interpretation of infrequent or novel METex14 variants timely without experimental validation.

Asian Thoracic Oncology Research Group (ATORG) Expert Consensus Statement on MET Alterations in NSCLC: Diagnostic and Therapeutic Considerations

Non-small cell lung cancer (NSCLC) is a heterogeneous disease, with many oncogenic driver mutations, including de novo mutations in the Mesenchymal Epithelial Transition (MET) gene (specifically in Exon 14 [ex14]), that lead to tumourigenesis. Acquired alterations in the MET gene, specifically MET amplification is also associated with the development of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance in patients with EGFR-mutant NSCLC. Although MET has become an actionable biomarker with the availability of MET-specific inhibitors in selected countries, there is differential accessibility to diagnostic platforms and targeted therapies across countries in Asia-Pacific (APAC). The Asian Thoracic Oncology Research Group (ATORG), an interdisciplinary group of experts from Australia, Hong Kong, Japan, Korea, Mainland China, Malaysia, the Philippines, Singapore, Taiwan, Thailand and Vietnam, discussed testing for MET alterations and considerations for using MET-specific inhibitors at a consensus meeting in January 2022, and in subsequent offline consultation. Consensus recommendations are provided by the ATORG group to address the unmet need for standardised approaches to diagnosing MET alterations in NSCLC and for using these therapies. MET inhibitors may be considered for first-line or second or subsequent lines of treatment for patients with advanced and metastatic NSCLC harbouring MET ex14 skipping mutations; MET ex14 testing is preferred within multi-gene panels for detecting targetable driver mutations in NSCLC. For patients with EGFR-mutant NSCLC and MET amplification leading to EGFR TKI resistance, enrolment in combination trials of EGFR TKIs and MET inhibitors is encouraged.

MET alterations in advanced pulmonary sarcomatoid carcinoma

Pulmonary sarcomatoid carcinoma (PSC) is a rare subset of NSCLC that accounts for about 0.5-1% of all primary lung carcinoma, and its malignant biological behavior is more aggressive than other pathological types of lung cancer. Recent studies have reported a variety of gene mutations associated with the occurrence, development and treatment of PSC, especially the mesenchymal-epithelial transition (MET) proto-oncogene alterations, including the exon 14 (METex14) skipping mutations as well as the amplification and overexpression of MET gene, which are associated with molecularly targeted therapy for PSC. METex14 skipping mutation is the most common and well-studied mutation type, occurring in about 22-31.8% of PSC patients, while the prevalence of MET amplification is reported as 4.8-13.6% and MET ovexpression is about 20.2%. Molecular pathology tests, including IHC and NGS, are valuable in determining the prognosis of patients with PSC and helping to determine the treatment. The existing clinical data have confirmed the efficacy of MET-TKI in PSC patients with MET alteration, among which the clinical study of Savolitinib has enrolled the largest proportion of PSC patients and achieved relatively good efficacy, but more clinical researches are still needed. The multi-disciplinary team may maximize the optimal treatment options for patients with the advanced PSC.

A lung adenocarcinoma patient harboring MET c. 3028 + 2 T >A variant sensitive to crizotinib treatment

Several studies have reported that patients harboring MET-ex14 skipping benefit from MET tyrosine kinase inhibitors (TKIs) such as crizotinib, however, the overall response of crizotinib was 32% in these patients. Therefore, the clinical outcome of patients harboring different MET 14 skipping subtypes are worthy to be concern. Based on NGS analysis, we described a lung adenocarcinoma patient harboring a MET c.3028 + 2 T > A mutation which was predicted to lead to MET-ex14 skipping. Moreover, we performed IHC and qPCR to verify this variant. Then the patient treated with crizotinib and achieved good therapeutic effect. This mutation is firstly verified not only by multiple methodologies, but also by clinical effect. Our finding expands the spectrum of MET 14 exon skipping variant and maybe offer available application basis of MET inhibitor to patients harboring MET c. 3028 + 2 T > A/C/G. Importantly, targeted NGS analysis could improve detection of MET alterations in routine practice.

Therapeutic Strategies for Ovarian Cancer in Point of HGF/c-MET Targeting

Ovarian cancer is the fifth leading cause of cancer deaths in women and is regarded as one of the most difficult cancers to treat. Currently, studies are being conducted to develop therapeutic agents for effective treatment of ovarian cancer. In this review, we explain the properties of the hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (c-MET) and how the signaling pathway of HGF/c-MET is activated in different cancers and involved in tumorigenesis and metastasis of ovarian cancer. We present the findings of clinical studies using small chemicals or antibodies targeting HGF/c-MET signaling in various cancer types, particularly in ovarian cancer. We also discuss that HGF/c-MET-targeted therapy, when combined with chemo drugs, could be an effective strategy for ovarian cancer therapeutics.

Case Report: A Lung Adenocarcinoma With Brain Metastasis Harbored Novel MET 14 Skipping Alteration Sensitive to Savolitinib

A splice-site mutation that results in a loss of transcription of exon 14 in the oncogenic driver MET occurs in 3 to 4% of patients with non-small-cell lung cancer (NSCLC). Several MET exon 14 skipping alterations have been identified, but different MET exon splice variants tend to have different clinical outcomes which deserve concern. Herein, based on NGS panel analysis, we firstly described a 61-year-old woman with lung adenocarcinoma who harbored a novel MET exon 14 skipping (c.3004_3028+3del) concurrent MET amplification (copy number: 3.91) and benefited from Savolitinib treatment. Moreover, CytoTest MET/CCP7 FISH Probe (c-MET/CCP7 Ratio:1.41 and mean gene copy number:6) and qPCR which based on ABI 7500 also were performed to confirm these two MET alterations. After 2 months of Savolitinib treatment, the clinical evaluation was a partial response (PR). In summary, our finding not only expanded the spectrum of the MET exon14 variant (METex14). Targeted NGS analysis could improve detection of MET alterations in routine practice.

Case Report: A 91-Year-Old Patient With Non-Small Cell Lung Cancer Harboring MET Y1003S Point Mutation

Background

The Y1003S point mutation in exon 14 of mesenchymal-epithelial transition (MET) is a rare mutation that can lead to oncogenic transformation. Few data are available on the characteristics of this mutation. This report presents an elderly patient with non-small cell lung cancer (NSCLC) and a Y1003S mutation in MET detected by next-generation sequencing (NGS).

Case Report

In October 2020, a 91-year-old male was admitted to the Department of Respiratory and Critical Care Medicine, Ruijin Hospital because of an increased carcinoembryonic antigen. Imaging revealed highly suspicious lesions in the right upper lobe of the lung, right apex, and left upper lobe with traction of the adjacent pleura. The patient was histologically confirmed as having adenocarcinoma and the MET Y1003S mutation was detected by the NGS subsequently. After evaluation, the patient started crizotinib treatment in December 2020. In the first assessment of tumor response, a chest CT scan in January 2021 showed a partial response. The patient experienced a pulmonary embolism and an abnormal liver function during the treatment and recovered after symptomatic treatment. He maintained a partial response in the last available assessment in July 2021, with the right upper lung lesion being 26 × 9 mm.

Conclusion

The MET Y1003S mutation was detected in this case, and the patient achieved a partial response using crizotinib. This case highlighted the role of NGS in detecting a rare mutation. Successful remission of complications in such an elderly patient necessitates careful and timely management.

Landscape and Clonal Dominance of Co-occurring Genomic Alterations in Non-Small-Cell Lung Cancer Harboring MET Exon 14 Skipping

MET exon 14 skipping alterations (METex14) comprise a diverse set of actionable oncogene drivers in non–small-cell lung cancer (NSCLC). Recent studies have established the efficacy of tyrosine kinase inhibitors for this patient population. The landscape of co-occurring genetic alterations in METex14 NSCLC and their potential impact to therapeutic sensitivities has not yet been fully described.

The treatment of advanced pulmonary sarcomatoid carcinoma

Pulmonary sarcomatoid carcinoma (PSC) is a pathological subtype of non-small cell lung cancer. Although the incidence of PSC in lung cancer is very low, it is an aggressive cancer, leading to a poor prognosis. Currently, there is no standard treatment for advanced PSC. Targeted therapy can be used for patients with MET exon 14 mutations and patients with other driver gene mutations may also benefit from treatment. The emergence of immune checkpoint inhibitors also provides potential options for advanced PSC treatment, but more clinical data is needed. Additionally, more research may be warranted to explore the effects of chemotherapy, radiotherapy and antiangiogenic therapy. In this review, the authors summarize the research regarding the treatment of advanced PSC.

Prognosis and Concurrent Genomic Alterations in Patients With Advanced NSCLC Harboring MET Amplification or MET Exon 14 Skipping Mutation Treated With MET Inhibitor: A Retrospective Study

Background

MET amplification or METex14 skipping mutations are uncommon oncogenic events in NSCLC patients. Clinicopathological characteristics, concurrent gene alterations, and prognosis of MET TKIs in these patients are yet to be elucidated.

Methods

We retrospectively analyzed the genomic profiles of 43 MET amplifications or 31 METex14 skipping mutations in NSCLC patients with no previous treatment with EGFR TKIs. Survival outcomes were analyzed in evaluable patients receiving MET TKI treatment: MET amplification cohort (n = 29) and METex14 skipping mutation cohort (n = 29).

Results

Among evaluable patients, a shorter PFS was observed in the MET amplification cohort than in the METex14 skipping mutation cohort (7.0 months vs. 11.0 months, P = 0.043). Concurrent mutations in both cohorts resulted in a statistically significant shorter PFS (MET amplification: 3.5 months versus 8.0 months, P = 0.038, METex14 skipping mutation: 7.0 versus NR months, P = 0.022). However, a statistically significant OS (17.0 months versus 20.0 months, P = 0.044) was only observed in the MET amplification cohort. TP53, the most common concurrent mutation in both cohorts, was associated with worse survival outcomes as compared to the wild type. The MET amplification cohort with a concurrent PIK3CA mutation exhibited primary resistance to MET TKIs and showed disease progression (80%).

Conclusion

MET TKIs could be a better treatment option for patients with METex14 skipping mutations. Concurrent mutations may deteriorate the PFS of MET TKIs in NSCLC patients with MET amplification or METex14 skipping mutations. PIK3CA mutations may confer primary resistance to MET TKIs in patients with MET amplification.

Combination of HGF/MET-targeting agents and other therapeutic strategies in cancer

MET receptor has emerged as a druggable target across several human cancers. Agents targeting MET and its ligand hepatocyte growth factor (HGF) including small molecules such as crizotinib, tivantinib and cabozantinib or antibodies including rilotumumab and onartuzumab have proven their values in different tumors. Recently, capmatinib was approved for treatment of metastatic lung cancer with MET exon 14 skipping. In this review, we critically examine the current evidence on how HGF/MET combination therapies may take advantage of synergistic effects, overcome primary or acquired drug resistance, target tumor microenvironment, modulate drug metabolism or tackle pharmacokinetic issues. Preclinical and clinical studies on the combination of HGF/MET-targeted agents with conventional chemotherapeutics or molecularly targeted treatments (including EGFR, VEGFR, HER2, RAF/MEK, and PI3K/Akt targeting agents) and also the value of biomarkers are examined. Our deeper understanding of molecular mechanisms underlying successful pharmacological combinations is crucial to find the best personalized treatment regimens for cancer patients.

Application of large-scale targeted sequencing to distinguish multiple lung primary tumors from intrapulmonary metastases

The effective differentiation between multiple primary lung tumors (MPs) and intrapulmonary metastases (IMs) in patients is imperative to discover the exact disease stage and to select the most appropriate treatment. In this study, the authors was to evaluate the efficacy and validity of large-scale targeted sequencing (LSTS) as a supplement to estimate whether multifocal lung cancers (MLCs) are primary or metastatic. Targeted sequencing of 520 cancer-related oncogenes was performed on 36 distinct tumors from 16 patients with MPs. Pairing analysis was performed to evaluate the somatic mutation pattern of MLCs in each patient. A total of 25 tumor pairs from 16 patients were sequenced, 88% (n = 22) of which were classified as MPs by LSTS, consistent with clinical diagnosis. One tumor pair from a patient with lymph node metastases had highly consistent somatic mutation profiles, thus predicted as a primary-metastatic pair. In addition, some matched mutations were observed in the remaining two paired ground-glass nodules (GGNs) and classified as high-probability IMs by LSTS. Our study revealed that LSTS can potentially facilitate the distinction of MPs from IMs. In addition, our results provide new genomic evidence of the presence of cancer invasion in GGNs, even pure GGNs.