MET-Targeted Therapies and Clinical Outcomes: A Systematic Literature Review

Introduction

Numerous therapeutic agents specifically targeting the mesenchymal-epithelial transition (MET) oncogene are being developed.

Objective

The aim of the current review was to systematically identify and analyze clinical trials that have evaluated MET inhibitors in various cancer types and to provide an overview of their clinical outcomes.

Methods

An electronic literature search was carried out in the PubMed and Embase databases to identify published clinical trials related to MET inhibitors. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement was followed for the systematic appraisal of the literature. Data related to clinical outcomes, including progression-free survival, overall survival, objective response rate, and overall tumor response, were extracted.

Results

In total, 49 publications were included. Among these, 51.02% were phase II studies, 14.28% were randomized controlled trials, three were phase III studies, two were prospective observational studies, and the remainder were either phase I or Ib studies. The majority (44.89%) of articles reported the clinical outcomes of MET inhibitors, including small molecules, monoclonal antibodies, and other agents, in patients with non-small-cell lung cancer (NSCLC) harboring MET alterations. MET amplification, overexpression, and MET exon 14 skipping mutations were the major MET alteration types reported across the included studies. Clinical responses/outcomes varied considerably.

Conclusion

This systematic literature review provides an overview of the literature available in Embase and PubMed regarding MET-targeted therapies. MET-selective tyrosine kinase inhibitors (TKIs) (capmatinib, tepotinib, and savolitinib) may become a new standard of care in NSCLC, specifically with MET exon 14 skipping mutations. A combination of MET TKIs with epidermal growth factor receptor (EGFR) TKIs (osimertinib + savolitinib, tepotinib + gefitinib) may be a potential solution for MET-driven EGFR TKI resistance. Further, MET alteration (MET amplification/overexpression) may be an actionable target in gastric cancer and papillary renal cell carcinoma.

HGF/MET pathway aberrations as diagnostic, prognostic, and predictive biomarkers in human cancers

Cancer is a major cause of death worldwide. MET tyrosine kinase receptor [MET, c-MET, hepatocyte growth factor (HGF) receptor] pathway activation is associated with the appearance of several hallmarks of cancer. The HGF/MET pathway has emerged as an important actionable target across many solid tumors; therefore, biomarker discovery becomes essential in order to guide clinical intervention and patient stratification with the aim of moving towards personalized medicine. The focus of this review is on how the aberrant activation of the HGF/MET pathway in tumor tissue or the circulation can provide diagnostic and prognostic biomarkers and predictive biomarkers of drug response. Many meta-analyses have shown that aberrant activation of the MET pathway in tumor tissue, including MET gene overexpression, gene amplification, exon 14 skipping and other activating mutations, is almost invariably associated with shorter survival and poor prognosis. Most meta-analyses have been performed in non-small cell lung cancer (NSCLC), breast, head and neck cancers as well as colorectal, gastric, pancreatic and other gastrointestinal cancers. Furthermore, several studies have shown the predictive value of MET biomarkers in the identification of patients who gain the most benefit from HGF/MET targeted therapies administered as single or combination therapies. The highest predictive values have been observed for response to foretinib and savolitinib in renal cancer, as well as tivantinib in NSCLC and colorectal cancer. However, some studies, especially those based on MET expression, have failed to show much value in these stratifications. This may be rooted in lack of standardization of methodologies, in particular in scoring systems applied in immunohistochemistry determinations or absence of oncogenic addiction of cancer cells to the MET pathway, despite detection of overexpression. Measurements of amplification and mutation aberrations are less likely to suffer from these pitfalls. Increased levels of MET soluble ectodomain (sMET) in circulation have also been associated with poor prognosis; however, the evidence is not as strong as it is with tissue-based biomarkers. As a diagnostic biomarker, sMET has shown its value in distinguishing cancer patients from healthy individuals in prostate and bladder cancers and in melanoma. On the other hand, increased circulating HGF has also been presented as a valuable prognostic and diagnostic biomarker in many cancers; however, there is controversy on the predictive value of HGF as a biomarker. Other biomarkers such as circulating tumor DNA (ctDNA) and tumor HGF levels have also been briefly covered. In conclusion, HGF/MET aberrations can provide valuable diagnostic, prognostic and predictive biomarkers and represent vital assets for personalized cancer therapy.

Second-line erlotinib after failure of pemetrexed-containing chemotherapy in advanced non-small cell lung cancer (NSCLC): Real-world effectiveness, safety and tolerability

INTRODUCTION

Little data is available on patients with advanced non-squamous NSCLC treated with erlotinib specifically after failure of first-line pemetrexed-containing chemotherapy. We assessed the effectiveness, safety and tolerability of erlotinib in a real-world setting.

METHODS

Prospective single-arm, open-label, multicenter, non-interventional study of erlotinib (150mg daily) in inoperable stage III/IV NSCLC after progression on first-line pemetrexed-containing chemotherapy without EGFR-mutation selection. Patients were followed according to routine practice and response assessment was performed using RECIST 1.1. The primary end point was progression-free survival (PFS). Secondary end points included best confirmed overall response rate (ORR), disease control rate (DCR), and overall survival (OS). Adverse events were recorded. An independent dataset was used to validate the results.

RESULTS

In all, 59 patients were screened, 57 enrolled, and 54 (36 men; median age 65 years) included in the per-protocol analysis. Median PFS was 1.8 (95% CI 1.4-2.6) months, with 11% (95% CI 5-21%) alive and progression-free at 6 months. The ORR was 0.0% (97.5% CI 0.0-6.8%) and the DCR 34.6% (95% CI 21.9-49.0%). Median overall survival was 5.8 (95% CI 3.3-8.6) months with 28% (95% CI 17-42%) alive at one year. Rash occurred in 60.7% (95% CI 46.7-73.5%), with severe rash in 12.5% (95% CI 5.1-24.1%). Any grade diarrhea was observed in 42.8% (95% CI 29.7-56.8%), with grade 3 occurring in 7.1% (95% CI 1.9-17.2%). Erlotinib was stopped in 21.0% (95% CI 11.3-33.9%) of patients due to adverse events, which were treatment related in 7%.

CONCLUSION

Second-line erlotinib after pemetrexed treatment results in similar real-world outcomes as reported after non-pemetrexed containing first-line therapy. However, the overall duration of response in unselected patients remains limited and other effective treatments have in the meantime been introduced. No new safety signals were detected.