Differential response to a combination of full-dose osimertinib and crizotinib in a patient with EGFR-mutant non-small cell lung cancer and emergent MET amplification

Combatting acquired resistance to osimertinib in EGFR-mutant lung cancer

The discovery of activating mutations in epidermal growth factor receptor (EGFR) in non-small-cell lung cancer transformed the care and prognosis of patients and heralded the era of 'personalized medicine' in thoracic oncology. Osimertinib, a third-generation EGFR inhibitor, has been established as the preferred EGFR inhibitor for newly diagnosed patients which urged the need to develop treatment options for patients progressing on first-line osimertinib. However, acquired resistance invariably emerges and numerous efforts have been attempted to delay or overcome acquired resistance. In this article, we thoroughly reviewed the current understanding of osimertinib resistance mechanisms and explored the established and emerging treatment options. Newer treatment strategies targeting EGFR-dependent or -independent resistance mechanisms, novel approaches using bispecific antibodies and antibody-drug conjugates will be discussed. Moreover, what to do with brain only progression, and how to incorporate immunotherapy in EGFR-mutant lung cancer will be discussed. Lastly, future perspectives on the ongoing clinical trials and combination of front-line therapy will be introduced.

Bioinformatically Expanded Next-Generation Sequencing Analysis Optimizes Identification of Therapeutically Relevant MET Copy Number Alterations in >50,000 Tumors

PURPOSE

Clinical relevance thresholds and laboratory methods are poorly defined for MET amplification, a targetable biomarker across malignancies.

EXPERIMENTAL DESIGN

The utility of next-generation sequencing (NGS) in assessing MET copy number alterations was determined in >50,000 solid tumors. Using fluorescence in situ hybridization as reference, we validated and optimized NGS analysis.

RESULTS

Incorporating read-depth and focality analyses achieved 91% concordance, 97% sensitivity, and 89% specificity. Tumor heterogeneity, neoplastic cell proportions, and genomic focality affected MET amplification assessment. NGS methodology showed superiority in capturing overall amplification status in heterogeneous tumors and defining amplification focality among other genomic alterations. MET copy gains and amplifications were found in 408 samples across 23 malignancies. Total MET copy number inversely correlated with amplified segment size. High-level/focal amplification was enriched in certain genomic subgroups and associated with targeted therapy response.

CONCLUSIONS

Leveraging our integrated bioinformatic approach, targeted therapy benefit was observed across diverse MET amplification contexts.

Acquired Resistance to Osimertinib in EGFR-Mutated Non-Small Cell Lung Cancer: How Do We Overcome It?

Osimertinib is currently the preferred first-line therapy in patients with non-small cell lung cancer (NSCLC) with common epidermal growth factor receptor (EGFR) mutation and the standard second-line therapy in T790M-positive patients in progression to previous EGFR tyrosine kinase inhibitor. Osimertinib is a highly effective treatment that shows a high response rate and long-lasting disease control. However, a resistance to the treatment inevitably develops among patients. Understanding the secondary mechanisms of resistance and the possible therapeutic options available is crucial to define the best management of patients in progression to osimertinib. We provide a comprehensive review of the emerging molecular resistance mechanism in EGFR-mutated NSCLC pre-treated with osimertinib and its future treatment applications.

Acquired Mechanisms of Resistance to Osimertinib-The Next Challenge

Simple Summary

Osimertinib has revolutionized the treatment of EGFR-mutated tumors. Its current applications include the first-line setting, second-line setting, as well as the adjuvant setting. Although it represents a milestone in the context of targeted therapy, inevitably all tumors develop an acquired resistance, some mechanisms involve EGFR, others do so through alternative pathways leading to a bypass in osimertinib inhibition. It is key to understand these acquired mechanisms of resistance, both in the clinical setting, as well as in preclinical models, in order to develop and contribute to the identification of possible therapeutic strategies to overcome this acquired resistance.

Abstract

EGFR-mutated tumors represent a significant percentage of non-small cell lung cancer. Despite the increasing use of osimertinib, a treatment that has demonstrated an outstanding clinical benefit with a tolerable toxicity profile, EGFR tumors eventually acquire mechanisms of resistance. In the last years, multiple mechanisms of resistance have been identified; however, after progressing on osimertinib, treatment options remain bleak. In this review, we cover the most frequent alterations and potential therapeutic strategies to overcome them.

Morphologic-Molecular Transformation of Oncogene Addicted Non-Small Cell Lung Cancer

Patients with non-small cell lung cancer, especially adenocarcinomas, harbour at least one oncogenic driver mutation that can potentially be a target for therapy. Treatments of these oncogene-addicted tumours, such as the use of tyrosine kinase inhibitors (TKIs) of mutated epidermal growth factor receptor, have dramatically improved the outcome of patients. However, some patients may acquire resistance to treatment early on after starting a targeted therapy. Transformations to other histotypes—small cell lung carcinoma, large cell neuroendocrine carcinoma, squamous cell carcinoma, and sarcomatoid carcinoma—have been increasingly recognised as important mechanisms of resistance and are increasingly becoming a topic of interest for all specialists involved in the diagnosis, management, and care of these patients. This article, after examining the most used TKI agents and their main biological activities, discusses histological and molecular transformations with an up-to-date review of all previous cases published in the field. Liquid biopsy and future research directions are also briefly discussed to offer the reader a complete and up-to-date overview of the topic.

Treating disease progression with osimertinib in EGFR-mutated non-small-cell lung cancer: novel targeted agents and combination strategies

A precision medicine approach has been successfully applied in medical oncology for the treatment of non-small-cell lung cancer (NSCLC) through the identification of targetable driver molecular aberrations; activating mutations of epidermal growth factor receptor (EGFR) are the most common. Osimertinib, a third-generation, wild-type sparing, irreversible EGFR tyrosine kinase inhibitor (TKI), originally showed a striking activity after progression to first- and second-generation EGFR-TKIs when T790M resistance mutation was identified. Thereafter, upfront use of osimertinib became the standard of care based on overall survival benefit over first-generation TKIs erlotinib and gefitinib as reported in the FLAURA trial. For patients progressing on osimertinib, identification of resistance mechanisms is crucial to develop novel targeted therapeutic approaches. Moreover, innovative drugs or combination therapies are being developed for cases in which a specific resistance mechanism is not identifiable. In this review, the post-osimertinib treatment options for EGFR-mutated NSCLC are analyzed, with an outlook to ongoing clinical trials. An algorithm to guide clinicians in managing progression on osimertinib is proposed.

Application of Circulating Tumor DNA as a Biomarker for Non-Small Cell Lung Cancer

Background

Non-small cell lung cancer (NSCLC) is one of the most prevalent causes of cancer-related death worldwide. Recently, there are many important medical advancements on NSCLC, such as therapies based on tyrosine kinase inhibitors and immune checkpoint inhibitors. Most of these therapies require tumor molecular testing for selecting patients who would benefit most from them. As invasive biopsy is highly risky, NSCLC molecular testing based on liquid biopsy has received more and more attention recently.

Objective

We aimed to introduce liquid biopsy and its potential clinical applications in NSCLC patients, including cancer diagnosis, treatment plan prioritization, minimal residual disease detection, and dynamic monitoring on the response to cancer treatment.

Method

We reviewed recent studies on circulating tumor DNA (ctDNA) testing, which is a minimally invasive approach to identify the presence of tumor-related mutations. In addition, we evaluated potential clinical applications of ctDNA as blood biomarkers for advanced NSCLC patients.

Results

Most studies have indicated that ctDNA testing is critical in diagnosing NSCLC, predicting clinical outcomes, monitoring response to targeted therapies and immunotherapies, and detecting cancer recurrence. Moreover, the changes of ctDNA levels are associated with tumor mutation burden and cancer progression.

Conclusion

The ctDNA testing is promising in guiding the therapies on NSCLC patients.

A case of synchronous multiple primary lung adenocarcinomas harboring epidermal growth factor receptor mutation and anaplastic lymphoma kinase rearrangement successfully treated with combination of osimertinib and alectinib

Synchronous multiple primary lung cancers (SMPLC) should be distinguished from intrapulmonary metastasis to define the optimal treatment approach. Epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements are typically mutually exclusive and the co-existence of both mutations is relatively rare. Herein, we report a case of SMPLC harboring each EGFR mutation and ALK rearrangement successfully treated with combination of osimertinib and alectinib. A combination of EGFR- and ALK-tyrosine kinase inhibitors could be an effective and tolerable therapeutic option for SMPLC with EGFR mutations and ALK rearrangement.

Emerging Approaches to Overcome Acquired Drug Resistance Obstacles to Osimertinib in Non-Small-Cell Lung Cancer

The pyrimidine core-containing compound Osimertinib is the only epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) from the third generation that has been approved by the U.S. Food and Drug Administration to target threonine 790 methionine (T790M) resistance while sparing the wild-type epidermal growth factor receptor (WT EGFR). It is nearly 200-fold more selective toward the mutant EGFR as compared to the WT EGFR. A tertiary cystein 797 to serine 797 (C797S) mutation in the EGFR kinase domain has hampered Osimertinib treatment in patients with advanced EGFR-mutated non-small-cell lung cancer (NSCLC). This C797S mutation is presumed to induce a tertiary-acquired resistance to all current reversible and irreversible EGFR TKIs. This review summarizes the molecular mechanisms of resistance to Osimertinib as well as different strategies for overcoming the EGFR-dependent and EGFR-independent mechanisms of resistance, new challenges, and a future direction.

Combination of Crizotinib and Osimertinib in T790M+ EGFR-Mutant Non-Small Cell Lung Cancer with Emerging MET Amplification Post-Osimertinib Progression in a 10-Year Survivor: A Case Report

Tyrosine kinase inhibitors (TKIs) represent the standard treatment for patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations. The duration of the response is, however, limited in time owing to the development of resistance mechanisms to both first- and second-generation agents such as MET oncogene amplification. This report describes the successful results obtained with the combination of the third-generation TKI osimertinib with the multitargeted TKI and MET inhibitor crizotinib in a patient with EGFR-mutant NSCLC with emerging MET amplification with a tolerable toxicity profile.

The novel MET inhibitor, HQP8361, possesses single agent activity and enhances therapeutic efficacy of AZD9291 (osimertinib) against AZD9291-resistant NSCLC cells with activated MET

HQP8361 (MK8033) is a novel and selective MET kinase inhibitor that has completed a phase I clinical trial. AZD9291 (osimertinib) represents the first-approved third generation EGFR-tyrosine kinase inhibitor (EGFR-TKI) for the treatment of non-small cell lung cancer (NSCLC) with activating EGFR mutations and resistant T790M mutation, but faces the giant challenge of acquired resistance developed in patients in the clinic. The current study focuses on determining the activity and mechanism of action of HQP8361 as a single agent and in combination with AZD9291 against human NSCLC cells, particularly those with acquired resistance to AZD9291. The majority of human NSCLC cell lines tested had very low levels of MET and p-MET and were insensitive to HQP8361. However, AZD9291-resistant (AR) cell lines with high levels of MET and p-MET responded to HQP8361 single agent and particularly to the combination of HQP8361 and AZD9291. The HQP8361 and AZD9291 combination synergistically decreased the survival of these HCC827/AR cell lines with enhanced induction of apoptosis that involved alteration of Bim and Mcl-1 levels via modulating their degradation. Moreover, the combination also very effectively inhibited the growth of HCC827/AR xenografts in nude mice. These preclinical findings support the potential of HQP8361 in the treatment of NSCLCs with MET amplification or highly activated MET and, when combined with AZD9291, in overcoming acquired resistance to EGFR-TKIs due to MET amplification.

Current Strategies for Treating NSCLC: From Biological Mechanisms to Clinical Treatment

The identification of specific epidermal growth factor receptor (EGFR)-activating mutations heralded a breakthrough in non-small-cell lung cancer (NSCLC) treatments, with the subsequent development of EGFR-tyrosine kinase inhibitor (TKIs) becoming the first-line therapy for patients harboring EGFR mutations. However, acquired resistance to EGFR-TKIs inevitably occurs in patients following initial TKI treatment, leading to disease progression. Various mechanisms are behind the acquired resistance, and mainly include (1) target gene modification, (2) alternative parallel pathway activation, (3) downstream pathway activation, and (4) histological/phenotypic transformation. Approaches to combat the acquired resistance have been investigated according to these mechanisms. Newer generations of TKIs have been developed to target the secondary/tertiary EGFR mutations in patients with acquired resistance. In addition, combination therapies have been developed as another promising strategy to overcome acquired resistance through the activation of other signaling pathways. Thus, in this review, we summarize the mechanisms for acquired resistance and focus on the potential corresponding therapeutic strategies for acquired resistance.

An advanced non-small cell lung cancer patient with epidermal growth factor receptor sensitizing mutation responded to toripalimab in combination with chemotherapy after resistance to osimertinib: a case report

The clinical activity and favorable toxicity profile of osimertinib has led it to be approved not only for advanced non-small cell lung cancer (NSCLC) patients with T790M-positive tumors when first, or second-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment fails, but also for untreated advanced NSCLC patients with EGFR sensitizing mutation, so how to manage patients who get acquired resistance to osimertinib has becoming an emerging clinical challenge. This presentation would report a case of an advanced NSCLC patient with EGFR 19DEL who received combination therapy of toripalimab and chemotherapy after resistance to first line osimertinib therapy and achieved a PFS benefit of over 8 months. This case highlighted that immune checkpoint blockade combined chemotherapy might be a new possibility for advanced NSCLC patients with acquired resistance to osimertinib.

Detection of MET Alterations Using Cell Free DNA and Circulating Tumor Cells from Cancer Patients

MET alterations may provide a potential biomarker to evaluate patients who will benefit from treatment with MET inhibitors. Therefore, the purpose of the present study is to investigate the utility of a liquid biopsy-based strategy to assess MET alterations in cancer patients. We analyzed MET amplification in circulating free DNA (cfDNA) from 174 patients with cancer and 49 healthy controls and demonstrated the accuracy of the analysis to detect its alteration in patients. Importantly, a significant correlation between cfDNA concentration and MET copy number (CN) in cancer patients (r = 0.57, p <10⁻¹⁰) was determined. Furthermore, we evaluated two approaches to detect the presence of MET on circulating tumor cells (CTCs), using the CellSearch^® and Parsortix systems and monitored patients under anti-EGFR treatment (n = 30) combining both cfDNA and CTCs analyses. This follow-up provides evidence for the potential of MET CN assessment when patients develop resistance to anti-EGFR therapy and a significant association between the presence of CTCs MET⁺ and the Overall Survival (OS) in head and neck cancer patients (P = 0.05; HR = 6.66). In conclusion, we develop specific and noninvasive assays to monitor MET status in cfDNA/CTCs and demonstrate the utility of plasma MET CN determination as a biomarker for monitoring the appearance of resistance to anti-EGFR therapy.

Impact of MET alterations on targeted therapy with EGFR-tyrosine kinase inhibitors for EGFR-mutant lung cancer

EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have achieved remarkable outcomes in the treatment of patients with EGFR-mutant non-small-cell lung cancer, but acquired resistance is still the main factor restricting their long-term use. In addition to the T790 M mutation of EGFR, amplification of the MET (or c-MET) gene has long been recognized as an important resistance mechanism for first- or second-generation EGFR-TKIs. Recent studies suggest that a key mechanism of acquired resistance to third-generation EGFR-TKIs (such as osimertinib) may be MET amplification and/or protein overactivation, especially when they are used as a first-line treatment. Therefore, in patients resistant to first-generation EGFR-TKIs caused by MET amplification and/or protein overactivation, the combination of osimertinib with MET or MEK inhibitors may be considered.

Resistance mechanisms to osimertinib in EGFR-mutated non-small cell lung cancer

Osimertinib is an irreversible, third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that is highly selective for EGFR-activating mutations as well as the EGFR T790M mutation in patients with advanced non-small cell lung cancer (NSCLC) with EGFR oncogene addiction. Despite the documented efficacy of osimertinib in first- and second-line settings, patients inevitably develop resistance, with no further clear-cut therapeutic options to date other than chemotherapy and locally ablative therapy for selected individuals. On account of the high degree of tumour heterogeneity and adaptive cellular signalling pathways in NSCLC, the acquired osimertinib resistance is highly heterogeneous, encompassing EGFR-dependent as well as EGFR-independent mechanisms. Furthermore, data from repeat plasma genotyping analyses have highlighted differences in the frequency and preponderance of resistance mechanisms when osimertinib is administered in a front-line versus second-line setting, underlying the discrepancies in selection pressure and clonal evolution. This review summarises the molecular mechanisms of resistance to osimertinib in patients with advanced EGFR-mutated NSCLC, including MET/HER2 amplification, activation of the RAS-mitogen-activated protein kinase (MAPK) or RAS-phosphatidylinositol 3-kinase (PI3K) pathways, novel fusion events and histological/phenotypic transformation, as well as discussing the current evidence regarding potential new approaches to counteract osimertinib resistance.

Understanding the Mechanisms of Resistance in EGFR-Positive NSCLC: From Tissue to Liquid Biopsy to Guide Treatment Strategy

Liquid biopsy has emerged as an alternative source of nucleic acids for the management of Epidermal Growth Factor Receptor (EGFR)-mutant non-Small Cell Lung Cancer (NSCLC). The use of circulating cell-free DNA (cfDNA) has been recently introduced in clinical practice, resulting in the improvement of the identification of druggable EGFR mutations for the diagnosis and monitoring of response to targeted therapy. EGFR-dependent (T790M and C797S mutations) and independent (Mesenchymal Epithelial Transition [MET] gene amplification, Kirsten Rat Sarcoma [KRAS], Phosphatidyl-Inositol 4,5-bisphosphate 3-Kinase Catalytic subunit Alpha isoform [PI3KCA], and RAF murine sarcoma viral oncogene homolog B1 [BRAF] gene mutations) mechanisms of resistance to EGFR tyrosine kinase inhibitors (TKIs) have been evaluated in plasma samples from NSCLC patients using highly sensitive methods (i.e., digital droplet PCR, Next Generation Sequencing), allowing for the switch to other therapies. Therefore, liquid biopsy is a non-invasive method able to detect the molecular dynamic changes that occur under the pressure of treatment, and to capture tumor heterogeneity more efficiently than is allowed by tissue biopsy. This review addresses how liquid biopsy may be used to guide the choice of treatment strategy in EGFR-mutant NSCLC.

MET inhibitors for targeted therapy of EGFR TKI-resistant lung cancer

Treatment of non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) activating mutation with EGFR-TKIs has achieved great success, yet faces the development of acquired resistance as the major obstacle to long-term disease remission in the clinic. MET (or c-MET) gene amplification has long been known as an important resistance mechanism to first- or second-generation EGFR-TKIs in addition to the appearance of T790 M mutation. Recent preclinical and clinical studies have suggested that MET amplification and/or protein hyperactivation is likely to be a key mechanism underlying acquired resistance to third-generation EGFR-TKIs such as osimertinib as well, particularly when used as a first-line therapy. EGFR-mutant NSCLCs that have relapsed from first-generation EGFR-TKI treatment and have MET amplification and/or protein hyperactivation should be insensitive to osimertinib monotherapy. Therefore, combinatorial therapy with osimertinib and a MET or even a MEK inhibitor should be considered for these patients with resistant NSCLC carrying MET amplification and/or protein hyperactivation.