From the beginning to resistance: Study of plasma monitoring and resistance mechanisms in a cohort of patients treated with osimertinib for advanced T790M-positive NSCLC

The impact of EGFR T790M mutation status following the development of Osimertinib resistance on the efficacy of Osimertinib in non-small cell lung cancer: A meta-analysis

BACKGROUND

Previous studies have suggested that loss of the EGFR T790M gene mutation may contribute to the development of resistance to Osimertinib in non-small cell lung cancer (NSCLC).

AIMS

This study aims to assess the relationship between the clinical effectiveness of Osimertinib in NSCLC patients and the T790M mutation status following resistance to Osimertinib and examine differences between plasma and tissue tests and between Asian and non-Asian groups.

METHODS

The PubMed, Web of Science, Cochrane, and EMBASE databases were comprehensively searched for studies on the association between T790M mutation status and the efficacy of Osimertinib between January 2014 and November 2023. Meta-analysis was carried out using Review Manager 5.4 software.

RESULTS

After evaluating 2727 articles, a total of 14 studies were included in the final analysis. Positive correlations between EGFR T790M mutation status after Osimertinib resistance and longer PFS (HR: 0.44, 95% CI: 0.30-0.66), longer OS (HR: 0.3, 95% CI: 0.10-0.86), longer TTD (HR: 0.69, 95% CI: 0.45-1.07), and improved clinical outcomes including PFS and TTD subgroups (HR: 0.58, 95% CI: 0.47-0.73) were observed. Subgroup analysis revealed that, compared with the blood tests, the results of the T790M mutation tests by the tissue are more significant (HR: 0.24, 95% CI: 0.11-0.52 for tissue tests; HR: 0.47, 95% CI: 0.22-1.00 for plasma tests), and the PFS of Osimertinib were similar for Asian and non-Asian patients (HR: 0.46, 95% CI: 0.31-0.68 for Asians; HR: 0.12, 95% CI: 0.01-1.27 for non-Asians).

CONCLUSIONS

Persistence of the T790M gene mutation after the development of Osimertinib resistance is associated with higher therapeutic benefits of Osimertinib in NSCLC patients. The results of tissue detection are more significant than those of plasma detection.

The study of primary and acquired resistance to first-line osimertinib to improve the outcome of EGFR-mutated advanced Non-small cell lung cancer patients: the challenge is open for new therapeutic strategies

The development of targeted therapy in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) patients has radically changed their clinical perspectives. Current first-line standard treatment for advanced disease is commonly considered third-generation tyrosine kinase inhibitors (TKI), osimertinib. The study of primary and acquired resistance to front-line osimertinib is one of the main burning issues to further improve patients' outcome. Great heterogeneity has been depicted in terms of duration of clinical benefit and pattern of progression and this might be related to molecular factors including subtypes of EGFR mutations and concomitant genetic alterations. Acquired resistance can be categorized into two main classes: EGFR-dependent and EGFR-independent mechanisms and specific pattern of progression to first-line osimertinib have been demonstrated. The purpose of the manuscript is to provide a comprehensive overview of literature about molecular resistance mechanisms to first-line osimertinib, from a clinical perspective and therefore in relationship to emerging therapeutic approaches.

Detection of EGFR T790M mutation using liquid biopsy for non-small cell lung cancer: Utility of droplet digital polymerase chain reaction vs. cobas real-time polymerase chain reaction

BACKGROUND

Digital platforms for mutation detection yield higher sensitivity than non-digital platforms but lack universal positive cut-off values that correlate with the outcome of osimertinib treatment. This study determined compared droplet digital polymerase chain reaction (ddPCR) to the standard cobas assay for epithelial growth factor receptor (EGFR) T790M mutation detection in patients with non-small cell lung cancer.

METHODS

Study patients had EGFR-mutant tumours with disease progression on first/second generation EGFR tyrosine kinase inhibitors, and osimertinib treatment after T790M mutation detection. T790M status was tested by cobas assay using liquid biopsy, and only by ddPCR if an EGFR mutation was identified but T790M was negative. Clinical efficacy of osimertinib was compared between patients with T790M detected by cobas vs. only by ddPCR. A positive cut-off value for ddPCR was determined by assessing efficacy with osimertinib.

RESULTS

61 patients had tumors with an acquired T790M mutation, 38 detected by cobas and an additional 23 only by ddPCR. The median progression-free survival (PFS) for the cobas- and ddPCR-positive groups was 9.5 and 7.8 months, respectively (p=0.43). For ddPCR, a fractional abundance (FA) of 0.1% was used as a cut-off value. The median PFS of patients with FA ≥0.1% and <0.1% was 8.3 and 4.6 months, respectively (p=0.08). FA ≥0.1% was independently associated with a longer PFS.

CONCLUSION

Using ddPCR to follow up the cobas assay yielded more cases (38% of total) with a T790M mutation. A cut-off value of FA ≥0.1% identified patients who responded as well to osimertinib as those identified by cobas assay. This sequential approach should detect additional patients who might benefit from osimertinib treatment.

Liquid biopsy for the management of NSCLC patients under osimertinib treatment

Therapeutic management of NSCLC patients is quite challenging as they are mainly diagnosed at a late stage of disease, and they present a high heterogeneous molecular profile. Osimertinib changed the paradigm shift in treatment of EGFR mutant NSCLC patients achieving significantly better clinical outcomes. To date, osimertinib is successfully administered not only as first- or second-line treatment, but also as adjuvant treatment while its efficacy is currently investigated during neoadjuvant treatment or in stage III, unresectable EGFR mutant NSCLC patients. However, resistance to osimertinib may occur due to clonal evolution, under the pressure of the targeted therapy. The utilization of liquid biopsy as a minimally invasive tool provides insight into molecular heterogeneity of tumor clonal evolution and potent resistance mechanisms which may help to develop more suitable therapeutic approaches. Longitudinal monitoring of NSCLC patients through ctDNA or CTC analysis could reveal valuable information about clinical outcomes during osimertinib treatment. Therefore, several guidelines suggest that liquid biopsy in addition to tissue biopsy should be considered as a standard of care in the advanced NSCLC setting. This practice could significantly increase the number of NSCLC patients that will eventually benefit from targeted therapies, such as EGFR TKIs.

MYC expression and fatty acid oxidation in EGFR-TKI acquired resistance

This report expands on our previous research, highlighting a unique inverse correlation between MYC expression in tumor cells and immune cells during the development of EGFR-TKI resistance. It is observed that MYC expression and fatty acid oxidation (FAO) metabolism in tissue-resident memory (TRM) CD8 + T cells are significantly impaired. These findings offer new insights into the mechanisms of TKI resistance. Although the study is preliminary, it suggests caution when interpreting the effectiveness of MYC inhibitors in reversing TKI resistance, especially when immune factors are not considered.

Predictive significance of circulating tumor DNA against patients with T790M-positive EGFR-mutant NSCLC receiving osimertinib

Circulating tumor DNA (ctDNA) provides molecular information on tumor heterogeneity. The prognostic usefulness of ctDNA after first-line epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are limited. Therefore, the present study evaluated ctDNA during osimertinib administration as a second-line or more setting to identify the relationship between EGFR mutation levels and outcomes in patients with advanced non-small cell lung cancer (NSCLC). Forty patients with EGFR T790M-positive NSCLC receiving osimertinib after prior EGFR-TKI treatment were registered. Plasma samples were collected at osimertinib pretreatment, after 1 month of treatment, and at the time of progressive disease (PD). ctDNA analysis was performed by digital polymerase chain reaction. The detection rate of copy numbers of exon 19 deletion, L858R, and T790M in plasma samples was significantly lower 1 month after osimertinib than at pretreatment, and significantly higher at PD than at 1 month, whereas that of C797S was significantly higher at PD than at 1 month. No statistically significant difference was observed in the copy numbers of exon 19 deletion, L858R, T790M, and C797S between complete response or partial response and stable disease or PD. The detection of T790M at PD after osimertinib initiation was a significant independent prognostic factor for predicting shorter prognosis, and the presence of major EGFR mutations at pretreatment and PD was closely linked to worse survival after osimertinib initiation. Molecular testing based on ctDNA is helpful for predicting outcomes of osimertinib treatment in T790M-positive NSCLC after previous EGFR-TKI treatment.

Liquid biopsy in clinical outcomes and detection of T790M mutation in metastatic non-small cell lung cancer after progression to EGFR-TKI

BACKGROUND

Liquid biopsy (LB) is used to detect epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) and has been demonstrated to have prognostic and predictive value.

OBJECTIVE

To associate the rates of EGFR and T790M mutations detected by LB during disease progression after first- or second-generation EGFR-TKIs with clinical characteristics and survival outcomes.

METHODS

From January 2018 to December 2021, 295 patients with advanced EGFR mutant (EGFRm) NSCLC treated with first- or second-generation EGFR-TKIs were retrospectively analyzed. LB was collected at the time of progression. The frequency of EGFRT790M mutations, overall survival (OS), and the clinical characteristics associated with LB positivity were determined.

RESULTS

The prevalence of EGFRT790M mutation detected using LB was 44%. In patients with negative vs. positive LB, the median OS was 45.0 months vs. 25.0 months (p= 0.0001), respectively. Patients with a T790M mutation receiving osimertinib had a median OS of 44 months (95% CI [33.05-54.99]). Clinical characteristics associated with positive LB at progression extra-thoracic involvement, > 3 metastatic sites, and bone metastases.

CONCLUSIONS

Our findings showed that LB positivity was associated with worse survival outcomes and specific clinical characteristics. This study also confirmed the feasibility and detection rate of T790M mutation in a Latin American population.

Monitoring of Plasma EGFR Mutations during Osimertinib Treatment for NSCLC Patients with Acquired T790M Mutation

BACKGROUND

Osimertinib was first approved for the treatment of non-small cell lung cancer (NSCLC) in patients who have developed the epidermal growth factor receptor (EGFR) T790M mutation after treatment with EGFR tyrosine kinase inhibitors (TKIs). We routinely evaluated the plasma of NSCLC patients with the T790M mutation to more rapidly detect an increase in disease activity and resistance to treatment.

METHODS

Eligible patients received osimertinib after resistance to the first- or second-generation of EGFR-TKIs in NSCLC harboring T790M mutation detectable in tumor tissue or plasma. Plasma samples were collected every 8 weeks during osimertinib treatment. The plasma analysis was performed using an improved PNA-LNA PCR clamp method. We tested samples for a resistance mechanism, including EGFR-activating, T790M, and C797S mutations, and assessed the association between the mutations and osimertinib treatment.

RESULTS

Of the 60 patients enrolled in the study, 58 were eligible for this analysis. In plasma collected before osimertinib treatment, activating mutations were detected in 47 of 58 patients (81.0%) and T790M was detected in 44 patients (75.9%). Activating mutations were cleared in 60.9% (28/46) and T790M was cleared in 93.0% (40/43). Of these, 71.4% (20/28) of activating mutations and 87.5% (35/40) of T790M mutation were cleared within 8 weeks of treatment. The total response rate (RR) was 53.4% (31/58). The median duration of treatment was 259 days, with a trend toward longer treatment duration in patients who experienced the clearance of activating mutations with osimertinib. At the time of disease progression during osimertinib treatment, C797S was detected in 3 of 37 patients (8.1%).

CONCLUSION

Plasma EGFR mutation analysis was effective in predicting the effect of osimertinib treatment.

Circulating tumor DNA detection in MRD assessment and diagnosis and treatment of non-small cell lung cancer

Circulating tumor DNA (ctDNA) has contributed immensely to the management of hematologic malignancy and is now considered a valuable detection tool for solid tumors. ctDNA can reflect the real-time tumor burden and be utilized for analyzing specific cancer mutations via liquid biopsy which is a non-invasive procedure that can be used with a relatively high frequency. Thus, many clinicians use ctDNA to assess minimal residual disease (MRD) and it serves as a prognostic and predictive biomarker for cancer therapy, especially for non-small cell lung cancer (NSCLC). Advanced methods have been developed to detect ctDNA, and recent clinical trials have shown the rationality and feasibility of ctDNA for identifying mutations and guiding treatments in NSCLC. Here, we have reviewed recently developed ctDNA detection methods and the importance of sequence analyses of ctDNA in NSCLC.

Resistance to TKIs in EGFR-Mutated Non-Small Cell Lung Cancer: From Mechanisms to New Therapeutic Strategies

Simple Summary

Resistance to tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) in advanced mutant non-small cell lung cancer (NSCLC) constitutes a therapeutic challenge. Resistance may occur as a result of EGFR-dependent and independent molecular pathways. The first commonly includes T790M, C797S, L792X and L718X mutations, while the latter pertains to HER2 and MET amplifications, gene rearrangements, disruption in PIK3CA, MAPK signaling and SCLC and epithelial–mesenchymal cells transformation. Liquid biopsies detecting mutant cell-free DNA (cfDNA) have a major potential in the detection of mutant clones before they become clinically apparent. Newer-generation TKIs, bispecific antibodies and antibody-drug conjugates or combinations of TKIs with other TKIs or chemotherapy, immunotherapy and anti-vascular endothelial growth factors (anti-VEGFs) are currently in use or under investigation in EGFR mutant NSCLC. In EGFR mutant NSCLC metastatic to the brain, the blood–brain barrier (BBB) decreases the ability of TKIs to reach the central nervous system (CNS), acting as an additional resistance factor, which can presently be addressed with osimertinib. The potential of rechallenging EFGR TKIs after chemotherapy and combining it with anti-PD-1 immunotherapeutics remains ambivalent. Harnessing nanocarriers to improve drug delivery in EGFR TKIs-resistant NSCLC has been promising in preclinical settings, but it is yet to be determined in a clinical context.

Abstract

Resistance to tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) in advanced mutant Non-Small Cell Lung Cancer (NSCLC) constitutes a therapeutic challenge. This review intends to summarize the existing knowledge about the mechanisms of resistance to TKIs in the context of EGFR mutant NSCLC and discuss its clinical and therapeutic implications. EGFR-dependent and independent molecular pathways have the potential to overcome or circumvent the activity of EGFR-targeted agents including the third-generation TKI, osimertinib, negatively impacting clinical outcomes. CNS metastases occur frequently in patients on EGFR-TKIs, due to the inability of first and second-generation agents to overcome both the BBB and the acquired resistance of cancer cells in the CNS. Newer-generation TKIs, TKIs targeting EGFR-independent resistance mechanisms, bispecific antibodies and antibody-drug conjugates or combinations of TKIs with other TKIs or chemotherapy, immunotherapy and Anti-Vascular Endothelial Growth Factors (anti-VEGFs) are currently in use or under investigation in EGFR mutant NSCLC. Liquid biopsies detecting mutant cell-free DNA (cfDNA) provide a window of opportunity to attack mutant clones before they become clinically apparent. Overall, EGFR TKIs-resistant NSCLC constitutes a multifaceted therapeutic challenge. Mapping its underlying mutational landscape, accelerating the detection of resistance mechanisms and diversifying treatment strategies are essential for the management of the disease.

Afatinib, an effective treatment for patient with lung squamous cell carcinoma harboring uncommon EGFR G719A and R776C co-mutations

BACKGROUND

Epidermal growth factor receptor (EGFR) is a crucial driven gene in non-small cell lung cancer (NSCLC), and the EGFR mutation rate in lung squamous cell carcinoma (SCC) is only 3 ~ 6.92%. Uncommon EGFR mutations, such as S768I, L861Q and G719X, accounting for approximately 15% of NSCLC harboring EGFR mutation. Afatinib, a second-generation EGFR-tyrosine kinase inhibitor (TKI), has been approved for NSCLC harboring uncommon mutations by the FDA in 2018. In our report, the lung SCC patient harboring uncommon compound EGFR mutation (G719A and R776C) benefited from afatinib.

CASE PRESENTATION

A case of a lung SCC patient harboring uncommon compound EGFR mutation (G719A and R776C) benefited from afatinib, and new MYC amplification was detected by next-generation sequencing (NGS) after disease progression.

CONCLUSIONS

This case first identified a patient with lung squamous cell carcinoma harboring uncommon compound EGFR mutation (G719A and R776C) benefited from afatinib and achieved 11 months of progression-free survival (PFS). Then, new MYC amplification was detected after disease progression, indicating that MYC amplification may be one of the reasons for afatinib resistance.

Resistance mechanisms to osimertinib and emerging therapeutic strategies in nonsmall cell lung cancer

PURPOSE OF REVIEW

This review aims to introduce the resistance mechanisms to osimertinib, discuss the therapeutic strategies, and make clinical updates in overcoming resistance to osimertinib.

RECENT FINDINGS

Osimertinib has shown favorable efficacy on second-line and first-line treatments in EGFR-mutant advanced nonsmall cell lung cancer (NSCLC). However, the presence of primary and acquired resistance to osimertinib restricts its clinical benefits. The primary resistance mainly consists of BIM deletion polymorphism and EGFR exon 20 insertions. Meanwhile, the heterogeneous mechanisms of acquired resistance include EGFR-dependent (on-target) and EGFR-independent (off-target) mechanisms. EGFR C797S mutation, MET amplification, HER2 amplification, and small cell lung cancer transformation were identified as frequent resistance mechanisms. Recently, more novel mechanisms, including rare EGFR point mutations and oncogenic fusions, were reported. With the results of completed and on-going clinical trials, the emerging therapeutic strategies of postosimertinib progression are summarized.

SUMMARY

The resistance mechanisms to osimertinib are heterogeneous and gradually perfected. The combination of osimertinib with bypass targeted therapy and other therapeutic approaches emerge as promising strategies.

Monitoring cfDNA in Plasma and in Other Liquid Biopsies of Advanced EGFR Mutated NSCLC Patients: A Pilot Study and a Review of the Literature

Simple Summary

In advanced non-small cell lung cancer (NSCLC) patients, tumor tissue biopsy represents the gold standard for molecular analysis procedures. However, to achieve the necessary information, both at the time of diagnosis and progressive disease, is sometimes challenging, considering the small cancer material available. Liquid biopsy consists of a non-invasive alternative approach that owns the potential to provide useful information for molecular diagnostic. We aimed to prove the worth of liquid biopsy as plasma but also as urine and exhaled breath condensate (EBC) as the best surrogate to tumor tissue as well as to explore the molecular mechanisms that underlying the resistance to second-line osimertinib in advanced EGFR mutated NSCLC. We believe that our findings, with the PLUREX study and the review of literature, may add another brick in the wall on the use of liquid biopsy in the clinical practice in the setting of EGFR-mutated NSCLC disease.

Abstract

In order to study alternatives at the tissue biopsy to study EGFR status in NSCLC patients, we evaluated three different liquid biopsy platforms (plasma, urine and exhaled breath condensate, EBC). We also reviewed the literature of the cfDNA biological sources other than plasma and compared our results with it about the sensitivity to EGFR mutation determination. Twenty-two EGFR T790M-mutated NSCLC patients in progression to first-line treatment were enrolled and candidate to osimertinib. Plasma, urine and EBC samples were collected at baseline and every two months until progression. Molecular analysis of cfDNA was performed by ddPCR and compared to tissue results. At progression NGS analysis was performed. The EGFR activating mutation detection reached a sensitivity of 58 and 11% and for the T790M mutation of 45 and 10%, in plasma and urine samples, respectively. Any DNA content was recovered from EBC samples. Considering the plasma monitoring study, the worst survival was associated with positive shedding status; both plasma and urine molecular progression anticipated the radiological worsening. Our results confirmed the role of plasma liquid biopsy in testing EGFR mutational status, but unfortunately, did not evidence any improvement from the combination with alternative sources, as urine and EBC.

Serial Plasma Cell-Free Circulating Tumor DNA Tests Identify Genomic Alterations for Early Prediction of Osimertinib Treatment Outcome in EGFR T790M-Positive NSCLC

Introduction

Recent advances in the detection of genomic DNA from plasma samples allow us to follow tumor DNA shedding in plasma during systemic treatment. Osimertinib is the standard of care for patients with NSCLC with acquired EGFR T790M mutations. We assessed changes in serial plasma cell-free circulating tumor DNA (ctDNA) genomic alterations to predict osimertinib efficacy.

Methods

We prospectively collected plasma from patients having EGFR-mutated advanced NSCLC previously treated with EGFR tyrosine kinase inhibitor therapy and with acquired EGFR T790M mutation detected by standard methods. Plasma samples were collected before starting osimertinib treatment, 4 weeks after osimertinib treatment, and on progression. ctDNA was analyzed using the Guardant360 assay.

Results

A total of 15 eligible patients received osimertinib. Before starting treatment, EGFR-activating mutations were detected in the ctDNA of all patients, and EGFR T790M was detected in 93% of the cases. Osimertinib treatment was associated with an objective response rate of 53% and a median progression-free survival of 7.3 months. A total of 12 of the 15 patients had undetectable plasma T790M and decreased activating mutation allelic frequency (AF) at week 4. None of the 12 patients had disease progression within 16 weeks. For the remaining three patients, with detectable plasma T790M (n = 2) or increased activating mutation AF (n = 1) at week 4, two had progressive disease within 16 weeks (p = 0.03).

Conclusions

In patients with EGFR-mutated advanced NSCLC, persistent EGFR T790M or increasing activating mutation AF as detected in ctDNA 4 weeks after the start of osimertinib treatment may predict disease progression within 16 weeks.

Molecular Mechanism of EGFR-TKI Resistance in EGFR-Mutated Non-Small Cell Lung Cancer: Application to Biological Diagnostic and Monitoring

Non-small cell lung cancer (NSCLC) is the most common cancer in the world. Activating epidermal growth factor receptor (EGFR) gene mutations are a positive predictive factor for EGFR tyrosine kinase inhibitors (TKIs). For common EGFR mutations (Del19, L858R), the standard first-line treatment is actually third-generation TKI, osimertinib. In the case of first-line treatment by first (erlotinib, gefitinib)- or second-generation (afatinib) TKIs, osimertinib is approved in second-line treatment for patients with T790M EGFR mutation. Despite the excellent disease control results with EGFR TKIs, acquired resistance inevitably occurs and remains a biological challenge. This leads to the discovery of novel biomarkers and possible drug targets, which vary among the generation/line of EGFR TKIs. Besides EGFR second/third mutations, alternative mechanisms could be involved, such as gene amplification or gene fusion, which could be detected by different molecular techniques on different types of biological samples. Histological transformation is another mechanism of resistance with some biological predictive factors that needs tumor biopsy. The place of liquid biopsy also depends on the generation/line of EGFR TKIs and should be a good candidate for molecular monitoring. This article is based on the literature and proposes actual and future directions in clinical and translational research.

Novel ETV1 mutation in small cell lung cancer transformation resistant to EGFR tyrosine kinase inhibitors

Background

Non-small cell lung cancer (NSCLC) patients harboring mutations in the epidermal growth factor receptor (EGFR) gene respond dramatically to EGFR tyrosine kinase inhibitors (TKIs). However, these patients inevitably develop acquired resistance to EGFR-TKIs. Among them, small cell lung cancer (SCLC) transformation is a relatively rare mechanism.

Methods

We used a 639 cancer-relevant gene panel to detect genetic differences in tissues before and after EGFR-TKIs resistance caused by SCLC transformation. In vitro experiments were conducted to study the role of ETS variant transcription factor 1 (ETV1) on SCLC transformation and EGFR-TKIs resistance.

Results

We present two EGFR-mutant lung adenocarcinoma (LUAD) patients. One patient, with EGFR exon 19 deletion (Ex19del), accepted first-line gefitinib treatment and then received osimertinib treatment due to acquisition of an EGFR-T790M mutation. A novel ETV1 mutation (p.P159S) was detected in the SCLC tissue after osimertinib resistance when not coexisting with T790M. The other patient harbored an EGFR exon 21 mutation (p.L858R), and had a long-lasting response to first-line gefitinib, and then transformed to SCLC after TKI resistance. A previously unreported ETV1 mutation (p.E462Q) was detected in the SCLC tissue. In vitro, ETV1 p.E462Q and p.P159S mutations participated in neuroendocrine differentiation by inducing the expression of achaete-scute homolog 1 (ASCL1) and promoting the proliferation of H69 cells. ETV1 p.E462Q and p.P159S mutations were also resistant to gefitinib and osimertinib after introduction into H358 cells.

Conclusions

Novel ETV1 p.E462Q and p.P159S mutations were found in the SCLC tissues of TKIs-resistant LUAD patients, providing a new understanding of ETV1 involvement in acquired resistance to EGFR-TKIs via SCLC transformation.

EGFR-plasma mutations in prognosis for non-small cell lung cancer treated with EGFR TKIs: A meta-analysis

BACKGROUND

The plasma-based epidermal growth factor receptor (EGFR) mutation testing is approved recently to use in clinical practice. However, it has not been used as a prognostic marker yet because of contradictory results.

AIM

This meta-analysis aims to clarify the role of the EGFR-plasma test in prognosis for non-small cell lung cancer (NSCLC) who have mutant tumors and receive EGFR tyrosine kinase inhibitors (TKIs).

METHODS AND RESULTS

The PubMed/MEDLINE, Web of Science, Cochrane Library, and Google Scholar databases were searched for relevant studies by April 10, 2021. The hazard ratio (HR) from reports was extracted and used to assess the correlation of EGFR-plasma status with progression-free survival (PFS) and overall survival (OS). A total of 35 eligible studies with 4106 patients were enrolled in the final analysis. Patients with concurrent EGFR mutations in pretreatment plasma have shorter PFS (HR = 2.00, 95% confidence interval [CI]: 1.73-2.31, p < .001) and OS time (HR = 2.31, 95% CI: 1.89-2.83, p < .001) compared to the tumor-only mutation cases. Besides, the persistence of EGFR-activating mutations in post-treatment plasma is associated with worse PFS (HR = 3.84, 95% CI: 2.96-4.99, p < .001) and OS outcome (HR = 3.22, 95% CI: 2.35-4.42, p < .001) compared to others. Notably, the prognostic value of the EGFR-plasma test is also validated in treatment with third-generation EGFR TKI and significance regardless of different detection methods.

CONCLUSION

The presence of EGFR-plasma mutations at pretreatment and after EGFR TKI initiation is the worse prognostic factor for PFS and OS in NSCLC.

Liquid Biopsy for Biomarker Testing in Non-Small Cell Lung Cancer: A European Perspective

The development of targeted therapies has improved survival rates for patients with advanced non-small cell lung cancer (NSCLC). However, tissue biopsy is unfeasible or inadequate in many patients, limiting biomarker testing and access to targeted therapies. The increasing numbers of established and emerging biomarkers with available targeted treatments highlights the challenges associated with sequential single-gene testing and limited tissue availability. Multiplex next-generation sequencing (NGS) offers an attractive alternative and represents a logical next step, and in cases where the tumour is inaccessible, tissue biopsy yields insufficient tumour content, or when the patient’s performance status does not allow a tissue biopsy, liquid biopsy can provide valuable material for molecular diagnosis. Here, we explore the role of liquid biopsy (i.e., circulating cell-free DNA analysis) in Europe. Liquid biopsies could be used as a complementary approach to increase rates of molecular diagnosis, with the ultimate aim of improving patient access to appropriate targeted therapies. Expert opinion is also provided on potential future applications of liquid biopsy in NSCLC, including for cancer prevention, detection of early stage and minimum residual disease, monitoring of response to therapy, selection of patients for immunotherapy, and monitoring of tumour evolution to enable optimal adaptation/combination of drug therapies.

Clinical Utility of Liquid Biopsy-Based Actionable Mutations Detected via ddPCR

Cancer is one of the leading causes of death worldwide and remains a major public health challenge. The introduction of more sensitive and powerful technologies has permitted the appearance of new tumor-specific molecular aberrations with a significant cancer management improvement. Therefore, molecular pathology profiling has become fundamental not only to guide tumor diagnosis and prognosis but also to assist with therapeutic decisions in daily practice. Although tumor biopsies continue to be mandatory in cancer diagnosis and classification, several studies have demonstrated that liquid biopsies could be used as a potential tool for the detection of cancer-specific biomarkers. One of the main advantages is that circulating free DNA (cfDNA) provides information about intra-tumoral heterogeneity, reflecting dynamic changes in tumor burden. This minimally invasive tool has become an accurate and reliable instrument for monitoring cancer genetics. However, implementing liquid biopsies across the clinical practice is still ongoing. The main challenge is to detect genomic alterations at low allele fractions. Droplet digital PCR (ddPCR) is a powerful approach that can overcome this issue due to its high sensitivity and specificity. Here we explore the real-world clinical utility of the liquid biopsy ddPCR assays in the most diagnosed cancer subtypes.

Liquid Biopsy for Disease Monitoring in Non-Small Cell Lung Cancer: The Link between Biology and the Clinic

INTRODUCTION

Cell-free DNA (cfDNA) analysis offers a non-invasive method to identify sensitising and resistance mutations in advanced Non-Small Cell Lung Cancer (NSCLC) patients. Next-generation sequencing (NGS) of circulating free DNA (cfDNA) is a valuable tool for mutations detection and disease's clonal monitoring.

MATERIAL AND METHODS

An amplicon-based targeted gene NGS panel was used to analyse 101 plasma samples of advanced non-small cell lung cancer (NSCLC) patients with known oncogenic mutations, mostly EGFR mutations, serially collected at different clinically relevant time points of the disease.

RESULTS

The variant allelic frequency (VAF) monitoring in consecutive plasma samples demonstrated different molecular response and progression patterns. The decrease in or the clearance of the mutant alleles was associated with response and the increase in or the emergence of novel alterations with progression. At the best response, the median VAF was 0% (0.0% to 3.62%), lower than that at baseline, with a median of 0.53% (0.0% to 9.9%) (p = 0.004). At progression, the VAF was significantly higher (median 4.67; range: 0.0-36.9%) than that observed at the best response (p = 0.001) and baseline (p = 0.006). These variations anticipated radiographic changes in most cases, with a median time of 0.86 months. Overall, the VAF evolution of different oncogenic mutations predicts clinical outcomes.

CONCLUSION

The targeted NGS of circulating tumour DNA (ctDNA) has clinical utility to monitor treatment response in patients with advanced lung adenocarcinoma.

Targeting c-Myc to overcome acquired resistance of EGFR mutant NSCLC cells to the third generation EGFR tyrosine kinase inhibitor, osimertinib

Osimertinib (AZD9291 or TAGRISSOTM) is a promising and approved third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) for treating patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR-activating mutations or the resistant T790M mutation. However, the inevitable emergence of acquired resistance limits its long-term efficacy. A fuller understanding of the mechanism of action of osimertinib and its linkage to acquired resistance will enable the development of more efficacious therapeutic strategies. Consequently, we have identified a novel connection between osimertinib or other EGFR TKI and c-Myc. Osimertinib rapidly and sustainably decreased c-Myc levels primarily via enhancing protein degradation in EGFR-mutant (EGFRm) NSCLC cell lines and xenograft tumors. c-Myc levels were substantially elevated in different EGFRm NSCLC cell lines with acquired resistance to osimertinib in comparison with their corresponding parental cell lines and could not be reduced any further by osimertinib. Consistently, c-Myc levels were elevated in the majority of EGFRm NSCLC tissues relapsed from EGFR-TKI treatment compared to their corresponding untreated baseline c-Myc levels. Suppression of c-Myc through knockdown or pharmacological targeting with BET inhibitors restored the response of resistant cell lines to osimertinib. These findings indicate that c-Myc modulation mediates the therapeutic efficacy of osimertinib and the development of osimertinib-acquired resistance. Furthermore, they establish c-Myc as a potential therapeutic target and warrant clinical testing of BET inhibition as a potential strategy to overcome acquired resistance to osimertinib or other EGFR inhibitors.

Impact of detecting plasma EGFR mutations with ultrasensitive liquid biopsy in outcomes of NSCLC patients treated with first- or second-generation EGFR-TKIs

BACKGROUND

Few trials have evaluated the utility of liquid biopsies to detect epidermal growth factor receptor mutations (EGFRm) at the time of response evaluation and its association with the clinical characteristics and outcomes of non-small-cell lung cancer (NSCLC) patients.

OBJECTIVE

This study aimed to evaluate, in a real-world clinical setting, the prevalence of plasma EGFRm and its association with the clinical characteristics, response and survival outcomes of NSCLC patients under treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKIs).

METHODS

This observational study enrolled advanced or metastatic NSCLC patients, with confirmed tumor EGFRm, receiving treatment with first- or second-generation EGFR-TKIs. Blood samples for the detection of plasma EGFRm were collected at the time of response evaluation and processed using the Target Selector™ assay. The main outcomes were the detection rate of plasma EGFRm, median Progression-Free Survival (PFS) and Overall Survival (OS) according to plasma EGFR mutational status.

RESULTS

Of 84 patients, 50 (59.5%) had an EGFRm detected in plasma. After a median follow-up of 21.1 months, 63 patients (75%) had disease progression. The detection rate of plasma EGFRm was significantly higher in patients with disease progression than in patients with partial response or stable disease (68.3% versus 33.3%; P< 0.01). PFS and OS were significantly longer in patients without plasma EGFRm than among patients with plasma EGFRm (14.3 months [95% CI, 9.25-19.39] vs 11.0 months [95% CI, 8.61-13.46]; P= 0.034) and (67.8 months [95% CI, 39.80-95.94] vs 32.0 months [95% CI, 17.12-46.93]; P= 0.006), respectively. A positive finding in LB was associated with the presence of ⩾ 3 more metastatic sites (P= 0.028), elevated serum carcinoembryonic (CEA) at disease progression (P= 0.015), and an increase in CEA with respect to baseline levels (P= 0.038).

CONCLUSIONS

In NSCLC patients receiving EGFR-TKIs, the detection of plasma EGFRm at the time of tumor response evaluation is associated with poor clinical outcomes.

Advances in Small-Cell Lung Cancer (SCLC) Translational Research

Over the past several years, we have witnessed a resurgence of interest in the biology and therapeutic vulnerabilities of small-cell lung cancer (SCLC). This has been driven in part through the development of a more extensive array of representative models of disease, including a diverse variety of genetically engineered mouse models and human tumor xenografts. Herein, we review recent progress in SCLC model development, and consider some of the particularly active avenues of translational research in SCLC, including interrogation of intratumoral heterogeneity, insights into the cell of origin and oncogenic drivers, mechanisms of chemoresistance, and new therapeutic opportunities including biomarker-directed targeted therapies and immunotherapies. Whereas SCLC remains a highly lethal disease, these new avenues of translational research, bringing together mechanism-based preclinical and clinical research, offer new hope for patients with SCLC.

Dynamic cfDNA Analysis by NGS in EGFR T790M-Positive Advanced NSCLC Patients Failed to the First-Generation EGFR-TKIs

Purpose

Circulating cell-free DNA (cfDNA) level has been demonstrated to be associated with efficacy in first generation EGFR TKIs in non-small cell lung cancer (NSCLC). However, the role of dynamic cfDNA analysis using next-generation sequencing (NGS) in patients with subsequent third-generation EGFR TKIs remains unclear.

Methods

From 2016 to 2019, 81 NSCLC patients with EGFR T790M mutation either in tissue or plasma who received third-generation EGFR TKIs treatment were enrolled. CfDNA were sequenced by NGS with a 425-gene panel. The association of clinical characteristics, pretreatment, dynamic cfDNA and T790M level with outcomes in patients treated with the third-generation TKIs were analyzed.

Results

In univariate analysis, the median PFS of patients with undetectable cfDNA level during treatment was significantly longer than those with detectable cfDNA (16.97 vs. 6.10 months; HR 0.2109; P < 0.0001). The median PFS of patients with undetectable T790M level during treatment was significantly longer than those with detectable T790M (14.1 vs. 4.4 months; HR 0.2192; P < 0.001). Cox hazard proportion model showed that cfDNA clearance was an independent predictor for longer PFS (HR 0.3085; P < 0.001) and longer OS (HR 0.499; P = 0.034). The most common resistant mutations of the third-generation TKIs were EGFR C797S (24%). CDK6 CNV, GRIN2A, BRCA2, EGFR D761N, EGFR Q791H, EGFR V843I, and ERBB4 mutation genes may possibly be new resistant mechanisms.

Conclusions

Patients with undetectable cfDNA during the third-generation EGFR TKI treatment have superior clinical outcomes, and dynamic cfDNA analysis by NGS is valuable to explore potential resistant mechanisms.

Liquid Biopsies: Applications for Cancer Diagnosis and Monitoring

The minimally-or non-invasive detection of circulating tumor-derived components in biofluids, such as blood, liquid biopsy is a revolutionary approach with significant potential for the management of cancer. Genomic and transcriptomic alterations can be accurately detected through liquid biopsies, which provide a more comprehensive characterization of the heterogeneous tumor profile than tissue biopsies alone. Liquid biopsies could assist diagnosis, prognosis, and treatment selection, and hold great potential to complement current surveilling strategies to monitor disease evolution and treatment response in real-time. In particular, these are able to detect minimal residual disease, to predict progression, and to identify mechanisms of resistance, allowing to re-orient treatment strategies in a timelier manner. In this review we gathered current knowledge regarding the role and potential of liquid biopsies for the diagnosis and follow-up of cancer patients. The presented findings emphasize the strengths of liquid biopsies, revealing their chance of improving the diagnosis and monitoring of several tumor types in the near future. However, despite growing evidence supporting their value as a management tool in oncology, some limitations still need to be overcome for their implementation in the routine clinical setting.

PTEN Loss as a Predictor of Tumor Heterogeneity and Poor Prognosis in Patients With EGFR-mutant Advanced Non-small-cell Lung Cancer Receiving Tyrosine Kinase Inhibitors

BACKGROUND

Rapid disease progression of patients with advanced epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) has been recently associated with tumor heterogeneity, which may be mirrored by coexisting concomitant alterations. The aim of this analysis was to investigate the correlation between loss of function of PTEN and the efficacy of tyrosine kinase inhibitors in this population.

MATERIALS AND METHODS

Archival tumor blocks from patients with EGFR-mutant NSCLC who were administered upfront tyrosine kinase inhibitors were retrospectively collected. The status of 4 genes (PTEN, TP53, c-MET, IGFR) was evaluated by immunohistochemistry, and it was correlated with overall response rate, overall survival (OS), and progression-free survival (PFS).

RESULTS

Fifty-one patients were included. In multivariate analysis, PTEN loss (hazard ratio [HR], 3.46; 95% confidence interval [CI], 1.56-7.66; P = .002), IGFR overexpression (HR, 2.22; 95% CI, 1.03-4.77; P = .04), liver metastases (HR, 3.55; 95% CI, 1.46-8.65; P = .005), and Eastern Cooperative Oncology Group performance status (ECOG PS) ≥ 1 (HR, 2.57; 95% CI, 1.04-6.34; P = .04) were significantly associated with shorter PFS. Patients with PTEN loss had a median PFS of 6 months (2-year PFS, 11.6%), whereas patients without PTEN loss had a median PFS of 18 months (2-year PFS, 43.6%) (log-rank P < .005). In the multivariate analysis, PTEN loss (HR, 5.92; 95% CI, 2.37-14.81; P < .005), liver metastases (HR, 2.63; 95% CI, 1.06-6.51; P = .037), and ECOG PS ≥ 1 (HR, 2.80; 95% CI, 1.15-6.81; P = .024) were significantly associated with shorter OS. Patients with PTEN loss had a median OS of 6 months (2-year OS, 12.2%), whereas in patients without PTEN loss, OS was not reached (2-year OS, 63.9%) (log-rank P < .0005).

CONCLUSIONS

A low-cost and reproducible immunohistochemistry assay for PTEN loss analysis represents a potential tool for identifying tumor heterogeneity in patients with advanced EGFR-mutant NSCLC.

The prognostic value of longitudinal circulating tumor DNA profiling during osimertinib treatment

Background

Serial profiling of circulating tumor DNA (ctDNA) could reflect dynamic molecular changes in response to treatment and potentially predict impending disease progression (PD). Herein, we investigated the molecular factors and dynamic changes in ctDNA that can serve as predictors of survival outcomes of patients with epidermal growth factor receptor (EGFR)-mutated advanced non-small cell lung cancer (NSCLC) who received osimertinib therapy after progression from prior EGFR inhibitor regimen.

Methods

Capture-based targeted sequencing was performed on the baseline and longitudinal plasma samples collected from 72 and 57 patients, respectively, using a 168-gene panel.

Results

Analysis revealed that inferior overall survival (OS) was correlated with various baseline molecular features including high allelic fraction (AF) of EGFR sensitizing mutations (P=0.045), high maximum AF (maxAF, P=0.060), or harboring concurrent genomic alterations such as copy number amplification (CNA) in EGFR (P=0.026) or in other genes (P=0.026), and genes involved in the cell cycle (P=0.004) or TP53 signaling pathway (P=0.032). Moreover, ctDNA clearance at first follow-up after 6 weeks of osimertinib therapy was correlated with significantly longer progression-free survival (PFS) (P=0.022) and OS (P=0.009). Molecular PD, reflected by the emergence of new mutation or increased AF of existing mutations, was detected at an average lead time of 2.5 months prior to radiological PD. Patients with molecular PD were more likely to harbor CNA (P=0.035) and TP53 mutations (P=0.023).

Conclusions

Molecular factors derived from serial ctDNA profiling can serve as predictive and prognostic markers, which could allow early detection of PD, preceding imaging modalities by 2.5 months.

Licochalcone A inhibits EGFR signalling and translationally suppresses survivin expression in human cancer cells

Dysfunction of epidermal growth factor receptor (EGFR) signalling plays a critical role in the oncogenesis of non–small‐cell lung cancer (NSCLC). Here, we reported the natural product, licochalcone A, exhibited a profound anti‐tumour efficacy through directly targeting EGFR signalling. Licochalcone A inhibited in vitro cell growth, colony formation and in vivo tumour growth of either wild‐type (WT) or activating mutation EGFR‐expressed NSCLC cells. Licochalcone A bound with L858R single‐site mutation, exon 19 deletion, L858R/T790M mutation and WT EGFR ex vivo, and impaired EGFR kinase activity both in vitro and in NSCLC cells. The in silico docking study further indicated that licochalcone A interacted with both WT and mutant EGFRs. Moreover, licochalcone A induced apoptosis and decreased survivin protein robustly in NSCLC cells. Mechanistically, we found that treatment with licochalcone A translationally suppressed survivin through inhibiting EGFR downstream kinases ERK1/2 and Akt. Depletion of the translation initiation complex by eIF4E knockdown effectively inhibited survivin expression. In contrast, knockdown of 4E‐BP1 showed the opposite effect and dramatically enhanced survivin protein level. Overall, our data indicate that targeting survivin might be an alternative strategy to sensitize EGFR‐targeted therapy.

Use of liquid biopsy in monitoring therapeutic resistance in EGFR oncogene addicted NSCLC

Liquid biopsy has emerged as a minimally invasive alternative to tumor tissue analysis for the management of lung cancer patients, especially for epidermal growth factor receptor (EGFR) oncogene addicted tumor. In these patients, despite the clear benefits of tyrosine kinase inhibitors therapy, the development of acquired resistance and progressive disease is inevitable in most cases and liquid biopsy is important for molecular characterization at resistance and, being non-invasive, may be useful for disease monitoring. In this review, the authors will focus on the applications of liquid biopsy in EGFR-mutated non small cells lung cancer at diagnosis, during treatment and at progression, describing available data and possible future scenarios.

Diagnostic and prognostic role of liquid biopsy in non-small cell lung cancer: evaluation of circulating biomarkers

Lung cancer is still one of the main causes of cancer-related death, together with prostate and colorectal cancers in males and breast and colorectal cancers in females. The prognosis for non-small cell lung cancer (NSCLC) is strictly dependent on feasibility of a complete surgical resection of the tumor at diagnosis. Since surgery is indicated only in early stages tumors, it is necessary to anticipate the timing of diagnosis in clinical practice. In the diagnostic and therapeutic pathway for NSCLC, sampling of neoplastic tissue is usually obtained using invasive methods that are not free from disadvantages and complications. A valid alternative to the standard biopsy is the liquid biopsy (LB), that is, the analysis of samples from peripheral blood, urine, and other biological fluids, with a simple and non-invasive collection. In particular, it is possible to detect in the blood different tumor derivatives, such as cell-free DNA (cfDNA) with its subtype circulating tumor DNA (ctDNA), cell-free RNA (cfRNA), and circulating tumor cells (CTCs). Plasma-based testing seems to have several advantages over tumor tissue biopsy; firstly, it reduces medical costs, risk of complications related to invasive procedures, and turnaround times; moreover, the analysis of genes alteration, such as EGFR, ALK, ROS1, and BRAF is faster and safer with this method, compared to tissue biopsy. Despite all these advantages, the evidences in literatures indicate that assays performed on liquid biopsies have a low sensitivity, making them unsuitable for screening in lung cancer at the current state. This is caused by lack of standardization in sampling and preparation of specimen and by the low concentration of biomarkers in the bloodstream. Instead, routinely use of LB should be preferred in revaluation of patients with advanced NSCLC resistant to chemotherapy, due to onset of new mutations.

Concomitant genetic alterations are associated with response to EGFR targeted therapy in patients with lung adenocarcinoma

BACKGROUND

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are considered to be more effective than chemotherapy in the treatment of EGFR-mutant advanced non-small cell lung cancer (NSCLC). However, in addition to EGFR-sensitive mutations, the genetic factors that affect the prognosis of patients who receive TKI treatment are not yet clear.

METHODS

The clinical data of 36 NSCLC patients with EGFR mutation who received TKI treatment were retrospectively analyzed. Liquid re-biopsy with next generation sequencing (NGS) analysis was performed to analyze genetic alterations and potential resistance mechanisms.

RESULTS

All of the patients harbored actionable sensitive EGFR mutations by NGS, with the major types being 19del or 21L858R (52.78%, 19/36 and 55.56%, 20/36, respectively). The 3 most frequent accompanying somatic mutations were TP53 (12, 48.4%), KRAS (7, 19.44%) and PIK3CA (3, 8.33%). Concomitant mutations were present in 16 patients (44.44%). The occurrence of co-mutation was found to be significantly related to a history of smoking [87.5% (7 of 8) vs. 32.14% (9 of 28); Pearson chi-square, P=0.005]. Patients who received EGFR-TKIs treatment (P=0.0079) or third-generation EGFR-TKIs only (P=0.0468) had better progression-free survival (PFS). Concomitant mutations were significantly related to lower objective response rates (43.75% vs. 80.0%; P=0.024) and poorer PFS (P<0.001). Patients with concomitant genetic alterations had a worse response after receiving EGFR-TKIs treatment (P=0.0033).

CONCLUSIONS

Our research underscores the importance of using multiple molecular profiles. Concomitant genetic alterations were significantly associated with response to EGFR targeted therapy in NSCLC. Therefore, research on multi-drug or sequential therapy to address the covariation that drives drug resistance is urgently needed.

Recent updates on the resistance mechanisms to epidermal growth factor receptor tyrosine kinase inhibitors and resistance reversion strategies in lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have led to a substantial improvement in the prognosis of lung cancer patients by explicitly targeting the activating mutations within the EGFR. Initially, patients harboring tumors with EGFR mutations show progression-free survival and improvement in the response rates toward all-generation EGFR-TKIs; however, these agents fail to deliver the intended results in the long-term due to drug resistance. Therefore, it is necessary to recognize specific cardinal mechanisms that regulate the resistance phenomenon. Understanding the intricate mechanisms underlying EGFR-TKIs resistance in lung cancer could provide cognizance for more advanced targeted therapeutics. The present review features insights into current updates on the discrete mechanisms, including secondary or tertiary mutations, parallel and downstream signaling pathways, acquiring an epithelial-to-mesenchymal transition (EMT) signature, microRNAs (miRNAs), and epigenetic alterations, which lead to intrinsic and acquired resistance against EGFR-TKIs in lung cancer. In addition, this paper also reviews current possible strategies to overcome this issue using combination treatment of recently developed MET inhibitors, allosteric inhibitors or immunotherapies, transformation of EMT, targeting miRNAs, and epigenetic alterations in intrinsic and acquired EGFR-TKIs resistant lung cancer. In conclusion, multiple factors are responsible for intrinsic and acquired resistance to EGFR-TKIs and understanding of the detailed molecular mechanisms, and recent advancements in pharmacological studies are needed to develop new strategies to overcome intrinsic and acquired EGFR-TKIs resistance in lung cancer.

Neuropilin-2b facilitates resistance to tyrosine kinase inhibitors in non-small cell lung cancer

OBJECTIVE

Innate and acquired resistance is the principle factor limiting the efficacy of tyrosine kinase inhibitors in lung cancer. We have observed a dramatic upregulation of the cell surface co-receptor neuropilin-2b in lung cancers clinically treated with tyrosine kinase inhibitors correlating with acquired resistance. We hypothesize that neuropilin-2b plays a functional role in acquired tyrosine kinase inhibitor resistance.

METHODS

Non-small cell lung cancer proliferation and survival were determined during chronic tyrosine kinase inhibitor exposure in the presence or absence of neuropilin-2b knock-down. Interactions of neuropilin-2a and neuropilin-2b isoforms with PTEN and GSK3β were assessed by immunoprecipitation. Neuropilin-2a and neuropilin-2b mutants deleted for their cytoplasmic domains were used to identify regions responsible for neuropilin-2b-GSK3β interaction. Because GSK3β is known to phosphorylate and degrade PTEN, phospho-PTEN and total PTEN levels were assessed after transfection of neuropilin-2a and neuropilin-2b wild-type and mutant constructs.

RESULTS

Non-small cell lung cancer cells chronically treated with gefitinib or osimertinib developed drug resistance and exhibited logarithmic growth in the presence of endothelial growth factor receptor tyrosine kinase inhibitors. However, neuropilin-2b knockdown cells remained sensitive to gefitinib. Likewise, neuropilin-2b knockdown suppressed and neuropilin-2a knockdown enhanced cellular migration. Acquired drug resistance and cell migration correlated with neuropilin-2b-dependent AKT activation with the intermediate step of GSK3β-dependent PTEN degradation. A specific binding site for GSK3β on the cytoplasmic domain of neuropilin-2b was identified with truncated protein constructs and computer modeling.

CONCLUSIONS

Neuropilin-2b facilitates non-small cell lung cancer resistance to tyrosine kinase inhibitors, and this biological effect relates to AKT activation. Neuropilin-2b GSK3β interactions appear to be essential for PTEN degradation and AKT activation in lung cancer cells. Disruption of the neuropilin-2b GSK3β interaction may represent a novel treatment strategy to preserve sensitivity to tyrosine kinase inhibitors in non-small cell lung cancer.

The Validity and Predictive Value of Blood-Based Biomarkers in Prediction of Response in the Treatment of Metastatic Non-Small Cell Lung Cancer: A Systematic Review

With the introduction of targeted therapies and immunotherapy, molecular diagnostics gained a more profound role in the management of non-small cell lung cancer (NSCLC). This study aimed to systematically search for studies reporting on the use of liquid biopsies (LB), the correlation between LBs and tissue biopsies, and finally the predictive value in the management of NSCLC. A systematic literature search was performed, including results published after 1 January 2014. Articles studying the predictive value or validity of a LB were included. The search (up to 1 September 2019) retrieved 1704 articles, 1323 articles were excluded after title and abstract screening. Remaining articles were assessed for eligibility by full-text review. After full-text review, 64 articles investigating the predictive value and 78 articles describing the validity were included. The majority of studies investigated the predictive value of LBs in relation to therapies targeting the epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) receptor (n = 38). Of studies describing the validity of a biomarker, 55 articles report on one or more EGFR mutations. Although a variety of blood-based biomarkers are currently under investigation, most studies evaluated the validity of LBs to determine EGFR mutation status and the subsequent targeting of EGFR tyrosine kinase inhibitors based on the mutation status found in LBs of NSCLC patients.

Detection of EGFR-Activating and T790M Mutations Using Liquid Biopsy in Patients With EGFR-Mutated Non-Small-Cell Lung Cancer Whose Disease Has Progressed During Treatment With First- and Second-Generation Tyrosine Kinase Inhibitors: A Multicenter Real-Life Retrospective Study

BACKGROUND

In advanced epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC) patients whose disease has progressed during treatment with first- and second-generation tyrosine kinase inhibitors (TKIs), liquid biopsy (LB) is routinely used to evaluate the presence of EGFR T790M as an acquired resistance mechanism. The objective of this study was to assess a real-life picture of EGFR T790M detection in LB.

MATERIALS AND METHODS

Liquid biopsies performed between June 2016 and October 2018 for advanced EGFR-mutated NSCLC at disease progression during treatment with first- and second-generation TKIs were retrospectively evaluated in 5 Italian centers. Circulating tumor DNA was extracted from plasma and tested with different commercial kits. The detection rate in LBs and the patients' characteristics were correlated.

RESULTS

We enrolled 120 consecutive patients. The overall T790M detection rate observed using LB was 25.8%. Fifty-four of 89 (60.7%) patients with negative LB results underwent tissue rebiopsy, and 56% were positive for T790M. The overall rate of T790M positivity in the study cohort was 49.2%. LB performed before formal tumor progression according to Response Evaluation Criteria In Solid Tumors criteria was negative for T790M in all patients (n = 21; P = .012). T790M positivity was statistically significantly higher in cases of disease progression at extrathoracic metastatic sites (P = .008) and, specifically, in the case of worsening bone disease (P = .003).

CONCLUSION

Our study shows that the detection of T790M-positive patients whose disease progressed during treatment with first- and second-generation TKIs in real life was according to the literature. However, this result was obtained with a specific clinical course (repeat LBs and tissue rebiopsy), thus implying the necessity for multidisciplinary management.

Detection of EGFR T790M Mutation by Droplet Digital Polymerase Chain Reaction in Lung Carcinoma Cytology Samples

CONTEXT.—

Advanced-stage non-small cell lung carcinoma patients on EGFR-targeted tyrosine kinase inhibitors frequently present with an acquired EGFR T790M resistance mutation. Early detection using a high-sensitivity assay is critical to allow patients to switch to third-generation tyrosine kinase inhibitors. The detection of EGFR T790M mutation is often challenging because of low tumor fraction in posttreatment specimens. Because a large fraction of non-small cell lung carcinoma patients are given a diagnosis by cytology, evaluating a high-sensitivity technique for EGFR T790M detection in these specimens is essential.

OBJECTIVE.—

To evaluate a high-sensitivity droplet digital polymerase chain reaction (ddPCR) assay for EGFR T790M using different cytologic specimen preparations.

DESIGN.—

A total of 42 cytology samples, including smears and cell block preparation, were evaluated for EGFR T790M using ddPCR. The results of the mutation assay were compared to the patient's known EGFR T790M mutation status.

RESULTS.—

The ddPCR assay successfully determined the EGFR T790M mutation status in 36 of 42 samples (86%), including samples with low tumor fraction (≤20%). In 4 cases the results of the ddPCR assay could not be compared because the mutation status was unknown at the time of collection of the cytology sample. There was 1 false-positive result, with borderline positivity, and 1 false-negative result. Overall sensitivity and specificity of the ddPCR assay were 93% and 96%, respectively.

CONCLUSIONS.—

Our results indicate that EGFR T790M ddPCR is a highly sensitive and specific mutational assay that can be used reliably in cytologic specimens, including samples with low tumor fraction.

Epidermal growth factor receptor mutation analysis in tissue and plasma from the AURA3 trial: Osimertinib versus platinum-pemetrexed for T790M mutation-positive advanced non-small cell lung cancer

BACKGROUND

This study assesses different technologies for detecting epidermal growth factor receptor (EGFR) mutations from circulating tumor DNA in patients with EGFR T790M-positive advanced non-small cell lung cancer (NSCLC) from the AURA3 study (NCT02151981), and it evaluates clinical responses to osimertinib and platinum-pemetrexed according to the plasma T790M status.

METHODS

Tumor tissue biopsy samples were tested for T790M during screening with the cobas EGFR Mutation Test (cobas tissue). Plasma samples were collected at screening and at the baseline and were retrospectively analyzed for EGFR mutations with the cobas EGFR Mutation Test v2 (cobas plasma), droplet digital polymerase chain reaction (ddPCR; Biodesix), and next-generation sequencing (NGS; Guardant360, Guardant Health).

RESULTS

With cobas tissue test results as a reference, the plasma T790M positive percent agreement (PPA) was 51% (110 of 215 samples) by cobas plasma, 58% (110 of 189) by ddPCR, and 66% (136 of 207) by NGS. Plasma T790M detection was associated with a larger median baseline tumor size (56 mm for T790M-positive vs 39 mm for T790M-negative; P < .0001) and the presence of extrathoracic disease (58% for M1b-positive vs 39% for M0-1a-positive; P = .002). Progression-free survival (PFS) was prolonged in randomized patients (tissue T790M-positive) with a T790M-negative cobas plasma result in comparison with those with a T790M-positive plasma result in both osimertinib (median, 12.5 vs 8.3 months) and platinum-pemetrexed groups (median, 5.6 vs 4.2 months).

CONCLUSIONS

PPA was similar between ddPCR and NGS assays; both were more sensitive than cobas plasma. All 3 test platforms are suitable for routine clinical practice. In patients with tissue T790M-positive NSCLC, an absence of detectable plasma T790M at the baseline is associated with longer PFS, which may be attributed to a lower disease burden.