The Evolving Landscape of Resistance to Osimertinib

Dacomitinib overcomes acquired resistance to osimertinib in advanced NSCLC patients with EGFR L718Q mutation: A two-case report

RATIONALE

Acquired resistance still inevitably occurs in patients treated with third-generation TKI osimertinib. Although the EGFR L718Q mutation has been reported as a scarce mechanism of osimertinib resistance, advanced therapeutic strategies are still in development. In this report, we included 2 cases of patients who acquired EGFR L858R/L718Q mutation after osimertinib and were overcome by dacomitinib.

PATIENT CONCERNS

Case 1: A 77-year-old woman was diagnosed with stage IV lung adenocarcinoma. Case 2: A 64-year-old woman was diagnosed with stage IV lung adenocarcinoma.

DIAGNOSES

Case 1: The patient was diagnosed with adenocarcinoma with EGFR L858R mutation. Since then, treatment with gefitinib was administrated, leading to a progression-free survival of 18 months. The treatment was switched to osimertinib based on the detection of EGFR T790M mutation, resulting in a progression-free survival of 24 months. Subsequently, EGFR L718Q mutation was detected. Case 2: The patient was diagnosed with adenocarcinoma with EGFR L858R mutation. Icotinib was used as the first-line treatment for 7 months. Osimertinib was applied as the second-line treatment for 13 months based on the EGFR T790M mutation. Subsequently, EGFR L718Q mutation was detected.

INTERVENTIONS

Case 1: Dacomitinib was administered. Case 2: Dacomitinib was administered.

OUTCOMES

Case 1:The progression-free survival was 8 months. Case 2: The progression-free survival was 3 months.

LESSONS

Dacomitinib is a potential treatment option for NSCLC patients with EGFR L718Q mutation after resistance to Osimertinib. Further research is needed to validate the efficacy of Dacomitinib in this context.

Histologic transformation of non-small-cell lung cancer in response to tyrosine kinase inhibitors: Current knowledge of genetic changes and molecular mechanisms

Lung cancer is the leading cause of cancer death and includes two major types: non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), accounting for 85% and 15% of cases, respectively. Non-small-cell lung cancer harboring actionable driver mutations is generally treated with tyrosine kinase inhibitors (TKIs) molecularly targeting individual oncogenes. Although TKIs have greatly contributed to better clinical outcomes, acquired resistance to them inevitably occurs. Histologic or lineage transformation is a rare but well-documented off-target mechanism associated with acquired resistance, and has been identified in settings following treatment with multiple different TKIs and other drugs. It includes neuroendocrine transformation, squamous cell transformation, and epithelial-to-mesenchymal transition. Here, we review the clinicopathologic features of transformed tumors and current understanding of the key genetic alterations and biologic mechanism of lineage transformation in NSCLC, particularly TKI-triggered transformation.

Revealing underlying regulatory mechanisms of LINC00313 in Osimertinib-resistant LUAD cells by ceRNA network analysis

BACKGROUND

Osimertinib, a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), is the preferred treatment for EGFR-mutated lung cancer. However, acquired resistance inevitably develops. While non-coding RNAs have been implicated in lung cancer through various functions, the molecular mechanisms responsible for osimertinib resistance remain incompletely elucidated.

METHODS

RNA-sequencing technology was employed to determine differentially expressed lncRNAs (DE-lncRNAs) and mRNAs (DE-mRNAs) between H1975 and H1975OR cell lines. Starbase 2.0 was utilized to predict DE-lncRNA and DE-mRNA interactions, constructing ceRNA networks. Subsequently, functional and pathway enrichment analysis were performed on target DE-mRNAs to identify pathways associated with osimertinib resistance. Key target DE-mRNAs were then selected as potential risk signatures for lung adenocarcinoma (LUAD) prognostic modeling using multivariate Cox regression analyses. The Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and immunohistochemistry staining were used for result validation.

RESULTS

Functional analysis revealed that the identified DE-mRNAs primarily enriched in EGFR-TKI resistance pathways, especially in the PI3K/Akt signaling pathway, where their concerted actions may lead to osimertinib resistance. Specifically, upregulation of LINC00313 enhanced COL1A1 expression by acting as a miR-218-5p sponge, triggering an upstream response that activates the PI3K/Akt pathway, potentially contributing to osimertinib resistance. Furthermore, the expressions of LINC00313 and COL1A1 were validated by qRT-PCR, and the activation of the PI3K/Akt pathway was confirmed by immunohistochemistry staining.

CONCLUSIONS

Our results suggest that the LINC00313/miR-218-5p/COL1A1 axis potentially contributes to osimertinib resistance through the PI3K/Akt signaling pathway, providing novel insights into the molecular mechanisms underlying acquired osimertinib resistance in LUAD. Additionally, our study may aid in the identification of potential therapeutic targets for overcoming resistance to osimertinib.

Real-World Analysis of Post-Progression Treatment Patterns and Outcomes for EGFR Mutation-Positive Patients Treated with First-Line Osimertinib

Introduction: The use of osimertinib in the first-line (1L) setting is an effective treatment option for sensitizing EGFR-mutations (EGFRm+) and has significantly altered the standard of care practice for EGFRm+ disease in Canada. Unfortunately, acquired resistance to osimertinib is almost universal, and outcomes are disparate. Post-progression treatment patterns and the outcome of real-world Canadian EGFRm+ patients receiving 1L osimertinib were the focus of this retrospective review. Methods: The Glans-Look Lung Cancer Research database was used to identify and collect demographic, clinical, treatment, and outcome data on EGFRm+ patients who received 1L osimertinib in the Canadian province of Alberta between 2018 and 2022. Results: A total of 150 patients receiving 1L osimertinib were identified. In total, 86 developed progressive disease, with 56 (65%) continuing systemic therapy, 73% continuing osimertinib, and 27% switching to second-line (2L) systemic therapy. Patients were similar both in clinical characteristics at 1L osimertinib initiation and patterns of treatment failure at progression; those continuing 1L osimertinib post-progression had a longer time to progression (13.5 vs. 8.8 months, p = 0.05) and subsequent post-osimertinib initiation survival (34.7 vs. 22.8 months, p = 0.11). Conclusions: The continuation of osimertinib post-progression is an effective disease management strategy for select real-world EGFRm+ patients, providing continued clinical benefit, potentially due to different underlying disease pathogenesis.

Discovery of a Novel Potent EGFR Inhibitor Against EGFR Activating Mutations and On-Target Resistance in NSCLC

PURPOSE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) serve as the standard first-line therapy for EGFR-mutated non-small cell lung cancer (NSCLC). Despite the sustained clinical benefits achieved through optimal EGFR-TKI treatments, including the third-generation EGFR-TKI osimertinib, resistance inevitably develops. Currently, there are no targeted therapeutic options available postprogression on osimertinib. Here, we assessed the preclinical efficacy of BI-4732, a novel fourth-generation EGFR-TKI, using patient-derived preclinical models reflecting various clinical scenarios.

EXPERIMENTAL DESIGN

The antitumor activity of BI-4732 was evaluated using Ba/F3 cells and patient-derived cell/organoid/xenograft models with diverse EGFR mutations. Intracranial antitumor activity of BI-4732 was evaluated in a brain-metastasis mouse model.

RESULTS

We demonstrated the remarkable antitumor efficacy of BI-4732 as a single agent in various patient-derived models with EGFR_C797S-mediated osimertinib resistance. Moreover, BI-4732 exhibited activity comparable to osimertinib in inhibiting EGFR-activating (E19del and L858R) and T790M mutations. In a combination treatment strategy with osimertinib, BI-4732 exhibited a synergistic effect at significantly lower concentrations than those used in monotherapy. Importantly, BI-4732 displayed potent antitumor activity in an intracranial model, with low efflux at the blood-brain barrier.

CONCLUSIONS

Our findings highlight the potential of BI-4732, a selective EGFR-TKI with high blood-brain barrier penetration, targeting a broad range of EGFR mutations, including C797S, warranting clinical development.

Real-World Genomic Profile of EGFR Second-Site Mutations and Other Osimertinib Resistance Mechanisms and Clinical Landscape of NSCLC Post-Osimertinib

INTRODUCTION

The emergence of osimertinib as standard of care for EGFR-mutant NSCLC has renewed the need to understand and overcome drug resistance. We sought to understand the genomics and real-world treatment landscape of NSCLC with EGFR C797S and other on- and off-target resistance mechanisms.

METHODS

Comprehensive genomic profiling (CGP) results from tissue or blood samples from 93,065 patients with NSCLC were queried for osimertinib EGFR second-site resistance mutations (ssEGFRms; C797, L718, G724, G796, L792). A real-world electronic health record-derived deidentified clinicogenomic database of patients with NSCLC undergoing CGP from approximately 280 U.S. cancer clinics was queried to assess post-osimertinib resistance and clinical treatment outcomes.

RESULTS

A ssEGFRm was identified in 239 of 8845 (2.7%) EGFR-driven (L858R or exon 19 deletion) NSCLCs, most frequently C797 (71%), L718 (15%), and G724 (9.5%). ssEGFRms were not equally distributed across drivers; C797 and G724 changes strongly favored exon 19 deletion and L718, G796 and L792 favored L858R. Post-osimertinib CGP detected ssEGFRm in 19% of the cases (39 of 205); in paired pre-/post-osimertinib samples, on- and off-target resistance was largely mutually exclusive and observed in 24% and 27% of the cases, respectively. Of 391 patients with post-osimertinib treatment data, 62% received a chemotherapy-based regimen, whereas 25% received a targeted therapy or clinical study drug. Median real-world overall survival was 11.4 months from osimertinib progression.

CONCLUSIONS

The osimertinib resistance landscape is diverse with on-target ssEGFRm and off-target resistance detected in tissue and liquid biopsy. Post-osimertinib, patients are receiving primarily chemotherapy-based regimens with poor outcomes, and CGP at resistance may offer an opportunity to inform therapeutic development and improve treatment selection.

C-IGF1R encoded by cIGF1R acts as a molecular switch to restrict mitophagy of drug-tolerant persister tumour cells in non-small cell lung cancer

The clinical efficacy of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors (EGFR-TKIs) is limited by the emergence of drug resistance. We hypothesise that restoring dysregulated circular RNAs under initial treatment with EGFR-TKIs may enhance their effectiveness. Through high-throughput screening, we identify that combining circular RNA IGF1R (cIGF1R) with EGFR-TKIs significantly synergises to suppress tumour regrowth following drug withdrawal. Mechanistically, cIGF1R interacts with RNA helicase A (RHA) to depress insulin-like growth factor 1 receptor (IGF1R) mRNA splicing, negatively regulating the parent IGF1R signalling pathway. This regulation is similar to that of IGF1R inhibitor, which induces drug-tolerant persister (DTP) state with activated mitophagy. The cIGF1R also encodes a peptide C-IGF1R that reduces Parkin-mediated ubiquitination of voltage-dependent anion channel 1 (VDAC1) to restrict mitophagy, acting as a molecular switch that promotes the transition of DTP to apoptosis. Our study shows that combining cIGF1R with EGFR-TKIs efficiently reduces the emergence of DTP.

PTPN23 ubiquitination by WDR4 suppresses EGFR and c-MET degradation to define a lung cancer therapeutic target

Aberrant overexpression or activation of EGFR drives the development of non-small cell lung cancer (NSCLC) and acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) by secondary EGFR mutations or c-MET amplification/activation remains as a major hurdle for NSCLC treatment. We previously identified WDR4 as a substrate adaptor of Cullin 4 ubiquitin ligase and an association of WDR4 high expression with poor prognosis of lung cancer. Here, using an unbiased ubiquitylome analysis, we uncover PTPN23, a component of the ESCRT complex, as a substrate of WDR4-based ubiquitin ligase. WDR4-mediated PTPN23 ubiquitination leads to its proteasomal degradation, thereby suppressing lysosome trafficking and degradation of wild type EGFR, EGFR mutant, and c-MET. Through this mechanism, WDR4 sustains EGFR and c-MET signaling to promote NSCLC proliferation, migration, invasion, stemness, and metastasis. Clinically, PTPN23 is downregulated in lung cancer and its low expression correlates with WDR4 high expression and poor prognosis. Targeting WDR4-mediated PTPN23 ubiquitination by a peptide that competes with PTPN23 for binding WDR4 promotes EGFR and c-MET degradation to block the growth and progression of EGFR TKI-resistant NSCLC. These findings identify a central role of WDR4/PTPN23 axis in EGFR and c-MET trafficking and a potential therapeutic target for treating EGFR TKI-resistant NSCLC.

Current Knowledge of Small Cell Lung Cancer Transformation from Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer related death, and is divided into two major histological subtypes, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Histological transformation from NSCLC to SCLC has been reported as a mechanism of treatment resistance in patients who received tyrosine kinase inhibitors (TKIs) targeting EGFR, ALK and ROS1 or immunotherapies. The transformed histology could be due to therapy-induced lineage plasticity or clonal selection of pre-existing SCLC cells. Evidence supporting either mechanism exist in the literature. Here, we discuss potential mechanisms of transformation and review the current knowledge about cell of origin of NSCLC and SCLC. In addition, we summarize genomic alterations that are frequently observed in both "De novo" and transformed SCLC, such as TP53, RB1 and PIK3CA. We also discuss treatment options for transformed SCLC, including chemotherapy, radiotherapy, TKIs, immunotherapy and anti-angiogenic agents.

Adjuvant icotinib versus observation in patients with completely resected EGFR-mutated stage IB NSCLC (GASTO1003, CORIN): a randomised, open-label, phase 2 trial

BACKGROUND

This phase 2 trial aimed to compare adjuvant icotinib with observation in patients with epidermal growth factor receptor (EGFR) mutation-positive resected stage IB non-small cell lung cancer (NSCLC).

METHODS

We performed a randomised, open-label, phase 2 trial from May 1, 2015 to December 29, 2020 at Sun Yat-sen University Cancer Center in China. Patients with completely resected, EGFR-mutant, stage IB (the 7th edition of TNM staging) NSCLC without adjuvant chemotherapy were randomised (1:1) to receive adjuvant therapy with icotinib (125 mg, three times daily) for 12 months or to undergo observation until disease progression or intolerable toxicity occurred. The primary endpoint was 3-year disease-free survival (DFS). CORIN (GASTO1003) was registered with Clinicaltrials.gov, with the number NCT02264210.

FINDINGS

A total of 128 patients were randomised, with 63 patients in the icotinib group and 65 patients in the observation group. The median duration of follow-up was 39.9 months. The three-year DFS was significantly higher in the icotinib group (96.1%, 95% confidence interval [CI], 91.3-99.9) than in the observation group (84.0%, 95% CI, 75.1-92.9; P = 0.041). The DFS was significantly longer in the icotinib group than in the observation group, with a hazard ratio (HR) of 0.23 (95% CI, 0.07-0.81; P = 0.013). The OS data were immature, with three deaths in the observation arm. In the icotinib group, adverse events (AEs) of any grade were reported in 49 patients (77.8%), and grade 3 or greater AEs occurred in four patients (6.3%). No treatment-related deaths occurred.

INTERPRETATION

Our findings suggested that adjuvant icotinib improved the 3-year DFS in patients with completely resected EGFR-mutated stage IB NSCLC with a manageable safety profile.

FUNDING

This study was sponsored by Betta Pharmaceutical Co., Ltd.

Treatment Strategies for Non-Small Cell Lung Cancer with Common EGFR Mutations: A Review of the History of EGFR TKIs Approval and Emerging Data

The development of targeted therapies over the past two decades has led to a dramatic change in the management of EGFR-mutant non-small cell lung cancer (NSCLC). While there are currently five approved EGFR tyrosine kinase inhibitors (TKIs) for treating EGFR-mutant NSCLC in the first-line setting, therapy selection after progression on EGFR TKIs remains complex. Multiple groups are investigating novel therapies and drug combinations to determine the optimal therapy and treatment sequence for these patients. In this review, we summarize the landmark trials and history of the approval of EGFR TKIs, their efficacy and tolerability, and the role of these therapies in patients with central nervous system metastasis. We also briefly discuss the mechanisms of resistance to EGFR TKIs, ongoing attempts to overcome resistance and improve outcomes, and finalize by offering treatment sequencing recommendations.

Therapeutic strategies for EGFR-mutated non-small cell lung cancer patients with osimertinib resistance

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the preferential options for advanced non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. Osimertinib is a potent irreversible third-generation EGFR-TKI targeting EGFR mutations but has little effect on wild-type EGFR. In view of its remarkable efficacy and manageable safety, osimertinib was recommended as the standard first-line treatment for advanced or metastatic NSCLC patients with EGFR mutations. However, as the other EGFR-TKIs, osimertinib will inevitably develop acquired resistance, which limits its efficacy on the treatment of EGFR-mutated NSCLC patients. The etiology of triggering osimertinib resistance is complex including EGFR-dependent and EGFR-independent pathways, and different therapeutic strategies for the NSCLC patients with osimertinib resistance have been developed. Herein, we comprehensively summarized the resistance mechanisms of osimertinib and discuss in detail the potential therapeutic strategies for EGFR-mutated NSCLC patients suffering osimertinib resistance for the sake of the improvement of survival and further achievement of precise medicine.

First-Line Osimertinib in Patients With EGFR-Mutated Non-Small Cell Lung Cancer: Effectiveness, Resistance Mechanisms, and Prognosis of Different Subsequent Treatments

BACKGROUND

Although the clinical application of osimertinib, a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), has been a new step forward in the first-line treatment of non-small cell lung cancer (NSCLC), an increasing number of patients with progression on osimertinib represents a great challenge clinically. The patterns of resistance mechanisms and subsequent treatment strategies after first-line osimertinib resistance are not well established.

METHODS

Between January 1, 2016 and October 31, 2020, a consecutive of 56 EGFR-mutant lung cancer patients treated with osimertinib as first-line therapy at Daping Hospital (Chongqing, China) were retrospective screened. The samples of pre-osimertinib and osimertinib-resistance were all detected by next-generation sequencing (NGS) panels. Statistical analyses were carried out using SPSS 23.0 software. Survival analyses were performed using the Kaplan-Meier method and compared using a log-rank test between groups.

RESULTS

Among 47 patients with osimertinib effectiveness analysis, the median progression free survival (mPFS) was 15.4 months (95% confidence interval [CI]: 12.2-24.9 months), and median overall survival (mOS) was 35.5 months (95% CI: 23.9 months -NA). A total of 21 patients underwent repeated NGS tests upon osimertinib resistance. MET amplification was the most common resistance mechanism (6/21, 28.6%), followed by C797S mutation (5/21, 23.8%). A total of 15 patients received subsequent treatments, with mPFS of 7.3 months (95% CI 5.0 months -NA). Among them, 7 patients with EGFR C797 S or/and MET amplification received subsequent second-line targeted therapy, achieving mPFS of 7.3 months (95% CI 4.5 months -NA). Of note, 3 patients received immunotherapy as second- or third-line treatment after osimertinib resistance, achieving median clinical benefit of 37.3 months.

CONCLUSIONS

MET amplification and C797S mutation are main resistance mechanisms, which could be targeted by crizotinib and gefitinib, respectively. More than 50% patients could receive subsequent anticancer targetable therapies after first-line osimertinib resistance. Immunotherapy may also be an acceptable choice after osimertinib resistance.

Influence of esomeprazole on the bioavailability of afatinib: A pharmacokinetic cross-over study in patients with non-small cell lung cancer

Afatinib is an oral small-molecule kinase inhibitor (SMKI) approved for treatment of metastatic non-small cell lung cancer (NSCLC) with an epidermal growth factor receptor (EGFR) driver mutation. Although oral administration is convenient, most SMKIs experience pH-dependent solubility. A drug-drug interaction between afatinib and proton-pump inhibitors (PPIs) has, however, never been studied in humans. Hence, we performed a randomized, three-period cross-over study. Afatinib (30 mg or 40 mg) was administered without PPI (period A), concomitantly with esomeprazole (period B) and three hours after esomeprazole intake (period C). Primary objective was the area under the curve (AUC_0-24 h) comparing period A to period B and period A to period C. Secondary objectives were other pharmacokinetic parameters and toxicity. Linear mixed effect modelling was performed for differences in AUC_0-24 h and C_max between periods A and B and periods A and C. In 18 evaluable NSCLC patients, concomitant use of 40 mg esomeprazole decreased the steady-state afatinib AUC_0-24 h with 10.2% (95% CI -29.2 to +14.0%; p = 0.564) compared to afatinib administration without PPI. Esomeprazole intake three hours prior to afatinib did not significantly influence afatinib AUC_0-24 h (-0.6%; 95% CI -14.9 to +16.1%; p = 1.0). No differences in toxicity were observed. To conclude, esomeprazole did not change the exposure to afatinib in patients with NSCLC. Since there is no clinically relevant drug-drug interaction, esomeprazole can safely be co-administered with afatinib. This is important for clinical practice, because other EGFR-SMKIs (e.g. erlotinib and gefitinib) do experience clinically relevant drug-drug interactions with acid-suppressive agents.

Exposure-Response Analysis of Osimertinib in Patients with Advanced Non-Small-Cell Lung Cancer

High interindividual variability (IIV) of the clinical response to epidermal growth factor receptor (EGFR) inhibitors such as osimertinib in non-small-cell lung cancer (NSCLC) might be related to the IIV in plasma exposure. The aim of this study was to evaluate the exposure−response relationship for toxicity and efficacy of osimertinib in unselected patients with advanced EGFR-mutant NSCLC. This retrospective analysis included 87 patients treated with osimertinib. Exposure−toxicity analysis was performed in the entire cohort and survival analysis only in second-line patients (n = 45). No significant relationship between occurrence of dose-limiting toxicity and plasma exposure was observed in the entire cohort (p = 0.23, n = 86). The median overall survival (OS) was approximately two-fold shorter in the 4th quartile (Q4) of osimertinib trough plasma concentration (>235 ng/mL) than in the Q1−Q3 group (12.2 months [CI95% = 8.0−not reached (NR)] vs. 22.7 months [CI95% = 17.1−34.1]), but the difference was not statistically significant (p = 0.15). To refine this result, the exposure−survival relationship was explored in a cohort of 41 NSCLC patients treated with erlotinib. The Q4 erlotinib exposure group (>1728 ng/mL) exhibited a six-fold shorter median OS than the Q1−Q3 group (4.8 months [CI95% = 3.3-NR] vs. 22.8 months (CI95% = 10.6−37.4), p = 0.00011). These results suggest that high exposure to EGFR inhibitors might be related to worse survival in NSCLC patients.

An updated network meta-analysis of EGFR-TKIs and combination therapy in the first-line treatment of advanced EGFR mutation positive non-small cell lung cancer

Objectives

Tyrosine kinase inhibitors (TKIs) are a standard care option in patients with non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutation. TKI-based combination treatment modes show encouraging outcomes. However, it remains unknown which is the optimal treatment as the first-line regimen for these patients on overall survival (OS).

Materials and methods

Randomized controlled trials and meeting abstracts that investigated EGFR-TKIs alone or in combination as front-line care for patients with NSCLC were systematically searched in relevant databases and reviewed. Fixed and random effects network meta-analysis models were used to estimate progression-free survival (PFS), OS, overall response rate, and grade three and higher adverse events (AEs). Surface under the cumulative ranking curves (SUCRAs) were used to rank treatment effects.

Results

Eighteen studies covering six treatments and involving a total of 4389 patients were included in this network meta-analysis. On OS, the top three treatment were first-generation EGFR-TKIs (1G EGFR-TKIs) plus chemotherapy (SUCRA, 88.1%), osimertinib (SUCRA, 65.8%) and second-generation EGFR-TKIs (2GEGFR-TKIs) (SUCRA, 63.3%). On PFS, the top three treatments were osimertinib (SUCRA, 96.0%), 1G EGFR-TKIs plus chemotherapy (SUCRA, 67.1%), and 1G EGFR-TKIs plus antiangiogenesis (SUCRA, 48.2%). Two types of TKI-based combination therapy have significantly higher risk of grade three and higher AEs than TKI alone.

Conclusion

1G EGFR-TKIs plus chemotherapy and osimertinib seem to be the two better options as first-line care in advanced NSCLC patients with EGFR-mutation. Osimertinib caused the lowest incidence of AEs. However, TKIs-based combination therapy significantly increased AEs.

Liquid biopsy and non-small cell lung cancer: are we looking at the tip of the iceberg?

The possibility to analyse the tumour genetic material shed in the blood is undoubtedly one of the main achievements of translational research in the latest years. In the modern clinical management of advanced non-small cell lung cancer, molecular characterisation plays an essential role. In parallel, immunotherapy is widely employed, but reliable predictive markers are not available yet. Liquid biopsy has the potential to face the two issues and to increase its role in advanced NSCLC in the next future. The aim of this review is to summarise the main clinical applications of liquid biopsy in advanced non-small cell lung cancer, underlining both its potential and limitations from a clinically driven perspective.

Results of a worldwide external quality assessment of cfDNA testing in lung Cancer

BACKGROUND

Circulating cell free DNA (cfDNA) testing of plasma for EGFR somatic variants in lung cancer patients is being widely implemented and with any new service, external quality assessment (EQA) is required to ensure patient safety. An international consortium, International Quality Network for Pathology (IQNPath), has delivered a second round of assessment to measure the accuracy of cfDNA testing for lung cancer and the interpretation of the results.

METHODS

A collaboration of five EQA provider organisations, all members of IQNPath, have delivered the assessment during 2018-19 to a total of 264 laboratories from 45 countries. Bespoke plasma reference material containing a range of EGFR mutations at varying allelic frequencies were supplied to laboratories for testing and reporting according to routine procedures. The genotyping accuracy and clinical reporting was reviewed against standardised criteria and feedback was provided to participants.

RESULTS

The overall genotyping error rate in the EQA was found to be 11.1%. Low allelic frequency samples were the most challenging and were not detected by some testing methods, resulting in critical genotyping errors. This was reflected in higher false negative rates for samples with variant allele frequencies (VAF) rates less than 1.5% compared to higher frequencies. A sample with two different EGFR mutations gave inconsistent detection of both mutations. However, for one sample, where two variants were present at a VAF of less than 1% then both mutations were correctly detected in 145/263 laboratories. Reports often did not address the risk that tumour DNA may have not been tested and limitations of the methodologies provided by participants were insufficient. This was reflected in the average interpretation score for the EQA being 1.49 out of a maximum of 2.

CONCLUSIONS

The variability in the standard of genotyping and reporting highlighted the need for EQA and educational guidance in this field to ensure the delivery of high-quality clinical services where testing of cfDNA is the only option for clinical management.

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.

Antibody-Drug Conjugates: A New Addition to the Treatment Landscape of EGFR-Mutant Non-Small Cell Lung Cancer

The emergence of treatment resistance to targeted agents is currently inevitable and inherently heterogeneous in cancer, presenting significant challenges for improving survival outcomes in patients. This is not an exception for cancers harboring EGFR mutations, one of the most prevalently observed oncogenic alterations in non-small cell lung cancer (NSCLC) targeted clinically. Currently, numerous efforts have attempted to delay or overcome acquired resistance to EGFR-tyrosine kinase inhibitors (TKI), changing the treatment landscape of EGFR-mutant NSCLC. Haikala and colleagues have developed a unique strategy using patritumab deruxtecan, an antibody-drug conjugate targeting human epidermal growth factor receptor 3 (HER3) linked to exatecan derivatives, for treating EGFR-mutant NSCLC. By incorporating EGFR TKIs to upregulate surface HER3 expression, the antitumor efficacy of patritumab deruxtecan was augmented in various preclinical models. In parallel, Jänne and colleagues reported the clinical activity of patrimumab deruxtecan in patients with EGFR-mutant NSCLC with prior EGFR TKI treatment. These two studies provide the grounds for hopeful anticipation for a novel strategy that concurrently targets compensatory feedback loops in addition to oncogenic signaling pathways.See related article by Haikala et al., p. 130.

Post-chemotherapy and targeted therapy imaging of the chest in lung cancer

Non-small-cell lung cancer (NSCLC) is frequently diagnosed when it is not amenable to local therapies; therefore, systemic agents are the mainstay of therapy for many patients. In recent years, treatment of advanced NSCLC has evolved from a general approach primarily involving chemotherapy to a more personalised strategy in which biomarkers such as the presence of genomic tumour aberrations and the expression of immune proteins such as programmed death-ligand 1 (PD-L1), in combination with other elements of clinical information such as histology and clinical stage, guide management. For instance, pathways resulting in uncontrolled growth and proliferation of tumour cells due to epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements may be targeted by tyrosine kinase inhibitors (TKIs). In this article, we review the current state of medical oncology, imaging characteristics of mutations, pitfalls in response assessments and the imaging of complications.

Acquired EGFR C797G Mutation Detected by Liquid Biopsy as Resistance Mechanism After Treatment With Osimertinib: A Case Report

BACKGROUND

Osimertinib is a third-generation EGFR-tyrosine kinase inhibitor approved for the treatment of T790M-positive non-small-cell lung cancer. More recently, osimertinib demonstrated improved disease control compared to other EGFR-TKIs. Multiple mechanisms of resistance have been described in T790M-positive patients who experienced treatment failure with osimertinib.

CASE REPORT

We report the case of a 78-year-old non-smoker woman with stage IV EGFR L858R-positive lung adenocarcinoma presented with T790M mutation after five years of treatment with gefitinib. The patient was started on osimertinib, but after two and a half years of treatment experienced disease progression. The analyses of circulating tumor DNA using next-generation sequencing showed, together with the pre-existing T790M and exon 21 L858R, the presence of the EGFR C797G resistance mutation.

CONCLUSION

Our case report revealed a rare EGFR-dependent acquired resistance mutation to osimertinib in circulating tumor DNA. Liquid biopsy appears to be a promising resource to understand the biology of osimertinib resistance by clonal evolution monitoring and the identification of novel resistance mechanisms.

Toward personalized treatment approaches for non-small-cell lung cancer

Worldwide, lung cancer is the most common cause of cancer-related deaths. Molecular targeted therapies and immunotherapies for non-small-cell lung cancer (NSCLC) have improved outcomes markedly over the past two decades. However, the vast majority of advanced NSCLCs become resistant to current treatments and eventually progress. In this Perspective, we discuss some of the recent breakthrough therapies developed for NSCLC, focusing on immunotherapies and targeted therapies. We highlight our current understanding of mechanisms of resistance and the importance of incorporating genomic analyses into clinical studies to decipher these further. We underscore the future role of neoadjuvant and maintenance combination therapy approaches to potentially cure early disease. A major challenge to successful development of rational combination therapies will be the application of robust predictive biomarkers for clear-cut patient stratification, and we provide our views on clinical research areas that could influence how NSCLC will be managed over the coming decade.

Small Cell Lung Cancer Transformation as a Resistance Mechanism to Osimertinib in Epidermal Growth Factor Receptor-Mutated Lung Adenocarcinoma: Case Report and Literature Review

Introduction: Small cell lung cancer (SCLC) transformation represents a mechanism of resistance to osimertinib in EGFR-mutated lung adenocarcinoma, which dramatically impacts patients' prognosis due to high refractoriness to conventional treatments. Case Description: We present the case of a patient who developed a SCLC phenotypic transformation as resistance mechanism to second-line osimertinib for T790M-positive EGFR-mutated NSCLC. Our patient received platinum-etoposide doublet following SCLC switch and achieved a modest clinical benefit which lasted 4 months. NGS and IHC analyses for p53 and Rb were performed on subsequent liver biopsies, revealing baseline TP53 mutation and complete absence of p53 and Rb expression. Primary cell cultures were established following a liver biopsy at the time of SCLC transformation, and drug sensitivity assays showed meaningful cell growth inhibition when osimertinib was added to platinum-etoposide compared with control (p < 0.05). A review of the current literature regarding SCLC transformation after failure of osimertinib was performed. Conclusions: Based on retrospective data available to date, platinum-etoposide chemotherapy is the preferred treatment choice in the occurrence of SCLC transformation after osimertinib failure. The extension of osimertinib in combination with chemotherapy in the occurrence of SCLC transformation as resistance mechanism to osimertinib is a matter of debate. The combination of osimertinib and platinum-etoposide was effective in inhibiting cell growth in our primary cell cultures. Clinical studies are needed to further explore this combination in the occurrence of SCLC transformation as a resistance mechanism to osimertinib.

Pilot Study of Dacomitinib for Patients With Metastatic EGFR-Mutant Lung Cancers With Disease Progression After Initial Treatment With Osimertinib

Patients with EGFR-mutant lung cancer have no approved targeted therapies after disease progression on first-line osimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). Preclinical studies suggest that tumors with both EGFR-sensitizing alteration and acquired second-site EGFR resistance alterations after treatment with osimertinib retain sensitivity to second-generation EGFR TKIs. We hypothesized that dacomitinib, a pan-human epidermal growth factor receptor TKI, may be effective in this setting.

METHODS

In this phase II study, patients who had progressed on first-line osimertinib were treated with dacomitinib 45 mg orally daily until disease progression or intolerability. The primary end point was objective response rate.

RESULTS

We enrolled 12 patients. Two partial responses were documented (17% objective response rate; 95% CI, 5 to 45). The median progression-free survival was 1.8 months (95% CI, 1.6 to not reached). One patient with an original sensitizing EGFR G719A mutation and one patient without molecular testing available had partial responses, whereas 0 of the 3 patients with second-site acquired EGFR resistance mutations (two C797S and one G724S) met the response criteria. The patient with EGFR G719A has an ongoing response at 17 months, which exceeds prior time on osimertinib (11 months).

CONCLUSION

In the first trial evaluating a second-generation EGFR TKI after first-line third-generation osimertinib, we found that dacomitinib after disease progression on osimertinib has limited benefit.

HSP90 inhibition overcomes EGFR amplification-induced resistance to third-generation EGFR-TKIs

Background

Patients with non‐small cell lung cancer (NSCLC) harboring activating EGFR mutations are sensitive to epidermal growth factor receptor‐tyrosine kinase inhibitors (EGFR‐TKIs) but inevitably develop resistance to the inhibitors mostly through acquisition of the secondary T790M mutation. Although third‐generation EGFR‐TKIs overcome this resistance by selectively inhibiting EGFR with EGFR‐TKI‐sensitizing and T790M mutations, acquired resistance to third‐generation EGFR‐TKIs invariably develops.

Methods

Next‐generation sequencing (NGS) and fluorescence in situ hybridization (FISH) analysis were performed in an EGFR T790M‐mutated NSCLC patient who had progressed after a third‐generation EGFR‐TKI, TAS‐121. EGFR‐mutated cell lines were subjected to a cell proliferation assay and western blotting analysis with EGFR‐TKIs and a heat shock protein 90 (HSP90) inhibitor.

Results

NGS and FISH analysis revealed EGFR amplification in the resistant cancer cells. While EGFR L858R/T90M‐mutated cell line was sensitive to osimertinib or TAS‐121 in vitro, EGFR‐overexpressing cell lines displayed resistance to these EGFR‐TKIs. Western blot analysis showed that EGFR phosphorylation and overexpression of EGFR in cell lines was not suppressed by third‐generation EGFR‐TKIs. In contrast, an HSP90 inhibitor reduced total and phosphorylated EGFR and inhibited the proliferation of resistant cell lines.

Conclusions

EGFR amplification confers resistance to third‐generation EGFR‐TKIs which can be overcome by HSP90 inhibition. The results provide a preclinical rationale for the use of HSP90 inhibitors to overcome EGFR amplification‐mediated resistance.

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.

Concurrent use of aspirin with osimertinib is associated with improved survival in advanced EGFR-mutant non-small cell lung cancer

BACKGROUND

Osimertinib is the treatment of choice for advanced EGFR-mutant non-small cell lung cancer (NSCLC). However, novel strategies to improve the duration of disease control are still urgently needed. Aspirin has been shown to decrease cancer incidence and improve outcomes in various malignancies. Therefore, we evaluated a cohort of patients who received osimertinib with or without concurrent use of aspirin to assess whether the addition of aspirin may lead to improved clinical outcomes.

METHODS

MD Anderson Cancer Center GEMINI database was retrospectively queried for EGFR-mutant NSCLC patients who received osimertinib with or without concurrent use of aspirin for progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 365 patients were identified including 77 which had concurrent use of aspirin. Patients in the aspirin-osimertinib group had significantly improved PFS (21.3 vs 11.6 months; HR, 0.52; 95 % CI, 0.38-0.70) and OS (Not reached vs 32.3 months; HR, 0.56; 95 % CI, 0.35-0.91) compared to osimertinib group. In subgroup analyses, the aspirin-associated PFS benefit was observed in patients with and without central nervous system (CNS) metastases, as well as in osimertinib first-line setting and in subsequent line setting. The median PFS in EGFR 19Del patients was longer than EGFR L858R patients with osimertinib, and when aspirin was added, the median PFS significantly improved in both groups regardless of lines of therapy. The benefit from aspirin was independent of age, gender, TP53 mutational status, or PD-L1 positivity.

CONCLUSION

Concurrent aspirin use with osimertinib in EGFR-mutant NSCLC patients was associated with improved survival, regardless of lines of therapy, CNS metastatic status, EGFR mutation type, age, gender, TP53, and PD-L1 status.

Lung cancer management: monitoring and treating resistance development in third-generation EGFR TKIs

INTRODUCTION

Patients treated with third-generation EGFR TKIs will develop resistance to treatment at a certain point. Early detection of resistance occurrence could allow more options for treatment.

AREAS COVERED

We discuss the development of third-generation EGFR TKIs, focusing on osimertinib and discuss the most common resistance mechanisms under evaluation. We also debate how this resistance can be detected; particularly we review the possible application of liquid biopsy in this scenario. Lastly we discuss available treatment options when resistance occurs, with an eye on ongoing trials and possible future developments.

EXPERT OPINION

As resistance will ultimately develop, a strict instrumental follow-up as per international guidelines is required with the aim of detecting this resistance in an early phase. Detecting an oligoprogression could allow the integration of local ablative therapies while further delaying the need for a systemic therapy change. By exploiting the increasing potentiality of liquid biopsy, in the near future, physicians could be able to understand why a patient develops resistance and therefore can choose the best possible individualized treatment option.

Let-7c regulated epithelial-mesenchymal transition leads to osimertinib resistance in NSCLC cells with EGFR T790M mutations

Epidermal growth factor receptor- tyrosine kinase inhibitors (EGFR-TKIs) have shown promise against non-small cell lung cancers (NSCLCs) in clinics but the utility is often short-lived because of T790M mutations in EGFR that help evade TKIs’ action. Osimertinib is the third and latest generation TKI that targets EGFRs with T790M mutations. However, there are already reports on acquired resistance against Osimertinib. Recent work has revealed the role that miRNAs, particularly tumor suppressor let-7c, play in the invasiveness and acquired resistance of NSCLCs, but the mechanistic details, particularly in Osimertinib resistance, remain elusive. Using two cells lines, H1975 (endogenous T790M mutation) and HCC827-T790M (with acquired T790M mutation), we found that let-7c is a regulator of EMT, as well as it affects CSC phenotype. In both the cell lines, transfection with pre-let-7c led to reversal of EMT as studied through EMT markers e-cadherin and ZEB1. This resulted in reduced proliferation and invasion. Conversely, reduced expression of let-7c through anti-let-7c transfections significantly increased proliferation and invasion of lung cancer cells. Expression of let-7c was functionally relevant as EMT correlated with resistance to Osimertinib. High let-7c expression reversed EMT and made cells sensitive to Osimertinib, and vice versa. WNT1 and TCF-4 were found to be two targets of let-7c which were epigenetic suppressed by let-7c through increased methylation. In vivo, pre-let-7c inhibited while anti-let-7c potentiated tumor growth and WNT1 and TCF-4 were downregulated in xenografts with pre-let-7c. Silencing of both WNT1 and TCF-4 resulted in potentiation of Osimertinib action. Our results suggest an important role of let-7c in regulating EMT and the resulting Osimertinib resistance in T790M NSCLCs. More clinical studies need to be performed to fully understand the translational relevance of this novel mechanism.