Double EGFR mutants containing rare EGFR mutant types show reduced in vitro response to gefitinib compared with common activating missense mutations

From Rarity to Reality: Osimertinib's Promising Horizon in Treating Uncommon EGFR Mutations in Non-Small Cell Lung Cancer

In the realm of advanced non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) therapy with tyrosine kinase inhibitors (TKI), addressing optimal treatment for uncommon EGFR mutations like G719X in exon 18, S768I in exon 20, and L861Q in exon 21 remains a pivotal yet challenging frontier. Contrary to the well-established efficacy of EGFR-TKIs in common EGFR mutations, these uncommon alterations pose unmet medical needs due to a lack of comprehensive evidence. While afatinib, a second-generation EGFR-TKI, has received FDA approval for patients with these uncommon EGFR mutations, the approval was based on a post-hoc analysis of randomized clinical trials. Recent developments include multiple clinical trials investigating the efficacy of both second- and third-generation EGFR-TKIs in patients with uncommon EGFR mutations. A noteworthy example is a prospective phase II trial of osimertinib including the landmark UNICORN study, which has shown promising results in treating uncommon EGFR mutations. Despite various reports on the efficacy of afatinib and osimertinib in treating uncommon EGFR mutations, the appropriate use of these TKIs remains unclear. This review aims to consolidate the findings from the latest clinical trials focused on uncommon EGFR mutations, outlining variations in the therapeutic efficacy of these TKIs based on the specific genetic mutation. By synthesizing these findings, we aim to guide oncologists toward more informed decisions in employing TKIs for NSCLC with uncommon EGFR mutations other than exon 20 insertion. Additionally, we explore potential treatment strategies tailored to these patient populations to address the challenges posed by these mutations.

Near-Complete Response to Osimertinib for Advanced Non-Small-Cell Lung Cancer in a Pretreated Patient Bearing Rare Compound Exon 20 Mutation (S768I + V774M): A Case Report

Third-generation tyrosine kinase inhibitors are the first-line gold standard in treating advanced non-small-cell lung cancer bearing common EGFR mutations, but data documenting clinical efficacy in uncommon mutations are currently limited. In this paper, we describe the case of a patient bearing uncommon compound EGFR mutations in exon 20, who experienced a near-complete response to third-line Osimertinib, with metabolic complete response of pulmonary, nodal and ostheolytic lesions. This radiological assessment corresponded to an ECOG PS improvement (from three to one) and a substantial clinical benefit for the patients. Out of two mutations, S768I was associated with poor response to third-generation TKI and V774M had unknown clinical significance, highlighting the complexity of the correct management of these kinds of mutations. We reviewed the literature to document the up-to-date preclinical and clinical data concerning third-generation tyrosine kinase inhibitors for the treatment of patients bearing uncommon EGFR mutations.

Furmonertinib and intrathecal pemetrexed chemotherapy rechallenges osimertinib-refractory leptomeningeal metastasis in a non-small cell lung cancer patient harboring EGFR20 R776S, C797S, and EGFR21 L858R compound EGFR mutations: a case report

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are considered the first-line treatment for advanced or metastatic non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. However, due to the rarity of cases, the response of EGFR-TKIs in patients harboring uncommon compound EGFR mutations still needs to be determined. Here, we demonstrated the case of a 47-year-old smoker diagnosed with leptomeningeal metastasis from NSCLC and had EGFR20 R776S, C797S, and EGFR21 L858R compound mutations. He was treated with furmonertinib combined with intrathecal pemetrexed chemotherapy following progression on osimertinib, which led to clinical improvement and successfully prolonged his survival by 3 months. Regrettably, the patient eventually died from heart disease. This report provides the first reported evidence for the use of furmonertinib and intrathecal pemetrexed chemotherapy in NSCLC patients harboring EGFR R776S/C797S/L858R mutations who progressed on previous EGFR-TKIs.

Genetic mutation profiling reveals biomarkers for targeted therapy efficacy and prognosis in non-small cell lung cancer

Introduction

The genetic heterogeneity of non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations may affect clinical responses and outcomes to EGFR tyrosine kinase inhibitors (EGFR-TKIs). This study aims to investigate the genomic factors that influence the efficacy and clinical outcomes of first-line, second-line and third-line treatments in NSCLC and explore the heterogeneity of resistance mechanisms.

Materials and methods

This real-world study comprised 65 patients with EGFR mutant NSCLC. Molecular alterations were detected using a customized DNA panel before and after administering targeted therapy. The efficacy and prognosis of each treatment line were evaluated.

Results

In first-generation EGFR-TKIs treatment, gefitinib showed favorable efficacy compared to icotinib and erlotinib, particularly in patients with EGFR L858R mutations. The resistance mechanisms to first-generation EGFR-TKIs varied among different EGFR mutation cohorts and different first-generation EGFR-TKIs. In second-line EGFR-TKIs treatment, EPH receptor A3 (EPHA3), IKAROS family zinc finger 1 (IKZF1), p21 (RAC1) activated kinase 5 (PAK5), DNA polymerase epsilon, catalytic subunit (POLE), RAD21 cohesin complex component (RAD21) and RNA binding motif protein 10 (RBM10) mutations were markedly associated with poorer progression-free survival (PFS). Notably, EPHA3, IKZF1 and RBM10 were identified as independent predictors of PFS. The mechanisms of osimertinib resistance exhibited heterogeneity, with a higher proportion of non-EGFR-dependent resistant mutations. In third-line treatments, the combination of osimertinib and anlotinib demonstrated superior efficacy compared to other regimens. Glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A) mutation was an independent risk indicator of shorter OS following third-line treatments.

Conclusions

Comprehending the tumor evolution in NSCLC is advantageous for assessing the efficacy and prognosis at each stage of treatment, providing valuable insights to guide personalized treatment decisions for patients.

An epidermal growth factor receptor compound mutation of L858R with S768I in advanced non-small-cell lung cancer: a case report

BACKGROUND

In the current treatment landscape for non-small cell lung cancers, epidermal growth factor receptor-tyrosine kinase inhibitors have emerged as a well-established treatment option for patients with advanced or metastatic disease. This is particularly true for those with commonly occurring epidermal growth factor receptor mutations. However, the therapeutic efficacy of these agents for so-called rare epidermal growth factor receptor mutations, and in particular those characterized by a high degree of complexity, such as double mutations, remains a subject of clinical uncertainty.

CASE PRESENTATION

In this context, we present the case of a 64-year-old man of Moroccan descent, a lifelong non-smoker, diagnosed with metastatic non-small cell lung cancer characterized by a complex epidermal growth factor receptor mutation encompassing L858R and S768I. The patient subsequently underwent afatinib-based treatment, showing notable clinical results. These included a remarkable overall survival of 51 months, with a median progression-free survival of more than 39 months.

CONCLUSIONS

This case report is a compelling testimony to the evolving therapeutic landscape of non-small cell lung cancers, providing valuable insight into the potential therapeutic efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors in the realm of rare and complex epidermal growth factor receptor mutations.

Inhibition of a lower potency target drives the anticancer activity of a clinical p38 inhibitor

The small-molecule drug ralimetinib was developed as an inhibitor of the p38α mitogen-activated protein kinase, and it has advanced to phase 2 clinical trials in oncology. Here, we demonstrate that ralimetinib resembles EGFR-targeting drugs in pharmacogenomic profiling experiments and that ralimetinib inhibits EGFR kinase activity in vitro and in cellulo. While ralimetinib sensitivity is unaffected by deletion of the genes encoding p38α and p38β, its effects are blocked by expression of the EGFR-T790M gatekeeper mutation. Finally, we solved the cocrystal structure of ralimetinib bound to EGFR, providing further evidence that this drug functions as an ATP-competitive EGFR inhibitor. We conclude that, though ralimetinib is >30-fold less potent against EGFR compared to p38α, its ability to inhibit EGFR drives its primary anticancer effects. Our results call into question the value of p38α as an anticancer target, and we describe a multi-modal approach that can be used to uncover a drug's mechanism-of-action.

Improved survival and intracranial tumor control of EGFR-mutated NSCLC patients with newly developed brain metastases following stereotactic radiosurgery and EGFR-TKI: a large retrospective cohort study and meta-analyses

PURPOSE

To examine the differential effects of SRS and TKI on EGFR-mutated NSCLC patients with brain metastases (BMs) and outcomes following continuation of the same TKI agent in case of new BMs.

METHODS

This study included 608 NSCLC patients (2,274 BMs) while meta-analyses included 1,651 NSCLC patients (> 3,944 BMs). Overall survival (OS) and intracranial progression free survival (iPFS) were estimated using Kaplan-Meier methods. Hazard ratios (95% CI) of prognostic factors were estimated using Cox regression models.

RESULTS

The median OS/iPFS (95% CI) (months) for patients with wildtype EGFR/ALK, EGFR mutations, and ALK rearrangements were 17.7 (12.9-23.6)/12.1 (9.8-15.6), 28.9 (23.8-33.3)/17.7 (14.8-21.2), and 118.0 (not reached)/71.7 (15.1-not reached), respectively. In EGFR-mutated patients, meta-analyses combining our data showed significantly improved OS and iPFS of patients who received SRS and TKI (OS:35.1 months, iPFS:20.0 months) when compared to those who have SRS alone (OS:20.8 months, iPFS:11.8 months) or TKI alone (OS:24.3 months, iPFS:13.8 months). Having SRS for newly diagnosed BMs while keeping the existing TKI agent yielded OS (30.0 vs. 32.1 months, p = 0.200) non-inferior to patients who started combined SRS and TKI therapy for their newly diagnosed NSCLC with BMs. Multivariable analyses showed that good performance score and TKI therapy were associated with improved outcomes.

CONCLUSIONS

Combined SRS and TKI resulted in favorable outcomes in EGFR-mutated NSCLC patients with newly diagnosed BMs. Continuation of the same TKI agent plus SRS in case of new brain metastases yielded good clinical outcomes and may be considered a standard-of-care treatment.

Rare mutation-dominant compound EGFR-positive NSCLC is associated with enriched kinase domain-resided variants of uncertain significance and poor clinical outcomes

BACKGROUND

Compound epidermal growth factor receptor (EGFR) mutations are less responsive to tyrosine kinase inhibitors (TKIs) than single EGFR mutations in non-small cell lung cancer (NSCLC). However, the detailed clinical characteristics and prognosis of various compound EGFR mutations remain to be elucidated.

METHODS

We retrospectively studied the next-generation sequencing (NGS) data of treatment-naïve tumors from 1025 NSCLC patients with compound EGFR mutations, which were sub-categorized into different combinations of common mutations (19-Del and EGFR exon 21 p.L858R), rare mutations, and variants of uncertain significance (VUSs). Prognosis and drug resistance to first-line TKIs were analyzed in 174 and 95 patients, respectively.

RESULTS

Compound EGFR mutations were enriched with EGFR exon 21 p.L858R and rare mutations, but not 19-Del (P < 0.001). The common + rare and rare + rare subtypes had fewer concurrent mutations in the PI3K pathway (P = 0.032), while the rare + rare and common + VUSs subtypes showed increased association with smoking- and temozolomide-related mutational signatures, respectively (P < 0.001). The rare mutation-dominant subtypes (rare + VUSs and rare + rare) had the worst clinical outcomes to first-line TKIs (P < 0.001), which was further confirmed using an external cohort (P = 0.0066). VUSs in the rare + VUSs subtype selectively reside in the EGFR kinase domain (P < 0.001), implying these tumors might select additional mutations to disrupt the regulation/function of the kinase domain.

CONCLUSIONS

Different subtypes of compound EGFR mutations displayed distinct clinical features and genetic architectures, and rare mutation-dominant compound EGFR mutations were associated with enriched kinase domain-resided VUSs and poor clinical outcomes. Our findings help better understand the oncogenesis of compound EGFR mutations and forecast prognostic outcomes of personalized treatments.

Clinical outcome of Brazilian patients with non-small cell lung cancer in early stage harboring rare mutations in epidermal growth factor receptor

The common epidermal growth factor receptor (EGFR) mutations, such as the L858R point mutation in exon 21 and the in-frame deletional mutation in exon 19, have been definitively associated with response to EGFR-tyrosine kinase inhibitors (EGFR-TKI). However, the clinical outcome and response to treatment for many other rarer mutations are still unclear. In this study, we report the results of Brazilian patients in stage IB-IIIA non-small cell lung cancer (NSCLC) following complete resection with minimal residual disease and EGFR mutations treated with adjuvant chemotherapy and/or EGFR-TKIs. The frequency of EGFR mutations was investigated in 70 cases of early stage NSCLC. Mutations in exons 18 and 20, uncommon mutations in exons 19 and 21, as well as in exons 3, 7, 14, 16, 22, 27, and 28, and/or the presence of different mutations in a single tumor (complex mutations) are considered rare. EGFR mutations were detected in 23 tumors (32.9%). Fourteen cases carried rare mutations and were treated with platinum-based chemotherapy and two cases were treated with erlotinib. The clinical outcome is described case by case with references to the literature. Notably, we found two rare EGFR mutations and one of them with an unknown response to chemotherapy and/or EGFR-TKIs. We have provided complementary information concerning the clinical outcome and treatment of patients with early stage NSCLC for several rare EGFR mutations not previously or only rarely reported. Description of cases harboring rare mutations can support the decision-making process in this subset of patients.

Uncommon EGFR Compound Mutations in Non-Small Cell Lung Cancer (NSCLC): A Systematic Review of Available Evidence

Compound epidermal growth factor receptor (EGFR) mutations represent a heterogeneous subgroup of non-small cell lung cancer (NSCLC) patients with uncommon EGFR mutations. We conducted a systematic review to investigate the available data on this patients' subgroup. Overall, we found a high heterogeneity in the incidence of compound mutations (4-26% of total EGFR mutant cases), which is dependent on the different testing methods adopted and the specific mutations considered. In addition, the relative incidence of distinct compound subclasses identified is reported with extreme variability in different studies. Preclinical and clinical data, excluding de novoEGFR exon 20 p.T790M compound mutations, show good responses with EGFR tyrosine kinase inhibitors (TKIs) (combined common mutations: response rate (RR) ≥ 75% with either first- or second-generation TKIs; combined common plus uncommon: RR 40-80% and 100% with first-generation TKIs and afatinib, respectively; combined uncommon: RR 20-70%, ~80% and ~75% with first-generation TKIs, afatinib and osimertinib, respectively). Overall, data are consistent in supporting the use of EGFR TKIs in treating compound EGFR mutations, taking into account different sensitivity profile of accompanying EGFR mutations for selecting the most adequate EGFR TKI for individual patients.

A rotamer relay information system in the epidermal growth factor receptor-drug complexes reveals clues to new paradigm in protein conformational change

Cancer cells can escape the effects of chemotherapy through mutations and upregulation of a tyrosine kinase protein called the epidermal growth factor receptor (EGFR). In the past two decades, four generations of tyrosine kinase inhibitors targeting EGFR have been developed. Using comparative structure analysis of 116 EGFR-drug complex crystal structures, cluster analysis produces two clans of 73 and 43 structures, respectively. The first clan of 73 structures is larger and is comprised mostly of the C-helix-IN conformation while the second clan of 43 structures correlates with the C-helix-OUT conformation. A deep rotamer analysis identifies 43 residues (18%) of the total of 237 residues spanning the kinase structures under investigation with significant rotamer variations between the C-helix-IN and C-helix-OUT clans. The locations of these rotamer variations take on the appearance of side chain conformational relays extending out from points of EGFR mutation to different regions of the EGFR kinase. Accordingly, we propose that key EGFR mutations act singly or together to induce drug resistant conformational changes in EGFR that are communicated via these side chain conformational relays. Accordingly, these side chain conformational relays appear to play a significant role in the development of tumour resistance. This phenomenon also suggests a new paradigm in protein conformational change that is mediated by supportive relays of rotamers on the protein surface, rather than through conventional backbone movements.

Uncommon single and compound EGFR mutations: clinical outcomes of a heterogeneous subgroup of NSCLC

Molecular characterization of non-small-cell lung cancer (NSCLC) is essential to define the correct therapeutic algorithm in metastatic disease. Approximately 90% of epidermal growth factor receptor (EGFR) mutations are usually associated with sensitivity to EGFR tyrosine kinase inhibitors (TKIs). The remaining 10% defines a small, extremely heterogeneous subgroup of mutations, with a varied profile of sensitivity and response to target therapies.This retrospective observational study includes 47 patients affected by metastatic NSCLC harboring uncommon EGFR mutations (single or compound mutation). Patients were treated with EGFR-targeting TKIs or platinum-based chemotherapy as first-line treatment.Median OS resulted longer in the compound mutation group when compared to single rare mutations (33.6 vs 12 months; P = 0.473); a similar result was observed for PFS (16 vs 7.6 months; P = 0.281), although statistical significance was not reached. ORR, PFS and OS resulted similar for patients treated with first-line EGFR TKIs or chemotherapy. No difference in terms of PFS and OS was found according to the TKI administered.Compound mutations seem to be a good prognostic indicator for OS; they are also predictive of response to 1st and 2nd generation EGFR TKIs, as well as exon 19 insertions and mutations in codon 719 of exon 18. For mutations in exon 18 (not in codon 719) and exon 20 insertions, chemotherapy seems the most effective available option. The addition of immunotherapy to chemotherapy could change this approach in the next future.

Proteogenomics of Non-smoking Lung Cancer in East Asia Delineates Molecular Signatures of Pathogenesis and Progression

Lung cancer in East Asia is characterized by a high percentage of never-smokers, early onset and predominant EGFR mutations. To illuminate the molecular phenotype of this demographically distinct disease, we performed a deep comprehensive proteogenomic study on a prospectively collected cohort in Taiwan, representing early stage, predominantly female, non-smoking lung adenocarcinoma. Integrated genomic, proteomic, and phosphoproteomic analysis delineated the demographically distinct molecular attributes and hallmarks of tumor progression. Mutational signature analysis revealed age- and gender-related mutagenesis mechanisms, characterized by high prevalence of APOBEC mutational signature in younger females and over-representation of environmental carcinogen-like mutational signatures in older females. A proteomics-informed classification distinguished the clinical characteristics of early stage patients with EGFR mutations. Furthermore, integrated protein network analysis revealed the cellular remodeling underpinning clinical trajectories and nominated candidate biomarkers for patient stratification and therapeutic intervention. This multi-omic molecular architecture may help develop strategies for management of early stage never-smoker lung adenocarcinoma.

Recent Advances on the Role of EGFR Tyrosine Kinase Inhibitors in the Management of NSCLC With Uncommon, Non Exon 20 Insertions, EGFR Mutations

The first-line treatment of choice for patients with EGFR mutation-positive NSCLC is an EGFR tyrosine kinase inhibitor (TKI), of which five as follows are predominantly available in practice: gefitinib, erlotinib, afatinib, dacomitinib, and osimertinib. Most prospective clinical trial data with these agents are limited to patients with the common activating and sensitizing EGFR mutations as follows: exon 19 deletions and exon 21 L858R point mutations. However, 10% to 20% of patients with NSCLC harbor uncommon EGFR mutations that have variable sensitivity to different EGFR TKIs. Owing to their molecular structures, afatinib, dacomitinib, and osimertinib have broader inhibitory profiles than the first-generation agents, gefitinib and erlotinib. Nevertheless, the paucity of prospective clinical data, the wide heterogeneity of uncommon mutations, and the existence of compound mutations in up to 25% of the cases complicate treatment decisions in this patient subgroup. Here, we collate the latest preclinical and clinical data regarding the activity of different TKIs against major uncommon EGFR mutations including compound mutations, but excluding exon 20 insertions which are generally insensitive to TKIs. On the basis of these data, we offer suggestions regarding treatment strategies for uncommon EGFR mutations. Moving forward, it will be important to include uncommon EGFR mutations in the first-line molecular analysis of all patients with adenocarcinoma of the lung, as this will help optimize patient outcomes according to their precise genotype.

The effectiveness of afatinib in patients with lung adenocarcinoma harboring complex epidermal growth factor receptor mutation

Background and aims:

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) are effective against classical EGFR mutations in lung cancer. However, their effectiveness and the prognosis of lung cancer patients with complex EGFR mutations are not well delineated. Therefore, we aimed to investigate the treatment effectiveness of different EGFR TKIs in patients with complex EGFR mutations.

Patients and methods:

From 2005 to 2020, we collected lung adenocarcinoma tissue samples for EGFR mutation analysis using direct Sanger sequencing. Patients with EGFR mutations treated with EGFR TKIs as first-line treatment were enrolled. Clinical characteristics, EGFR mutation status, treatment response, progression-free survival (PFS), and overall survival (OS) were analyzed.

Results:

Among 2675 patients with EGFR mutations, 239 (8.9%) had complex EGFR mutations, of whom 125 received EGFR TKI treatment as first-line treatment. Multivariate analysis revealed that afatinib was a more favorable factor for PFS than gefitinib [hazard ratio (HR), 2.01; 95% confidence interval (CI), 1.11–3.62] and erlotinib (HR, 2.61; 95% CI, 1.31–5.22), especially in patients with uncommon mutation patterns. Afatinib treatment as first-line treatment was also associated with longer OS compared with erlotinib (HR, 2.48; 95% CI, 1.20–5.12). Classical mutation pattern was associated with longer PFS (p = 0.001) and OS (p = 0.020). Secondary T790M was detected in 22 of 52 (42.3%) patients who had re-biopsied tissue samples after acquiring resistance to EGFR TKIs. There was no significant difference in secondary T790M formation after acquired resistance to the three EGFR TKIs (p = 0.261). Furthermore, three (5.8%) patients had small-cell lung cancer transformation.

Conclusion:

Afatinib is an effective first-line treatment for patients with lung adenocarcinoma harboring complex EGFR mutations, especially those with uncommon mutation patterns.

Epidermal growth factor receptor variants in patients from Myanmar with lung adenocarcinoma

Background

Epidermal growth factor receptor (EGFR) sequence variants in patients from Myanmar have not yet been reported.

Objectives

To describe the molecular epidemiology of EGFR variants in patients from Myanmar with lung adenocarcinoma.

Methods

Histological diagnosis and categorization of biopsies collected from 66 patients (28–78 years) with lung cancer was conducted using a panel of antibodies including those to: TTF1, P40, synaptophysin, CK7, and napsin-A. Samples from patients with confirmed adenocarcinoma were tested for EGFR variants using a cobas EGFR Mutation Test kit and cobas z 480 System (Roche). We conducted a univariate analysis of categorical factors using a χ2 or Fisher exact test.

Results

Histological types were adenocarcinoma (61%, 40/66), squamous cell carcinoma (24%, 16/66), neuroendocrine carcinoma (9%, 6/66), undifferentiated carcinoma (2%, 1/66), adenosquamous carcinoma (2%, 1/66), small cell anaplastic carcinoma (2%, 1/66), and pleomorphic sarcoma (2%, 1/66). EGFR variants were detected in 15 of 40 (38%) cases of adenocarcinoma. Among them, 6 patients (40%) had an exon 19 deletion, another 6 (40%) had exon 21 substitutions, 1 (7%) had exon 20 insertion S768I, and 2 (13%) had compound variations (1 of exon 21 L858R and exon 18 G719X, and 1 of exon 20 S768I and exon 18 G719X). Although limited by small sample size, no significant association was found between the variants and factors including family cancer history, age group, sex, ethnicity, or occupation. However, there was a strong significant association between never-smokers and EGFR variants (P = 0.008).

Conclusion

Knowledge of EGFR variants in patients from Myanmar is encouraging for their effective cancer treatment.

The significance of epidermal growth factor receptor uncommon mutations in non-small cell lung cancer: A systematic review and critical appraisal

Uncommon epidermal growth factor receptor (EGFR) mutations collectively account for 10% of EGFR mutations, harboring heterogeneous molecular alterations within exons 18-21 with clinically variable responses to EGFR tyrosine kinase inhibitors (TKIs) in advanced Non-Small Cell Lung Cancer (NSCLC) patients. In addition, with the introduction of different NGS gene approach an improvement of EGFR mutations detection was reported. Today, no specific studies have prospectively evaluated uncommon sensitizing mutations in detail and no firm standard of care has been established in the first-line setting. The aim of this comprehensive review is to critically consider the clinical role of uncommon EGFR mutations highlighting the results of several in vitro and in vivo studies, which singly evaluated the sensitivity of uncommon mutations to currently European of Medicines Agency (EMA)-approved EGFR TKIs in cell lines, xenograft models and humans, in order to obtain a practical guide for refining the clinical decision-making process.

Clinical outcome of treatment of metastatic non-small cell lung cancer in patients harboring uncommon EGFR mutation

Background

Uncommon epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is a rare subset of NSCLC. The aim of this study was to investigate the prevalence, characteristics, and clinical outcomes of metastatic NSCLC harboring uncommon EGFR mutation at Thailand’s largest national tertiary hospital. The secondary objective was to compare treatment efficacy between EGFR-tyrosine kinase inhibitor (EGFR-TKI) and chemotherapy.

Methods

This retrospective chart review included patients that were tested for EGFR-mutation NSCLC during 2014–2018. Patient demographic and clinical data, treatment data, and outcome data were collected and analyzed.

Results

Of the 681 patients that were evaluated for EGFR mutation, 317 (47.0%) had EGFR-mutant NSCLC, and 28 (8.8%) of those harbored uncommon EGFR mutations. The median follow-up was 19.1 months. History of tobacco use was reported in 50% of patients. The most common single mutation among uncommon EGFR was exon 20 insertion (n = 6), followed by L861Q (n = 5) and G719X (n = 4). Thirteen (46%) patients had compound mutations. One hundred percent of male patients with G719X mutation were smokers. Sixteen of 28 patients were treated with EGFR-TKI. Most received first-generation EGFR-TKI, and 29% were treated with chemotherapy alone. The objective response rate was 37.5% in the EGFR-TKI group. Median progression-free survival (PFS) in the EGFR-TKI group was 10.2 months. Median PFS among the 8 patients in the chemotherapy group that received first-line platinum doublet was 6.5 months. Three-year overall survival (OS) among 28 patients was 34%. Three-year OS was significantly better in patients treated with EGFR-TKI.

Conclusions

Uncommon EGFR mutations was detected in 8.8% of EGFR-mutant NSCLC. Exon 20 insertion was the most common mutation, and 50% of patients had history of tobacco use. First- or second-generation EGFR-TKI demonstrated greater OS benefit than platinum-doublet chemotherapy among patients harboring uncommon EGFR-mutant NSCLC. Survival outcomes were comparable to those reported from previous large cohort studies.

The in cis compound EGFR mutations in Chinese advanced non-small cell lung cancer patients

Literatures regarding the prevalence and clinical significance of compound EGFR mutations are limited. Until now, none of retrospective or prospective research has focused on in cis compound EGFR mutations except case reports. In this study, we screened a cohort of 3,000 treatment-naïve Chinese advanced NSCLC patients using capture-based ultra-deep targeted sequencing to evaluate the prevalence of EGFR in cis compound mutations and the efficacy of EGFR-TKI in this population. Of the 3,000 patients screened, 1,266 (42.2%) had EGFR mutation; among them, 15 patients (1.2%) harboring in cis compound EGFR mutations, with 10 patients carrying EGFR L858R in combination with a rare mutation and five patients carrying two rare EGFR mutations. No patient with EGFR 19del was observed. Interestingly, no in trans configuration was identified in this cohort. All of the patients harboring in cis compound EGFR mutations were non-smokers, histologically diagnosed with adenocarcinoma and received first-generation EGFR-TKI. Furthermore, our data also revealed that patients with in cis compound EGFR mutations exhibit comparable PFS to first generation EGFR-TKI comparing to patients with single activating EGFR mutation. This observation was further supported by in silico molecular modeling analyses which demonstrated in cis compound mutations do not alter the ATP-binding pocket of EGFR, thus having no effect on the interaction between gefitinib and EGFR.

Heterogeneous Responses to Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitors (TKIs) in Patients with Uncommon EGFR Mutations: New Insights and Future Perspectives in this Complex Clinical Scenario

Uncommon Epidermal Growth Factor Receptor (EGFR) mutations represent a distinct and highly heterogeneous subgroup of Non-Small Cell Lung Cancers (NSCLCs), that accounts for approximately 10% of all EGFR-mutated patients. The incidence of uncommon EGFR mutations is growing, due to the wider adoption of next-generation sequencing (NGS) for diagnostic purposes, which enables the identification of rare variants, usually missed with available commercial kits that only detect a limited number of EGFR mutations. However, the sensitivity of uncommon mutations to first- and second-generation EGFR Tyrosine Kinase Inhibitors (TKIs) is widely heterogeneous and less well known, compared with classic mutations (i.e., exon 19 deletions and exon 21 L858R point mutation), since most of the pivotal studies with EGFR TKIs in the first line, with few exceptions, excluded patients with rare and/or complex variants. Recently, the third generation EGFR TKI osimertinib further revolutionized the therapeutic algorithm of EGFR-mutated NSCLC, but its role in patients harboring EGFR mutations besides exon 19 deletions and/or L858R is largely unknown. Therefore, a better knowledge of the sensitivity of uncommon mutations to currently available EGFR TKIs is critical to guiding treatment decisions in clinical practice. The aim of this paper is to provide a comprehensive overview of the treatment of NSCLC patients harboring uncommon EGFR mutations with currently approved therapies and to discuss the emerging therapeutic opportunities in this peculiar subgroup of patients, including chemo-immunotherapy combinations, next-generation EGFR TKIs, and novel targeted agents.

Epidermal growth factor receptor somatic mutation analysis in 354 Chinese patients with non-small cell lung cancer

Lung cancer is one of the most common types of cancer worldwide, with the highest mortality rate of all types of cancer. In the present study, epidermal growth factor receptor (EGFR) mutations of 354 primary patients with non-small cell lung cancer (NSCLC) of Chinese ethnicity were detected following formalin-fixed and paraffin-embedded specimen DNA extraction, polymerase chain reaction amplification, and sanger sequencing. The total rate of occurrence of EGFR somatic mutation in these 354 patients was 48.02%. Of these detected EGFR mutations, 27.40% were located in exon 19 and 25.99% in exon 21. The most frequent mutation in exon 19 was E746-A750del (8.47%), and in exon 21, L858R (10.17%). EGFR mutation rates were significantly associated with sex [female vs. male: 60.13 vs. 38.81%; adjusted odds ratio (OR), 1.93, 95% confidence interval (CI), 1.07–3.51, P=0.029], age (<60 vs. ≥60; 58.62 vs. 40.67%; adjusted OR, 1.87; 95% CI, 1.20–2.92; P=0.006) and histology [adenocarcinoma (ADC) vs. non-ADC; 52.76 vs. 26.56%; adjusted OR, 2.35; 95% CI, 1.28–4.50; P=0.007]. The frequency of E746_A750del, Q787Q and L858R mutations were significantly different in ADC patients compared with squamous cell carcinoma patients (P<0.001). Furthermore, a novel EGFR mutation, M793K, was detected in 7 NSCLC patients with possible gefitinib resistance. The present study analyzed the EGFR exon 18–21 mutation occurrence profile for Chinese patients with NSCLC and identified significant associations between different EGFR mutations with demographic and histological factors. These results may offer clinical benefits and potential novel treatments.

Clinical Characteristics and Survival Outcomes for Non-Small-Cell Lung Cancer Patients with Epidermal Growth Factor Receptor Double Mutations

Multiple randomized clinical trials have demonstrated that epidermal growth factor receptor (EGFR) exon 19 deletion (19Del) and exon 21 L858R mutation (L858R) are highly correlated with sensitivity to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment in non-small-cell lung cancer (NSCLC). A mutation in exon 20 (T790M) is reportedly associated with resistance to EGFR-TKIs. However, few studies have focused on patients harboring double mutations in these 3 mutation sites. In this retrospective study, forty-five patients (45/2546, 1.7%) harbored double mutations of 19Del, L858R, and T790M. Twenty-four patients with EGFR double mutations received EGFR-TKI therapy. Clinical characteristics of these patients, including the response to EGFR-TKIs and progression-free survival outcome for EGFR-TKI treatment (PFS-TKI), were analyzed. Patients with EGFR double mutations were more likely to be nonsmokers, have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1, have adenocarcinoma, and be at stage III-IV. The ORR, DCR, and median PFS-TKI in patients harboring EGFR double mutations were lower than in patients with a single EGFR-activating mutation. The differences in ORR and DCR were statistically insignificant between the 3 groups. Patients with double mutations of 19Del and T790M had longer PFS-TKIs than patients in the other 2 groups.

Tumor molecular profiling of NSCLC patients using next generation sequencing

Non‑small cell lung cancer (NSCLC) is the most common type of lung cancer and a tumor with a broad spectrum of targeted therapies already available or in clinical trials. Thus, molecular characterization of the tumor using next generation sequencing (NGS) technology, has become a key tool for facilitating treatment decisions and the clinical management of NSCLC patients. The performance of a custom 23 gene multiplex amplification hot spot panel, based on Ion AmpliSeq™ technology, was evaluated for the analysis of tumor DNA extracted from formalin-fixed and paraffin-embedded (FFPE) tissues. Furthermore, the Ion AmpliSeq™ RNA Fusion Lung Cancer Research Panel was used for fusion RNA transcript analysis. The mutation spectrum of the tumors was determined in a cohort of 502 patients with NSCLC using the aforementioned targeted gene panels. The panel used for tumor DNA analysis in this study exhibited high rates (100%) of sensitivity, specificity and reproducibility at a mutation allelic frequency of 3%. At least one DNA mutation was detected in 374 patients (74.5%) and an RNA fusion was identified in 16 patients, (3.2%). In total, alterations in a cancer-driver gene were identified (including point mutations, gene rearrangements and MET amplifications) in 77.6% of the tumors tested. Among the NSCLC patients, 23% presented a mutation in a gene associated with approved or emerging targeted therapy. More specifically, 13.5% (68/502) presented a mutation in a gene with approved targeted therapy (EGFR, ALK, ROS1) and 9.4% (47/502) had an alteration in a gene related to emerging targeted therapies (ERBB2, BRAF, MET and RET). Furthermore, 51.6% of the patients had a mutation in a gene that could be related to an off label therapy or indicative for access to a clinical trial. Thus, the targeted NGS panel used in this study is a reliable approach for tumor molecular profiling and can be applied in personalized treatment decision making for NSCLC patients.

Uncommon EGFR mutations in advanced non-small cell lung cancer

Molecular profiling in advanced non-small cell lung cancer (NSCLC) has allowed for the detection of actionable mutations, which has revolutionized the treatment paradigm in this highly fatal disease. Mutations involving the epidermal growth factor receptor (EGFR) gene are most common and the 'classical mutations', exon 19 deletions and the point mutation L858R at exon 21, predict response to EGFR tyrosine kinase inhibitors (TKIs). The 'uncommon' EGFR mutations account for 10-18% of all EGFR mutations and primarily consist of exon 20 insertions, exon 18 point mutations and complex mutations. Improved detection techniques have broadened the spectrum of reported aberrations within the 'uncommon group' but response to TKIs is variable and not fully elucidated. This review provides an overview of the biology and incidence of uncommon EGFR mutations and summarizes reported outcomes when treated with EGFR-TKIs.

Shikonin inhibits gefitinib-resistant non-small cell lung cancer by inhibiting TrxR and activating the EGFR proteasomal degradation pathway

Non-small cell lung cancer (NSCLC) is the dominant type of lung cancer. Molecular targeting has highly improved the treatment efficacy of lung cancer, but new challenges have emerged, such as gefitinib-resistance and cancer recurrence. Therefore, new chemotherapeutic agents and treatment strategies are urgently needed. Shikonin is the main active component of a Chinese medicinal plant 'Zi Cao', which has been shown to exhibit powerful anti-cancer activity in certain types of cancer; however, its activity in gefitinib-resistant lung cancer has never been addressed. In this study, we used a high-throughput screening assay for epidermal growth factor receptor (EGFR) inhibitors and discovered that Shikonin is a potent inhibitor of EGFR. The cytotoxicity of Shikonin and its anti-cancer mechanism in NSCLC was deeply explored. Shikonin exhibited selective cytotoxicity among two NSCLC cell lines (H1975 and H1650) and one normal lung fibroblast cell line (CCD-19LU). Shikonin significantly increased the activity of caspases and poly (ADP-ribosyl) polymerase (PARP), which are indicators of apoptosis, and the intensity of ROS by greater than 10-fold. NAC, an inhibitor of ROS, completely blocked apoptosis, caspase and PARP activation induced by Shikonin. Shikonin remarkably suppressed the phosphorylation of EGFR and led to EGFR degradation. The enhancement of ROS generation in H1650 and H1975 gefitinib-resistant NSCLC cells leads to impairment of growth and induction of apoptosis, whereas modulation of EGFR degradation and its downstream signalling pathways by Shikonin contributes to its anti-tumour properties in H1975 gefitinib-resistant NSCLC cells (with T790M and L858R activating mutations). Shikonin-induced cell apoptosis is closely associated with ROS elevation in the cells. These findings indicate that Shikonin can be an effective small molecule treating gefitinib-resistant NSCLC.

EGFR mutations in non-small cell lung cancer: an audit from West China Hospital

OBJECTIVES

To discover the incidence and characteristics of EGFR mutations in non-small cell lung cancer (NSCLC) in a single, large cohort as a part of routine diagnostic investigations.

METHODS

We reviewed EGFR mutations investigated by Amplification Refractory Mutation System (ARMS) PCR (covering 29 known mutations) using DNA samples from FFPE tissue or cell clot specimens in a total of 3894 cases of NSCLC analysed between 2012-2014.

RESULTS

EGFR mutations are preferentially associated with adenocarcinomaand adenosquamous histology, particularly those well to moderately differentiated, and were significantly more common in female than male patients irrespective of histological subtypes. Exon 19 deletion (45.7%) and exon 21 L858R (45.6%) accounted for the vast majority of the EGFR mutations detected, with the remaining mutations being infrequent (<2%). Compound mutations were seen in 51 (3%) of the mutant cases, the combination of these compound mutations could be classified into three subgroups according to the potential impact of individual mutations on EGFR TKI therapy. Accordingly, 7 cases had both sensitive mutations, 4 cases harboured one sensitive and one less responsive /uncertain mutation, 19 cases contained one sensitive and one resistant change, and a further 21 cases had two less responsive /uncertain mutations.

CONCLUSION

Our data represents the largest EGFR mutation survey based on routine clinical diagnostic laboratory data from a single institution, it confirms the incidence and characteristics of EGFR mutations in NSCLC seen in Asian patients, and also unravels the combinatorial nature of rare compound EGFR mutations.

Targeting Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer by Inducing Epidermal Growth Factor Receptor Degradation via Methionine 790 Oxidation

AIMS

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been developed to treat non-small cell lung cancer (NSCLC) patients with EGFR mutation, but TKI resistance is common. Almost half of the acquired resistance patients are due to additional T790M mutation on EGFR (EGFR(T790M)), thus overcoming TKI resistance is important. In this study, we aim to investigate the role of reactive oxygen species (ROS) in TKI resistance as well as the molecular and biological effects of EGFR(T790M) after redox manipulation.

RESULTS

The basal ROS levels in EGFR(T790M)-containing TKI-resistant NSCLC cell lines were substantially high. Sixty-three human lung tumors showed higher NADPH oxidase isoform 2 (NOX2) expression than normal lung tissues, which may contribute to high basal ROS in cancer and poor survival. Interestingly, only NOX3 was upregulated by sanguinarine, a pharmacological agent to elevate ROS, and resulted in EGFR overoxidation, degradation, and apoptosis. By contrast, such responses were lacking in EGFR(WT) cells. Selective EGFR(T790M) degradation was manipulated by redox imbalance between NOX3 and methionine reductase A (MsrA). Furthermore, the in vivo tumor suppression effect of sanguinarine, NOX3 upregulation, and EGFR degradation were confirmed.

INNOVATION

We have found a new treatment strategy to overcome TKI resistance by selectively inducing EGFR(T790M) degradation via specific stimulation of methionine 790 (M790) oxidation. It can be achieved via manipulating redox imbalance between NOX3 and MsrA.

CONCLUSION

Targeting EGFR by elevating ROS and redox imbalance is a potential new strategy to develop a new EGFR inhibitor for TKI-resistant patients with a wide therapeutic window between EGFR(T790M) and EGFR(WT).

Combined analysis of rearrangement of ALK, ROS1, somatic mutation of EGFR, KRAS, BRAF, PIK3CA, and mRNA expression of ERCC1, TYMS, RRM1, TUBB3, EGFR in patients with non-small cell lung cancer and their clinical significance

PURPOSE

The assessment of single gene such as ERCC1, TYMS, RRM1, TUBB3, EGFR, KRAS, BRAF, PIK3CA, ALK, and ROS1 is now widely applied in therapeutic decisions of non-small cell lung cancer (NSCLC). The aim of our study was to concurrently analyze these genes and evaluate their clinical significance in patients with NSCLC.

METHODS

Rearrangement of ALK and ROS1 was analyzed in 120 patients using FISH assays. Somatic mutation of EGFR, KRAS, BRAF, PIK3CA and mRNA expression of ERCC1, TYMS, RRM1, TUBB3, EGFR were examined by liquidchip platform in 350 patients . Data on clinical features were obtained from medical records of 119 patients, and the follow-up was conducted in 106 patients who received platinum-based adjuvant chemotherapy.

RESULTS

We identified 5.0% ALK rearrangements, 1.7% ROS1 rearrangements, 36.6% EGFR mutations, 8.9% KRAS mutations, 0% BRAF mutations, and 4.0% PIK3CA mutations. Double or coexisting mutations were identified in 13 patients. Significant correlations were observed among EGFR, KRAS mutation, ERCC1, TYMS, RRM1, TUBB3, EGFR expression, and clinical features, especially histology (P < 0.05). Significant cross-correlations were observed in some pairs of genes (P < 0.05). Patients with low RRM1 expression had a better progression-free survival (PFS) (P < 0.05). Furthermore, EGFR-mutated patients with low RRM1 expression or patients with both ERCC1 and RRM1 low expression had a better PFS (P < 0.05).

CONCLUSION

Combined analysis of these commonly studied genes may promote the individual treatment in NSCLC. RRM1 may be a prognostic and predictive biomarker for PFS in patients with NSCLC who received platinum-based adjuvant chemotherapy, and combining EGFR mutation and RRM1 expression or combining ERCC1 and RRM1 expression can enhance prognostic and predictive power for PFS.

Towards a Molecular Understanding of the Link between Imatinib Resistance and Kinase Conformational Dynamics

Due to its inhibition of the Abl kinase domain in the BCR-ABL fusion protein, imatinib is strikingly effective in the initial stage of chronic myeloid leukemia with more than 90% of the patients showing complete remission. However, as in the case of most targeted anti-cancer therapies, the emergence of drug resistance is a serious concern. Several drug-resistant mutations affecting the catalytic domain of Abl and other tyrosine kinases are now known. But, despite their importance and the adverse effect that they have on the prognosis of the cancer patients harboring them, the molecular mechanism of these mutations is still debated. Here by using long molecular dynamics simulations and large-scale free energy calculations complemented by in vitro mutagenesis and microcalorimetry experiments, we model the effect of several widespread drug-resistant mutations of Abl. By comparing the conformational free energy landscape of the mutants with those of the wild-type tyrosine kinases we clarify their mode of action. It involves significant and complex changes in the inactive-to-active dynamics and entropy/enthalpy balance of two functional elements: the activation-loop and the conserved DFG motif. What is more the T315I gatekeeper mutant has a significant impact on the binding mechanism itself and on the binding kinetics.

Merlin negative regulation by miR-146a promotes cell transformation

Inactivation of the tumor suppressor Merlin, by deleterious mutations or by protein degradation via sustained growth factor receptor signaling-mediated mechanisms, results in cell transformation and tumor development. In addition to these mechanisms, here we show that, miRNA-dependent negative regulation of Merlin protein levels also promotes cell transformation. We provide experimental evidences showing that miR-146a negatively regulates Merlin protein levels through its interaction with an evolutionary conserved sequence in the 3´ untranslated region of the NF2 mRNA. Merlin downregulation by miR-146a in A549 lung epithelial cells resulted in enhanced cell proliferation, migration and tissue invasion. Accordingly, stable miR-146a-transfectant cells formed tumors with metastatic capacity in vivo. Together our results uncover miRNAs as yet another negative mechanism controlling Merlin tumor suppressor functions.

Next-Generation Sequencing of a Cohort of Pulmonary Large Cell Carcinomas Reclassified by World Health Organization 2015 Criteria

CONTEXT

The classification of pulmonary large cell carcinoma has undergone a major revision with the recent World Health Organization (WHO) 2015 Classification. Many large cell carcinomas are now reassigned to either adenocarcinoma with solid pattern or nonkeratinizing squamous cell carcinoma based on immunopositivity for adenocarcinoma markers or squamous cell carcinoma markers, respectively. Large cell carcinomas that are negative for adenocarcinoma and squamous cell carcinoma immunomarkers are now classified as large cell carcinoma with null immunohistochemical features (LCC-N). Although a few studies investigated the mutation profile of large cell carcinomas grouped by immunostain profile before the publication of the new WHO classification, investigation of tumors previously diagnosed as large cell carcinoma and reclassified according to the 2015 WHO classification has not, to our knowledge, been reported.

OBJECTIVE

To determine the mutation profiles of pulmonary large cell carcinomas reclassified by WHO 2015 criteria.

DESIGN

Archival cases of non-small cell lung carcinoma with large cell carcinoma morphology (n = 17) were reclassified according to 2015 WHO criteria. To determine mutation profile, we employed Ion Torrent (Life Technologies, Carlsbad, California)-based next-generation sequencing (50 genes; more than 2800 mutations) in addition to real-time quantitative reverse transcription polymerase chain reaction for ALK translocation detection.

RESULTS

Two of 17 cases (12%) were reclassified as LCC-N, and both had mutations-BRAF D594N in one case and KRAS G12C in the other case. Seven of 17 cases (41%) were reclassified in the adenocarcinoma with solid pattern group, which showed one KRAS G12C and one EGFR E709K + G719C double mutation in addition to mutations in TP53. Eight of 17 cases (47%) were reclassified in the nonkeratinizing squamous cell carcinoma group, which showed mutations in PIK3CA, CDKN2A, and TP53. No ALK translocations or amplifications were detected.

CONCLUSIONS

The adenocarcinoma with solid pattern group showed mutations typical of adenocarcinoma, whereas the nonkeratinizing squamous cell carcinoma group showed mutations typical of squamous cell carcinoma. Both LCC-N cases had mutations associated with adenocarcinoma, supporting the hypothesis that LCC-N is related to adenocarcinoma.

Discrimination of driver and passenger mutations in epidermal growth factor receptor in cancer

Cancer is one of the most life-threatening diseases and mutations in several genes are the vital cause in tumorigenesis. Protein kinases play essential roles in cancer progression and specifically, epidermal growth factor receptor (EGFR) is an important target for cancer therapy. In this work, we have developed a method to classify single amino acid polymorphisms (SAPs) in EGFR into disease-causing (driver) and neutral (passenger) mutations using both sequence and structure based features of the mutation site by machine learning approaches. We compiled a set of 222 features and selected a set of 21 properties utilizing feature selection methods, for maximizing the prediction performance. In a set of 540 mutants, we obtained an overall classification accuracy of 67.8% with 10 fold cross validation using support vector machines. Further, the mutations have been grouped into four sets based on secondary structure and accessible surface area, which enhanced the overall classification accuracy to 80.2%, 81.9%, 77.9% and 75.1% for helix, strand, coil-buried and coil-exposed mutants, respectively. The method was tested with a blind dataset of 60 mutations, which showed an average accuracy of 85.4%. These accuracy levels are superior to other methods available in the literature for EGFR mutants, with an increase of more than 30%. Moreover, we have screened all possible single amino acid polymorphisms (SAPs) in EGFR and suggested the probable driver and passenger mutations, which would help in the development of mutation specific drugs for cancer treatment.

Detection of EGFR mutational profile by direct dideoxy sequencing in cytology and non-cytology biopsy samples

Epidermal growth factor receptor (EGFR) mutational analysis is recommended in the diagnostic work-up of non-small cell lung carcinoma. The first diagnostic biopsy is usually obtained by a minimally invasive procedure, especially in patients with unresectable disease. This paper aims to compare the types of somatic EGFR mutations detected by cytology and non-cytology samples by direct dideoxy sequencing and propose practical guidelines for handling such material. Only samples with sufficient polymerase chain reaction (PCR) product were considered, a total 310 samples (302 patients), of which 168 samples were cytology material and 142 samples were non-cytology biopsy material. All samples were assessed for tumour content and bidirectional direct sequencing was performed on exons 18, 19, 20 and 21. There were 49 cases with EGFR mutation detected (16.2%), without a significant difference in the detection of mutations between either cytology or non-cytology material. EGFR mutation was detected in most sample types including endoscopic ultrasound guided FNA, bronchial washings/brushings and pleural/peritoneal fluid samples. Cytology material can provide an adequate source of material for EGFR mutational analysis, with coordinated effort between clinicians and pathologists critical for best outcome.

A Predictive Model for Personalized Therapeutic Interventions in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) constitutes the most common type of lung cancer and is frequently diagnosed at advanced stages. Clinical studies have shown that molecular targeted therapies increase survival and improve quality of life in patients. Nevertheless, the realization of personalized therapies for NSCLC faces a number of challenges including the integration of clinical and genetic data and a lack of clinical decision support tools to assist physicians with patient selection. To address this problem, we used frequent pattern mining to establish the relationships of patient characteristics and tumor response in advanced NSCLC. Univariate analysis determined that smoking status, histology, epidermal growth factor receptor (EGFR) mutation, and targeted drug were significantly associated with response to targeted therapy. We applied four classifiers to predict treatment outcome from EGFR tyrosine kinase inhibitors. Overall, the highest classification accuracy was 76.56% and the area under the curve was 0.76. The decision tree used a combination of EGFR mutations, histology, and smoking status to predict tumor response and the output was both easily understandable and in keeping with current knowledge. Our findings suggest that support vector machines and decision trees are a promising approach for clinical decision support in the patient selection for targeted therapy in advanced NSCLC.

Structural signature of the G719S-T790M double mutation in the EGFR kinase domain and its response to inhibitors

Some individuals with non-small-cell lung cancer (NSCLC) benefit from therapies targeting epidermal growth factor receptor (EGFR), and the characterization of a new mechanism of resistance to the EGFR-specific antibody gefitinib will provide valuable insight into how therapeutic strategies might be designed to overcome this particular resistance mechanism. The G719S and T790M mutations and their combination were involved in causing different conformational redistribution of EGFR. In the present computational study, we analyzed the impact and structural influence of G719S/T790M double mutation (DM) in EGFR with ligand (gefitinib) through molecular dynamic simulation (50 ns) and docking analysis. We observed the escalation in distance between the functional loop and activation loop with respect to T790M mutation compared to the G719S mutation. Furthermore, we confirmed that the G719S mutation causes the ligand to move closer to the hinge region, whereas T790M makes the ligand escape from the binding pocket. Obtained results provide with an explanation for the resistance induced by T790M and a vital clue for the design of drugs to combat gefitinib resistance.

Celastrol induces apoptosis in gefitinib-resistant non-small cell lung cancer cells via caspases-dependent pathways and Hsp90 client protein degradation

Celastrol, a triterpene extracted from the Chinese herb Tripterygium wilfordii, has been shown to have multiple bioactivities. Although among these activities, its anti-cancer effects have attracted the most attention, the effect of celastrol on gefitinib-resistant non-small cell lung cancer (NSCLC) cells is not clearly known. Here, we examined the potency of celastrol in three different NSCLC cell lines. We explored its treatment mechanism in two gefitinib-resistant NSCLC cell lines (H1650 and H1975). Our data demonstrated that celastrol exerted its apoptotic effect in a dose- and time-dependent manner. Also, the mitochondria membrane potential was gradually lost and the ratio of Bax/Bcl-2 increased after the treatment of celastrol, both of which are indicators of mitochondria membrane integrity. Although the caspases were activated, the treatment with pan-caspase inhibitor could partially inhibit the level of apoptosis. Moreover, the protein level of Hsp90 client proteins, EGFR and AKT, was measured. Interestingly, both client proteins were remarkably down-regulated after the treatment of celastrol. Taken together, our data showed that celastrol may be developed as a promising agent for treating gefitinib-resistant NSCLCs by inducing apoptosis through caspase-dependent pathways and Hsp90 client protein degradation.

[Research progress of the resistance mechanism of non-small cell lung cancer to EGFR-TKIs]

目前，肺癌是全世界范围内发病率和死亡率最高的恶性肿瘤，其中非小细胞肺癌（non-small cell lung cancer, NSCLC）占全部肺癌的80%左右，而NSCLC患者中有很大一部分在确诊时已经处于晚期。因此，对于晚期NSCLC的治疗也越来越受到人们的重视。虽然晚期NSCLC的标准治疗为含铂双药联合化疗，但是化疗药物对改善晚期NSCLC患者的生存期方面作用十分有限，因此寻求新的治疗方式迫在眉睫。随着对肺癌发病机制及其生物学行为的深入研究，分子靶向治疗已成为治疗晚期NSCLC最具前景的研究领域。其中表皮生长因子受体-酪氨酸激酶抑制剂（epidermal growth factor receptor tyrosine kinase inhibitors, EGFR-TKIs）在晚期NSCLC治疗方面取得了突破性进展，其代表药物为吉非替尼和厄洛替尼，这两种EGFR-TKIs已在全世界范围内得到认可并被广泛用于晚期NSCLC的治疗，尤其是对于EGFR敏感突变者。然而，经过一段时间（中位时间为6个月-12个月）的治疗后，大部分患者会对EGFR-TKIs产生耐药，其耐药机制主要包括原发性和获得性耐药。由于EGFR-TKIs在改善晚期NSCLC患者总生存期和无进展生存期方面的突出作用，对于EGFR-TKIs耐药机制的探索已成为国内外研究的热点。该文章就EGFR-TKI耐药机制的研究进展进行了综述。

Patterns of DNA mutations and ALK rearrangement in resected node negative lung adenocarcinoma

BACKGROUND

Many studies have examined specific mutations in patients with resected lung adenocarcinoma across heterogeneous stages, comprising predominantly advanced/metastatic disease, but there is little data regarding the mutation profile of patients with early stage node negative disease. The aim of this study was to identify patterns of mutations in early stage node negative lung adenocarcinoma.

METHODS

A total of 204 patients who underwent resection for stage IB (sixth Ed American Joint Committee on Cancer) lung adenocarcinoma and received no neoadjuvant or adjuvant treatments were identified. Tumors were genotyped using the OncoCarta v1.0 kit (Sequenom, San Diego, CA) on the Sequenom MassARRAY platform. Fluorescence in situ hybridization for ALK rearrangement was also performed.

RESULTS

A total of 110 (54%) patients' tumors harbored at least one mutation. KRAS, EGFR, PIK3CA, ALK, PDGFRA, AKT1, BRAF, FGFR1, and HRAS mutations were detected in tumors from 77 (37.7%), 29 (14.2%), 9 (4.4%), 2 (1%), 2 (1%), 1 (0.5%), 1 (0.5%), 1 (0.5%), and 1 (0.5%) patients respectively. Synchronous mutations (either comutations or double mutations) were identified in 18 (8.8%) patients. KRAS and PIK3CA mutations were associated with poorly differentiated tumors (p = 0.03; p = 0.02), whereas EGFR mutations were associated with well-differentiated tumors (p = 0.001). Five tumours contained EGFR mutations (one T790M and four exon 20 insertions), which are associated with resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs).

CONCLUSIONS

Diverse patterns of mutations are seen in resected node-negative lung adenocarcinoma including an unexpectedly low rate of ALK rearrangement, EGFR mutations associated with resistance to EGFR-TKIs and a high rate of synchronous mutations. These data may influence the design of future adjuvant targeted therapy trials.

Effects of oncogenic mutations on the conformational free-energy landscape of EGFR kinase

Activating mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase are frequently found in many cancers. It has been suggested that changes in the equilibrium between its active and inactive conformations are linked to its oncogenic potential. Here, we quantify the effects of some of the most common single (L858R and T790M) and double (T790M-L858R) oncogenic mutations on the conformational free-energy landscape of the EGFR kinase domain by using massive molecular dynamics simulations together with parallel tempering, metadynamics, and one of the best force-fields available. Whereas the wild-type EGFR catalytic domain monomer is mostly found in an inactive conformation, our results show a clear shift toward the active conformation for all of the mutants. The L858R mutation stabilizes the active conformation at the expense of the inactive conformation and rigidifies the αC-helix. The T790M gatekeeper mutant favors activation by stabilizing a hydrophobic cluster. Finally, T790M with L858R shows a significant positive epistasis effect. This combination not only stabilizes the active conformation, but in nontrivial ways changes the free-energy landscape lowering the transition barriers.

Compound EGFR mutations and response to EGFR tyrosine kinase inhibitors

BACKGROUND

Non-small-cell lung cancers (NSCLCs) containing EGFR mutations are exquisitely sensitive to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). This is the case of the most common EGFR mutations affecting exon 18 (G719X), 19 (inframe deletions), and 21 (L858R and L861Q). However, the frequency of compound (i.e., double or complex) EGFR mutations-where an EGFR TKI sensitizing or other mutation is identified together with a mutation of unknown clinical significance-and their pattern of response/resistance to EGFR TKIs are less well described.

METHODS

We analyzed the EGFR mutation pattern of 79 cases of NSCLC harboring EGFR mutations and compiled the genotype-response data for patients with NSCLCs with compound EGFR mutations treated with EGFR TKIs.

RESULTS

Of the 79 EGFR-mutated tumors identified, 11 (14%) had compound mutations. Most involved the EGFR TKI-sensitizing G719X (n = 3, plus S768I or E709A), L858R (n = 4, plus L747V, R776H, T790M, or A871G), L861Q (n = 1, plus E709V), and delL747_T751 (n = 1, plus R776H). Eight patients received an EGFR TKI: three cases with G719X plus another mutation had partial responses (PRs) to erlotinib; of three cases with L858R plus another mutation, two displayed PRs and one (with EGFR-L858R+A871G) progressive disease (PD) to erlotinib; one NSCLC with EGFR-L861Q+E709A and one with delL747_T751+R776S had PRs to EGFR TKIs.

CONCLUSION

Compound EGFR mutations comprised 14% of all mutations identified during routine sequencing of exons 18-21 of EGFR in our cohort. Most patients with an EGFR TKI-sensitizing mutation (G719X, exon 19 deletion, L858R, and L861Q) in addition to an atypical mutation responded to EGFR TKIs. Reporting of the genotype-response pattern of NSCLCs with EGFR compound and other rare mutations, and the addition of this information to searchable databases, will be helpful to select the appropriate therapy for EGFR-mutated NSCLC.

Detection of epidermal growth factor receptor mutations in formalin fixed paraffin embedded biopsies in Malaysian non-small cell lung cancer patients

Background

Somatic mutations of the epidermal growth factor receptor (EGFR) are reportedly associated with various responses in non-small cell lung cancer (NSCLC) patients receiving the anti-EGFR agents. Detection of the mutation therefore plays an important role in therapeutic decision making. The aim of this study was to detect EGFR mutations in formalin fixed paraffin embedded (FFPE) samples using both Scorpion ARMS and high resolution melt (HRM) assay, and to compare the sensitivity of these methods.

Results

All of the mutations were found in adenocarcinoma, except one that was in squamous cell carcinoma. The mutation rate was 45.7% (221/484). Complex mutations were also observed, wherein 8 tumours carried 2 mutations and 1 tumour carried 3 mutations.

Conclusions

Both methods detected EGFR mutations in FFPE samples. HRM assays gave more EGFR positive results compared to Scorpion ARMS.

Oncogenic potential is related to activating effect of cancer single and double somatic mutations in receptor tyrosine kinases

Aberrant activation of receptor tyrosine kinases (RTKs) is a common feature of many cancer cells. It was previously suggested that the mechanisms of kinase activation in cancer might be linked to transitions between active and inactive states. Here, we estimate the effects of single and double cancer mutations on the stability of active and inactive states of the kinase domains from different RTKs. We show that singleton cancer mutations destabilize active and inactive states; however, inactive states are destabilized more than the active ones, leading to kinase activation. We show that there exists a relationship between the estimate of oncogenic potential of cancer mutation and kinase activation. Namely, more frequent mutations have a higher activating effect, which might allow us to predict the activating effect of the mutations from the mutation spectra. Independent evolutionary analysis of mutation spectra complements this observation and finds the same frequency threshold defining mutation hotspots. We analyze double mutations and report a positive epistasis and additional advantage of doublets with respect to cancer cell fitness. The activation mechanisms of double mutations differ from those of single mutations and double mutation spectrum is found to be dissimilar to the mutation spectrum of singletons.

Targeting the epidermal growth factor receptor in non-small cell lung cancer cells: the effect of combining RNA interference with tyrosine kinase inhibitors or cetuximab

BACKGROUND

The epidermal growth factor receptor (EGFR) is a validated therapeutic target in non-small cell lung cancer (NSCLC). However, current single agent receptor targeting does not achieve a maximal therapeutic effect, and some mutations confer resistance to current available agents. In the current study we have examined, in different NSCLC cell lines, the combined effect of RNA interference targeting the EGFR mRNA, and inactivation of EGFR signaling using different receptor tyrosine kinase inhibitors (TKIs) or a monoclonal antibody cetuximab.

METHODS

NSCLC cells (cell lines HCC827, H292, H358, H1650, and H1975) were transfected with EGFR siRNA and/or treated with the TKIs gefitinib, erlotinib, and afatinib, and/or with the monoclonal antibody cetuximab. The reduction of EGFR mRNA expression was measured by real-time quantitative RT-PCR. The down-regulation of EGFR protein expression was measured by western blot, and the proliferation, viability, caspase3/7 activity, and apoptotic morphology were monitored by spectrophotometry, fluorimetry, and fluorescence microscopy. The combined effect of EGFR siRNA and different drugs was evaluated using a combination index.

RESULTS

EGFR-specific siRNA strongly inhibited EGFR protein expression almost equally in all cell lines and inhibited cell growth and induced cell apoptosis in all NSCLC cell lines studied, albeit with a different magnitude. The effects on growth obtained with siRNA was strikingly different from the effects obtained with TKIs. The effects of siRNA probably correlate with the overall oncogenic significance of the receptor, which is only partly inhibited by the TKIs. The cells which showed weak response to TKIs, such as the H1975 cell line containing the T790M resistance mutation, were found to be responsive to siRNA knockdown of EGFR, as were cell lines with downstream TKI resistance mutations. The cell line HCC827, harboring an exon 19 deletion mutation, was more than 10-fold more sensitive to TKI proliferation inhibition and apoptosis induction than any of the other cell lines. Cetuximab alone had no relevant in vitro activity at concentrations obtainable in the clinic. The addition of EGFR siRNA to either TKIs or cetuximab additively enhanced growth inhibition and induction of apoptosis in all five cell lines, independent of the EGFR mutation status (wild-type or sensitizing mutation or resistant mutation). The strongest biological effect was observed when afatinib was combined with an EGFR-specific siRNA.

CONCLUSIONS

EGFR knockdown by siRNA further decreases the cell growth of lung cancer cells that are treated with TKIs or cetuximab alone, confirming that single agent drug targeting does not achieve a maximal biological effect. The siRNA inhibits EGFR oncogenic activity that bypasses downstream "resistance" mutations such as KRAS and PTEN. The combined treatment of siRNA and EGFR inhibitory agents is additive. The combination of a potent, irreversible kinase inhibitor such as afatinib, with EGFR-specific siRNAs should be further investigated as a new strategy in the treatment of lung cancer and other EGFR dependent cancers, including those with downstream resistance mutations.

Molecular pathology of lung cancer: key to personalized medicine

The majority of lung adenocarcinoma patients with epidermal growth factor receptor- (EGFR) mutated or EML4-ALK rearrangement-positive tumors are sensitive to tyrosine kinase inhibitors. Both primary and acquired resistance in a significant number of those patients to these therapies remains a major clinical problem. The specific molecular mechanisms associated with tyrosine kinase inhibitor resistance are not fully understood. Clinicopathological observations suggest that molecular alterations involving so-called 'driver mutations' could be used as markers that aid in the selection of patients most likely to benefit from targeted therapies. In this review, we summarize recent developments involving the specific molecular mechanisms and markers that have been associated with primary and acquired resistance to EGFR-targeted therapy in lung adenocarcinomas. Understanding these mechanisms may provide new treatment avenues and improve current treatment algorithms.