Rociletinib in EGFR-Mutated Non-Small-Cell Lung Cancer

Resistance of Lung Cancer to EGFR-Specific Kinase Inhibitors: Activation of Bypass Pathways and Endogenous Mutators

Epidermal growth factor receptor (EGFR)-specific tyrosine kinase inhibitors (TKIs) have changed the landscape of lung cancer therapy. For patients who are treated with the new TKIs, the current median survival exceeds 3 years, substantially better than the average 20 month survival rate only a decade ago. Unfortunately, despite initial efficacy, nearly all treated patients evolve drug resistance due to the emergence of either new mutations or rewired signaling pathways that engage other receptor tyrosine kinases (RTKs), such as MET, HER3 and AXL. Apparently, the emergence of mutations is preceded by a phase of epigenetic alterations that finely regulate the cell cycle, bias a mesenchymal phenotype and activate antioxidants. Concomitantly, cells that evade TKI-induced apoptosis (i.e., drug-tolerant persister cells) activate an intrinsic mutagenic program reminiscent of the SOS system deployed when bacteria are exposed to antibiotics. This mammalian system imbalances the purine-to-pyrimidine ratio, inhibits DNA repair and boosts expression of mutation-prone DNA polymerases. Thus, the net outcome of the SOS response is a greater probability to evolve new mutations. Deeper understanding of the persister-to-resister transformation, along with the development of next-generation TKIs, EGFR-specific proteolysis targeting chimeras (PROTACs), as well as bispecific antibodies, will permit delaying the onset of relapses and prolonging survival of patients with EGFR+ lung cancer.

Chromosomal Copy Number Variation Predicts EGFR-TKI Response and Prognosis for Patients with Non-Small Cell Lung Cancer

Purpose

Chromosomal abnormalities represent genomic signatures linked to cancer prognosis and responses to chemotherapy, immunotherapy, and drug resistance. This study aimed to investigate the impact of chromosome copy number variants (CNVs) on the efficacy of tyrosine kinase inhibitors (TKIs) in EGFR-mutated non-small cell lung cancer (NSCLC) patients, as well as its prognostic implications for progression-free survival (PFS) and overall survival (OS) in EGFR wild-type patients.

Methods

A total of 110 patients with advanced NSCLC were enrolled in this study and categorized into EGFR-mutated and wild-type groups. Utilizing next-generation sequencing (NGS) technology, we assessed 24 genes and chromosome CNVs associated with lung cancer pathways in patients' tissue samples.

Results

Within the EGFR-mutated group, patients with a gain in Chr 1p13.3-p13.1 exhibited poor TKI responses, a high relapse rate, and shortened PFS (P = 0.002). Conversely, EGFR-mutated patients with a gain in 14q31.1-q31.3 demonstrated favorable TKI responses and relatively extended PFS (P = 0.005). Among EGFR wild-type patients, the presence of 7q31.1-q31.31 CNV emerged as an independent factor influencing both PFS and OS (P = 0.013, P = 0.004). Notably, patients with a gain in 7q31.1-q31.31 exhibited prolonged PFS and OS. Additionally, independent prognostic significance for OS in EGFR wild-type patients was observed for CNVs in 9q21.31-q22.2 and 11p11.11-q12.1 regions (P = 0.001). Patients with gains in these regions experienced extended OS, while losses were predictive of poorer outcomes.

Conclusion

Our results suggested that chromosomal copy number variation is a practical indicator for predicting the response of EGFR-targeted therapy and prognosis for NSCLC patients.

Recent advances in targeting the "undruggable" proteins: from drug discovery to clinical trials

Undruggable proteins are a class of proteins that are often characterized by large, complex structures or functions that are difficult to interfere with using conventional drug design strategies. Targeting such undruggable targets has been considered also a great opportunity for treatment of human diseases and has attracted substantial efforts in the field of medicine. Therefore, in this review, we focus on the recent development of drug discovery targeting "undruggable" proteins and their application in clinic. To make this review well organized, we discuss the design strategies targeting the undruggable proteins, including covalent regulation, allosteric inhibition, protein-protein/DNA interaction inhibition, targeted proteins regulation, nucleic acid-based approach, immunotherapy and others.

Identification of the structural features of quinazoline derivatives as EGFR inhibitors using 3D-QSAR modeling, molecular docking, molecular dynamics simulations and free energy calculations

Epidermal growth factor receptor (EGFR) is a promising target for the treatment of different types of malignant tumors. Therefore, a combined molecular modeling study was performed on a series of quinazoline derivatives as EGFR inhibitors. The optimum ligand-based CoMFA and CoMSIA models showed reliable and satisfactory predictability (with R²_cv=0.681, R²_ncv=0.844, R²_pred=0.8702 and R²_cv=0.643, R²_ncv=0.874, R²_pred=0.6423). The derived contour maps provide structural features to improve inhibitory activity. Furthermore, the contour maps, molecular docking, and molecular dynamics (MD) simulations have good consistency, illustrating that the derived models are reliable. In addition, MD simulations and binding free energy calculations were also carried out to understand the conformational fluctuations at the binding pocket of the receptor. The results indicate that hydrogen bond, hydrophobic and electrostatic interactions play significant roles on activity and selectivity. Furthermore, amino acids Val31, Lys50, Thr95, Leu149 and Asp160 are considered as essential residues to participate in the ligand-receptor interactions. Overall, this work would offer reliable theoretical basis for future structural modification, design and synthesis of novel EGFR inhibitors with good potency.Communicated by Ramaswamy H. Sarma.

Efficacy and safety of nivolumab for advanced/recurrent non-small-cell lung cancer: an up-to-date meta-analysis of large-scale phase III randomized controlled trials

Aim: To evaluate the efficacy and safety of nivolumab for advanced/recurrent non-small-cell lung cancer (NSCLC). Methods: Electronic databases were searched, and a systematic evaluation was performed. Results: Seven phase III randomized controlled trials and 4705 patients were included. Nivolumab improved overall survival, progression-free survival and overall response rate for advanced/recurrent NSCLC. The efficacy of nivolumab was not correlated with PD-L1 expression levels. Nivolumab combination therapy was superior to nivolumab monotherapy. NSCLC patients may benefit from nivolumab in both first-line and second-line treatment. Nivolumab did not enhance the risk of commonly reported adverse events such as fatigue, hepatotoxicity and gastrointestinal events, but enhanced the risk of immune-related adverse events. Nivolumab-associated pneumonitis is a concern. Conclusion: Nivolumab showed improved efficacy for advanced/recurrent NSCLC but increased the risk of immune-related adverse events.

Efficacy and safety of pembrolizumab for treating advanced non-small-cell lung cancer: a meta-analysis of phase II and III randomized controlled trials

We conducted a meta-analysis to systematically review the efficacy and safety of pembrolizumab for advanced NSCLC. Databases were searched for randomized controlled trials (RCTs) treated with pembrolizumab till July 2021. Seven RCTs and 3988 patients were included. Our analysis suggests that pembrolizumab was more effective at improving PFS (HR, 0.59; 95% CI: 0.43-0.79; p = 0.0005), OS (HR, 0.65; 95% CI: 0.55-0.76; p ＜ 0.00001) and ORR (RR, 1.85; 95% CI: 1.64-2.09; p ＜ 0.00001) than chemotherapy. Patients with higher PD-L1 expression level were tend to have a better PFS, OS and ORR. Combination therapy of pembrolizumab was superior to pembrolizumab monotherapy in enhancing PFS. Pembrolizumab did not increase the frequency of commonly reported adverse events, but the immune-related adverse events (irAEs) occurred more frequently in the pembrolizumab group than those in the chemotherapy group. The pembrolizumab significantly improved the PFS, OS and ORR, simultaneously increasing the irAEs.

Mechanisms and management of 3rd‑generation EGFR‑TKI resistance in advanced non‑small cell lung cancer (Review)

Targeted therapy with epidermal growth factor receptor (EGFR)‑tyrosine kinase inhibitors (TKIs) is a standard modality of the 1st‑line treatments for patients with advanced EGFR‑mutated non‑small cell lung cancer (NSCLC), and substantially improves their prognosis. However, EGFR T790M mutation is the primary mechanism of 1st‑ and 2nd‑generation EGFR‑TKI resistance. Osimertinib is a representative of the 3rd‑generation EGFR‑TKIs that target T790M mutation, and has satisfactory efficacy in the treatment of T790M‑positive NSCLC with disease progression following use of 1st‑ or 2nd‑generation EGFR‑TKIs. Other 3rd‑generation EGFR‑TKIs, such as abivertinib, rociletinib, nazartinib, olmutinib and alflutinib, are also at various stages of development. However, the occurrence of acquired resistance is inevitable, and the mechanisms of 3rd‑generation EGFR‑TKI resistance are complex and incompletely understood. Genomic studies in tissue and liquid biopsies of resistant patients reveal multiple candidate pathways. The present review summarizes the recent findings in mechanisms of resistance to 3rd‑generation EGFR‑TKIs in advanced NSCLC, and provides possible strategies to overcome this resistance. The mechanisms of acquired resistance mainly include an altered EGFR signaling pathway (EGFR tertiary mutations and amplification), activation of aberrant bypassing pathways (hepatocyte growth factor receptor amplification, human epidermal growth factor receptor 2 amplification and aberrant insulin‑like growth factor 1 receptor activation), downstream pathway activation (RAS/RAF/MEK/ERK and PI3K/AKT/mTOR) and histological/phenotypic transformations (SCLC transformation and epithelial‑mesenchymal transition). The combination of targeted therapies is a promising strategy to treat osimertinib‑resistant patients, and multiple clinical studies on novel combined therapies are ongoing.

Serum microRNA-365 suppresses non-small-cell lung cancer metastasis and invasion in patients with bone metastasis of lung cancer

Objective

In the present investigation, we evaluated the effects of microRNA-365 (miR-365) on non-small-cell lung cancer (NSCLC) cell metastasis and invasion in patients with bone metastasis of lung cancer.

Methods

Blood samples from patients with NSCLC and healthy controls and the A549 adenocarcinoma cell line were included in this study. Quantitative real-time PCR and microarray were performed on blood samples. The MTT assay, luciferase reporter assay, Transwell assay, ELISA, and western blot were performed to evaluate expression of associated factors.

Results

Expression of miR-365 was reduced in patients with bone metastasis of NSCLC. Downregulation of miR-365 promoted cell growth, metastasis, and invasion of NSCLC. Upregulation of miR-365 reduced cell growth, metastasis, and invasion of NSCLC. Downregulation of miR-365 induced expression of NKX homeobox-1 (NKX2-1), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase (PI3K), and p-Akt proteins in an in vitro model of NSCLC. Inhibition of NKX2-1 reduced the effects of miR-365 on cell growth, metastasis, and invasion of NSCLC. Activation of EGFR reduced the effects of miR-365 on cell growth, metastasis, and invasion of NSCLC.

Conclusions

The study established that the serum miR-365 suppresses NSCLC cell metastasis and invasion in patients with bone metastasis of lung cancer via EGFR/PI3K through NKX2-1.

Updates in the molecular pathology of non-small cell lung cancer

An understanding of the molecular pathology of non-small cell lung cancer (NSCLC) is important for pathologists as molecular characterization is now required for treatment decisions in advanced stage disease. While assessment for EGFR mutations, ALK and ROS1 fusions, and in some countries BRAF mutations, is now standard practice, other oncogenic mutations are also emerging that may impact routine clinical practice including alterations involving KRAS, NTRK, RET, MET and HER2. In addition, molecular pathology alterations of NSCLC are associated with responses to immune checkpoint therapy and are being increasingly investigated. Finally, specific molecular pathological alterations define some rarer subtypes of NSCLC such as salivary gland tumours, NUT carcinoma and SMARCA4-deficient undifferentiated tumour, and an understanding of the molecular pathology is important for their accurate diagnosis. In this review, the molecular pathology of NSCLC is discussed with a focus on clinically relevant molecular alterations.

Detection of EGFR Mutations in Plasma Cell-Free Tumor DNA of TKI-Treated Advanced-NSCLC Patients by Three Methodologies: Scorpion-ARMS, PNAClamp, and Digital PCR

Analysis of circulating cell-free tumor DNA (cftDNA) has emerged as a specific and sensitive blood-based approach to detect epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) patients. Still, there is some debate on what should be the preferential clinical method for plasma-derived cftDNA analysis. We tested 31 NSCLC patients treated with anti-EGFR tyrosine kinase inhibitors (TKIs), at baseline and serially during therapy, by comparing three methodologies in detecting EGFR mutations (L858R, exon 19 deletion, and T790M) from plasma: scorpions-amplification refractory mutation system (ARMS) methodology by using EGFR Plasma RGQ PCR Kit-QIAGEN, peptide nucleic acid (PNA) clamp and PANA RealTyper integration by using PNAClamp EGFR-PANAGENE, and digital real time PCR by using QuantStudio 3D Digital PCR System-Thermo Fisher Scientific. Specificity was 100% for all three mutations, independently from the platform used. The sensitivity for L858R (42.86%) and T790M (100%) did not change based on the method, while the sensitivity for Del 19 differed markedly (Scorpion-ARMS 45%, PNAClamp 75%, and Digital PCR 85%). The detection rate was also higher (94.23%) as measured by Digital PCR, and when we monitored the evolution of EGFR mutations over time, it evidenced the extreme inter-patient heterogeneity in terms of levels of circulating mutated copies. In our study, Digital PCR showed the best correlation with tissue biopsy and the highest sensitivity to attain the potential clinical utility of monitoring plasma levels of EGFR mutations.

The next tier of EGFR resistance mutations in lung cancer

EGFR mutations account for the majority of druggable targets in lung adenocarcinoma. Over the past decades the optimization of EGFR inhibitors revolutionized the treatment options for patients suffering from this disease. The pace of this development was largely dictated by the inevitable emergence of resistance mutations during drug treatment. As a result, a rapid understanding of the structural and molecular biology of the individual mutations is the key for the development of next-generation inhibitors. Currently, the field faces an unprecedented number of combinations of activating mutations with distinct resistance mutations in parallel to the approval of osimertinib as a first-line drug for EGFR-mutant lung cancer. In this review, we present a survey of the diverse landscape of EGFR resistance mechanisms with a focus on new insights into on-target EGFR kinase mutations. We discuss array of mutations, their structural effects on the EGFR kinase domain as well as the most promising strategies to overcome the individual resistance profiles found in lung cancer patients.

Natural tyrosine kinase inhibitors acting on the epidermal growth factor receptor: Their relevance for cancer therapy

Epidermal growth factor receptor (EGFR), also known as ErbB-1/HER-1, plays a key role in the regulation of the cell proliferation, migration, differentiation, and survival. Since the constitutive activation or overexpression of EGFR is nearly found in various cancers, the applications focused on EGFR are the most widely used in the clinical level, including the therapeutic drugs of targeting EGFR, monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs).Over the past decades, the compounds from natural sources have been a productive source of novel drugs, especially in both discovery and development of anti-tumor drugs by targeting the EGFR pathways as the TKIs. This work presents a review of the compounds from natural sources as potential EGFR-TKIs involved in the regulation of cancer. Moreover, high-throughput drug screening of EGFR-TKIs from the natural compounds has also been summarized.

Development and Validation of an LC-MS/MS Method for Quantitative Determination of EAI045, A Novel EGFR Inhibitor, in Rat Plasma

Background:

EAI045 is the fourth-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI), which can overcome acquired resistance to the third-generation EGFR TKIs and is the first allosteric inhibitor that targets T790M and C797S EGFR mutants.

Methods:

A rapid and sensitive LC-MS/MS method was established and validated for the quantification of EAI045 in rat plasma. Chromatographic separation was carried out at 25°C on a Hypersil GOLD C18 column (50 mm × 2.1 mm, 3 μm) and eluted on a gradient mobile phase of water (containing 0.1% formic acid) and acetonitrile at a flow rate of 0.5 mL/min. The mass spectrometer was operated in the positive ESI mode and selected reaction monitoring mode.

Results:

The assay was validated over a concentration range of 1.0 - 1000 ng/mL for EAI045 with a lower limit of quantification (LLOQ) of 1.0 ng/mL. The intra- and inter-batch accuracy for the EAI045 ranged from 92.25% to 97.18% and 95.94% to 102.69%, and the intra- and inter-batch precision for the EAI045 ranged from 1.41% to 4.57% and 5.18% to 6.37%, respectively. The extraction recovery, matrix effect and stability met all requirements of the guidelines for bioanalytical method validation.

Conclusion:

The rapid and sensitive LC-MS/MS method was successfully applied in a pharmacokinetic study of EAI045 following oral administration (5 mg/kg) to rats.

Discovery of a Potent and Mutant-Selective EGFR Inhibitor that Overcomes T790M-Mediated Resistance in Lung Cancer

BACKGROUND

Despite remarkable activity in epidermal growth factor receptor (EGFR)-mutant lung cancer patients, the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) is limited by the emergence of acquired resistance, which is mostly caused by a secondary T790M mutation. Fortunately, newly developed, mutant-selective EGFR-TKIs against T790M have been proven as an effective therapeutic approach although only osimertinib has received the FDA approval until now.

OBJECTIVE

To determine the in vitro and in vivo efficacy of a new EGFR TKI, OBX1-012 in cells with mutant EGFR.

METHODS

Effects of OBX1-012 on cellular viability and EGFR-related signaling were determined in EGFR-mutant non-small cell lung cancer (NSCLC) cells, including cells harboring T790M mutations. In addition, in vivo efficacy of OBX1-012 was evaluated in xenograft models.

RESULTS

We report the discovery and preclinical assessment of another novel, mutant-selective EGFR-TKI, OBX1-012. Compared with other mutant-selective EGFR-TKIs such as olumitinib and osimertinib, it showed similar potency and selectivity for mutant EGFR. OBX1-012 treatment was highly effective against human EGFR-mutant lung cancer models with or without EGFR T790M, not only in vitro but also in vivo. However, OBX1-012 like other EGFR-TKIs failed to exhibit efficacy for the exon 20 insertion mutation or C797S mutation, which was generated by site-directed mutagenesis and stable transfection of Ba/F3 cells.

CONCLUSIONS

These results identify OBX1-012 as a highly effective, mutant-selective EGFR-TKI for the treatment of T790M-mediated resistance in NSCLC.

Treatment of EGFR T790M-Positive Non-Small Cell Lung Cancer

The treatment of lung cancer has changed dramatically with the development of tyrosine kinase inhibitors (TKIs) that target sensitizing somatic mutations of the epidermal growth factor receptor (EGFR). Despite remarkable initial responses, patients eventually develop progressive disease, with the most common cause of resistance to first-line EGFR TKIs being the acquired T790M mutation. Various third-generation EGFR TKIs have been developed to specifically target this acquired mutation, of which osimertinib is currently the only approved agent. In addition, the eagerly anticipated data from the FLAURA study recently found improved efficacy with increased progression-free survival (PFS) with osimertinib compared to standard of care first-generation EGFR TKIs in the first-line setting. Of note, osimertinib has also demonstrated promising efficacy in patients with known brain metastases. However, as patients invariably develop resistance during treatment with osimertinib, most commonly with the development of triple mutated EGFR (sensitizing mutations/T790M/C797S), which is resistant to all existing EGFR TKIs, efforts are currently ongoing to develop new strategies or novel compounds to specifically target this resistance mechanism.

Current status of clinical proteogenomics in lung cancer

Introduction: Lung cancer is the leading cause of cancer death worldwide. Proteogenomics, a way to integrate genomics, transcriptomics, and proteomics, have emerged as a way to understand molecular causes in cancer tumorigenesis. This understanding will help identify therapeutic targets that are urgently needed to improve individual patient outcomes. Areas covered: To explore underlying molecular mechanisms of lung cancer subtypes, several efforts have used proteogenomic approaches that integrate next generation sequencing (NGS) and mass spectrometry (MS)-based technologies. Expert opinion: A large-scale, MS-based, proteomic analysis, together with both NGS-based genomic data and clinicopathological information, will facilitate establishing extensive databases for lung cancer subtypes that can be used for further proteogenomic analyzes. Proteogenomic strategies will further be understanding of how major driver mutations affect downstream molecular networks, resulting in lung cancer progression and malignancy, and how therapy-resistant cancers resistant are molecularly structured. These strategies require advanced bioinformatics based on a dynamic theory of network systems, rather than statistics, to accurately identify mutant proteins and their affected key networks.

Validation of Cell-Free DNA Collection Tubes for Determination of EGFR Mutation Status in Liquid Biopsy from NSCLC Patients

INTRODUCTION

Precision medicine has revolutionized the understanding and treatment of cancer by identifying subsets of patients who are amenable to specific treatments according to their molecular characteristics, as exemplified by epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC). Although tissue biopsy is the gold standard for determining molecular alterations in tumors, its limitations have prompted the development of new techniques for studying tumor biomarkers in liquid biopsies, such as mutation analysis in cell-free DNA (cfDNA). cfDNA analysis can accurately determine tumor progression and prognosis and more effectively identify appropriate targeted therapies. However, cfDNA is vulnerable, particularly during plasma sample shipping.

OBJECTIVE

We compared the cell- and DNA-stabilizing properties of cell-free DNA blood collection tubes (BCTs) with those of the traditional shipping method (frozen plasma) for EGFR mutation testing using the cobas^® EGFR Mutation Test v2 in a prospective cohort of 49 patients from three different Spanish hospitals.

METHODS

In total, 98 NSCLC samples, two from each patient, were studied; five of the 49 cases were considered invalid by cobas^® with one of the two shipping methods analyzed. After excluding these samples, we analyzed 88 samples from 44 patients. Considering the current methodology (frozen plasma) for sending samples as the gold standard, we evaluated the sensitivity and specificity of cfDNA BCT shipment.

RESULTS

The global agreement between the two methods was 95.4%, with 100% sensitivity and 94.6% specificity for the cfDNA BCTs. cfDNA BCTs had a positive predictive value of 81.8% and negative predictive value of 100%.

CONCLUSION

cfDNA BCTs have the same sensitivity for EGFR mutation analysis in liquid biopsy as the current methodology and very high specificity. They also have some additional advantages in terms of collection and further shipment. Therefore, cfDNA BCTs can be perfectly incorporated into the routine practice for EGFR mutation determination.

FUNDING

Roche Farma S.A., Spain.

PD-L1 expression and EGFR status in advanced non-small-cell lung cancer patients receiving PD-1/PD-L1 inhibitors: a meta-analysis

Aim: To identify whether PD-L1 expression and EGFR status are associated with response to treatment benefit in advanced non-small-cell lung cancer (NSCLC) patients receiving PD-1/PD-L1 inhibitors. Methods: The relevant studies were retrieved and systematic evaluation was conducted. Databases were searched until November 2018. Results: A total of 12 randomized controlled trials (RCTs) with 6932 patients were included. Patients with the higher PD-L1 expression level tend to have a longer progression-free survival (PFS), overall survival (OS) and overall response rate (ORR). PFS and OS were significantly prolonged in all the subgroups of PD-L1 expression levels. For patients with PD-L1 expression levels of ≥1%, overall response rates were significantly prolonged, but there was no difference in patients with PD-L1 expression levels of <1% (hazard ratio [HR]: 1.75; 95% CI: 0.87–3.52; p = 0.12). EGFR wild-type NSCLC patients could benefit from PD-1/PD-L1 inhibitors in PFS (HR: 0.65; 95% CI: 0.45–0.91; p = 0.01) and OS (HR: 0.67; 95% CI: 0.62–0.73; p < 0.00001). Conclusion: This study indicates that PD-L1-positive or EGFR wild-type advanced NSCLC patients might get potential benefit from PD-1/PD-L1 inhibitors.

Targeting EGFR in Lung Cancer: Current Standards and Developments

Lung cancer is the second most common malignant tumor and the leading cause of cancer death. Epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is a distinct subtype of lung cancer comprising approximately 15-40% of non-squamous tumors. The development of first- and second-generation EGFR tyrosine kinase inhibitors (TKIs) has been a significant step forward in the treatment of patients with EGFR-mutant tumors, and over the last few years has been the therapy of choice in the initial management of patients with activating mutations in EGFR, with some differences in efficacy and toxicity profile. Up to 50% of patients treated with first- and second-generation TKIs develop an EGFR exon 20 T790M mutation at the time of progression. In this context, osimertinib has shown a great benefit in terms of progression-free survival (PFS) in the second-line setting, including central nervous system metastasis control. The FLAURA trial, which compared osimertinib to first-generation inhibitors as first-line therapy, showed a clear PFS advantage for osimertinib and a trend towards an increased overall survival (OS) assessed by investigator review. Although T790M mutation is the most common mechanism of resistance to first- and second-generation EGFR TKIs, other EGFR-dependent and -independent mechanisms have been described, such as HER2 and MET amplifications or BRAF and MEK mutations. Some mechanisms of resistance to osimertinib and other third-generation TKIs have also been described. Several fourth-generation TKIs, targeted drug combinations and immunotherapy strategies are under investigation to overcome resistance to EGFR TKIs in order to improve EGFR-mutant NSCLC patient outcomes.

Concurrent Genetic Alterations Predict the Progression to Target Therapy in EGFR-Mutated Advanced NSCLC

INTRODUCTION

EGFR-mutant NSCLC displays diverse outcomes to tyrosine kinase inhibitor (TKI) treatment. Because co-occurring genomic alterations might describe different biological subsets of patients with this cancer, exploring co-occurring genomic alterations that impact patients' outcomes using a comprehensive gene panel is potentially important.

METHODS

This retrospective cohort study was conducted with the panel-sequencing data acquired from January 2014 to May 2017, and clinical outcome data collected until February 2018. This study includes all eligible patients who possess panel-sequencing data before treatment with first-/second-generation EGFR-TKIs (cohort 1) or third-generation EGFR-TKIs following initial EGFR-TKI failure (cohort 2).

RESULTS

Seventy-five patients (mean [SD] age, 58.5 [11.0] years; 68.0% women) were included in cohort 1, and 82 patients (mean [SD] age, 57.3 [9.1] years; 67.1% women) were included in cohort 2. In cohort 1, alterations in TP53 were independently associated with worse progression-free survival (PFS) (hazard ratio [HR]: 2.02; 95% confidence interval [CI]: 1.04-3.93; p = 0.038) in multivariate analysis. In cohort 2, TP53 mutation was associated with significantly worse PFS (8.9 versus 12.8 months; p = 0.029). RB1 mutation was significantly associated with worse (median PFS, 1.9 versus 11.7 months; p < 0.001). PTEN mutation was associated with significantly worse PFS (2.6 versus 10.3 months; p = 0.001). MDM2 amplification was associated with worse PFS (6.6 versus 10.4 months; p = 0.025). In cohort 2, multivariate analysis revealed that alterations in TP53 (HR: 2.23; 95% CI: 1.16-4.29; p = 0.017), RB1 (HR: 5.62; 95% CI: 1.96-16.13; p = 0.001), PTEN (HR: 5.84; 95% CI: 1.56-21.85; p = 0.009), and MDM2 (HR: 2.46; 95% CI: 1.02-5.94; p = 0.046) were independently associated with worse PFS.

CONCLUSIONS

Co-occurring genomic alterations detected by panel sequencing are associated with the clinical outcomes of EGFR-TKI treatment in NSCLC.

Increased Synthesis of MCL-1 Protein Underlies Initial Survival of EGFR-Mutant Lung Cancer to EGFR Inhibitors and Provides a Novel Drug Target

Purpose: EGFR inhibitors (EGFRi) are effective against EGFR-mutant lung cancers. The efficacy of these drugs, however, is mitigated by the outgrowth of resistant cells, most often driven by a secondary acquired mutation in EGFR, T790M We recently demonstrated that T790M can arise de novo during treatment; it follows that one potential therapeutic strategy to thwart resistance would be identifying and eliminating these cells [referred to as drug-tolerant cells (DTC)] prior to acquiring secondary mutations like T790M Experimental Design: We have developed DTCs to EGFRi in EGFR-mutant lung cancer cell lines. Subsequent analyses of DTCs included RNA-seq, high-content microscopy, and protein translational assays. Based on these results, we tested the ability of MCL-1 BH3 mimetics to combine with EGFR inhibitors to eliminate DTCs and shrink EGFR-mutant lung cancer tumors in vivo Results: We demonstrate surviving EGFR-mutant lung cancer cells upregulate the antiapoptotic protein MCL-1 in response to short-term EGFRi treatment. Mechanistically, DTCs undergo a protein biosynthesis enrichment resulting in increased mTORC1-mediated mRNA translation of MCL-1, revealing a novel mechanism in which lung cancer cells adapt to short-term pressures of apoptosis-inducing kinase inhibitors. Moreover, MCL-1 is a key molecule governing the emergence of early EGFR-mutant DTCs to EGFRi, and we demonstrate it can be effectively cotargeted with clinically emerging MCL-1 inhibitors both in vitro and in vivo Conclusions: Altogether, these data reveal that this novel therapeutic combination may delay the acquisition of secondary mutations, therefore prolonging therapy efficacy. Clin Cancer Res; 24(22); 5658-72. ©2018 AACR.

Immunotherapy and targeted therapy in brain metastases: emerging options in precision medicine

Brain metastases (BM) continue to represent an unmet clinical need in oncology. Immunotherapy and targeted therapy hold great promise in the treatment of BM. Emerging data are confirming the activity of these agents in patients with BM. Genomic studies have confirmed that clinically actionable mutations are present in BM and they can be used in clinical studies to link targeted therapies with their genetic targets. Furthermore, as molecular signatures associated with sensitivity and resistance to immunotherapies are developed, we will better be able to select BM patients who will most benefit from these therapies. Understanding the genetic and immune evolution within BM should drive the next generation of immunotherapy and target therapy, as well as increase the accuracy of the selection process for these therapies.

Improved EGFR mutation detection using combined exosomal RNA and circulating tumor DNA in NSCLC patient plasma

Background

A major limitation of circulating tumor DNA (ctDNA) for somatic mutation detection has been the low level of ctDNA found in a subset of cancer patients. We investigated whether using a combined isolation of exosomal RNA (exoRNA) and cell-free DNA (cfDNA) could improve blood-based liquid biopsy for EGFR mutation detection in non-small-cell lung cancer (NSCLC) patients.

Patients and methods

Matched pretreatment tumor and plasma were collected from 84 patients enrolled in TIGER-X (NCT01526928), a phase 1/2 study of rociletinib in mutant EGFR NSCLC patients. The combined isolated exoRNA and cfDNA (exoNA) was analyzed blinded for mutations using a targeted next-generation sequencing panel (EXO1000) and compared with existing data from the same samples using analysis of ctDNA by BEAMing.

Results

For exoNA, the sensitivity was 98% for detection of activating EGFR mutations and 90% for EGFR T790M. The corresponding sensitivities for ctDNA by BEAMing were 82% for activating mutations and 84% for T790M. In a subgroup of patients with intrathoracic metastatic disease (M0/M1a; n = 21), the sensitivity increased from 26% to 74% for activating mutations (P = 0.003) and from 19% to 31% for T790M (P = 0.5) when using exoNA for detection.

Conclusions

Combining exoRNA and ctDNA increased the sensitivity for EGFR mutation detection in plasma, with the largest improvement seen in the subgroup of M0/M1a disease patients known to have low levels of ctDNA and poses challenges for mutation detection on ctDNA alone.

Clinical Trials

NCT01526928.

Glucocorticoids may compromise the effect of gefitinib in non-small cell lung cancer

The epidermal growth factor receptor (EGFR)-targeting tyrosine kinase inhibitors (TKIs) have shown remarkable benefits in non-small cell lung cancer (NSCLC) patients with drug-sensitive mutations in the EGFR gene. Responsive patients are usually continuously prescribed with TKIs until disease progression. Glucocorticoids (GCs) are potent homeostasis maintaining drugs and are frequently used in cancer patients to alleviate discomforts caused by anti-cancer therapies. Several previous studies reported that concomitant use of GCs may compromise the efficacy of chemo-therapeutics in patients with solid tumors. Little is known in the concomitant use of target therapy with GCs in treating NSCLC. In this study, we hypothesized that concomitant use of GCs in EGFR-TKI therapy may be detrimental and addressed this issue using cell cultures and xenograft studies followed by a retrospective population study based on data from the Taiwan national health insurance system. In cell cultures and xenograft studies, GCs were shown to unequally compromise the anti-cancer efficacy of TKIs in both PC9 and NCI-H1975 NSCLC cells models. In the retrospective population study, patients with similar disease status that were co-medicated with GCs had a significantly higher risk of disease progression.

EGFR-TKIs resistance via EGFR-independent signaling pathways

Tyrosine kinase inhibitors (TKIs)-treatments bring significant benefit for patients harboring epidermal growth factor receptor (EGFR) mutations, especially for those with lung cancer. Unfortunately, the majority of these patients ultimately develop to the acquired resistance after a period of treatment. Two central mechanisms are involved in the resistant process: EGFR secondary mutations and bypass signaling activations. In an EGFR-dependent manner, acquired mutations, such as T790 M, interferes the interaction between TKIs and the kinase domain of EGFR. While in an EGFR-independent manner, dysregulation of other receptor tyrosine kinases (RTKs) or abnormal activation of downstream compounds both have compensatory functions against the inhibition of EGFR through triggering phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling axes. Nowadays, many clinical trials aiming to overcome and prevent TKIs resistance in various cancers are ongoing or completed. EGFR-TKIs in accompany with the targeted agents for resistance-related factors afford a promising first-line strategy to further clinical application.

Combination Strategies Using EGFR-TKi in NSCLC Therapy: Learning from the Gap between Pre-Clinical Results and Clinical Outcomes

Although epidermal growth factor receptor (EGFR) inhibitors have been used to treat non-small cell lung cancer (NSCLC) for decades with great success in patients with EGFR mutations, acquired resistance inevitably occurs after long-term exposure. More recently, combination therapy has emerged as a promising strategy to overcome this issue. Several experiments have been carried out to evaluate the synergism of combination therapy both in vitro and in vivo. Additionally, many clinical studies have been carried out to investigate the feasibility of treatment with EGFR-tyrosine kinase inhibitors (TKi) combined with other NSCLC treatments, including radiotherapy, cytotoxic chemotherapies, targeted therapies, and emerging immunotherapies. However, a significant gap still exists when applying pre-clinical results to clinical scenarios, which hinders the development and use of these strategies. This article is a literature review analysing the rationalities and controversies in the transition from pre-clinical investigation to clinical practice associated with various combination strategies. It also highlights clues and challenges regarding future combination therapeutic options in NSCLC treatment.

An oligoclonal antibody durably overcomes resistance of lung cancer to third-generation EGFR inhibitors

Epidermal growth factor receptor (EGFR) mutations identify patients with lung cancer who derive benefit from kinase inhibitors. However, most patients eventually develop resistance, primarily due to the T790M second-site mutation. Irreversible inhibitors (e.g., osimertinib/AZD9291) inhibit T790M-EGFR, but several mechanisms, including a third-site mutation, C797S, confer renewed resistance. We previously reported that a triple mixture of monoclonal antibodies, 3×mAbs, simultaneously targeting EGFR, HER2, and HER3, inhibits T790M-expressing tumors. We now report that 3×mAbs, including a triplet containing cetuximab and trastuzumab, inhibits C797S-expressing tumors. Unlike osimertinib, which induces apoptosis, 3×mAbs promotes degradation of the three receptors and induces cellular senescence. Consistent with distinct mechanisms, treatments combining 3×mAbs plus sub-inhibitory doses of osimertinib synergistically and persistently eliminated tumors. Thus, oligoclonal antibodies, either alone or in combination with kinase inhibitors, might preempt repeated cycles of treatment and rapid emergence of resistance.

AZD9291 Increases Sensitivity to Radiation in PC-9-IR Cells by Delaying DNA Damage Repair after Irradiation and Inducing Apoptosis

AZD9291 is a novel, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), which is administered orally. It has been proven effective in non-small cell lung cancer (NSCLC) patients, with both EGFR-sensitizing and EGFR T790M mutations in preclinical models. However, the potential therapeutic effects of AZD9291 combined with other modalities, including ionizing radiation, are not well understood. The presence of AZD9291 significantly increases the cell-killing effects of radiation in PC-9-IR cells with a secondary EGFR mutation (T790M), which was developed from NSCLC PC-9 cells (human lung adenocarcinoma cell with EGFR 19 exon 15 bp deletion) after chronic exposure to increasing doses of gefitinib, and in H1975 cells (human lung adenocarcinoma cell with EGFR exon 20 T790M mutation de novo), but not in PC-9 cells or in H460 cells (human lung adenocarcinoma cell with wild-type EGFR). In PC-9-IR cells, AZD9291 remarkably decreases phosphorylation levels of EGFR, extracellular regulated protein kinase (ERK), and protein kinase B (AKT). AZD9291 increases sensitivity to radiation in PC-9-IR cells by delaying deoxyribonucleic acid (DNA) damage repair after irradiation and inducing apoptosis, and enhances tumor growth inhibition when combined with radiation in PC-9-IR xenografts. Our findings suggest a potential therapeutic effect of AZD9291 as a radiation sensitizer in lung cancer cells with an acquired EGFR T790M mutation, providing a rationale for a clinical trial using the combination of AZD9291 and radiation in NSCLCs harboring acquired T790M mutation.

Comparison of cross-platform technologies for EGFR T790M testing in patients with non-small cell lung cancer

Somatic mutations in the gene encoding epidermal growth factor receptor (EGFR) play an important role in determining targeted treatment modalities in non-small cell lung cancer (NSCLC). The EGFR T790M mutation emerges in approximately 50% of cases who acquire resistance to tyrosine kinase inhibitors. Detecting EGFR T790M mutation in tumor tissue is challenging due to heterogeneity of the tumor, low abundance of the mutation and difficulty for re-biopsy in patients with advanced disease. Alternatively, circulating tumor DNA (ctDNA) has been proposed as a non-invasive method for mutational analysis. The presence of EGFR mutations in ctDNA predicts response to the EGFR TKIs in the first-line setting. Molecular testing is now considered a standard care for NSCLC. The advent of standard commercially available kits and targeted mutational analysis has revolutionized the accuracy of mutation detection platforms for detection of EGFR mutations. Our review provides an overview of various commonly used platforms for detecting EGFR T790M mutation in tumor tissue and plasma.

Liquid biopsy in non-small cell lung cancer: a key role in the future of personalized medicine?

INTRODUCTION

Liquid biopsies, especially the analysis of circulating tumor DNA (ctDNA), as a novel and non-invasive method for the diagnosis and monitoring of non-small cell lung cancer (NSCLC) have already been implemented in clinical settings. The majority of ctDNA is released from apoptotic or necrotic tumor cells, thus reflecting the genetic profile of a tumor. Numerous studies have reported a high concordance in mutation profiles derived from liquid biopsy and tissue biopsy, especially in driver genes. Liquid biopsy could overcome the clonal heterogeneity of tumour biopsy, as it provides a single snapshot of a tumour tissue. Moreover, non-invasiveness is the biggest advantage for liquid biopsy, and the procedure can be repeatedly performed during the treatment for the purpose of monitoring. Therefore, ctDNA could act as a potential complementary method for tissue biopsies in diagnosis, prognostic, treatment response and resistance. Areas covered: This review summarizes the recent advancements in liquid biopsy with a focus on NSCLC, including its applications and technologies associated with assessing ctDNA. The authors conclude the review by discussing the challenges associated with liquid biopsy. Expert commentary: The analysis of ctDNA represents a promising method for liquid biopsy, which will be a novel and potentially complementary method in diagnosis, treatment and prognostic in NSCLC at all stages.

Histological evolution from primary lung adenocarcinoma harboring EGFR mutation to high-grade neuroendocrine carcinoma

Background

Although patients with EGFR mutated lung adenocarcinoma benefit greatly from tyrosine kinase inhibitors (TKIs), they inevitably develop acquired resistance after an average of 10–14 months of continuous treatment.

Methods

We retrospectively analyzed the clinical and histopathological data of eight patients with primary lung adenocarcinoma harboring EGFR mutations that transformed into high‐grade neuroendocrine carcinoma after TKI therapy. Morphology scanning for neuroendocrine differentiation and immunohistochemistry for neuroendocrine markers CD56, chromogranin, and synaptophysin were performed on primary adenocarcinoma tissues and repeated biopsies. Mutations of EGFR exons 19–21 were reexamined using the amplification refractory mutation system.

Results

The carcinoma in seven patients transformed to small cell lung carcinoma; two of these patients enrolled in theAZD9291 study after acquiring a T790M missense mutation. The carcinoma in one patient transformed to large cell neuroendocrine carcinoma. None of the eight primary tumors exhibited neuroendocrine morphologic features and only one surgical specimen displayed a weak stain for neuroendocrine marker synaptophysin. Drug resistant high‐grade neuroendocrine carcinomas retained their initial activating EGFR mutations.

Conclusions

Lung adenocarcinoma in eight patients transformed into high‐grade neuroendocrine carcinoma and retained the original activating EGFR mutations after targeted therapy by TKIs. Furthermore, the prognosis of the transformed carcinoma was worse than the original primary genetic and morphologic type.

Phase I study of the combination of quinacrine and erlotinib in patients with locally advanced or metastatic non small cell lung cancer

Introduction Preclinical data suggest quinacrine acts as an inhibitor of FACT (facilitates chromatin transcription) complex, which may play a role in TKI (tyrosine kinase inhibitor) resistance. The aim of this Phase I study was to study the safety and assess the maximum tolerated dose of quinacrine in combination with erlotinib in non small cell lung cancer (NSCLC). Methods This was a phase I study with standard 3 + 3 dose escalation design with the primary aim of determining the maximum tolerated dose. Two of 3 patients enrolled at dose level 1 experienced dose limiting toxicity (DLT). The next 6 patients were enrolled at dose level - 1 and none of these 6 patients experienced DLT. The dose of 50 mg of quinacrine every other day with 150 mg of erlotinib was established as the maximum tolerated and the recommended phase II dose. One of 3 patients treated at dose level 1 had stable disease. One of 6 patients treated at dose level - 1 had partial response for 6 months, the rest had progressive disease at the time of first assessment. Conclusion Combination of quinacrine and erlotinib was well tolerated but showed limited efficacy in advanced NSCLC.

A Phase I, Dose Escalation Study of Oral ASP8273 in Patients with Non-small Cell Lung Cancers with Epidermal Growth Factor Receptor Mutations

Purpose: Acquired EGFR T790M mutations are the most frequently identified resistance mechanism to EGFR tyrosine kinase inhibitors (TKI) in patients with EGFR-mutant lung cancers. ASP8273 is a third-generation EGFR TKI with antitumor activity in preclinical models of EGFR-mutant lung cancer that targets mutant EGFR, including EGFR T790M.Experimental Design: In this multicohort, phase I study (NCT02113813), escalating doses of ASP8273 (25-500 mg) were administered once daily to non-small cell lung cancer (NSCLC) patients with disease progression after prior treatment with an EGFR TKI. EGFR T790M was required for all cohorts, except the dose escalation cohort. Primary endpoints were safety/tolerability; secondary endpoints were determination of the RP2D, pharmacokinetic profile, and preliminary antitumor activity of ASP8273. Evaluation of the use of EGFR mutations in circulating free DNA (cfDNA) as a biomarker of ASP8273 treatment effects was an exploratory endpoint.Results: A total of 110 patients were treated with ASP8273 across dose escalation (n = 36), response-expansion (n = 36), RP2D (300 mg; n = 19) and food-effect (n = 19) cohorts. The most common treatment-emergent adverse events included diarrhea, nausea, fatigue, constipation, vomiting, and hyponatremia. Across all doses, in patients with EGFR T790M, the response rate was 30.7% (n = 27/88; 95% CI, 19.5%-44.5%), and median progression-free survival was 6.8 months (95% CI, 5.5-10.1 months). EGFR mutations in cfDNA, both the activating mutation and EGFR T790M, became undetectable in most patients in the setting of clinical response and reemerged upon disease progression.Conclusions: ASP8273 was well tolerated and promoted antitumor activity in patients with EGFR-mutant lung cancer with disease progression on prior EGFR TKI therapy. Clin Cancer Res; 23(24); 7467-73. ©2017 AACR.

Addressing the challenges of applying precision oncology

Precision oncology is described as the matching of the most accurate and effective treatments with the individual cancer patient. Identification of important gene mutations, such as BRCA1/2 that drive carcinogenesis, helped pave the way for precision diagnosis in cancer. Oncoproteins and their signaling pathways have been extensively studied, leading to the development of target-based precision therapies against several types of cancers. Although many challenges exist that could hinder the success of precision oncology, cutting-edge tools for precision diagnosis and precision therapy will assist in overcoming many of these difficulties. Based on the continued rapid progression of genomic analysis, drug development, and clinical trial design, precision oncology will ultimately become the standard of care in cancer therapeutics.

Prevalence of Epidermal Growth Factor Receptor Mutations in Patients with Non-Small Cell Lung Cancer in Turkish Population

Aims:

Epidermal growth factor receptor mutation analysis in non-small cell lung cancer is important for selecting patients who will receive treatment with tyrosine kinase inhibitors. In this study, we aimed to investigate the prevalence of epidermal growth factor receptor mutations and mutation patterns in the Turkish population.

Methods:

We retrospectively reviewed molecular pathology reports of 959 cases with lung cancer analysed for epidermal growth factor receptor mutations. We analysed all four epidermal growth factor receptorexon mutations using a real-time polymerase chain reaction platform.

Results:

In this study, the epidermal growth factor receptor mutation rate in the Turkish population was 16.7% (160 of 959). The epidermal growth factor receptor mutation frequency was significantly higher in women (37.1%, n=96) than in men (9.1%, n=64) (p<0.001). In addition, the epidermal growth factor receptor mutation rate was higher in the adenocarcinoma histologic type (p<0.001). Patients with mutations were older than those without mutations (p=0.003). The most frequent mutations were exon 19 deletions (48.8%, 78/160) and exon 21 L858R point mutations (38.1.1%, 61/160). We also detected compound mutation patterns in three cases (1.9%).

Conclusion:

The prevalence of epidermal growth factor receptor mutations in the Turkish population was slightly higher than that in the Caucasian population and lower than that in the East Asian population. The results of this study may provide guidance in personalized therapy of non-small cell lung cancer in the Turkish population.

Polyphyllin I Overcomes EMT-Associated Resistance to Erlotinib in Lung Cancer Cells via IL-6/STAT3 Pathway Inhibition

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is the most important limiting factor for treatment efficiency in EGFR-mutant non-small cell lung cancer (NSCLC). Much work has linked the epithelial-mesenchymal transition (EMT) to the emergence of drug resistance, consequently, ongoing research has been focused on exploring the therapeutic options to reverse EMT for delaying or preventing drug resistance. Polyphyllin I (PPI) is a natural compound isolated from Paris polyphylla rhizomes and displayed anti-cancer properties. In the current work, we aimed to testify whether PPI could reverse EMT and overcome acquired EGFR-TKI resistance. We exposed HCC827 lung adenocarcinoma cells to erlotinib which resulted in acquired resistance with strong features of EMT. PPI effectively restored drug sensitivity of cells that obtained acquired resistance. PPI reversed EMT and decreased interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling pathway activation in erlotinib-resistant cells. Moreover, addition of IL-6 partially abolished the sensitization response of PPI. Furthermore, co-treatment of erlotinib and PPI completed abrogation of tumor growth in xenografts, which was associated with EMT reversal. In conclusion, PPI serves as a novel solution to conquer the EGFR-TKI resistance of NSCLC via reversing EMT by modulating IL-6/STAT3 signaling pathway. Combined PPI and erlotinib treatment provides a promising future for lung cancer patients to strengthen drug response and prolong survival.

Plasma epidermal growth factor receptor mutation testing with a chip-based digital PCR system in patients with advanced non-small cell lung cancer

OBJECTIVES

Epidermal growth factor receptor (EGFR) mutation testing is a companion diagnostic to determine eligibility for treatment with EGFR tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC). Recently, plasma-based EGFR testing by digital polymerase chain reaction (dPCR), which enables accurate quantification of target DNA, has shown promise as a minimally invasive diagnostic. Here, we aimed to evaluate the accuracy of a plasma-based EGFR mutation test developed using chip-based dPCR-based detection of 3 EGFR mutations (exon 19 deletions, L858R in exon 21, and T790M in exon 20).

MATERIALS AND METHODS

Forty-nine patients with NSCLC harboring EGFR-activating mutations were enrolled, and circulating free DNAs (cfDNAs) were extracted from the plasma of 21 and 28 patients before treatment and after progression following EGFR-TKI treatment, respectively.

RESULTS

Using reference genomic DNA containing each mutation, the detection limit of each assay was determined to be 0.1%. The sensitivity and specificity of detecting exon 19 deletions and L858R mutations, calculated by comparing the mutation status in the corresponding tumors, were 70.6% and 93.3%, and 66.7% and 100%, respectively, showing similar results compared with previous studies. T790M was detected in 43% of 28 cfDNAs after progression with EGFR-TKI treatment, but in no cfDNAs before the start of the treatment.

CONCLUSION

This chip-based dPCR assay can facilitate detection of EGFR mutations in cfDNA as a minimally invasive method in clinical settings.

Lung cancer: current therapies and new targeted treatments

Lung cancer is the most frequent cause of cancer-related deaths worldwide. Every year, 1·8 million people are diagnosed with lung cancer, and 1·6 million people die as a result of the disease. 5-year survival rates vary from 4-17% depending on stage and regional differences. In this Seminar, we discuss existing treatment for patients with lung cancer and the promise of precision medicine, with special emphasis on new targeted therapies. Some subgroups, eg-patients with poor performance status and elderly patients-are not specifically addressed, because these groups require special treatment considerations and no frameworks have been established in terms of new targeted therapies. We discuss prevention and early detection of lung cancer with an emphasis on lung cancer screening. Although we acknowledge the importance of smoking prevention and cessation, this is a large topic beyond the scope of this Seminar.

Effect of dasatinib on EMT-mediated-mechanism of resistance against EGFR inhibitors in lung cancer cells

OBJECTIVE

The epithelial to mesenchymal transition (EMT) is associated with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in certain non-small cell lung cancers that harbor EGFR mutations. Because no currently available drugs specifically kill cancer cells via EMT, novel treatment strategies that overcome or prevent EMT are needed. A recent report suggested that dasatinib (an ABL/Src kinase inhibitor) inhibits EMT induced by transforming growth factor (TGF)-beta in lung cancer cells (Wilson et al., 2014). In this study, we analyzed effects of dasatinib on the resistance mechanism in HCC4006 cells, which tend to acquire resistance to EGFR-TKIs via EMT.

MATERIALS AND METHODS

Sensitivity to dasatinib in HCC4006 and HCC4006 erlotinib-resistant (ER) cells with an EMT phenotype was analyzed. HCC4006 cells acquired resistance against the combination of erlotinib and dasatinib (HCC4006EDR) following chronic treatment with these drugs. The expression of EMT markers and the resistance mechanism were analyzed.

RESULTS

Short-term or long-term treatment with dasatinib did not reverse EMT in HCC4006ER. In contrast, HCC4006EDR cells maintained an epithelial phenotype, and the mechanism underlying resistance to erlotinib plus dasatinib combination therapy was attributable to a T790M secondary mutation. HCC4006EDR cells, but not HCC4006ER cells, were highly sensitive to a third-generation EGFR-TKI, osimertinib.

CONCLUSIONS

Although dasatinib monotherapy did not reverse EMT in HCC4006ER cells, preemptive combination treatment with erlotinib and dasatinib prevented the emergence of acquired resistance via EMT, and led to the emergence of T790M. Our results indicate that preemptive combination therapy may be a promising strategy to prevent the emergence of EMT-mediated resistance.

Histone Deacetylase 3 Inhibition Overcomes BIM Deletion Polymorphism-Mediated Osimertinib Resistance in EGFR-Mutant Lung Cancer

Purpose: The BIM deletion polymorphism is associated with apoptosis resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI), such as gefitinib and erlotinib, in non-small cell lung cancer (NSCLC) harboring EGFR mutations. Here, we investigated whether the BIM deletion polymorphism contributes to resistance against osimertinib, a third-generation EGFR-TKI. In addition, we determined the efficacy of a histone deacetylase (HDAC) inhibitor, vorinostat, against this form of resistance and elucidated the underlying mechanism.Experimental Design: We used EGFR-mutated NSCLC cell lines, which were either heterozygous or homozygous for the BIM deletion polymorphism, to evaluate the effect of osimertinib in vitro and in vivo Protein expression was examined by Western blotting. Alternative splicing of BIM mRNA was analyzed by RT-PCR.Results:EGFR-mutated NSCLC cell lines with the BIM deletion polymorphism exhibited apoptosis resistance to osimertinib in a polymorphism dosage-dependent manner, and this resistance was overcome by combined use with vorinostat. Experiments with homozygous BIM deletion-positive cells revealed that vorinostat affected the alternative splicing of BIM mRNA in the deletion allele, increased the expression of active BIM protein, and thereby induced apoptosis in osimertinib-treated cells. These effects were mediated predominantly by HDAC3 inhibition. In xenograft models, combined use of vorinostat with osimertinib could regress tumors in EGFR-mutated NSCLC cells homozygous for the BIM deletion polymorphism. Moreover, this combination could induce apoptosis even when tumor cells acquired EGFR-T790M mutations.Conclusions: These findings indicate the importance of developing HDAC3-selective inhibitors, and their combined use with osimertinib, for treating EGFR-mutated lung cancers carrying the BIM deletion polymorphism. Clin Cancer Res; 23(12); 3139-49. ©2016 AACR.

The End of Nihilism: Systemic Therapy of Advanced Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer death in the United States and many other parts of the world. Non-small cell lung cancer (NSCLC) comprises 85-90% of lung cancers. Historically, the expected survival of patients with advanced disease has been estimated in months. In recent years, however, lung cancer has come to be seen as a treatable disease with multiple therapeutic options. Enormous advances in the understanding of its pathways and mechanisms have enabled personalized therapy in NSCLC. The evolving approach to therapy focuses on genomic profiling of the tumors to find molecular targets and develop specific agents for individualized therapy. In addition, maintenance therapy has emerged as a valid approach, and the choice of chemotherapy now varies by histology. Most recently, immunotherapy with checkpoint inhibitors has shown promising results, with impressive durations of response and a tolerable toxicity profile. Together, these discoveries have improved overall survival substantially in patient populations that have access to these advancements. We review the clinical data surrounding these impressive improvements.

Detection of Therapeutically Targetable Driver and Resistance Mutations in Lung Cancer Patients by Next-Generation Sequencing of Cell-Free Circulating Tumor DNA

PURPOSE

The expanding number of targeted therapeutics for non-small cell lung cancer (NSCLC) necessitates real-time tumor genotyping, yet tissue biopsies are difficult to perform serially and often yield inadequate DNA for next-generation sequencing (NGS). We evaluated the feasibility of using cell-free circulating tumor DNA (ctDNA) NGS as a complement or alternative to tissue NGS.

EXPERIMENTAL DESIGN

A total of 112 plasma samples obtained from a consecutive study of 102 prospectively enrolled patients with advanced NSCLC were subjected to ultra-deep sequencing of up to 70 genes and matched with tissue samples, when possible.

RESULTS

We detected 275 alterations in 45 genes, and at least one alteration in the ctDNA for 86 of 102 patients (84%), with EGFR variants being most common. ctDNA NGS detected 50 driver and 12 resistance mutations, and mutations in 22 additional genes for which experimental therapies, including clinical trials, are available. Although ctDNA NGS was completed for 102 consecutive patients, tissue sequencing was only successful for 50 patients (49%). Actionable EGFR mutations were detected in 24 tissue and 19 ctDNA samples, yielding concordance of 79%, with a shorter time interval between tissue and blood collection associated with increased concordance (P = 0.038). ctDNA sequencing identified eight patients harboring a resistance mutation who developed progressive disease while on targeted therapy, and for whom tissue sequencing was not possible.

CONCLUSIONS

Therapeutically targetable driver and resistance mutations can be detected by ctDNA NGS, even when tissue is unavailable, thus allowing more accurate diagnosis, improved patient management, and serial sampling to monitor disease progression and clonal evolution. Clin Cancer Res; 22(23); 5772-82. ©2016 AACR.