Tumor heterogeneity and resistance to EGFR-targeted therapy in advanced nonsmall cell lung cancer: challenges and perspectives

Comprehensive liquid biopsy analysis for monitoring NSCLC patients under second-line osimertinib treatment

Background

The heterogeneous and complex genetic landscape of NSCLC impacts the clinical outcomes of patients who will eventually develop resistance to osimertinib. Liquid biopsy (LB) analysis as a minimally invasive approach is a key step to efficiently identify resistance mechanisms and adjust to proper subsequent treatments.

Materials and methods

In the present study, we combined plasma-cfDNA and CTC analysis from 30 NSCLC patients in samples collected before treatment and at the progression of disease (PD). We detected molecular alterations at the DNA mutation (EGFR, PIK3CA, KRAS G12C, BRAF V600E), DNA methylation (RASSF1A, BRMS1, FOXA1, SLFN1, SHISA3, RARβ,, WIF-1, RASSF10 and APC), gene expression (CK-19, CK-18, CK-8, AXL, TWIST-1, PD-L1, PIM-1, Vimentin, ALDH-1, and B2M) and chromosomal level (HER2 and MET amplification) as possible resistance mechanisms and druggable targets. We also studied the expression of PD-L1 in single CTCs using immunofluorescence.

Results

In some cases, T790M resistance EGFR mutation was detected at baseline in CTCs but not in the corresponding plasma cfDNA. PIK3CA mutations were detected only in plasma-cfDNA but not in corresponding CTCs. KRAS G12C and BRAF V600E mutations were not detected in the samples analyzed. MET amplification was detected in the CTCs of two patients before treatment whereas HER2 amplification was detected in the CTCs of three patients at baseline and in one patient at PD. DNA methylation analysis revealed low concordance between CTCs and cfDNA, indicating the complementary information obtained through parallel LB analysis. Results from gene expression analysis indicated high rates of vimentin-positive CTCs detected at all time points during osimertinib. Moreover, there was an increased number of NSCLC patients at PD harboring CTCs positive in PD-L1. AXL and PIM-1 expression detected in CTCs during treatment suggesting new possible therapeutic strategies.

Discussion

Our results reveal that comprehensive liquid biopsy analysis can efficiently represent the heterogeneous molecular landscape and provide prominent information on subsequent treatments for NSCLC patients at PD since druggable molecular alterations were detected in CTCs.

EGFR-T790M Mutation-Derived Interactome Rerouted EGFR Translocation Contributing to Gefitinib Resistance in Non-Small Cell Lung Cancer

Secondary mutation, T790M, conferring tyrosine kinase inhibitors (TKIs) resistance beyond oncogenic epidermal growth factor receptor (EGFR) mutations presents a challenging unmet need. Although TKI-resistant mechanisms are intensively investigated, the underlying responses of cancer cells adapting drug perturbation are largely unknown. To illuminate the molecular basis linking acquired mutation to TKI resistance, affinity purification coupled mass spectrometry was adopted to dissect EGFR interactome in TKI-sensitive and TKI-resistant non-small cell lung cancer cells. The analysis revealed TKI-resistant EGFR-mutant interactome allocated in diverse subcellular distribution and enriched in endocytic trafficking, in which gefitinib intervention activated autophagy-mediated EGFR degradation and thus autophagy inhibition elevated gefitinib susceptibility. Alternatively, gefitinib prompted TKI-sensitive EGFR translocating toward cell periphery through Rab7 ubiquitination which may favor efficacy to TKIs suppression. This study revealed that T790M mutation rewired EGFR interactome that guided EGFR to autophagy-mediated degradation to escape treatment, suggesting that combination therapy with TKI and autophagy inhibitor may overcome acquired resistance in non-small cell lung cancer.

Single-center study on clinicopathological and typical molecular pathologic features of metastatic brain tumor

BACKGROUND

The metastatic brain tumor is the most common brain tumor. The aim of this study was to demonstrate the clinicopathological and molecular pathologic features of brain metastases (BM).

METHODS

A total of 269 patients were diagnosed with BM through surgical resection at Seoul St. Mary's Hospital from January 2010 to March 2020. We reviewed the clinicopathological features and molecular status of primary and metastatic brain tissues using immunohistochemistry and molecular pathology results.

RESULTS

Among 269 patients, 139 males and 130 females were included. The median age of primary tumor was 58 years (range, 13 to 87 years) and 86 patients (32.0%) had BM at initial presentation. Median BM free interval was 28.0 months (range, 1 to 286 months). The most frequent primary site was lung 46.5% (125/269), and followed by breast 15.6% (42/269), colorectum 10.0% (27/269). Epidermal growth factor receptor (EGFR) mutation was found in 50.8% (32/63) and 58.0% (40/69) of lung primary and BM, respectively. In both breast primary and breast cancer with BM, luminal B was the most frequent subtype at 37.9% (11/29) and 42.9% (18/42), respectively, followed by human epidermal growth factor receptor 2 with 31.0% (9/29) and 33.3% (14/42). Triple-negative was 20.7% (6/29) and 16.7% (7/42), and luminal A was 10.3% (3/29) and 7.1% (3/42) of breast primary and BM, respectively. In colorectal primary and colorectal cancer with BM, KRAS mutation was found in 76.9% (10/13) and 66.7% (2/3), respectively.

CONCLUSIONS

We report the clinicopathological and molecular pathologic features of BM that can provide useful information for understanding the pathogenesis of metastasis and for clinical trials based on the tumor's molecular pathology.

Overview on Therapeutic Options in Uncommon EGFR Mutant Non-Small Cell Lung Cancer (NSCLC): New Lights for an Unmet Medical Need

The majority of epidermal growth factor receptor (EGFR) mutations (85-90%) are exon 19 deletions and L858R point mutations of exon 21, characterized by high sensitivity to EGFR-tyrosine kinase inhibitors (TKIs). Less is known about uncommon mutations (10-15% of EGFR mutations). The predominant mutation types in this category include exon 18 point mutations, exon 21 L861X, exon 20 insertions, and exon 20 S768I. This group shows a heterogeneous prevalence, partly due to different testing methods and to the presence of compound mutations, which in some cases can lead to shorter overall survival and different sensitivity to different TKIs compared to simple mutations. Additionally, EGFR-TKI sensitivity may also vary depending on the specific mutation and the tertiary structure of the protein. The best strategy remains uncertain, and the data of EGFR-TKIs efficacy are based on few prospective and some retrospective series. Newer investigational agents are still under study, and there are no other approved specific treatments targeting uncommon EGFR mutations. Defining the best treatment option for this patient population remains an unmet medical need. The objective of this review is to evaluate existing data on the outcomes, epidemiology, and clinical characteristics of lung cancer patients with rare EGFR mutations, with a focus on intracranial activity and response to immunotherapy.

Intratumoral Heterogeneity in Lung Cancer

The diagnosis and treatment of lung cancer (LC) is always a challenge. The difficulty in the decision of therapeutic schedule and diagnosis is directly related to intratumoral heterogeneity (ITH) in the progression of LC. It has been proven that most tumors emerge and evolve under the pressure of their living microenvironment, which involves genetic, immunological, metabolic, and therapeutic components. While most research on ITH revealed multiple mechanisms and characteristic, a systemic exposition of ITH in LC is still hard to find. In this review, we describe how ITH in LC develops from the perspective of space and time. We discuss elaborate details and affection of every aspect of ITH in LC and the relationship between them. Based on ITH in LC, we describe a more accurate multidisciplinary therapeutic strategy on LC and provide the newest opinion on the potential approach of LC therapy.

Evaluation of molecular methods for plasma detection of EGFR mutations in non-small cell lung cancer

AIM

Epidermal growth factor receptor (EGFR) mutations are detected in non-small cell lung cancer (NSCLC) and associated with responses to therapy with tyrosine kinase inhibitors (TKIs). We compared the analytical performances of two real-time PCRs and droplet digital PCR (ddPCR) to detect EGFR mutations using plasma.

METHODS

Plasma EGFR tests were performed using 86 plasma samples from 75 prospectively enrolled NSCLC patients with early and advanced stages. Analytical performances of plasma-using two real-time PCR, Cobas EGFR mutation v2 and PANAMutyper, EGFR kit, and ddPCR were evaluated based on the tissue EGFR test results. The frequencies of EGFR mutations and acquired T790M mutation after TKI therapy were also assessed.

RESULTS

The incidence of all EGFR mutations was 52.3% (23/44) in tissue and was up to 43.2% (19/44) in plasma. The Cobas detection rates of three EGFR mutations (exon 19 deletions, L858R, and T790M) in plasma were similar to those in tissue. The Cobas showed a higher detection rate (76.7%) than that by the PANAMutyper (60.5%). Sensitivity for T790M mutation was lower than the sensitivity for the exon 19 deletions or L858R in both tests. Mutant allele frequency measured by ddPCR was significantly correlated with the semi-quantitative values of the Cobas.

CONCLUSIONS

Plasma EGFR tests showed similar detection rates for common EGFR mutations compared to the tissue EGFR tests. Cobas showed higher sensitivity in detection of EGFR mutations in body fluids than the PANAMutyper. Real-time PCR using plasma or body fluids could be a suitable first test for the detection of EGFR mutations.

Heterogeneity among tumors with acquired resistance to EGFR tyrosine kinase inhibitors harboring EGFR ‐T790M mutation in non‐small cell lung cancer cells

EGFR‐T790M mutation is a major mechanism underlying acquired resistance to first‐ and second‐generation EGFR tyrosine kinase inhibitors (EGFR‐TKIs) in lung cancer with mutated EGFR. However, differences in the biological characteristics of T790M tumors based on treatment regimens with each generation of EGFR‐TKI are not fully understood. We established cell lines with acquired resistance harboring EGFR‐T790M mutation derived from xenograft tumors treated with each generation of EGFR‐TKI and examined their biological characteristics with respect to third‐generation EGFR‐TKI osimertinib sensitivity. Second‐generation EGFR‐TKI dacomitinib‐resistant cells with T790M‐exhibited higher sensitivity to osimertinib than first‐generation EGFR‐TKI gefitinib‐resistant cells with T790M via inhibition of AKT and ERK signaling and promotion of apoptosis. Furthermore, gefitinib‐resistant cells showed enhanced intratumor heterogeneity accompanied by genomic instability and activation of alternative resistance mechanisms compared with dacomitinib‐resistant cells; this suggests that the maintenance of EGFR dependency after acquiring resistance might depend on the type of EGFR‐TKI. Our results demonstrate that the progression of tumor heterogeneity via both genetic and non‐genetic mechanisms might affect osimertinib sensitivity in tumors with acquired resistance harboring EGFR‐T790M mutation.

Subclonal landscape of cancer drives resistance to immune therapy

Tumor mutation burden (TMB) is often used as a biomarker for immunogenicity and prerequisite for immune checkpoint inhibitor (ICI) therapy. However, it is becoming increasingly evident that not all tumors with high TMB respond to ICIs as expected. It has been shown that the ability of T-cells to infiltrate the tumor microenvironment and elicit a specific immune response is dependent not only on the TMB, but also on intra-tumor heterogeneity and the fraction of low-frequency subclonal mutations that make up the tumor. High intra-tumor heterogeneity leads to inefficient recognition of tumor neoantigens by T-cells due to their diluted frequency and spatial heterogeneity. Clinical studies have shown that tumors with a high degree of intra-tumor heterogeneity respond poorly to ICI therapy, and previous cytotoxic treatment may increase the intra-tumor heterogeneity and render second-line ICI therapy less effective. This paper reviews the role of ICI therapy when following chemotherapy or radiation to determine if they may be better suited as first-line therapy in patients with high TMB, low intra-tumor heterogeneity, and high PD-1, PD-L1, or CTLA-4 expression.

Non-small cell lung cancer: Emerging molecular targeted and immunotherapeutic agents

Non-small cell lung cancer (NSCLC) represents the most common and fatal type of primary lung malignancies. NSCLC is often diagnosed at later stages and requires systemic therapies. Despite recent advances in surgery, chemotherapy, and targeted molecular therapies the outcomes of NSCLC remain disproportionately poor. Immunotherapy is a rapidly developing area in NSCLC management and presents opportunities for potential improvements in clinical outcomes. Indeed, different immunotherapeutics have been approved for clinical use in various settings for NSCLC. Their promise is especially poignant in light of improved survival and quality of life outcomes. Herein, we comprehensively review emerging NSCLC therapeutics. We discuss the limitations of such strategies and summarize the present status of various immunotherapeutic agents in key patient populations. We also examine the data from ongoing studies in immunotherapy and consider future areas of study, including novel inhibition targets, therapeutic vaccination, tumor genome modification, and improvements to drug delivery systems.

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

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

Celastrol acts synergistically with afatinib to suppress non-small cell lung cancer cell proliferation by inducing paraptosis

Non-small cell lung cancer (NSCLC) with wild-type epidermal growth factor receptor (EGFR) is intrinsic resistance to EGFR-tyrosine kinase inhibitors (TKIs), such as afatinib. Celastrol, a natural compound with antitumor activity, was reported to induce paraptosis in cancer cells. In this study, intrinsic EGFR-TKI-resistant NSCLC cell lines H23 (EGFR wild-type and KRAS mutation) and H292 (EGFR wild-type and overexpression) were used to test whether celastrol could overcome primary afatinib resistance through paraptosis induction. The synergistic effect of celastrol and afatinib on survival inhibition of the NSCLC cells was evaluated by CCK-8 assay and isobologram analysis. The paraptosis and its modulation were assessed by light and electron microscopy, Western blot analysis, and immunofluorescence. Xenografts models were established to investigate the inhibitory effect of celastrol plus afatinib on the growth of the NSCLC tumors in vivo. Results showed that celastrol acted synergistically with afatinib to suppress the survival of H23 and H292 cells by inducing paraptosis characterized by extensive cytoplasmic vacuolation. This process was independent of apoptosis and not associated with autophagy induction. Afatinib plus celastrol-induced cytoplasmic vacuolation was preceded by endoplasmic reticulum stress and unfolded protein response. Accumulation of intracellular reactive oxygen species and mitochondrial Ca2+ overload may be initiating factors of celastrol/afatinib-induced paraptosis and subsequent cell death. Furthermore, Celastrol and afatinib synergistically suppressed the growth of H23 cell xenograft tumors in vivo. The data indicate that a combination of afatinib and celastrol may be a promising therapeutic strategy to surmount intrinsic afatinib resistance in NSCLC cells.

Amplifications of Stemness Gene Loci-New Markers for the Determination of the Need for Neoadjuvant Chemotherapy for Patients with Breast Cancer. A Prospective Study

In this prospective study, a new strategy for the prescription of neoadjuvant chemotherapy (NAC) was prospectively tested and depended on the presence of stemness gene amplifications in the tumor before treatment, which in our early studies showed a connection with metastasis. The study included 92 patients with grade IIA–IIIB luminal B breast cancer. Patients underwent a biopsy before treatment, and with the use of a CytoScan HD Array microarray (Affymetrix, Santa Clara, CA, USA), the presence of stemness gene amplifications (3q, 5p, 6p, 7q, 8q, 13q, 9p, 9q, 10p, 10q21.1, 16p, 18chr, 19p) in the tumor was determined. In group 1 (n = 41), in the presence of two or more amplifications, patients were prescribed a personalized NAC regimen. In group 2 (n = 21), if there was no amplification of stemness genes in the tumor, then patients were not prescribed NAC, and treatment began with surgery. Group 3 (n = 30) served as a historical control. The frequency of an objective response to NAC in groups 1 and 3 was 79%. Nonmetastatic survival was found in 100% of patients in group 2, who did not undergo NAC. In patients in group 1, the frequency of metastasis was 10% (4/41). At the same time, in patients in group 3, who received NAC, the rate of metastasis was 47% (14/30). The differences between group 1 and group 3 and between group 2 and group 3 were statistically significant, both by Fisher’s criterion and a log-rank test. The appointment of NAC was most feasible in patients with clones with stemness gene amplifications in the primary tumor, while in the absence of amplifications, preoperative chemotherapy led to a sharp decrease in metastasis-free survival. This strategy of NAC prescription allowed us to achieve 93% metastatic survival in patients with breast cancer.

Primary Tumor Resection Improves Survival for EGFR-TKI-Treated Patients With Occult M1a Lung Adenocarcinoma

Background

The role of primary tumor resection in occult M1a lung adenocarcinoma remains unclear, especially for patients receiving targeted therapy. The purpose of this study is to assess the effect of primary tumor resection on overall survival (OS) in lung adenocarcinoma patients with occult pleural disseminations receiving targeted therapy.

Methods

Lung adenocarcinoma patients with intraoperatively-confirmed occult pleural dissemination (M1a), who hospitalized in the Department of Thoracic Surgery in Fudan Shanghai Cancer Center from May 2008 to December 2017 and received EGFR-TKIs therapy, were enrolled. Log-rank tests were used to compare the survival differences between groups.

Results

34 patients receiving EGFR-TKIs were enrolled. The majority of them were never smokers (29/34, 85.3%). Among the enrolled patients, 20 (58.8%) patients underwent primary tumor resection, while 14 (41.2%) patients not. There was no distributional difference of baselines between patients undergoing and not undergoing primary tumor resection. Further analyses demonstrated that the patients undergoing primary tumor resection had a prolonged OS compared with those not (log-rank P= 0.042). The 2-year and 5-year OS for patients receiving primary tumor resection and EGFR-TKIs was 90.0% and 60.1%.

Conclusions

Primary tumor resection was associated with improved survival in patients with occult intraoperatively-confirmed M1a adenocarcinoma receiving EGFR-TKIs.

Zinc-finger E-box-binding homeobox 1 (ZEB1) plays a crucial role in the maintenance of lung cancer stem cells resistant to gefitinib

Background

Zinc‐finger E‐box‐binding homeobox 1 (ZEB1) is an important regulator of epithelial‐mesenchymal transition (EMT) and is involved in the maintenance of cancer stem cells (CSCs) via miR‐200c and BMI1 pathway. Recent studies revealed that ZEB1 contributes to the EMT‐mediated acquired resistance to gefitinib in EGFR‐mutant non‐small cell lung cancer (NSCLC). However, the precise role of ZEB1 in the maintenance of lung CSCs that lead to acquired resistance to gefitinib remains unclear.

Methods

PC9 and HCC827 NSCLC cell lines were treated with high concentrations of gefitinib, and surviving cells were referred to as “gefitinib‐resistant persisters” (GRPs). ZEB1 knockdown or overexpression was performed to determine the biological significance of ZEB1 in the CSC features of GRPs, and animal models were studied for in vivo validation. Expression of ZEB1, BMI1, and ALDH1A1 was analyzed by immunohistochemistry in tumor specimens from NSCLC patients with acquired resistance to gefitinib.

Results

GRPs had characteristic features of mesenchymal and CSC phenotypes with high expression of ZEB1 and BMI1, and decreased miR‐200c, in vitro and in vivo. ZEB1 silencing attenuated the suppression of miR‐200c, resulting in the reduction in BMI1 and reversed the mesenchymal and CSC features of GRPs. Furthermore, ZEB1 overexpression induced EMT and increased the levels of CD133‐ and BMI1‐positive GRPs in vitro and gefitinib resistance in vivo. Finally, ZEB1, BMI1, and ALDH1A1 were highly expressed in tumor specimens from EGFR‐mutant NSCLC patients with gefitinib resistance.

Conclusions

ZEB1 plays an important role in gefitinib‐resistant lung CSCs with EMT features via regulation of miR‐200c and BMI1.

Synthesis and evaluation of 68Ga-labeled dimeric cNGR peptide for PET imaging of CD13 expression with ovarian cancer xenograft

Introduction: Previous studies have shown that peptides containing the asparagine-glycine-arginine (NGR) sequence can specifically bind to CD13 (aminopeptidase N) receptor, a tumor neovascular biomarker that is over-expressed on the surface of angiogenic blood vessels and various tumor cells, and it plays an important role in angiogenesis and tumor progression. In the present study, we aimed to evaluate the efficacy of a gallium-68 (⁶⁸Ga)-labeled dimeric cyclic NGR (cNGR) peptide as a new molecular probe that binds to CD13 in vitro and in vivo.

Materials and Methods: A dimeric cNGR peptide conjugated with 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) was synthesized and labeled with ⁶⁸Ga. In vitro uptake and binding analyses of the ⁶⁸Ga- DOTA-c(NGR)₂ were performed in two ovarian tumor cell lines, ES2 and SKOV3, which had different CD13 expression patterns. An in vivo biodistribution study was performed in normal mice, and micro positron emission tomography (PET) imaging was conducted in nude mice bearing ES2 and SKOV3 tumors.

Results:⁶⁸Ga-DOTA-c(NGR)₂ was prepared with high radiochemical purity (>95%), and it was stable both in saline at room temperature and in bovine serum at 37°C for 3 h. In vitro studies showed that the uptake of ⁶⁸Ga-DOTA-c(NGR)₂ in ES2 cells was higher compared with SKOV3 cells, and such uptake could be blocked by the cold DOTA-c(NGR)₂. Biodistribution studies demonstrated that ⁶⁸Ga-DOTA-c(NGR)₂ was rapidly cleared from blood and mainly excreted from the kidney. MicroPET imaging of ES2 tumor xenografts showed the focal uptake of ⁶⁸Ga-DOTA-c(NGR)₂ in tumors from 1 to 1.5 h post-injection. The high-contrast tumor visualization occurred at 1 h, corresponding to the highest tumor/background ratio of 10.30±0.26. The CD13-specific tumor targeting of the ⁶⁸Ga-DOTA-c(NGR)₂ was further supported by the reduced uptake of the probe in ES2 tumors by co-injection of the unlabeled cold peptide. In SKOV3 tumor models, the tumor was not obviously visible under the same imaging conditions.

Conclusions:⁶⁸Ga-DOTA-c(NGR)₂ was easily synthesized, and it showed favorable CD13-specific targeting ability by in vitro data and microPET imaging with ovarian cancer xenografts. Collectively, ⁶⁸Ga-DOTA-c(NGR)₂ might be a potential PET imaging probe for non-invasive evaluation of the CD13 receptor expression in tumors.

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

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

HDAC inhibition synergizes with ALK inhibitors to overcome resistance in a novel ALK mutated lung adenocarcinoma model

OBJECTIVES

Somatic chromosomal rearrangements resulting in ALK fusion oncogenes are observed in 3-7 % of lung adenocarcinomas. ALK tyrosine kinase inhibitors (ALKi) induce initially response, however, various resistance mechanisms limit their efficacy. Novel therapeutic approaches are of utmost importance to tailor these targeted therapies.

MATERIALS AND METHODS

A synchronous ALK-rearranged and mutated lung cancer cell line pair was established from malignant pleural effusion (PF240-PE) and carcinosis (PF240-PC) at time of ALKi resistance. Immunohistochemistry, FISH and sequencing were performed in pre- and post-treatment tumors and in both cell lines. Differentiation markers were measured by immunoblot. Viability was tested following treatment with ALKi and/or a pan-HDAC inhibitor. Additionally, a novel treatment-naïve ALK-rearranged cell line served as control. In vivo tumorigenicity was evaluated in subcutaneous xenografts.

RESULTS

Two distinct resistance mutations were identified in different carcinosis tissues at time of resistance, the previously described resistance mutation L1152R and the hitherto uncharacterized E1161K. Strikingly, PF240-PC cells carried E1161K and PF240-PE cells harbored L1152R. Immunohistochemistry and immunoblot identified epithelial-to-mesenchymal transition markers upregulated following ALKi resistance development both in carcinosis tissues and cell lines. While both lines grew as xenografts, they differed in morphology, migration, in vivo growth and sensitivity to ALKi in vitro. Strikingly, the combination of ALKi with SAHA yielded strong synergism.

CONCLUSION

Using a patient-derived ALKi resistant lung cancer model we demonstrated the synergism of HDAC and ALK inhibition. Furthermore, our findings provide strong evidence for intratumoral heterogeneity under targeted therapy and highlight the importance of site-specific mutational analysis.

Research progress on the relationship between lung cancer drug-resistance and microRNAs

Lung cancer, a malignant tumor with the highest death rate of cancer, seriously endangers human health. And its pathogenesis and mechanism of drug resistance has been partially clarified, especially for the signal pathway of epidermal growth factor receptor (EGFR). The targeting therapy of EGFR signaling pathway in non-small cell lung cancer (NSCLC) has achieved a certain effect, but the two mutation of EGFR and other mechanisms of lung cancer resistance still greatly reduce the therapeutic effect of chemotherapy on it. MicroRNA is an endogenous non coding RNA, which has a regulatory function after transcriptional level. Recent studies on the mechanism of lung cancer resistance have found that a variety of microRNAs are related to the mechanism of lung cancer drug-resistance. They can regulate lung cancer resistance by participating in signal pathways, drug resistance genes and cell apoptosis, thus affecting the sensitivity of cancer cells to drugs. Therefore, microRNAs can be used as a specific target for the treatment of lung cancer and plays a vital role in the early diagnosis, prognosis and treatment of lung cancer. This article reviews the mechanisms of lung cancer resistance and its relationship with microRNAs.

Drug resistance to targeted therapeutic strategies in non-small cell lung cancer

Rapidly developing molecular biology techniques have been employed to identify cancer driver genes in specimens from patients with non-small cell lung cancer (NSCLC). Inhibitors and antibodies that specifically target driver gene-mediated signaling pathways to suppress tumor growth and progression are expected to extend the survival time and further improve the quality of life of patients. However, the health of patients with advanced and metastatic NSCLC presents significant challenges due to treatment resistance, mediated by cancer driver gene alteration, epigenetic alteration, and tumor heterogeneity. In this review, we discuss two different resistance mechanisms in NSCLC targeted therapies, namely changes in the targeted oncogenes (on-target resistance) and changes in other related signaling pathways (off-target resistance) in tumor cells. We highlight the conventional mechanisms of drug resistance elicited by the complex heterogeneous microenvironment of NSCLC during targeted therapy, including mutations in epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), the receptor tyrosine kinase ROS proto-oncogene 1 (ROS1), and the serine/threonine-protein kinase BRAF (v-Raf murine sarcoma viral oncogene homolog B). We also discuss the mechanism of action of less common oncoproteins, as in-depth understanding of these molecular mechanisms is important for optimizing treatment strategies.

Comparative review of drug-drug interactions with epidermal growth factor receptor tyrosine kinase inhibitors for the treatment of non-small-cell lung cancer

The development of small-molecule tyrosine kinase inhibitors (TKIs) that target the epidermal growth factor receptor (EGFR) has revolutionized the management of non-small-cell lung cancer (NSCLC). Because these drugs are commonly used in combination with other types of medication, the risk of clinically significant drug–drug interactions (DDIs) is an important consideration, especially for patients using multiple drugs for coexisting medical conditions. Clinicians need to be aware of the potential for clinically important DDIs when considering therapeutic options for individual patients. In this article, we describe the main mechanisms underlying DDIs with the EGFR-TKIs that are currently approved for the treatment of NSCLC, and, specifically, the potential for interactions mediated via effects on gastrointestinal pH, cytochrome P450-dependent metabolism, uridine diphosphate-glucuronosyltransferase, and transporter proteins. We review evidence of such DDIs with the currently approved EGFR-TKIs (gefitinib, erlotinib, afatinib, osimertinib, and icotinib) and discuss several information sources that are available online to aid clinical decision-making. We conclude by summarizing the most clinically relevant DDIs with these EFGR-TKIs and provide recommendations for managing, minimizing, or avoiding DDIs with the different agents.

A comparison of EGFR mutation status in tissue and plasma cell-free DNA detected by ADx-ARMS in advanced lung adenocarcinoma patients

Background

Previous studies have shown that there are different methods used to detect the epidermal growth factor receptor (EGFR) mutation status in plasma cell-free DNA (cfDNA) for advanced lung adenocarcinoma patients including the ADx-Amplification Refractory Mutation System (ADx-ARMS). We explored the performance of the ADx-ARMS in detecting the EGFR mutations in cfDNA.

Methods

This prospective cohort study enrolled patients who presented with advanced (stage IIIb/IV) lung adenocarcinoma. EGFR mutations in plasma cfDNA and tumor tissues by ADx-ARMS were detected. Next-generation sequencing (NGS) in plasma was performed in patients with inconsistent gene region mutations in the plasma and matched tissue samples. We calculated the clinical parameters of the ADx-ARMS for EGFR mutation status in the plasma of cfDNA, using the tumor tissues as the standard for measurement. The objective response rate (ORR) and progression-free survival (PFS) were also calculated for patients receiving first-generation EGFR-tyrosine kinase inhibitors (TKIs) therapy.

Results

In total, 203 patients were included in the final analysis. Mutations were discovered in 58.6% (119/203) of the tumor tissues and 31.0% (63/203) were detected EGFR mutations in both tumor tissues and matched plasma. The sensitivity and the specificity setting for detecting the EGFR mutations in the plasma using the ADx-ARMS were configured to 52.9% and 98.8%. An ORR of 64.8% was observed among the 71 patients who were identified as being EGFR-positive in their tumor tissues, who had received treatments using Gefitinib or Icotinib. Next, the ORR was observed to be 69.0% among the 42 patients with an EGFR mutation in their plasma. The median PFS of the patients with an EGFR mutation in tumor tissues and plasma were 10.0 vs. 11.0 months (P=0.175). The median PFS of the patients with an EGFR wild-type in the plasma was 8.7 months, which was significantly shorter than the EGFR mutant-type in plasma (P=0.001).

Conclusions

Using ADx-ARMS as an approach with high specificity but moderate sensitivity to detect the EGFR mutations in plasma cfDNA and EGFR mutation status in plasma cfDNA using the ADx-ARMS can predict the tumor response for EGFR-TKIs.

Detection of EGFR mutations using target capture sequencing in plasma of patients with non-small-cell lung cancer

PURPOSE : Circulating tumour DNA (ctDNA) is a promising biomarker for detection of non-invasive epidermal growth factor receptor ( EGFR) mutations in patients with non-small-cell lung cancer (NSCLC). However, the existing methods have limitations in sensitivity or in availability. The aim was to evaluate the accuracy of capture target sequencing for detecting EGFR mutations in ctDNA. METHODS : A total of 79 patients with NSCLC and available plasma and matched tissue specimens were enrolled. Through capture target sequencing, mutations were searched in over 20 000 reads obtained from each exon region. Parameters corresponding to the limit of detection and limit of quantification were used as the thresholds for mutation detection. To evaluate the accuracy, detection of EGFR mutations in matched tissue samples was performed by target capture sequencing and the amplification refractory mutation system (ARMS). RESULTS:   : EGFR mutations were discovered in 32.9 % (26/79) of the patients with NSCLC, the overall rate of consistency for the 79 paired plasma and tissue samples was 86.1 % (68/79). The sensitivity and specificity of detecting EGFR mutations in the plasma were 72.7 % and 95.7 %. In terms of the EGFR mutations identified by ARMS, the overall consistency was 78.5 % (62/79) in three groups. Of 21 patients with EGFR sensitive mutation defined by next generation sequencing in ctDNA, 20 (95.2%) showed long-term disease control with epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) treatment; the median progression-free survival was 10.8 months (95% CI 9.1 to 16.8). CONCLUSIONS: Target capture sequencing of ctDNA can be used for genotyping of EGFR in patients with NSCLC, which may enable a direct recommendation for EGFR TKI on the basis of positive results with plasma DNA.

Successful treatment of a lung adenocarcinoma patient with a novel EGFR exon 20-ins mutation with afatinib: A case report

RATIONALE

Comprehensive genomic profiling for non-small cell lung cancer (NSCLC) is likely to identify more patients with rare genetic alterations, including uncommon epidermal growth factor receptor (EGFR) gene mutation.

PATIENT CONCERNS

A 63-year-old Chinese woman who had never smoked visited our lung cancer clinic due to a chronic cough.

DIAGNOSIS

The patient was diagnosed with lung adenocarcinoma by transbronchial lung biopsy. An EGFR mutation (exon 20 insertion H773_V774insH, D770_N771insG, V769_D770insASV, D770_N771insSVD) was detected in the biopsy specimen by quantitative real-time PCR.

INTERVENTIONS

The patient was treated with osimertinib first, and the progression-free survival (PFS) was 4.4 months. After the disease progressed, the second genetic test of pleural effusion suggesting the EGFR exon 20-ins mutation site changed to A767delinsASVD only. Then the patient was treated with afatinib with informed consent.

OUTCOMES

The treatment of afatinib in this patient was successful, PFS was 7.4 months.

LESSONS

To our knowledge, EGFR exon 20-ins mutation A767delinsASVD has never been reported, and the successful treatment of afatinib may provide a new therapeutic option for this type of exon 20 insertion mutations.

TPD52L2 impacts proliferation, invasiveness and apoptosis of glioblastoma cells via modulation of wnt/β-catenin/snail signaling

Intratumoral heterogeneity greatly hinders efficiency of target therapy in glioblastoma (GBM). To decipher the underlying mechanisms of heterogeneity, patient-derived adult GBM cells were separately isolated from margins of T1 gadolinium enhancing tumor lesions (PNCs) and T1 gadolinium enhancing core lesions (ECs). Single clone culture was conducted in ECs and U87MG cell line to screen clones with distinct biological phenotypes. Single cell clones with diverse phenotypes were simultaneously separated from ECs and U87 cell line. PNCs, GCs(H) and U87(H) exhibited longer cellular protrusion than ECs, GCs(L) and U87(L), respectively. Cell strains with longer protrusion exhibited higher invasive ability and lower sensitivity to temozolomide (TMZ) and radiation. Subsequently, TPD52L2 was verified as the functional protein to regulate the cellular heterogeneity by the proteomics analysis. Downregulation of TPD52L2 enhanced cell invasion whereas inhibited cell proliferation rate and sensitivity to chemotherapy in vivo and in vitro, this condition was reversed when TPD52L2 was overexpressed. The invasiveness was facilitated by up-regulating CTNNB1/β-catenin and SNAI1/Snail mediated EMT process. In addition, the clinical data of 88 GBM cases in our neurosurgery center was analyzed to reveal the influence of TPD52L2 in the prognosis of GBM. Low expression of TPD52L2 exacerbated prognosis of GBM patients received standard radiotherapy plus concomitant and adjuvant TMZ (Stupp strategy). Taken together, TPD52L2 is an important biomarker influencing GBM prognosis.

Acquired resistance in oncogene-addicted non-small-cell lung cancer

The advance of tyrosine kinase inhibitors has profoundly changed the therapeutic algorithm of non-small-cell lung cancer in molecularly selected patients. However, benefit from these agents is often transient and usually most patients progress within 12 months from treatment. Novel and more potent and selective tyrosine kinase inhibitors have been developed to overcome acquired resistance; however, these agents are once again associated with only temporary benefit and patients frequently develop secondary resistance, a heterogeneous phenomenon that involves different molecular mechanisms simultaneously. The aim of our paper is to provide a comprehensive overview of the mechanisms of acquired resistance in oncogene-addicted non-small-cell lung cancer, focusing on the two most studied target, EGFR mutations and ALK translocation, and reviewing the main challenges in clinical practice.

Anti-cancer effects of 3,5-dimethylaminophenol in A549 lung cancer cells

Exposure to 3,5-dimethylaminophenol (3,5-DMAP), the metabolite of the 3-5-dimethylaniline, was shown to cause high levels of oxidative stress in different cells. The aim of the present work was to observe whether this metabolite can lead to cytotoxicity, oxidative stress, DNA damage and cell cycle changes in non-small cell lung cancer A549 cells. 3,5-DMAP caused a dose-dependent increase in cytotoxicity, generation of superoxide (O₂^-.), inductions in the enzyme activities orchestrating cellular antioxidant balance, increases in lipid peroxidation as well as DNA damage. However, 3,5-DMAP showed significantly lower cytotoxicity towards human lung fibroblast (HLF) cells. 3,5-DMAP also led to molecular events, like inducing apoptotic markers (ie. p53, Bad, Bax and cytochrome c); decreasing anti-apoptotic proteins (Bcl-2) and alterations in cell cycle. Our findings indicate that the cytotoxicity caused by this particular alkylaniline metabolite led to initiation of caspase 3-mediated apoptosis. Furthermore, 3,5-DMAP attenuated carcinogenic properties like migration capacity of A549 cells and eventually inhibited growth of A549 cells in an in vivo mouse model. Tumor sections showed that 3,5-DMAP down-regulated c-Myc expression but up-regulated p53 and cytochrome c, all of which might result in tumor growth arrest. Co-treatment with N-acetylcysteine provided reductions in cytotoxicity and positively modulated genetic events induced by 3,5-DMAP in A549 cells. In conclusion, our findings demonstrate 3,5-DMAP may be a potential anti-cancer drug in cancer, due to its self redox cycling properties.

Intratumoral heterogeneity of copy number variation in lung cancer harboring L858R via immunohistochemical heterogeneous staining

BACKGROUND

Although intratumoral heterogeneity is commonly observed in several cancers, few studies have shown its presence in EGFR-mutated lung cancer. We performed immunohistochemistry to analyze the intratumoral heterogeneity in EGFR-mutated (L858R) lung cancer and performed targeted sequencing in specific cases. We discuss the effects of intratumoral heterogeneity and acquired resistance to EGFR-TKI.

METHODS

Twenty resected primary lung cancers known to harbor EGFR L858R were analyzed. IHC was performed using an L858R mutant-specific rabbit monoclonal antibody and the samples were scored by staining intensity (0-3) and proportion. For cases with heterogeneous L858R protein expression, the nucleic acids were extracted from each differently stained lesion, and targeted sequencing was performed. Single nucleotide variations (SNVs) and copy number variations (CNVs) were then analyzed. The cell proliferation and apoptosis were also evaluated by the ki-67 labeling index and TUNEL staining.

RESULTS

Among 20 cases, 3 showed heterogeneous staining. Genetic analyses for cases with heterogeneous staining revealed an increase in the copy number of EGFR in the IHC-positive part compared to the negative part, and an increase in the copy number of CCNE1 was observed in the IHC-positive part compared to the negative part in one case (case 1). In another case (case 2), an increase in the copy number of EGFR was observed in the IHC-positive part compared to the negative part, and an increase in the copy number of MDM2 was observed in the IHC-positive part compared to the negative part. In three cases, no SNV changes were observed. An increase in the ki-67 labeling index in the L858R-positive part in case 1 and increased apoptosis in the L858R-positive part in case 2 were observed, suggesting the functional significance of CNV changes.

CONCLUSION

These cases exhibiting L858R IHC intratumoral heterogeneity suggest a heterogeneous effect on the cell activity due to CNV heterogeneity.

Irreversible tyrosine kinase inhibition of epidermal growth factor receptor with afatinib in EGFR activating mutation-positive advanced non-small-cell lung cancer

Despite recent advances in the systemic therapy of non-small-cell lung cancer (nsclc), the prognosis for stage iv disease remains poor. The discovery of targetable mutations has led to new treatment options. The most common mutations, the EGFR activating mutations, are present in about 50% of Asian patients and up to 15% of white patients. First-generation reversible epidermal growth factor receptor (egfr) tyrosine kinase inhibitors (tkis) have led to improved survival in patients positive for EGFR activating mutations, but resistance eventually leads to disease progression. The irreversible egfr tki afatinib was developed to counter such resistance. The clinical efficacy of afatinib has been shown in first-line studies comparing it with both cytotoxic chemotherapy and first-generation egfr tkis. Afatinib has also shown continued benefit beyond progression while a patient is taking an egfr inhibitor. Furthermore, its toxicity profile is both predictable and manageable. The results of the principal clinical trials assessing afatinib are reviewed here.

Concise Review: Resistance to Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer: The Role of Cancer Stem Cells

Among the potential mechanisms involved in resistance to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer, the manifestation of stem-like properties in cancer cells seems to have a crucial role. Alterations involved in the development of TKI resistance may be acquired in a very early phase of tumorigenesis, supporting the hypothesis that these aberrations may be present in cancer stem cells (CSCs). In this regard, the characterization of tumor subclones in the initial phase and the identification of the CSCs may be helpful in planning a specific treatment to target selected biomarkers, suppress tumor growth, and prevent drug resistance. The aim of this review is to elucidate the role of CSCs in the development of resistance to TKIs and its implication for the management of patients. Stem Cells 2018;36:633-640.

Inhibition of the colony-stimulating-factor-1 receptor affects the resistance of lung cancer cells to cisplatin

In the present work we show that multiple lung cancer cell lines contain cisplatin resistant cell subpopulations expressing the Colony-Stimulating-Factor-Receptor-1 (CSF-1R) and surviving chemotherapy-induced stress. By exploiting siRNA-mediated knock down in vitro and the use of an investigational CSF-1R TKI (JNJ-40346527) in vitro and in vivo, we show that expression and function of the receptor are required for the clonogenicity and chemoresistance of the cell lines. Thus, inhibition of the kinase activity of the receptor reduced the levels of EMT-associated genes, stem cell markers and chemoresistance genes. Additionally, the number of high aldehyde dehydrogenase (ALDH) expressing cells was reduced, consequent to the lack of cisplatin-induced increase of ALDH isoforms. This affected the collective chemoresistance of the treated cultures. Treatment of tumor bearing mice with JNJ-40346527, at pharmacologically relevant doses, produced strong chemo-sensitizing effects in vivo. These anticancer effects correlated with a reduced number of CSF-1Rpos cells, in tumors excised from the treated mice. Depletion of the CD45pos cells within the treated tumors did not, apparently, play a major role in mediating the therapeutic response to the TKI. Thus, lung cancer cells express a functional CSF-1 and CSF-1R duo which mediates pro-tumorigenic effects in vivo and in vitro and can be targeted in a therapeutically relevant way. These observations complement the already known role for the CSF-1R at mediating the pro-tumorigenic properties of tumor-infiltrating immune components.

MMP-2 and MMP-13 affect vasculogenic mimicry formation in large cell lung cancer

Matrix metalloproteinases (MMPs) have critical functions in tumour vasculogenic mimicry (VM). This study explored the mechanisms underlying MMP-13 and MMP-2 regulation of tumour VM formation in large cell lung cancer (LCLC). In our study, laminin5 (Ln-5) fragments cleaved by MMP-2 promoted tubular structure formation by the LCLC cell lines H460 and H661 in three-dimensional (3D) cultures. Transient up-regulation of MMP-13 or treatment with recombinant MMP-13 protein abrogated tubular structure formation of H460 cells in 3D culture. Treated cells with Ln-5 fragments cleaved by MMP-2 stimulated EGFR and F-actin expression. Ln-5 fragments cleaved by MMP-13 decreased EGFR/F-actin expression and disrupted VM formation. MMP-13 expression was negatively correlated with VM, Ln-5 and EGFR in LCLC tissues and xenograft. In vivo experiments revealed that VM was decreased when the number of endothelium-dependent vessels (EDVs) increased during xenograft tumour growth, whereas MMP-13 expression was progressively increased. In conclusion, MMP-2 promoted and MMP-13 disrupted VM formation in LCLC by cleaving Ln-5 to influence EGFR signal activation. MMP-13 may regulate VM and EDV formation.

Hit discovery of 4-amino-N-(4-(3-(trifluoromethyl)phenoxy)pyrimidin-5-yl)benzamide: A novel EGFR inhibitor from a designed small library

Searching for hit compounds within the huge chemical space resembles the attempt to find a needle in a haystack. Cheminformatics-guided selection of few representative molecules of a rationally designed virtual combinatorial library is a powerful tool to confront this challenge, speed up hit identification and cut off costs. Herein, this approach has been applied to identify hit compounds with novel scaffolds able to inhibit EGFR kinase. From a generated virtual library, six 4-aryloxy-5-aminopyrimidine scaffold-derived compounds were selected, synthesized and evaluated as hit EGFR inhibitors. 4-Aryloxy-5-benzamidopyrimidines inhibited EGFR with IC₅₀ 1.05-5.37 μM. Cell-based assay of the most potent EGFR inhibitor hit (10ac) confirmed its cytotoxicity against different cancerous cells. In spite of no EGFR, HER2 or VEGFR1 inhibition was elicited by 4-aryloxy-5-(thio)ureidopyrimidine derivatives, cell-based evaluation suggested them as antiproliferative hits acting by other mechanism(s). Molecular docking study provided a plausible explanation of incapability of 4-aryloxy-5-(thio)ureidopyrimidines to inhibit EGFR and suggested a reasonable binding mode of 4-aryloxy-5-benzamidopyrimidines which provides a basis to develop more optimized ligands.

Identification of prognostic genes through expression differentiation during metastatic process in lung adenocarcinoma

Cancer is a highly complicated biological process due to large scale heterogeneity. Identification of differentially expressed genes between normal and cancer samples is widely utilized in the discovery of prognostic factors. In this study, based on RNA sequencing data of lung adenocarcinoma, we focused on the expression differentiation during confined (with neither lymph node invasion nor distant metastasis) primary tumors and lymphnode (with only lymph node invasion but not distant metastasis) primary tumors. The result indicated that differentially expressed genes during confined-lymphnode transition were more closely related to patient’s overall survival comparing with those identified from normal-cancer transition. With the aid of public curated biological network, we successfully retrieved the biggest connected module composed of 135 genes, of which the expression was significantly associated with patient’s overall survival, confirmed by 9 independent microarray datasets.

Comparison of the Amplification Refractory Mutation System, Super Amplification Refractory Mutation System, and Droplet Digital PCR for T790 M Mutation Detection in Non-small Cell Lung Cancer after Failure of Tyrosine Kinase Inhibitor Treatment

Plasma mutation detection has the advantages of non-invasiveness and accessibility. Here, we evaluated three methods, the amplification refractory mutation system (ARMS), second-generation ARMS (SuperARMS), and droplet digital PCR (ddPCR), to assess their concordance and feasibility for the detection of mutations in plasma samples. Non-small lung cancer patients with stage IIIB/IV that were resistant to epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment were enrolled. Blood samples were collected within 14 days after TKI resistance. Each sample was simultaneously assessed by the three methods. In total, 169 patients were enrolled; 54.4% were female, 72.2% were diagnosed with stage IV disease; and 97.6% had adenocarcinoma. T790 M mutations were detected in 42 (24.8%) of the 169 samples using ARMS, one of which carried the T790 M alone, 22 that also encoded exon 19 deletions, and 19 with L858R mutations. For the SuperARMS assay, 59 (34.9%) samples exhibited the T790 M mutation, and 110 (65.1%) showed no detectable T790 M mutation. ddPCR showed that 61 (36.1%) samples contained the T790 M mutation, whereas 108 (63.9%) were not positive. T790 M abundance ranged from 0.04% to 38.2%. The median T790 M abundance was 0.15% for total samples and 2.98% for T790 M mutation samples. The overall concordance was 78.7% (133/169) among ARMS, SuperARMS, and ddPCR. Compared with patients with stage III disease, patients with stage IV disease exhibited a higher T790 M mutation detection rate (28.7% vs. 14.9% by ARMS; 37.7% vs. 27.7% by SuperARMS; and 41.8% vs. 21.3% by ddPCR). Liquid biopsy showed promise and has the advantages of non-invasiveness and accessibility. T790 M detection based on circulating tumor DNA showed high concordance. Compared with non-digital platforms, ddPCR showed higher sensitivity and provided both frequency and abundance information, which might be important for treatment decisions.

Current Progresses of Single Cell DNA Sequencing in Breast Cancer Research

Breast cancers display striking genetic and phenotypic diversities. To date, several hypotheses are raised to explain and understand the heterogeneity, including theories for cancer stem cell (CSC) and clonal evolution. According to the CSC theory, the most tumorigenic cells, while maintaining themselves through symmetric division, divide asymmetrically to generate non-CSCs with less tumorigenic and metastatic potential, although they can also dedifferentiate back to CSCs. Clonal evolution theory recapitulates that a tumor initially arises from a single cell, which then undergoes clonal expansion to a population of cancer cells. During tumorigenesis and evolution process, cancer cells undergo different degrees of genetic instability and consequently obtain varied genetic aberrations. Yet the heterogeneity in breast cancers is very complex, poorly understood and subjected to further investigation. In recent years, single cell sequencing (SCS) technology developed rapidly, providing a powerful new way to better understand the heterogeneity, which may lay foundations to some new strategies for breast cancer therapies. In this review, we will summarize development of SCS technologies and recent advances of SCS in breast cancer.

Structure-Guided Design of C4-alkyl-1,4-dihydro-2H-pyrimido[4,5-d][1,3]oxazin-2-ones as Potent and Mutant-Selective Epidermal Growth Factor Receptor (EGFR) L858R/T790M Inhibitors

Epidermal growth factor receptor (EGFR) T790M acquired drug-resistance mutation has become a major clinical challenge for the therapy of non-small cell lung cancer. Here, we applied a structure-guided approach on the basis of the previous reported EGFR inhibitor (compound 9), and designed a series of C4-alkyl-1,4-dihydro-2H-pyrimido[4,5-d][1,3]oxazin-2-one derivatives as novel mutant-selective EGFR inhibitors. Finally, the most representative compound 20a was identified, which showed high selectivity at both enzymatic and cellular levels against EGFR^L858R/T790M (H1975 cell lines) over EGFR^WT (A431 cell lines). The representative compound 20a also showed promising antitumor efficiency in the in vivo antitumor efficacy study of H1975 xenograft mouse model driven by EGFR^L858R/T790M. These results provide a new scaffold for the treatment of dual-mutant-driven non-small cell lung cancer.

Natural and Chemotherapy-Induced Clonal Evolution of Tumors

Evolution and natural selection of tumoral clones in the process of transformation and the following carcinogenesis can be called natural clonal evolution. Its main driving factors are internal: genetic instability initiated by driver mutations and microenvironment, which enables selective pressure while forming the environment for cell transformation and their survival. We present our overview of contemporary research dealing with mechanisms of carcinogenesis in different localizations from precancerous pathologies to metastasis and relapse. It shows that natural clonal evolution establishes intratumoral heterogeneity and enables tumor progression. Tumors of monoclonal origin are of low-level intratumoral heterogeneity in the initial stages, and this increases with the size of the tumor. Tumors of polyclonal origin are of extremely high-level intratumoral heterogeneity in the initial stages and become more homogeneous when larger due to clonal expansion. In cases of chemotherapy-induced clonal evolution of a tumor, chemotherapy becomes the leading factor in treatment. The latest research shows that the impact of chemotherapy can radically increase the speed of clonal evolution and lead to new malignant and resistant clones that cause tumor metastasis. Another option of chemotherapy-induced clonal evolution is formation of a new dominant clone from a clone that was minor in the initial tumor and obtained free space due to elimination of sensitive clones by chemotherapy. As a result, in ~20% of cases, chemotherapy can stimulate metastasis and relapse of tumors due to clonal evolution. The conclusion of the overview formulates approaches to tumor treatment based on clonal evolution: in particular, precision therapy, prediction of metastasis stimulation in patients treated with chemotherapy, methods of genetic evaluation of chemotherapy efficiency and clonal-oriented treatment, and approaches to manipulating the clonal evolution of tumors are presented.

Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Treatment of Metastatic Non-Small Cell Lung Cancer, with a Focus on Afatinib

Somatic epidermal growth factor receptor (EGFR) mutations are present in around 50% of Asian patients and in 10–15% of Caucasian patients with metastatic non-small cell lung cancer (NSCLC) of adenocarcinoma histology. The first-generation EGFR-tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib have demonstrated improved progression-free survival (PFS) and response rates but not overall survival (OS) benefit in randomized phase III trials when compared with platinum-doublet chemotherapy. All patients treated with EGFR-TKIs will eventually develop acquired resistance to these agents. Afatinib, an irreversible ErbB family blocker, has shown in two randomly controlled trials in patients with EGFR-activating mutations, a significant improvement in PFS and health-related quality of life when compared to platinum-based chemotherapy. Afatinib improved OS in patients with Del19 mutations. In patients having progressed on first-generation EGFR-TKIs, afatinib did lead to a clinical benefit. A randomly controlled trial showed that PFS was significantly superior with afatinib vs. erlotinib in patients with squamous NSCLC in the second-line setting. A phase IIb trial comparing afatinib and gefitinib in first-line EGFR positive NSCLC showed significantly improved PFS with afatinib but OS was not significantly improved.

[Advances in the Research of the Regulation of Chinese Traditional Medicine Monomer and Its Derivatives on Autophagy in Non-small Cell Lung Cancer]

The high morbidity and mortality of non-small cell lung cancer (NSCLC) did influence the quality of life of tumor patients world-wide. There is an urgent need to develop new therapies that have high anti-tumor activity and low toxicity side effects. It is widely accepted that autophagy can play diverse roles in carcinogenesis, such as induces pro-death of lung cancer cells or helps the escape from cell death, making it become a proper anticancer target. It's believed that various monomers of Chinese traditional medicine closely correlates to anti-NSCLC activities, and that even could affect the acquired multiple drug resistance (MDR). Furthermore, autophagy might be the underling mechanisms which could play a role as the candidate targets of natural active compounds. Recent studies of terpenoids, alkaloid, dietary polyphenols, saponins and other active ingredients that extracted from a large variety of herbs suggest that different monomer compounds could either regulate the activity of pro-death autophagy or influence the level of protective autophagy of NSCLC cells, thus changing their drug sensitivity and cell viability. This paper aims to give a systemic description of the latest advances about natural compounds and their derivatives that involved in tumorigenesis of NSCLC via inducing the autophagy.

Nigericin decreases the viability of multidrug-resistant cancer cells and lung tumorspheres and potentiates the effects of cardiac glycosides

Multiple factors including tumor heterogeneity and intrinsic or acquired resistance have been associated with drug resistance in lung cancer. Increased stemness and the plasticity of cancer cells have been identified as important mechanisms of resistance; therefore, treatments targeting cancer cells independent of stemness phenotype would be much more effective in treating lung cancer. In this article, we have characterized the anticancer effects of the antibiotic Nigericin in cells displaying varying degrees of stemness and resistance to anticancer drugs, arising from (1) routine culture conditions, (2) prolonged periods of serum starvation. These cells are highly resistant to conventional anticancer drugs such as Paclitaxel, Hydroxyurea, Colchicine, Obatoclax, Wortmannin, and LY294002, and the multidrug-resistant phenotype of cells growing under prolonged periods of serum starvation is likely the result of extensive rewiring of signaling pathways, and (3) lung tumorspheres that are enriched for cancer stem-like cells. We found that Nigericin potently inhibited the viability of cells growing under routine culture conditions, prolonged periods of serum starvation, and lung tumorspheres. In addition, we found that Nigericin downregulated the expression of key proteins in the Wnt canonical signaling pathway such as LRP6, Wnt5a/b, and β-catenin, but promotes β-catenin translocation into the nucleus. The antitumor effects of Nigericin were potentiated by the Wnt activator HLY78 and by therapeutic levels of the US Food and Drug Administration–approved drug Digitoxin and its novel synthetic analog MonoD. We believe that Nigericin may be used in a co-therapy model in combination with other novel chemotherapeutic agents in order to achieve potent inhibition of cancers that display varying degrees of stemness, potentially leading to sustained anticancer effects.

Synonymous EGFR variant p.Q787Q is neither prognostic nor predictive in patients with lung adenocarcinoma

Patients with non-small cell lung cancer (NSCLC) harboring activating mutations in the Epidermal Growth Factor Receptor (EGFR) benefit from targeted therapies. A synonymous polymorphism (rs1050171, p.Q787Q) was shown to be associated with improved overall survival (OS) in colorectal cancer patients. As data in NSCLC are limited, we retrospectively analyzed associations of p.Q787Q with clinicopathological parameters including clinical response and outcome in patients with lung adenocarcinoma (ADC) who received tyrosine kinase inhibitor (TKI) therapy. Of 642 ADC patients whose tumors were profiled by next generation sequencing, 102 (15.9%) carried EGFR mutations targetable by TKIs (30.4% male patients, median age 65.1 y, 19.6% smokers with 12.8 median pack years). Seventy-nine patients (77.5%) received TKI therapy either as a first- or second-line therapy. Of the 102 EGFR-mutant tumors, 72 (70.6%) exhibited the p.Q787Q polymorphism and another 12 (11.8%) cases with p.Q787Q harbored an additional TKI insensitive mutation (p.T790M). The polymorphism was neither associated with classic clinicopathological parameters nor with overall survival (21.1 months vs. 20.1 months; P-value = 0.91) or clinical response (P-value = 0.122). The patients with p.T790M had worse survival compared to EGFR activating mutation carriers with and without p.Q787Q when analyzed as a separate group (27.5 months, P-value = 0.02). In conclusion, p.Q787Q is neither a suitable prognostic nor predictive biomarker for ADC patients receiving anti-EGFR therapy in first- or second-line of therapy. © 2016 Wiley Periodicals, Inc.

Cell-Free RNA Content in Peripheral Blood as Potential Biomarkers for Detecting Circulating Tumor Cells in Non-Small Cell Lung Carcinoma

Circulating tumor cells (CTCs) have been implicated in tumor progression and prognosis. Techniques detecting CTCs in the peripheral blood of patients with non-small cell lung carcinoma (NSCLC) may help to identify individuals likely to benefit from early systemic treatment. However, the detection of CTCs with a single marker is challenging, owing to low specificity and sensitivity and due to the heterogeneity and rareness of CTCs. Herein, the probability of cell-free RNA content in the peripheral blood as a potential biomarker for detecting CTCs in cancer patients was investigated. An immunomagnetic enrichment of real-time reverse-transcription PCR (RT-PCR) technology for analysis of CTCs in NSCLC patients was also developed. The mRNA levels of four candidate genes, cytokeratin 7 (CK7), E74-like factor 3 (ELF3), epidermal growth factor receptor (EGFR), and erythropoietin-producing hepatocellular carcinoma receptor B4 (EphB4) that were significantly elevated in tumor tissues and peripheral blood mononuclear cells (PBMCs) were determined. The expression of CK7 and ELF3 in tumor tissues and EGFR in PBMCs was associated with lymph node metastasis (all p < 0.05). The expression of CK7 in PBMCs was correlated with age and EphB4 in PBMCs correlated with histopathological type, respectively (all p < 0.05). The expression of all four genes in tumor tissues and PBMCs was significantly correlated with the clinical stage (all p < 0.01). Survival analysis showed that the patients with enhanced expression of CK7, ELF3, EGFR, and EphB4 mRNA in PBMCs had poorer disease-free survival (DFS) and overall survival (OS) than those without (all p < 0.0001). The present study showed that this alteration of cell-free RNA content in peripheral blood might have clinical ramifications in the diagnosis and treatment of NSCLC patients.

Yu Ping Feng San reverses cisplatin-induced multi-drug resistance in lung cancer cells via regulating drug transporters and p62/TRAF6 signalling

Yu Ping Feng San (YPFS), an ancient Chinese herbal decoction composed of Astragali Radix, Atractylodis Macrocephalae Rhizoma and Saposhnikoviae Radix, has been used in the clinic for treating immune deficiency. In cancer therapy, YPFS is being combined with chemotherapy drugs to achieve improved efficacy; however, scientific evidence to illustrate this combination effect is lacking. The present study aims to demonstrate the anti-drug resistance of YPFS in cisplatin (DDP)-resistant non-small cell lung cancer cells (A549/DDP). The application of YPFS exhibited a synergistic enhancement of DDP-induced cytotoxicity as well as of the apoptotic signalling molecules. DDP-induced expression of the multi-drug-resistance efflux transporters was markedly reduced in the presence of YPFS, resulting in a higher intracellular concentration of DDP. In addition, the application of YPFS increased DDP-induced ROS accumulation and MMP depletion, decreased p62/TRAF6 signalling in DDP-treated A549/DDP cells. The co-treatment of DDP and YPFS in tumour-bearing mice reduced the tumour size robustly (by more than 80%), which was much better than the effect of DDP alone. These results indicate that YPFS can notably improve the DDP-suppressed cancer effect, which may be a consequence of the elevation of intracellular DDP via the drug transporters as well as the down regulation of p62/TRAF6 signalling.

Potential Combinational Anti-Cancer Therapy in Non-Small Cell Lung Cancer with Traditional Chinese Medicine Sun-Bai-Pi Extract and Cisplatin

Traditional lung cancer treatments involve chemical or radiation therapies after surgical tumor removal; however, these procedures often kill normal cells as well. Recent studies indicate that chemotherapies, when combined with Traditional Chinese Medicines, may offer a new way to treat cancer. In vitro tests measuring the induction of autophagy and/or apoptosis were used to examine the cytotoxicity of SBPE, commonly used for lung inflammation on A549 cell line. The results indicated that intercellular levels of p62 and Atg12 were increased, LC3-I was cleaved into LC3-II, and autophagy was induced with SBPE only. After 24 hours, the apoptotic mechanism was induced. If the Cisplatin was added after cells reached the autophagy state, we observed synergistic effects of the two could achieve sufficient death of lung cancer cells. Therefore, the Cisplatin dosage used to induce apoptosis could be reduced by half, and the amount of time needed to achieve the inhibitory concentration of 50% was also half that of the original. In addition to inducing autophagy within a shortened period of time, the SBPE and chemotherapy drug combination therapy was able to achieve the objective of rapid low-dosage cancer cell elimination. Besides, SBPE was applied with Gemcitabine or Paclitaxel, and found that the combination treatment indeed achieve improved lung cancer cell killing effects. However, SBPE may also be less toxic to normal cells.

Tyrosine kinase receptor EGFR regulates the switch in cancer cells between cell survival and cell death induced by autophagy in hypoxia

Autophagy is an intracellular lysosomal degradation pathway where its primary function is to allow cells to survive under stressful conditions. Autophagy is, however, a double-edge sword that can either promote cell survival or cell death. In cancer, hypoxic regions contribute to poor prognosis due to the ability of cancer cells to adapt to hypoxia in part through autophagy. In contrast, autophagy could contribute to hypoxia induced cell death in cancer cells. In this study, we showed that autophagy increased during hypoxia. At 4 h of hypoxia, autophagy promoted cell survival whereas, after 48 h of hypoxia, autophagy increased cell death. Furthermore, we found that the tyrosine phosphorylation of EGFR (epidermal growth factor receptor) decreased after 16 h in hypoxia. Furthermore, EGFR binding to BECN1 in hypoxia was significantly higher at 4 h compared to 72 h. Knocking down or inhibiting EGFR resulted in an increase in autophagy contributing to increased cell death under hypoxia. In contrast, when EGFR was reactivated by the addition of EGF, the level of autophagy was reduced which led to decreased cell death. Hypoxia led to autophagic degradation of the lipid raft protein CAV1 (caveolin 1) that is known to bind and activate EGFR in a ligand-independent manner during hypoxia. By knocking down CAV1, the amount of EGFR phosphorylation was decreased in hypoxia and amount of autophagy and cell death increased. This indicates that the activation of EGFR plays a critical role in the switch between cell survival and cell death induced by autophagy in hypoxia.