Serum detection of epidermal growth factor receptor gene mutations using mutant-enriched sequencing in Chinese patients with advanced non-small cell lung cancer

A meta-analysis of liquid biopsy versus tumor histology for detecting EGFR mutations in non-small cell lung cancer

OBJECTIVE

To assess the consistency of liquid biopsy and histologic analysis for detecting epidermal growth factor receptor (EGFR) gene mutations in patients with advanced non-small cell lung cancer (NSCLC).

METHODS

The PubMed, Cochrane Library, and CNKI et al. databases were searched to collect studies comparing liquid biopsy and histopathologic specimens. The EGFR mutation status was extracted from the studies, and meta-analysis was carried out using Stata 12.0 software.

RESULTS

We included 22 studies of 3359 NSCLC patients. In the meta-analysis, eight papers with a sample size of size <150 had an OR of 45, indicating that liquid biopsy had high sensitivity for detecting EGFR mutations. In addition, seven papers with a sample size ≥150, with an OR of 70, reported that liquid biopsy was highly susceptible to detecting EGFR mutations. The pooled diagnostic effect size of 6 for literature that included the T790M mutation was smaller than that of 69 for literature that did not include the T790M mutation, and I2 >50 %, showing that literature that did not include the T790M mutation was more heterogeneous. The combined diagnostic effect size of 34 in the exon 19 group was smaller than that in the group with no exon 19, with an I2>50 %. There was substantial heterogeneity in both the exon 19 group and the non-exon 19 group. The group with the L858R mutation had a greater diagnostic effect size of 28, lower I2, and less heterogeneity than the group without the L858R mutation. The exon 21 group had a larger pooled diagnostic effect size of 66, a smaller I2, and less heterogeneity than the group without exon 21.

CONCLUSION

Liquid biopsy and histologic analysis have high concordance for detecting EGFR mutations in NSCLC. Liquid biopsy can provide an alternative technology for individualized treatment and monitoring of minimal residual disease (MRD) in advanced NSCLC patients with EGFR tyrosine kinase inhibitor-sensitive and drug resistance (T790M) mutations.

Interpretation of Lung Cancer Plasma EGFR Mutation Tests in the Clinical Setting

OBJECTIVES

Comprehensive data synthesis of the clinical parameters that affect plasma EGFR mutation test results in non-small cell lung carcinoma is lacking. Although individual studies have suggested a variety of patient characteristics that can affect diagnostic accuracy, no unified conclusion has been reached.

METHODS

We analyzed 170 plasma EGFR mutation tests performed between 2015 and 2021 at our institution and carried out a systematic review and meta-analysis to identify clinical and imaging features that correlate with plasma EGFR mutation test sensitivity.

RESULTS

Data synthesis from 14 studies of 2,576 patients revealed that patients with stage IV disease had a significantly lower false-negative rate than those with stage I through III disease. For our institutional cohort, which consisted of 75 paired plasma and tissue tests that were assessable for diagnostic accuracy, the overall sensitivity was 70.59% (95% confidence interval, 56.17%-82.51%). Patients who had distant metastases and more suspicious lymph nodes on imaging findings correlated with a low false-negative rate.

CONCLUSIONS

While interpreting plasma EGFR mutation results, extra caution should be exercised for patients with early-stage, localized disease to accommodate the possibility of false-negative results. These meta-analyses and clinical data may enable clinicians to make evidence-based judgments for individual patients.

Detection of epidermal growth factor receptor mutations in peripheral blood circulating tumor DNA in patients with advanced non-small cell lung cancer: A PRISMA-compliant meta-analysis and systematic review

BACKGROUND

The epidermal growth factor receptor (EGFR) mutation status related to the treatment approach for advanced non-small cell lung cancer (NSCLC) patients. This study aimed to evaluate the diagnostic accuracy of peripheral blood circulating tumor DNA (ctDNA) in EGFR mutated advanced NSCLC patients.

METHOD

The related database was systematically searched with keywords until January 19, 2020. Studies contained the histopathological and cytological advanced NSCLC samples were included, and the diagnostic data were recorded for calculating sensitivity and specificity. I statistics were used for detecting heterogeneity across studies, and the meta-regression was performed to seek the source of heterogeneity.

RESULT

A total of 32 studies with 4527 advanced NSCLC patients were included in our meta-analysis. Among them, 87% of the patients were diagnosed as stage IV. The pooled sensitivity of peripheral blood ctDNA was 0.70 (95% CI: 0.63-0.75, I = 81.76) and the pooled specificity was 0.98 (95% CI: 0.96-0.99, I = 88.33). The meta-regression showed that the prospective study design and the ARMS detection method were the main source of heterogeneity for sensitivity (P < .05), and the publication country (Asia or non-Asia) was the main source of heterogeneity for specificity (P < .01).

CONCLUSION

ctDNA biopsy has high specificity and diagnostic accuracy in detection of EGFR mutation in advanced NSCLC patients. When the ctDNA gene test result is negative, we should fully consider the risk of missed diagnosis, and further tissue biopsy is still needed to undertake.

The Diagnostic Accuracy of Liquid Biopsy in EGFR-Mutated NSCLC: A Systematic Review and Meta-Analysis of 40 Studies

Epidermal growth factor receptor (EGFR) mutations are the most common carcinogenic driver mutations in non-small-cell lung cancer (NSCLC) patients, while invasive tissue biopsy has certain inherent defects. PubMed, Ovid Medline, Embase, and the Cochrane Library were systematically searched on January 4, 2020, using the keywords "liquid biopsy," "EGFR," and "NSCLC." The pooled sensitivity and specificity of EGFR mutations in paired tissue and blood were calculated. The accuracy was assessed by receiver operating characteristic curve. The meta-regression of the subgroup was performed to analyze the heterogeneity. Hazard ratio (HR) and 95% confidence interval (CI) were combined for evaluating the impact of EGFR mutation in tissue and liquid blood biopsy. A total of 40 studies with 5,995 patients were involved in the study. The pooled sensitivity was 68% (95% CI = 60-75%), and the specificity was 98% (95% CI = 95-99%). The diagnostic odds ratio was 88 (95% CI = 40-195), and the area under the curve was 0.91 (95% CI = 0.88-0.93). In the meta-regression, the sensitivity and specificity remain lower in the Asian studies than non-Asian studies (sensitivity: 66% vs. 73%, P = 0.04; specificity: 96% vs. 97%, P = 0.03, respectively). The EGFR mutation was associated with a better progression-free survival than wild type in both tissue (HR = 0.54, 95% CI = 0.34-0.85, P = 0.007) and blood (HR = 0.81, 95% CI = 0.71-0.92, P = 0.001) detection. Peripheral blood liquid biopsy had a better specificity for detecting EGFR mutation in NSCLC patients, while tissue biopsy still needs to be undertaken for negative blood biopsy patients due to its lower sensitivity.

Evaluation of PCR-HRM, RFLP, and direct sequencing as simple and cost-effective methods to detect common EGFR mutations in plasma cell-free DNA of non-small cell lung cancer patients

BACKGROUND

Lung cancer patients with mutations in epidermal growth factor receptor (EGFR) gene are treated with tyrosine kinase inhibitor (TKI).

AIMS

We aimed to evaluate polymerase chain reaction (PCR)-high-resolution melting (HRM), restriction fragment length polymorphism (RFLP), and direct sequencing (DS) to detect EGFR mutations in cell-free DNA (cfDNA) before and after TKI treatment in real-world settings of a developing country.

METHODS

Paired cytology and plasma samples were collected from 116 treatment-naïve lung cancer patients. DNA from both plasma and cytology specimens was isolated and analyzed using PCR-HRM (to detect exon 19 insertion/deletion), RFLP (to genotypes L858R and L861Q), and DS (to detect uncommon mutations G719A, G719C, or G719S [G719Xaa] in exon 18 and T790M and insertion mutations in exon 20).

RESULTS

EGFR genotypes were obtained in all 116 (100%) cfDNA and 110/116 (94.82%) of cytological specimens of treatment-naïve patient (baseline samples). EGFR-activating mutations were detected in 46/110 (40.6%) plasma samples, and 69/110 (63.2%) mutations were found in routine cytology samples. Using cytological EGFR genotypes as reference, we found that sensitivity and specificity of baseline plasma EGFR testing varied from 9.1% to 39.39% and 83.12% to 96.55%, respectively. In particular, the sensitivity and specificity of this assay in detecting baseline T790M mutations in exon 20 were 30% and 89.58%, respectively. Three months after TKI treatment, plasma T790M and insertion exon 20 mutations appeared in 5.4% and 2.7% patients, respectively.

CONCLUSIONS

Despite low sensitivity, combined DS, RFLP, and PCR-HRM was able to detect EGFR mutations in plasma cfDNA with high specificity. Moreover, TKI resistance exon 20 insertions mutation was detected as early as 3 months post TKI treatment.

Tissue or blood: which is more suitable for detection of EGFR mutations in non-small cell lung cancer?

BACKGROUND

Many studies have evaluated the accuracy of EGFR mutation status in blood against that in tumor tissues as the reference. We conducted this systematic review and meta-analysis to assess whether blood can be used as a substitute for tumor tissue in detecting EGFR mutations.

METHODS

Investigations that provided data on EGFR mutation status in blood were searched in the databases of Medline, Embase, Ovid Technologies and Web of Science. The detect efficiency of EGFR mutations in paired blood and tissues was compared using a random-effects model of meta-analysis. Pooled sensitivity and specificity and diagnostic accuracy were calculated by receiver operating characteristic curve.

RESULTS

A total of 19 studies with 2,922 individuals were involved in this meta-analysis. The pooled results showed the positive detection rate of EGFR mutations in lung cancer tissues was remarkably higher than that of paired blood samples (odds ratio [OR] = 1.47, p<0.001). The pooled sensitivity and specificity of blood were 0.65 and 0.91, respectively, and the area under the receiver operating characteristic curve was 0.89.

CONCLUSIONS

Although blood had a better specificity for detecting EGFR mutations, the absence of blood positivity should not necessarily be construed as confirmed negativity. Patients with negative results for blood should decidedly undergo further biopsies to ascertain EGFR mutations.

Liquid Biopsy as Surrogate to Tissue in Lung Cancer for Molecular Profiling: A Meta-Analysis

Background:

The accurate microscopic diagnosis of lung cancer has become insufficient due to the concept of personalized medicine. Tissue samples are used not only for microscopic diagnosis but also for the assessment of the different targets. Biopsies are performed in 80% of the patients and they are not sufficient for molecular diagnosis in 30% of the cases. Liquid biopsy (LB) has been reported as a possible surrogate to tissue samples and has been introduced in the management scheme of the patients since 2014. We aimed to highlight the diagnostic value of liquid biopsy in assessing the molecular profile of non small cell carcinomas in comparison with tissue biopsy.

Methods:

We retracted eligible articles from PubMed, Embase and Cochrane databases. We calculated the pooled sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR). A summary receiver operating characteristic curve (SROC) and area under curve (AUC) were used to evaluate the overall diagnostic performance using the Meta-Disc software 5.1.32. The heterogeneity was assessed using I square statistics. A meta-regression was performed in case of heterogeneity. In case of absence of covariates, a sensitivity analysis was done in order to assess publications that induced a statistical bias.

Results:

39 eligible studies involving 4782 patients were included. The overall statistical studies showed heterogeneity in the SEN, SPE, PLR, NLR and DOR. No threshold effect was revealed. The meta-regression incorporating the ethnicity, the test, the technique used in tissue and plasma and the use of plasma or serum as covariates showed no impact of these factors. A sensitivity analysis allowed achieving the homogeneity in the SPE and DOR. The overall pooled SEN and SPE were 0.61 and 0.95 respectively. The PLR was 9.51, the NLR was 0.45 and DOR was 24.58. The SROC curve with AUC of 0,93 indicated that the liquid biopsy is capable of identifying wild type samples from mutated ones with a relatively high accuracy.

Conclusion:

This meta-analysis suggested that detection of molecular mutations by cfDNA is of adequate diagnostic accuracy in association to tissues. The high specificity and the moderate sensitivity highlight the value of LB as a screening test

Circulating tumor DNA measurement provides reliable mutation detection in mice with human lung cancer xenografts

Genotype-directed targeted therapy has become one of the standard treatment options for non-small cell lung cancer (NSCLC). There have been numerous limitations associated with mutation analysis of tissue samples. Consequently, mutational profile analysis of circulating cell-free DNA (cfDNA) by highly sensitive droplet digital PCR (ddPCR) assay has been developed. Possibly due to differences in cfDNA concentrations, previous studies have shown numerous discrepancies in mutation detection consistency between tissue and cfDNA. In order to rigorously analyze the amount of cfDNA needed, we constructed 72 athymic nude mice xenografted with NCI-H1975 (harboring a EGFR T790M mutation) or NCI-H460 (harboring a KRAS Q61H mutation) human NSCLC. We thoroughly investigated the relationship between plasma cfDNA using Q-PCR targeting human long interspersed nuclear element-1 (LINE-1) retrotransposon and the mouse ACTB gene, and the accuracy of mutation detection by ddPCR at different times post-graft. Our results show that the concentration and fragmentation of human (tumor) derived cfDNA (hctDNA) were positively correlated with tumor weight, but not with mouse-derived cfDNA (mcfDNA). Quantification of cfDNA by Q-PCR depends on the amplified target length. Mutation copies in plasma of per milliliter were positively linked to tumor weight, hctDNA level and hctDNA/mcfDNA ratio, respectively. Furthermore, tumor weight, hctDNA level and ratio of hctDNA/mcfDNA were significantly higher in cfDNA mutation-positive mice than in negative mice. Also, our data indicate that when plasma hctDNA level and hctDNA/mcfDNA ratio reach a certain level in xenografted mice, plasma cfDNA mutation can be detected. In summary, the present study suggests that determination of ctDNA levels may be essential for reliable mutation detection by analysis of cfDNA.

Incorporating blood-based liquid biopsy information into cancer staging: time for a TNMB system?

Tissue biopsy is the standard diagnostic procedure for cancer. Biopsy may also provide material for genotyping, which can assist in the diagnosis and selection of targeted therapies but may fall short in cases of inadequate sampling, particularly from highly heterogeneous tumors. Traditional tissue biopsy suffers greater limitations in its prognostic capability over the course of disease, most obviously as an invasive procedure with potential complications, but also with respect to probable tumor clonal evolution and metastasis over time from initial biopsy evaluation. Recent work highlights circulating tumor DNA (ctDNA) present in the blood as a supplemental, or perhaps an alternative, source of DNA to identify the clinically relevant cancer mutational landscape. Indeed, this noninvasive approach may facilitate repeated monitoring of disease progression and treatment response, serving as a means to guide targeted therapies based on detected actionable mutations in patients with advanced or metastatic solid tumors. Notably, ctDNA is heralding a revolution in the range of genomic profiling and molecular mechanisms to be utilized in the battle against cancer. This review will discuss the biology of ctDNA, current methods of detection and potential applications of this information in tumor diagnosis, treatment, and disease prognosis. Conventional classification of tumors to describe cancer stage follow the TNM notation system, heavily weighting local tumor extent (T), lymph node invasion (N), and detectable metastasis (M). With recent advancements in genomics and bioinformatics, it is conceivable that routine analysis of ctDNA from liquid biopsy (B) may make cancer diagnosis, treatment, and prognosis more accurate for individual patients. We put forward the futuristic concept of TNMB tumor classification, opening a new horizon for precision medicine with the hope of creating better outcomes for cancer patients.

Clinical efficacy and safety of afatinib in the treatment of non-small-cell lung cancer in Chinese patients

Compared with various malignant tumors, lung cancer has high incidence and the highest mortality worldwide. Non-small-cell lung cancer (NSCLC), the most common kind of lung cancer, is still a great threat to the world, including China. Surgery, platinum-based chemotherapy, and radiotherapy are still the primary treatments for NSCLC patients in the clinic, whereas immunotherapy and targeted therapy are gradually playing more important roles. A next-generation tyrosine kinase inhibitor (TKI), afatinib, was developed as a targeted reagent for epidermal growth factor receptor (EGFR). This targeted drug was effective in a series of trials. The US Food and Drug Administration then approved afatinib as a new first-line treatment for EGFR L858R and exon 19 deletion mutant patients in 2013. This review focused on current clinical studies of afatinib. Although this TKI was not widely available in China until recently, we aim to provide a reference for its future use in China.

Circulating cell-free DNA has a high degree of specificity to detect exon 19 deletions and the single-point substitution mutation L858R in non-small cell lung cancer

Detection of an epidermal growth factor receptor (EGFR) mutation in circulating cell-free DNA (cfDNA) is a noninvasive method to collect genetic information to guide treatment of lung cancer with tyrosine-kinase inhibitors (TKIs). However, the association between cfDNA and detection of EGFR mutations in tumor tissue remains unclear. Here, a meta-analysis was performed to determine whether cfDNA could serve as a substitute for tissue specimens for the detection of EGFR mutations. The pooled sensitivity, specificity, and areas under the curve of cfDNA were 0.60, 0.94, and 0.9208 for the detection of EGFR mutations, 0.64, 0.99, and 0.9583 for detection of the exon 19 deletion, and 0.57, 0.99, and 0.9605 for the detection of the L858R mutation, respectively. Our results showed that cfDNA has a high degree of specificity to detect exon 19 deletions and L858R mutation. Due to its high specificity and noninvasive characteristics, cfDNA analysis presents a promising method to screen for mutations in NSCLC and predict patient response to EGFR-TKI treatment, dynamically assess treatment outcome, and facilitate early detection of resistance mutations.

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.

Discovery of targetable genetic alterations in advanced non-small cell lung cancer using a next-generation sequencing-based circulating tumor DNA assay

Next-generation sequencing (NGS)-based circulating tumor DNA (ctDNA) assays have provided a new method of identifying tumor-driving genes in patients with advanced non-small cell lung carcinoma (NSCLC), especially in those whose cancer tissues are unavailable or in those that have acquired treatment resistance. Here, we describe a total of 119 patients with advanced EGFR-TKI-naive NSCLC and 15 EGFR-TKI-resistant patients to identify somatic SNVs, small indels, CNVs and gene fusions in 508 tumor-related genes. Somatic ctDNA mutations were detected in 82.8% (111/134) of patients in the total cohort. Of the 119 patients with advanced NSCLC, 27.7% (33/119) were suitable for treatment with National Comprehensive Cancer Network (NCCN) guideline-approved targeted drugs. Actionable genetic alterations included 25 EGFR mutations, 5 BRAF mutations, and 1 MET mutation, as well as 1 EML4-ALK gene fusion and 1 KIF5B-RET gene fusion. In 19.3% (23/119) of the patients, we also identified genomic alterations with that could be targeted by agents that are in clinical trials, such as mTOR inhibitors, PARP inhibitors, and CDK4/6 inhibitors. Additionally, the EGFR T790M mutation was found in 46.7% (7/15) of the patients with EGFR-TKI-resistant NSCLC, suggesting that the NGS-based ctDNA assay might be an optional method to monitor EGFR-TKI resistance and to discover mechanisms of drug resistance.

Can peripheral blood be used as surrogate in detecting epidermal growth factor receptor mutation status in advanced non-small cell lung cancer patients? A meta-analysis

Background

Apply peripheral blood as a surrogate for detecting epidermal growth factor receptor mutation status in tumor, also called liquid biopsy, has been reported to be a feasible method in patients with advanced non-small lung cancer. But the diagnostic yield varies in different studies.

Methods

A meta-analysis was carried out to evaluate the sensitivity and specificity of peripheral blood in detection epidermal growth factor receptor mutation status in advanced non-small lung cancer patients. Publications up to October 2016 were searched using PubMed, Embase and Web of Science databases. Sensitivity, specificity and other parameters were pooled using the bivariate mixed-effects regression model.

Results

Fifteen studies meeting the inclusion criteria were included. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were 0.69 (95% CI: 0.59~0.78), 0.97 (95% CI: 0.94~0.99), 23.1 (95% CI: 11.6~46.1), 0.32 (95% CI: 0.23~0.44), 73 (95% CI: 33~159), respectively. The summary receiver operating characteristic curve was 0.93 (95% CI: 0.91–0.95).

Discussion

Detecting epidermal growth factor receptor mutation in peripheral blood is a reliable and non-invasive method in patients with advanced non-small lung cancer. More sensitive detection methods are required to increase the sensitivity of liquid biopsy of ctDNA.

EGFR mutation detection in circulating cell-free DNA of lung adenocarcinoma patients: analysis of LUX-Lung 3 and 6

BACKGROUND

In the Phase III LUX-Lung 3/6 (LL3/LL6) trials in epidermal growth factor receptor (EGFR) mutation-positive lung adenocarcinoma patients, we evaluated feasibility of EGFR mutation detection using circulating cell-free DNA (cfDNA) and prognostic and predictive utility of cfDNA positivity (cfDNA+).

METHODS

Paired tumour and blood samples were prospectively collected from randomised patients. Mutations were detected using cfDNA from serum (LL3) or plasma (LL6) by a validated allele-specific quantitative real-time PCR kit.

RESULTS

EGFR mutation detection rates in cfDNA were 28.6% (serum) and 60.5% (plasma). Mutation detection in blood was associated with advanced disease characteristics, including higher performance score, number of metastatic sites and bone/liver metastases, and poorer prognosis. In patients with common EGFR mutations, afatinib improved progression-free survival vs chemotherapy in cfDNA+ (LL3: HR, 0.35; P=0.0009; LL6: HR, 0.25; P<0.0001) and cfDNA- (LL3: HR, 0.46; P<0.0001; LL6: HR, 0.12; P<0.0001) cohorts. A trend towards overall survival benefit with afatinib was observed in cfDNA+ patients.

CONCLUSIONS

Plasma cfDNA is a promising alternative to biopsy for EGFR testing. Detectable mutation in blood was associated with more advanced disease and poorer prognosis. Afatinib improved outcomes in EGFR mutation-positive patients regardless of blood mutation status.

Digital PCR analysis of plasma cell-free DNA for non-invasive detection of drug resistance mechanisms in EGFR mutant NSCLC: Correlation with paired tumor samples

As the development of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has become an issue of concern, identification of the mechanisms responsible has become an urgent priority. However, for research purposes, it is not easy to obtain tumor samples from patients with EGFR mutation-positive non-small-cell lung cancer (NSCLC) that has relapsed after treatment with EGFR-TKIs. Here, using digital PCR assay as an alternative and noninvasive method, we examined plasma and tumor samples from patients with relapsed NSCLC to establish the inter-relationships existing among T790M mutation, activating EGFR mutations, HER2 amplification, and MET amplification. Paired samples of tumor and blood were obtained from a total of 18 patients with NSCLC after they had developed resistance to EGFR-TKI treatment, and the mechanisms of resistance were analyzed by digital PCR. Digital PCR analysis of T790M mutation in plasma had a sensitivity of 81.8% and specificity of 85.7%, the overall concordance between plasma and tissue samples being 83.3%. MET gene copy number gain in tumor DNA was observed by digital PCR in three patients, of whom one exhibited positivity for MET amplification by FISH, whereas no patient demonstrated MET and HER2 copy number gain in plasma DNA. Digital PCR analysis of plasma is feasible and accurate for detection of T790M mutation in NSCLC that becomes resistant to treatment with EGFR-TKIs.

Clinical Utility of Liquid Diagnostic Platforms in Non-Small Cell Lung Cancer

: A firmer understanding of the genomic landscape of lung cancer has recently led to targeted, therapeutic advances in non-small cell lung cancer. Historically, the reference standard for the diagnosis and genetic interrogation for advanced-stage patients has been tissue acquisition via computed tomography-guided core or fine needle aspiration biopsy. However, this process can frequently put the patient at risk and remains complicated by sample availability and tumor heterogeneity. In addition, the time required to complete the diagnostic assays can negatively affect clinical care. Technological advances in recent years have led to the development of blood-based diagnostics or "liquid biopsies" with great potential to quickly diagnose and genotype lung cancer using a minimally invasive technique. Recent studies have suggested that molecular alterations identified in cell-free DNA (cfDNA) or circulating tumor DNA can serve as an accurate molecular proxy of tumor biology and reliably predict the response to tyrosine kinase therapy. In addition, several trials have demonstrated the high accuracy of microRNA (miRNA) platforms in discerning cancerous versus benign nodules in high-risk, screened patients. Despite the promise of these platforms, issues remain, including varying sensitivities and specificities between competing platforms and a lack of standardization of techniques and downstream processing. In the present report, the clinical applications of liquid biopsy technologies, including circulating tumor cells, proteomics, miRNA, and cfDNA for NSCLC, are reviewed and insight is provided into the diagnostic and therapeutic implications and challenges of these platforms.

IMPLICATIONS FOR PRACTICE

Although tumor biopsies remain the reference standard for the diagnosis and genotyping of non-small cell lung cancer, they remain fraught with logistical complexities that can delay treatment decisions and affect clinical care. Liquid diagnostic platforms, including cell-free DNA, proteomic signatures, RNA (mRNA and microRNA), and circulating tumor cells, have the potential to overcome many of these barriers, including rapid and accurate identification of de novo and resistant genetic alterations, real-time monitoring of treatment responses, prognosis of outcomes, and identification of minimal residual disease. The present report provides insights into new liquid diagnostic platforms in non-small cell lung cancer and discusses the promise and challenges of their current and future clinical use.

Circulating DNA in diagnosis and monitoring EGFR gene mutations in advanced non-small cell lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are current treatments for advanced non-small cell lung cancer (NSCLC) harboring activating EGFR gene mutations. Histological or cytological samples are the standard tumor materials for EGFR mutation analysis. However, the accessibility of tumor samples is not always possible and satisfactory in advanced NSCLC patients. Moreover, totality of EGFR mutated NSCLC patients will develop resistance to EGFR-TKIs. Repeat biopsies to study genetic evolution as a result of therapy are difficult, invasive and may be confounded by intra-tumor heterogeneity. Thus, exploring accurate and less invasive techniques to (I) diagnosis EGFR mutation if tissue is not available or not appropriate for molecular analysis and to (II) monitor EGFR-TKI treatment are needed. Circulating DNA fragments carrying tumor specific sequence alterations [circulating cell-free tumor DNA (cftDNA)] are found in the cell-free fraction of blood, representing a variable and generally small fraction of the total circulating DNA. cftDNA has a high degree of specificity to detect EGFR gene mutations in NSCLC. Studies have shown the feasibility of using cftDNA to diagnosis of EGFR activating gene mutations and also to monitor tumor dynamics in NSCLC patients treated with EGFR-TKIs. These evidences suggested that non-invasive techniques based on blood samples had a great potential in EGFR mutated NSCLC patients. In this review, we summarized these non-invasive approaches and relative scientific data now available, considering their possible applications in clinical practice of NSCLC treatment.

Emerging platforms using liquid biopsy to detect EGFR mutations in lung cancer

Advances in target therapies for lung cancer have enabled detection of gene mutations, specifically those of EGFR. Assays largely depend on the acquisition of tumor tissue biopsy, which is invasive and may not reflect the genomic profile of the tumor at treatment due to tumor heterogeneity or changes that occur during treatment through acquired resistance. Liquid biopsy, a blood test that detects evidence of cancer cells or tumor DNA, has generated considerable interest for its ability to detect EGFR mutations. However, its clinical application is limited by complicated collection methods and the need for technique-dependent platforms. Recently, simpler techniques for EGFR mutant detection in urine or saliva samples have been developed. This review focuses on advances in liquid biopsy and discusses its potential for clinical implementation in lung cancer.

Role of circulating-tumor DNA analysis in non-small cell lung cancer

The discovery of actionable driver mutations such as epidermal growth factor receptor (EGFR) and microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) and their highly responses to EGFR and ALK tyrosine kinase inhibitors (TKIs) in patients with advanced non-small-cell lung cancer (NSCLC) allowed precise medicine into reality. However, a substantial part of patients still have no sufficient tissue to perform genomic analysis. As a promising noninvasive biomarker and potential surrogate for the entire tumor genome, circulating tumor DNA (ctDNA) has been applied to the detection of driver gene mutations and epigenetic alteration and monitoring of tumor burden, acquired resistance, tumor heterogeneity and early diagnosis. Since precise therapy is a strategy that optimal therapy is decided based on simultaneous tumor genome information, ctDNA, as a liquid biopsy, may help to perform dynamic genetic surveillance. In this paper we will perspectively discuss the biology and identification of ctDNA in the blood of NSCLC patients and its clinical applications in patient management.

The Emergent Landscape of Detecting EGFR Mutations Using Circulating Tumor DNA in Lung Cancer

The advances in targeted therapies for lung cancer are based on the evaluation of specific gene mutations especially the epidermal growth factor receptor (EGFR). The assays largely depend on the acquisition of tumor tissue via biopsy before the initiation of therapy or after the onset of acquired resistance. However, the limitations of tissue biopsy including tumor heterogeneity and insufficient tissues for molecular testing are impotent clinical obstacles for mutation analysis and lung cancer treatment. Due to the invasive procedure of tissue biopsy and the progressive development of drug-resistant EGFR mutations, the effective initial detection and continuous monitoring of EGFR mutations are still unmet requirements. Circulating tumor DNA (ctDNA) detection is a promising biomarker for noninvasive assessment of cancer burden. Recent advancement of sensitive techniques in detecting EGFR mutations using ctDNA enables a broad range of clinical applications, including early detection of disease, prediction of treatment responses, and disease progression. This review not only introduces the biology and clinical implementations of ctDNA but also includes the updating information of recent advancement of techniques for detecting EGFR mutation using ctDNA in lung cancer.

Non-invasive approaches to monitor EGFR-TKI treatment in non-small-cell lung cancer

Tyrosine kinase inhibitors of epidermal growth factor receptor (EGFR-TKIs) are standard treatments for advanced non-small-cell lung cancer (NSCLC) patients harboring activating epidermal growth factor receptor (EGFR) mutations. Nowadays, tumor tissues acquired by surgery or biopsy are the routine materials for EGFR mutation analysis. However, the accessibility of tumor tissues is not always satisfactory in advanced NSCLC. Moreover, a high proportion of NSCLC patients will eventually develop resistance to EGFR-TKIs. Invasive procedures, such as surgery or biopsy, are impractical to be performed repeatedly to assess the evolution of EGFR-TKI resistance. Thus, exploring some convenient and less invasive techniques to monitor EGFR-TKI treatment is urgently needed. Circulating cell-free tumor DNA (ctDNA) has a high degree of specificity to detect EGFR mutations in NSCLC. Besides, ctDNA is capable of monitoring the disease progression during EGFR-TKI treatment. Certain serum microRNAs that correlate with EGFR signaling pathway, such as miR-21 and miR-10b, have been demonstrated to be helpful in evaluating the efficiency of EGFR-TKI therapeutics. A commercialized serum-based proteomic test, named VeriStrat test, has shown an outstanding ability to predict the clinical outcome of NSCLC patients receiving EGFR-TKIs. Analysis of EGFR mutations in circulating tumor cells (CTCs) is feasible, and CTCs represent a promising material to predict EGFR-TKI-treatment efficacy and resistance. These evidences suggested that non-invasive techniques based on serum or plasma samples had a great potential for monitoring EGFR-TKI treatment in NSCLC. In this review, we summarized these non-invasive approaches and considered their possible applications in EGFR-TKI-treatment monitoring.

Blood as a Substitute for Tumor Tissue in Detecting EGFR Mutations for Guiding EGFR TKIs Treatment of Nonsmall Cell Lung Cancer: A Systematic Review and Meta-Analysis

Tumor tissues are often absent or insufficient for testing epidermal growth factor receptor (EGFR) mutations to guide EGFR tyrosine kinase inhibitors (TKIs) treatment of patients with nonsmall cell lung cancer (NSCLC). We conducted this systematic review and meta-analysis to assess whether blood can be used as a substitute for tumor tissue in detecting EGFR mutations. MEDLINE, EMBASE, and the Cochrane Library were searched for studies that provided data to estimate the accuracy of blood testing against tissue testing in NSCLC patients and/or those directly compared the efficacy of EGFR TKIs in EGFR mutant and wild-type patients according to sources of specimens. Sensitivity, specificity, and concordance rate were used as measures of the accuracy. Risk ratio (RR) for objective response and hazard ratio (HR) for progression-free survival (PFS) and overall survival (OS) were used as measures for treatment efficacy. We combined the effects by using the fixed-effects model unless there was evidence of heterogeneity, in which case a random-effects mode was used. This systematic review included 25 studies with 2605 patients. The pooled overall sensitivity, specificity, and concordance rate were 0.61, 0.90, and 0.79, respectively. Serum showed lower sensitivity (0.56 vs 0.65) but higher specificity (0.95 vs 0.85) and higher concordance (0.86 vs 0.74) than plasma. EGFR mutations (exon 19 or 21) in blood were significantly associated with objective response (RR: 4.08; 95% confidence interval [CI] 2.48-6.70), PFS (HR: 0.72; 95% CI 0.64-0.80), and OS (HR: 0.71; 95% CI 0.50-0.99). Importantly, the association of the mutations with the 3 clinical outcomes for serum was similar to that for tumor tissue and higher than that for plasma. Blood, in particular serum, is a good substitute when tumor tissue is absent or insufficient for testing EGFR mutations to guide EGFR TKIs treatment in patients with NSCLC. EGFR mutation positivity in blood could be used to recommend EGFR TKIs treatment, but the absence of blood positivity should not necessarily be construed with confirmed negativity.

High resolution melting analysis for epidermal growth factor receptor mutations in formalin-fixed paraffin-embedded tissue and plasma free DNA from non-small cell lung cancer patients

BACKGROUND

The aim of the research was to explore a cost effective, fast, easy to perform, and sensitive method for epidermal growth factor receptor (EGFR) mutation testing.

METHODS

High resolution melting analysis (HRM) was introduced to evaluate the efficacy of the analysis for dectecting EGFR mutations in exons 18 to 21 using formalin-fixed paraffin-embedded (FFPE) tissues and plasma free DNA from 120 patients.

RESULTS

The total EGFR mutation rate was 37.5% (45/120) detected by direct sequencing. There were 48 mutations in 120 FFPE tissues assessed by HRM. For plasma free DNA, the EGFR mutation rate was 25.8% (31/120). The sensitivity of HRM assays in FFPE samples was 100% by HRM. There was a low false-positive mutation rate but a high false-negative rate in plasma free DNA detected by HRM.

CONCLUSIONS

Our results show that HRM analysis has the advantage of small tumor sample need. HRM applied with plasma free DNA showed a high false-negative rate but a low false-positive rate. Further research into appropriate methods and analysis needs to be performed before HRM for plasma free DNA could be accepted as an option in diagnostic or screening settings.

Targeted treatment of mutated EGFR-expressing non-small-cell lung cancer: focus on erlotinib with companion diagnostics

Deeper understanding of the pathobiology of non-small-cell lung cancer (NSCLC) has led to the development of small molecules that target genetic mutations known to play critical roles in the progression to metastatic disease. The discovery of epidermal growth factor receptor (EGFR) mutations in 15%–20% of lung adenocarcinomas and the associated response to EGFR tyrosine kinase inhibitors have provided a successful avenue of attack in late-stage adenocarcinomas. Use of the EGFR tyrosine kinase inhibitors gefitinib, erlotinib, and afatinib is limited to patients who have adenocarcinomas with known activating EGFR mutations. However, the EGFR mutation testing landscape is varied and includes many screening and targeted methods, each with its own benefits and limitations. These tests can simplify the drug discovery process, make clinical trials more efficient and informative, and individualize cancer therapy. In practice, the choice of method should be determined by the nature of the sample to be tested, the testing laboratory’s expertise and access to equipment, and whether the detection of only known activating EGFR mutations, or of all possible mutations, is required. Development of companion diagnostic tests for this identification is advancing; nevertheless, the use of such tests merits greater attention.

Cell-free circulating tumor DNA in plasma/serum of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the common type of lung cancer, which is the leading cause of cancer death throughout the world. Most patients were diagnosed too late for curative treatment. So, it is necessary to develop a minimal invasive method to identify NSCLC at an early stage. In recent years, cell-free circulating tumor DNA (ctDNA) has attracted increasing attention as a potential tumor marker for its minimal invasive, convenient, and easily accepted properties. The amount of ctDNA in plasma or serum was significantly higher in NSCLC patients than that in healthy controls or patients with benign diseases. Furthermore, many studies have proved an association among tumor stage, tumor grade, lymph node involvement, the number of metastatic sites, tumor response, survival outcome, and the ctDNA levels. Many genetic changes, such as gene mutation, loss of heterozygosity, microsatellite instability, and gene methylation were also found in ctDNA in NSCLC patients. These findings demonstrated that the ctDNA could serve as a viable tool to monitor NSCLC and prompted us to find more sensitive and specific biomarkers for clinical practice, especially monitor these cases with at least one known gene abnormality. Here, we reviewed the evidence of ctDNA in NSCLC and consider possible future applications in patient management.

Circulating tumor DNA is effective for the detection of EGFR mutation in non-small cell lung cancer: a meta-analysis

BACKGROUND

Circulating tumor DNA (ctDNA) has offered a minimally invasive and feasible approach for detection of EGFR mutation for non-small cell lung cancer (NSCLC). This meta-analysis was designed to investigate the diagnostic value of ctDNA, compared with current "gold standard," tumor tissues.

METHODS

We searched PubMed, EMBASE, Cochrane Library, and Web of Science to identify eligible studies that reported the sensitivity and specificity of ctDNA for detection of EGFR mutation status in NSCLC. Eligible studies were pooled to calculate the pooled sensitivity, specificity, and diagnostic odds ratio (DOR). The summary ROC curve (SROC) and area under SROC (AUSROC) were used to evaluate the overall diagnostic performance.

RESULTS

Twenty-seven eligible studies involving 3,110 participants were included and analyzed in our meta-analysis, and most studies were conducted among Asian population. The pooled sensitivity, specificity, and DOR were 0.620 [95% confidence intervals (CI), 0.513-0.716), 0.959 (95% CI, 0.929-0.977), and 38.270 (95% CI, 21.090-69.444), respectively. The AUSROC was 0.91 (95% CI, 0.89-0.94), indicating the high diagnostic performance of ctDNA.

CONCLUSION

ctDNA is a highly specific and effective biomarker for the detection of EGFR mutation status.

IMPACT

ctDNA analysis will be a key part of personalized cancer therapy of NSCLC.

Diagnostic value of circulating free DNA for the detection of EGFR mutation status in NSCLC: a systematic review and meta-analysis

Epidermal growth factor receptor (EGFR) mutation is a reliable and sensitive biomarker for EGFR-TKI therapy in non-small-cell lung cancer (NSCLC). However, detection of EGFR mutation in tissues has obvious limitations. Circulating free DNA (cfDNA) has been reported as an alternative approach for the detection of EGFR mutations. This systematic review and meta-analysis was designed to assess the diagnostic performance of cfDNA, compared with tissues. True-positive (TP), false-positive (FP), false-negative (FN), and true-negative (TN) values were extracted or calculated for each study. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. A summary receiver operating characteristic curve (SROC) and area under curve (AUC) were used to evaluate the overall diagnostic performance. 20 eligible studies involving 2012 cases were included in this meta-analysis. The pooled sensitivity, specificity, PLR, NLR, andDORwere 0.674 (95%CI: 0.517–0.800), 0.935 (95%CI: 0.888–0.963), 10.307 (95%CI: 6.167–17.227), 0.348 (95%CI: 0.226–0.537), and 29.582 (95%CI: 4.582–60.012), respectively. The AUC was 0.93 (95% CI: 0.90–0.95). The meta-analysis suggests that detection of EGFR mutation by cfDNA is of adequate diagnostic accuracy and cfDNA analysis could be a promising screening test for NSCLC.

Peripheral blood for epidermal growth factor receptor mutation detection in non-small cell lung cancer patients

OBJECTIVE: It is important to analyze and track Epidermal Growth Factor Receptor (EGFR) mutation status for predicting efficacy and monitoring resistance throughout EGFR-tyrosine kinase inhibitors (TKIs) treatment in non-small cell lung cancer (NSCLC) patients. The objective of this study was to determine the feasibility and predictive utility of EGFR mutation detection in peripheral blood. METHODS: Plasma, serum and tumor tissue samples from 164 NSCLC patients were assessed for EGFR mutations using Amplification Refractory Mutation System (ARMS). RESULTS: Compared with matched tumor tissue, the concordance rate of EGFR mutation status in plasma and serum was 73.6% and 66.3%, respectively. ARMS for EGFR mutation detection in blood showed low sensitivity (plasma, 48.2%; serum, 39.6%) but high specificity (plasma, 95.4%; serum, 95.5%). Treated with EGFR-TKIs, patients with EGFR mutations in blood had significantly higher objective response rate (ORR) and insignificantly longer progression-free survival (PFS) than those without mutations (ORR: plasma, 68.4% versus 38.9%, P = 0.037; serum, 75.0% versus 39.5%, P = 0.017; PFS: plasma, 7.9 months versus 6.1 months, P = 0.953; serum, 7.9 months versus 5.7 months, P = 0.889). In patients with mutant tumors, those without EGFR mutations in blood tended to have prolonged PFS than patients with mutations (19.7 months versus 11.0 months, P = 0.102). CONCLUSIONS: EGFR mutations detected in blood may be highly predictive of identical mutations in corresponding tumor, as well as showing correlations with tumor response and survival benefit from EGFR-TKIs. Therefore, blood for EGFR mutation detection may allow NSCLC patients with unavailable or insufficient tumor tissue the opportunity to benefit from personalized treatment. However, due to the high false negative rate in blood samples, analysis for EGFR mutations in tumor tissue remains the gold standard.

Novel therapeutic strategies for patients with NSCLC that do not respond to treatment with EGFR inhibitors

INTRODUCTION

Treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) yields tumour responses in non-small cell lung cancer (NSCLC) patients harbouring activating EGFR mutations. However, even in long-lasting responses, resistance to EGFR TKIs invariably occurs.

AREAS COVERED

This review examines resistance mechanisms to EGFR TKI treatment, which mainly arise from secondary EGFR mutations. Other resistance-inducing processes include mesenchymal-epithelial transition factor (MET) amplification, epithelial-mesenchymal transformation, phenotypic change from NSCLC to small-cell lung carcinoma, and modifications in parallel signalling pathways. Current therapeutic strategies to overcome these EGFR TKI resistance mechanisms focus on the inhibition or blocking of multiple members of the ErbB family. Several molecules which target multiple ErbB receptors are being investigated in NSCLC and other indications including afatinib, an ErbB Family Blocker, as well as dacomitinib and lapatinib. Novel, non-quinazoline, EGFR inhibitors, that also target EGFR activating and resistance (T790M) mutations, are currently under clinical development. Other therapeutic strategies include inhibition of parallel and downstream pathways, using agents which target heat shock protein (HSP)90 or poly (ADP-ribose) polymerase in addition to mammalian target of rapamycin (mTOR), monoclonal antibodies against the insulin-like growth factor-1 receptor, and fulvestrant-mediated oestrogen receptor regulation.

CONCLUSION

Improved understanding of mechanisms underlying resistance to EGFR TKIs emphasises the importance of a genotype-guided approach to therapy. Elucidation of resistance mechanisms is indeed crucial to target innovative therapeutic approaches and to improve the efficacy of anticancer regimes in NSCLC.

Monitoring of carcinoembryonic antigen levels is predictive of EGFR mutations and efficacy of EGFR-TKI in patients with lung adenocarcinoma

For the detection of epidermal growth factor receptor (EGFR) mutations, tumor tissues may not always be available. Not all the patients harboring EGFR mutation have a clinical response after the treatment of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI). EGFR mutations were detected in 70 cases of newly diagnosed non-smoking adenocarcinoma, and patients harboring EGFR mutations received EGFR-TKI treatment. The EGFR mutation status of these patients' blood was analyzed by amplification refractory mutation system (ARMS). The patients' carcinoembryonic antigen (CEA) levels were tested on the third, seventh, 15(th), and 30th days after EGFR-TKI treatment. Forty-four cases were found with EGFR mutations. EGFR mutation rate of CEA high-level group was significantly higher than low-level group (70.8% vs. 40.9%, P = 0.017). Multivariate analysis showed that high-level CEA is independently associated with EGFR gene mutation (P = 0.020, OR = 3.508, 95%CI, 1.223-10.059). The sensitivity of high CEA level and ARMS to predict EGFR mutation were 79.1% and 51.2%. We divided the patients who received EGFR-TKI treatment into three groups by the variation types of CEA. Univariate analysis showed that patients in descending type group have longer progression-free survival (P = 0.001, HR 6.981, 95%CI, 2.534-19.237). Multivariate Cox proportional hazards model analyses shows the same result (P = 0.001, HR 9.82, 95%CI, 3.322-26.031). In conditions of the current technique, using high CEA level to predict EGFR mutations seems to be more sensitive than using EGFR mutations in plasma. The variation types of CEA level could help us to predict the efficacy of EGFR-TKI in patients harboring EGFR mutation within only 1 month of tyrosine kinase inhibitor therapy.

Role of quantitative and qualitative characteristics of free circulating DNA in the management of patients with non-small cell lung cancer

BACKGROUND

The release of DNA into peripheral blood is a common event in cancer patients, occurring as a consequence of necrotic and apoptotic processes typical of tumor cells. However, free circulating DNA (fcDNA) is also present in patients with benign diseases and in healthy individuals. Both quantitative and qualitative aspects of fcDNA have been studied as potential biomarkers in a number of tumor types. In particular, quantitative analysis of fcDNA has been shown to play an important role in the diagnosis of non-small cell lung cancer (NSCLC), because of its ability to discriminate between healthy subjects and individuals with NSCLC. Additionally, fcDNA in cancer patients derives predominantly from tumor tissue and, as such, it can be used for the molecular characterization of the primary tumor. Targeted therapies in NSCLC have, in recent years, produced promising results, highlighting the importance of molecular profiling of the primary cancer lesions. Considering that little or no tumor material is available for at least some of the patients, the possibility of using fcDNA for molecular analysis becomes increasingly important. In the present review we evaluated several quantitative and qualitative aspects of fcDNA that could be instrumental for the differential diagnosis of lung disease.

CONCLUSIONS

There is ample evidence in the literature to support the possible use of peripheral blood-derived fcDNA in the early diagnosis and molecular characterization of lung cancer. This non-invasive method may also turn out to be valuable in monitoring drug response and in identifying induced mechanisms of drug resistance. Before it can be implemented in routine clinical practice, however, additional efforts are needed to standardize the methodology.

Detection of EGFR mutations in circulating free DNA by PNA-mediated PCR clamping

Background

Epidermal growth factor receptor (EGFR)-activating mutations are major determinants in predicting the tumor response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). Noninvasive test for the detection of EGFR mutations is required, especially in NSCLC patients from whom tissue is not available. In this study, we assessed the feasibility of detection of EGFR mutations in free DNA circulating in plasma.

Methods

Plasma samples of 60 patients with partial response to gefitinib were analyzed to detect EGFR-activating mutations in exons 19 and 21. Forty (66.7%) of patients had tumor EGFR mutation results. EGFR mutations in plasma were detected using the peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping method. All clinical data and plasma samples were obtained from 11 centers of the Korean Molecular Lung Cancer Group (KMLCG).

Results

Of the 60 patients, 39 were female and the median age was 62.5 years. Forty-three patients never smoked, 53 had adenocarcinomas, and seven had other histologic types. EGFR-activating mutation was detected in plasma of 10 cases (exon 19 deletion in seven and exon 21 L858R point mutation in three). It could not be found in plasma after treatment for 2 months. When only patients with confirmed EGFR mutation in tumor were analyzed, 17% (6 of 35) of them showed positive plasma EGFR mutation and the mutation type was completely matched with that in tumor. There was no statistically significant difference in clinical parameters between patients with EGFR mutations in plasma and those without EGFR mutations.

Conclusions

The detection rate of EGFR mutations from plasma was not so high despite highly sensitive EGFR mutation test suggesting that more advances in detection methods and further exploration of characteristics of circulating free DNA are required.

Target therapy in NSCLC patients: Relevant clinical agents and tumour molecular characterisation

In recent years, a number of new agents that target specific molecular pathways in non-small cell lung cancer (NSCLC) have been investigated. Much effort has been focused on identifying specific markers that are predictive of treatment response, given that a tailored approach would maximise the therapeutic index and cost-effectiveness. Gefitinib and erlotinib are selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) and have produced good results in selected cases in terms of objective response rate and overall survival. At present, EGFR gene mutations are considered the most important predictors of clinical response to TKI therapy and tumour characterisation for these alterations is mandatory prior to any decision making. Echinoderm microtubule-like protein 4-anaplastic lymphoma kinase (EML4-ALK) translocation is another alteration capable of predicting the efficacy of anti-ALK agents, such as crizotinib. Moreover, emerging target agents, such as MET inhibitors, are likely to increase the amount of molecular characterisation required before a decision is made on treatment. The main limiting factor for adequate characterisation of metastatic NSCLC patients is the small quantity of tumour cells available for molecular analysis. In this study, we provided an overview of the most important and clinically relevant target agents in NSCLC patients as well as the most important mechanisms of resistance. The issue of the scant amount of biological samples available for analysis as well as alternative sampling approaches such as plasma- or serum-derived DNA were also examined.

Therapeutic and preventive effects of an epidermal growth factor receptor inhibitor on oral squamous cell carcinoma

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is the sixth most common human neoplasm worldwide. Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is highly expressed in human OSCC and is a target for cancer therapy and prevention. This study investigated the therapeutic and preventive effects of an inhibitor of EGFR (PD153035) on OSCC.

METHODS

The effects of PD153035 were examined in human cancer cell lines in vitro, in an athymic nude mouse xenograft model in vivo, and in the 7,12-dimethyl benz[a]anthracene (DMBA)-induced hamster cheek pouch tumour model in vivo.

RESULTS

PD153035 significantly inhibited cell growth, delayed cell cycle progression and induced apoptosis in human OSCC cells in vitro. In vivo, PD153035 inhibited xenograft tumour growth in nude mice in a dose-dependent manner and prevented the development of OSCC at the postinitiation stage in the DMBA-induced hamster cheek pouch tumour model. PD153035 inhibited the DMBA-induced increases in cell proliferation and in levels of phosphorylated EGFR and phosphorylated signal transducer and activator of transcription 3 (STAT3) protein in the hamster cheek pouch.

CONCLUSIONS

Inhibitors of EGFR, such as PD153035, have potential value in the treatment and prevention of OSCC.