Gefitinib treatment in EGFR mutated caucasian NSCLC: circulating-free tumor DNA as a surrogate for determination of EGFR status

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

Background

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

Patients and methods

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

Results

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

Conclusions

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

Clinical Trials

NCT01526928.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

- In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

- To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

- The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

- Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

- The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes ( ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes (ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Selective gene amplification to detect the T790M mutation in plasma from patients with advanced non-small cell lung cancer (NSCLC) who have developed epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance

Background

The epidermal growth factor receptor (EGFR) T790M mutation is associated with resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC). However, tissues for the genotyping of the EGFR T790M mutation can be difficult to obtain in a clinical setting. The aims of this study were to evaluate a blood-based, non-invasive approach to detecting the EGFR T790M mutation in advanced NSCLC patients using the PointMan™ EGFR DNA enrichment kit, which is a novel method for the selective amplification of specific genotype sequences.

Methods

Blood samples were collected from NSCLC patients who had activating EGFR mutations and who were resistant to EGFR-TKI treatment. Using cell-free DNA (cfDNA) from plasma, EGFR T790M mutations were amplified using the PointMan™ enrichment kit, and all the reaction products were confirmed using direct sequencing. The concentrations of plasma DNA were then determined using quantitative real-time PCR.

Results

Nineteen patients were enrolled, and 12 patients (63.2%) were found to contain EGFR T790M mutations in their cfDNA, as detected by the kit. T790M mutations were detected in tumor tissues in 12 cases, and 11 of these cases (91.7%) also exhibited the T790M mutation in cfDNA samples. The concentrations of cfDNA were similar between patients with the T790M mutation and those without the mutation.

Conclusions

The PointMan™ kit provides a useful method for determining the EGFR T790M mutation status in cfDNA.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes (ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Total DNA input is a crucial determinant of the sensitivity of plasma cell-free DNA EGFR mutation detection using droplet digital PCR

We evaluated the use of droplet digital PCR (ddPCR) to detect plasma cell-free DNA (cfDNA) epidermal growth factor receptor (EGFR) mutations in advanced non-small cell lung cancer (NSCLC) patients. Compared with tumor-tissue-based detection, the sensitivity of ddPCR for detecting plasma cfDNA tyrosine kinase inhibitor (TKI)-sensitizing EGFR mutations was 61.3%, the specificity was 96.7%, and the consistency rate was 81.4% (?=0.605, 95% confidence interval: 0.501-0.706, p <0.0001). The sensitivity declined from 82.6% to 46.7% with decreasing cfDNA inputs (p=0.028). The plasma cfDNA concentration correlated with gender (males vs.females =11.69 ng/mL vs. 9.508 ng/mL; p=0.044), EGFR mutation status (tumor-tissue EGFR mutation-positive (EGFR M+) vs. EGFR mutation-negative (EGFR M-) = 9.61 ng/mL vs. 12.82 ng/mL; p =0.049) and specimen collection time (=2 years vs. >2 years=13.83 ng/mL vs. 6.575 ng/mL; p <0.001), and was greater in tumor-tissue EGFR M+ / plasma EGFR M+ patients than in tumor-tissue EGFR M+/plasma EGFR M- patients (11.61 vs. 7.73 ng/mL, respectively; p=0.003). Thus total cfDNA input crucially influences the sensitivity of plasma cfDNA EGFR mutation testing with ddPCR. Such analysis could be an effective supplemental test for advanced NSCLC patients.

Management of acquired resistance to EGFR TKI-targeted therapy in advanced non-small cell lung cancer

Recent advances in diagnosis and treatment are enabling a more targeted approach to treating lung cancers. Therapy targeting the specific oncogenic driver mutation could inhibit tumor progression and provide a favorable prognosis in clinical practice. Activating mutations of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) are a favorable predictive factor for EGFR tyrosine kinase inhibitors (TKIs) treatment. For lung cancer patients with EGFR-exon 19 deletions or an exon 21 Leu858Arg mutation, the standard first-line treatment is first-generation (gefitinib, erlotinib), or second-generation (afatinib) TKIs. EGFR TKIs improve response rates, time to progression, and overall survival. Unfortunately, patients with EGFR mutant lung cancer develop disease progression after a median of 10 to 14 months on EGFR TKI. Different mechanisms of acquired resistance to first-generation and second-generation EGFR TKIs have been reported. Optimal treatment for the various mechanisms of acquired resistance is not yet clearly defined, except for the T790M mutation. Repeated tissue biopsy is important to explore resistance mechanisms, but it has limitations and risks. Liquid biopsy is a valid alternative to tissue re-biopsy. Osimertinib has been approved for patients with T790M-positive NSCLC with acquired resistance to EGFR TKI. For other TKI-resistant mechanisms, combination therapy may be considered. In addition, the use of immunotherapy in lung cancer treatment has evolved rapidly. Understanding and clarifying the biology of the resistance mechanisms of EGFR-mutant NSCLC could guide future drug development, leading to more precise therapy and advances in treatment.

Biopsy-free circulating tumor DNA assay identifies actionable mutations in lung cancer

INTRODUCTION

The potential of oncogene-driven targeted therapy is perhaps most fully realized in non-small cell lung cancer (NSCLC), given the number of genomic targets and approved matched therapies. However, invasive tissue biopsy at the time of each disease progression may not be possible and is associated with high morbidity and cost. Use of newly available "liquid biopsies" can circumvent these issues.

RESULTS

83% of subjects had at least one genomic alteration identified in plasma. Most commonly mutated genes were TP53, KRAS and EGFR. Subjects with no detectable ctDNA were more likely to have small volume disease, lepidic growth pattern, mucinous tumors or isolated leptomeningeal disease.

METHODS

Subjects were individuals with NSCLC undergoing analysis of cell-free circulating tumor DNA using a validated, commercially-available next-generation sequencing assay at a single institution. Demographic, clinicopathologic information and results from tissue and plasma-based genomic testing were reviewed for each subject.

CONCLUSIONS

This is the first clinic-based series of NSCLC patients assessing outcomes of targeted therapies using a commercially available ctDNA assay. Over 80% of patients had detectable ctDNA, concordance between paired tissue and blood for truncal oncogenic drivers was high and patients with biomarkers identified in plasma had PFS in the expected range. These data suggest that biopsy-free ctDNA analysis is a viable first choice when the diagnostic tissue biopsy is insufficient for genotyping or at the time of progression when a repeated invasive tissue biopsy is not possible/preferred.

Development and Clinical Utility of a Blood-Based Test Service for the Rapid Identification of Actionable Mutations in Non-Small Cell Lung Carcinoma

Nearly 80% of cancer patients do not have genetic mutation results available at initial oncology consultation; up to 25% of patients begin treatment before receiving their results. These factors hinder the ability to pursue optimal treatment strategies. This study validates a blood-based genome-testing service that provides accurate results within 72 hours. We focused on targetable variants in advanced non-small cell lung carcinoma-epidermal growth factor receptor gene (EGFR) variant L858R, exon 19 deletion (ΔE746-A750), and T790M; GTPase Kirsten ras gene (KRAS) variants G12C/D/V; and echinoderm microtubule associated protein like and 4 anaplastic lymphoma receptor tyrosine kinase fusion (EML4-ALK) transcripts 1/2/3. Test development included method and clinical validation using samples from donors with (n = 219) or without (n = 30) cancer. Clinical sensitivity and specificity for each variant ranged from 78.6% to 100% and 94.2% to 100%, respectively. We also report on 1643 non-small cell lung carcinoma samples processed in our CLIA-certified laboratory. Mutation results were available within 72 hours for 94% of the tests evaluated. We detected 10.5% mutations for EGFR sensitizing (n = 2801 samples tested), 13.8% mutations for EGFR resistance (n = 1055), 13.2% mutations in KRAS (n = 3477), and 2% mutations for EML4-ALK fusion (n = 304). This rapid, highly sensitive, and actionable blood-based assay service expands testing options and supports faster treatment decisions.

Limits and potential of targeted sequencing analysis of liquid biopsy in patients with lung and colon carcinoma

The circulating free tumor DNA (ctDNA) represents an alternative, minimally invasive source of tumor DNA for molecular profiling. Targeted sequencing with next generation sequencing (NGS) can assess hundred mutations starting from a low DNA input. We performed NGS analysis of ctDNA from 44 patients with metastatic non-small-cell lung carcinoma (NSCLC) and 35 patients with metastatic colorectal carcinoma (CRC). NGS detected EGFR mutations in 17/22 plasma samples from EGFR-mutant NSCLC patients (sensitivity 77.3%). The concordance rate between tissue and plasma in NSCLC was much lower for other mutations such as KRAS that, based on the allelic frequency and the fraction of neoplastic cells, were likely to be sub-clonal. NGS also identified EGFR mutations in plasma samples from two patients with EGFR wild type tumor tissue. Both mutations were confirmed by droplet digital PCR (ddPCR) in both plasma and tissue samples. In CRC, the sensitivity of the NGS plasma analysis for RAS mutations was 100% (6/6) in patients that had not resection of the primary tumor before blood drawing, and 46.2% (6/13) in patients with primary tumor resected before enrollment. Our study showed that NGS is a suitable method for plasma testing. However, its clinical sensitivity is significantly affected by the presence of the primary tumor and by the heterogeneity of driver mutations.

Multiple Hotspot Mutations Scanning by Single Droplet Digital PCR

BACKGROUND

Progress in the liquid biopsy field, combined with the development of droplet digital PCR (ddPCR), has enabled noninvasive monitoring of mutations with high detection accuracy. However, current assays detect a restricted number of mutations per reaction. ddPCR is a recognized method for detecting alterations previously characterized in tumor tissues, but its use as a discovery tool when the mutation is unknown a priori remains limited.

METHODS

We established 2 ddPCR assays detecting all genomic alterations within KRAS exon 2 and EGFR exon 19 mutation hotspots, which are of clinical importance in colorectal and lung cancer, with use of a unique pair of TaqMan® oligoprobes. The KRAS assay scanned for the 7 most common mutations in codons 12/13 but also all other mutations found in that region. The EGFR assay screened for all in-frame deletions of exon 19, which are frequent EGFR-activating events.

RESULTS

The KRAS and EGFR assays were highly specific and both reached a limit of detection of &lt;0.1% in mutant allele frequency. We further validated their performance on multiple plasma and formalin-fixed and paraffin-embedded tumor samples harboring a panel of different KRAS or EGFR mutations.

CONCLUSIONS

This method presents the advantage of detecting a higher number of mutations with single-reaction ddPCRs while consuming a minimum of patient sample. This is particularly useful in the context of liquid biopsy because the amount of circulating tumor DNA is often low. This method should be useful as a discovery tool when the tumor tissue is unavailable or to monitor disease during therapy.

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.

Development and clinical validation of a circulating tumor DNA test for the identification of clinically actionable mutations in nonsmall cell lung cancer

Molecular analysis of potentially actionable mutations has become routine practice in oncological pathology. However, testing a wide range of oncogenes and mutations can be technically challenging because of limitations associated with tumor biopsy. Circulating tumor DNA (ctDNA) is a potential tool for the noninvasive profiling of tumors. In this study, we developed a next-generation sequencing (NGS)-based test for the detection of clinically relevant mutations in ctDNA and evaluated the feasibility of using this ctDNA NGS-based assay as an alternative to tissue genotyping. Tissue and matched blood samples were obtained from 72 patients with advanced nonsmall cell lung cancer (NSCLC). NGS-based testing was performed using plasma cell-free DNA (cfDNA) samples of all 72 patients as well as tumor DNA samples of 46 patients. Of the remaining 26 patients, tDNA was tested by amplification refractory mutation system PCR (ARMS-PCR) because of insufficient tissue sample or quality for NGS. Of the 46 patients who had tDNA and cfDNA NGS performed, we found 20 patients were concordant between tDNA and ctDNA alterations and 21 sample pairs were discordant because of additional alterations found in tDNA. Considering all clinically relevant alterations, the concordance rate between tDNA and ctDNA alterations was 54.9% with a sensitivity of 53.2% and a specificity of 75.0%. Our findings demonstrate that targeted NGS using cfDNA is a feasible approach for rapid and accurate identification of actionable mutations in patients with advanced NSCLC, and may provide a safe and robust alternative approach to tissue biopsy.

Extracellular vesicle-derived DNA for performing EGFR genotyping of NSCLC patients

Tumor cells shed an abundance of extracellular vesicles (EVs) to body fluids containing bioactive molecules including DNA, RNA, and protein. Investigations in the field of tumor-derived EVs open a new horizon in understanding cancer biology and its potential as cancer biomarkers as well as platforms for personalized medicine. This study demonstrates that successfully isolated EVs from plasma and bronchoalveolar lavage fluid (BALF) of non-small cell lung cancer (NSCLC) patients contain DNA that can be used for EGFR genotyping through liquid biopsy. In both plasma and BALF samples, liquid biopsy results using EV DNA show higher accordance with conventional tissue biopsy compared to the liquid biopsy of cfDNA. Especially, liquid biopsy with BALF EV DNA is tissue-specific and extremely sensitive compared to using cfDNA. Furthermore, use of BALF EV DNA also demonstrates higher efficiency in comparison to tissue rebiopsy for detecting p.T790 M mutation in the patients who developed resistance to EGFR-TKIs. These finding demonstrate possibility of liquid biopsy using EV DNA potentially replacing the current diagnostic methods for more accurate, cheaper, and faster results.

Quantification of mutant alleles in circulating tumor DNA can predict survival in lung cancer

Purpose

We aimed to investigate the feasibility of droplet digital PCR (ddPCR) for the quantitative and dynamic detection of EGFR mutations and next generation sequencing (NGS) for screening EGFR-tyrosine kinase inhibitors (EGFR-TKIs) resistance-relevant mutations in circulating tumor DNA (ctDNA) from advanced lung adenocarcinoma (ADC) patients.

Results

Detection limit of EGFR mutation in ctDNA by ddPCR was 0.04%. Taking the EGFR mutation in tumor tissue as the golden standard, the concordance of EGFR mutations detected in ctDNA was 74% (54/73). Patients with EGFR mutation in ctDNA (n = 54) superior progression-free survival (PFS, median, 12.6 vs. 6.7 months, P < 0.001) and overall survival (OS, median, 35.6 vs. 23.8 months, P = 0.028) compared to those with EGFR wild type in ctDNA (n = 19). Patients with high EGFR-mutated abundance in ctDNA (> 5.15%) showed better PFS compared to those with low EGFR mutated abundance (≤ 5.15%) (PFS, median, 15.4 vs. 11.1 months, P = 0.021). NGS results showed that 66.6% (8/12) total mutational copy number were elevated and 76.5% (26/34) mutual mutation frequency increased after disease progression.

Methods

Seventy-three advanced ADC patients with tumor tissues carrying EGFR mutations and their matched pre- and post-EGFR-TKIs plasma samples were enrolled in this study. Absolute quantities of plasma EGFR mutant and wild-type alleles were measured by ddPCR. Multi-genes testing was performed using NGS in 12 patients.

Conclusions

Dynamic and quantitative analysis of EGFR mutation in ctDNA could guide personalized therapy for advanced ADC. NGS shows good performance in multiple genes testing especially novel and uncommon genes.

Detection of circulating tumor DNA in patients with osteosarcoma

Identification and quantification of somatic alterations in plasma-derived, circulating tumor DNA (ctDNA) is gaining traction as a non-invasive and cost effective method of disease monitoring in cancer patients, particularly to evaluate response to treatment and monitor for disease recurrence. To our knowledge, genetic analysis of ctDNA in osteosarcoma has not yet been studied. To determine whether somatic alterations can be detected in ctDNA and perhaps applied to patient management in this disease, we collected germline, tumor, and serial plasma samples from pediatric, adolescent, and young adult patients with osteosarcoma and used targeted Next Generation Sequencing (NGS) to identify somatic single nucleotide variants (SNV), insertions and deletions (INDELS), and structural variants (SV) in 7 genes commonly mutated in osteosarcoma. We demonstrate that patient-specific somatic alterations identified through comparison of tumor-germline pairs can be detected and quantified in cell-free DNA of osteosarcoma patients.

Circulating cell-free DNA as a prognostic and predictive biomarker in non-small cell lung cancer

Circulating cell-free DNA (cfDNA), which can be obtained from plasma or serum by non-invasive procedures, has showed great potential to predict treatment response and survival for cancer patients. Several studies have assessed the prognostic and predictive value of cfDNA in non-small cell lung cancer (NSCLC). However, these studies were often small and reported varying results. To address this issue, a meta-analysis was carried out. A total of 22 studies involving 2518 patients were subjected to the final analysis. Our results indicated that NSCLC patients with higher cfDNA concentration had shorter median progression-free survival (PFS) and overall survival (OS) time. In addition, high levels of cfDNA were significantly associated with poor PFS (hazard ratio or HR, 1.32; 95% CI, 1.02-1.71) and OS (HR, 1.64; 95% CI, 1.26-2.15). With respect to tumor specific mutations, we failed to reveal significant differences for PFS (HR, 1.30; 95% CI, 0.66-2.56) and OS (HR, 1.05; 95% CI, 0.49-2.25) when NSCLC patients were grouped according to KRAS genotype detected in cfDNA. However, NSCLC patients which harbored EGFR activating mutation in cfDNA had a greater chance of response to EGFR-TKIs (odds ratio or OR, 1.96; 95% CI, 1.59-2.42). No significant publication bias was detected in this study. In conclusion, cfDNA could act as a prognostic and predictive biomarker for patients with NSCLC.

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.

Are liquid biopsies a surrogate for tissue EGFR testing?

Molecular profiling has changed the treatment landscape in advanced non-small-cell lung cancer. Accurately identifying the tumours that harbour sensitizing EGFR mutations, the most common targetable molecular alteration, as well as those with acquired resistance mutations (e.g. T790M) on treatment is a high clinical priority. The current clinical gold standard is genotyping of tumour specimens. However, the practical utility of this approach is limited by the lack of available tissue and the potential complications associated with biopsies. With the advent of newer sequencing assays, it has become feasible to assess tumour genomics via a blood sample, termed a 'liquid biopsy'. In this review, we summarize the available techniques for liquid biopsies and their applicability for detecting sensitizing and resistance EGFR mutations and how these results may be used for making treatment decisions.

Validation of liquid biopsy: plasma cell-free DNA testing in clinical management of advanced non-small cell lung cancer

Plasma cell-free tumor DNA, or circulating tumor DNA (ctDNA), from liquid biopsy is a potential source of tumor genetic material, in the absence of tissue biopsy, for EGFR testing. Our validation study reiterates the clinical utility of ctDNA next generation sequencing (NGS) for EGFR mutation testing in non-small cell lung cancer (NSCLC). A total of 163 NSCLC cases were included in the validation, of which 132 patients had paired tissue biopsy and ctDNA. We chose to validate ctDNA using deep sequencing with custom designed bioinformatics methods that could detect somatic mutations at allele frequencies as low as 0.01%. Benchmarking allele specific real time PCR as one of the standard methods for tissue-based EGFR mutation testing, the ctDNA NGS test was validated on all the plasma derived cell-free DNA samples. We observed a high concordance (96.96%) between tissue biopsy and ctDNA for oncogenic driver mutations in Exon 19 and Exon 21 of the EGFR gene. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the assay were 91.1%, 100% 100%, 95.6%, and 97%, respectively. A false negative rate of 3% was observed. A subset of mutations was also verified on droplet digital PCR. Sixteen percent EGFR mutation positivity was observed in patients where only liquid biopsy was available, thus creating options for targeted therapy. This is the first and largest study from India, demonstrating successful validation of circulating cell-free DNA as a clinically useful material for molecular testing in NSCLC.

Blood-based tumor biomarkers in lung cancer for detection and treatment

The therapeutic landscape of lung cancer has expanded significantly over the past decade. Advancements in molecularly targeted therapies, strategies to discover and treat resistance mutations, and development of personalized cancer treatments in the context of tumor heterogeneity and dynamic tumor biology have made it imperative to obtain tumor samples on several different occasions through the course of patient treatment. While this approach is critical to the delivery of optimal cancer treatment, it is fraught with a number of barriers including the need for invasive procedures with associated complications, access to limited amount of tissue, logistical delays in obtaining the biopsy, high healthcare cost, and in many cases inability to obtain tissue because of technically difficult location of the tumor. Given multiple limitations of obtaining tissue samples, the use of blood-based biomarkers ("liquid biopsies") may enable earlier diagnosis of cancer, lower costs by avoiding complex invasive procedures, tailoring molecular targeted treatments, improving patient convenience, and ultimately supplement clinical oncologic decision-making. In this paper, we review various blood-based biomarkers including circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), tumor derived exosomes, tumor educated platelets (TEPs), and microRNA; and highlight current evidence for their use in detection and treatment of lung cancer.

An update on liquid biopsy analysis for diagnostic and monitoring applications in non-small cell lung cancer

INTRODUCTION

Collection of tumor samples is not always feasible in non-small cell lung cancer (NSCLC) patients, and circulating free DNA (cfDNA) extracted from blood represents a viable alternative. Different sensitive platforms have been developed for genetic cfDNA testing, some of which are already in clinical use. However, several difficulties remain, particularly the lack of standardization of these methodologies. Areas covered: Here, the authors present a review of the literature to update the applicability of cfDNA for diagnosis and monitoring of NSCLC patients. Expert commentary: Detection of somatic alterations in cfDNA is already in use in clinical practice and provides valuable information for patient management. Monitoring baseline alterations and emergence of resistance mutations is one of the most important clinical applications and can be used to non-invasively track disease evolution. Today, different technologies are available for cfDNA analysis, including whole-genome or exome sequencing and targeted methods that focus on a selection of genes of interest in a specific disease. In the case of Next Generation Sequencing (NGS) approaches, in depth coverage of candidate mutation loci can be achieved by selecting a limited number of targeted genes.

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.

Detection of somatic variants and EGFR mutations in cell-free DNA from non-small cell lung cancer patients by ultra-deep sequencing using the ion ampliseq cancer hotspot panel and droplet digital polymerase chain reaction

Highly sensitive genotyping assays can detect mutations in cell-free DNA (cfDNA) from cancer patients, reflecting the biology of each patient’s cancer. Because circulating tumor DNA comprises a small, variable fraction of DNA circulating in the blood, sensitive parallel multiplexing tests are required to determine mutation profiles. We prospectively examined the clinical utility of ultra-deep sequencing analysis of cfDNA from 126 non-small cell lung cancer (NSCLC) patients using the Ion AmpliSeq Cancer Hotspot Panel v2 (ICP) and validated these findings with droplet digital polymerase chain reaction (ddPCR). ICP results were compared with tumor tissue genotyping (TTG) results and clinical outcomes. A total of 853 variants were detected, with a median of four variants per patient. Overall concordance of ICP and TTG analyses was 90% for EGFR exon 19 deletion and 88% for the L858R mutation. Of 34 patients with a well-defined EGFR activating mutation defined based on the results of ICP and TTG, 31 (81.6%) showed long-term disease control with EGFR TKI treatment. Of 56 patients treated with an EGFR tyrosine kinase inhibitor (TKI), the presence of the de novo T790M mutation was confirmed in 28 (50%). Presence of this de novo mutation did not have a negative effect on EGFR TKI treatment. Ultra-deep sequencing analysis of cfDNA using ICP combined with confirmatory ddPCR was effective at defining driver genetic changes in NSCLC patients. Comprehensive analysis of tumor DNA and cfDNA can increase the specificity of molecular diagnosis, which could translate into tailored treatment.

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

INTRODUCTION

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

Liquid Biopsy and Therapeutic Targets: Present and Future Issues in Thoracic Oncology

The practice of liquid biopsy (LB) has revolutionized the care of patients with metastatic lung cancer. Many oncologists now use this approach in daily practice, applying precise procedures for the detection of activating or resistance mutations in EGFR. These tests are performed with plasma DNA and have been approved as companion diagnostic test for patients treated with tyrosine kinase inhibitors. ALK is another important target in lung cancer since it leads to treatment of patients who are positive for a rearrangement in ALK identified with tumor tissue. By analogy with EGFR, LB for detection of genomic alterations in ALK (rearrangements or mutations) has been rapidly adopted in the clinic. However, this promising approach has some limitations and has not yet been disseminated as much as the blood test targeting EGFR. In addition to these two therapeutic targets LB can be used for evaluation of the genomic status of other genes of interest of patients with lung cancer (ROS1, RET, NTRK MET, BRAF, HER2, etc.). LB can be performed to evaluate a specific target or for a more or less complex panel of genes. Considering the number of potential targets for clinical trials, techniques of next-generation sequencing of circulating DNA are on the rise. This review will provide an update on the contribution of LB to care of patients with metastatic lung cancer, including the present limits of this approach, and will consider certain perspectives.

The liquid biopsy: a tool for a combined diagnostic and theranostic approach for care of a patient with late-stage lung carcinoma presenting with bilateral ocular metastases

INTRODUCTION

Liquid biopsies (LB) are used routinely in clinical practice in two situations for late stage non-small-cell lung cancer (NSCLC) patients, (i) at the initial diagnosis when looking for activating mutations in EGFR in the absence of analyzable tissue DNA and, (ii) during tumor progression on a tyrosine kinase inhibitor treatment to look for the resistance mutation T790M in EGFR. LB is not presently recommended in daily practice for the diagnosis of NSCLC. Areas covered: We report the diagnosis of a NSCLC in a patient with bilateral ocular metastases after detection of a deletion in exon 19 of EGFR when using plasma DNA. Without histological analysis, the origin of the primary ocular metastasis was uncertain. In this context, a LB showing an activating mutation in EGFR and circulating tumor cells positive for TTF1 led to the diagnosis of NSCLC and targeted therapy. Expert commentary: When no tumor tissue sample is available a LB can be used to diagnose for metastatic NSCLC, when a mutation in EGFR is identified. While a tissue biopsy is the gold standard approach for the diagnosis of a NSCLC and for identification of activating mutations, LB can exceptionally provide both a diagnosis of the primitive tumor and indicate appropriate therapy based on a molecular analysis.

Circulating Tumor DNA in Non–Small-Cell Lung Cancer: A Primer for the Clinician

Circulating tumor DNA (ctDNA) consists of short, double-stranded DNA fragments that are released into the circulation by tumor cells. With the advent of newer molecular platforms, ctDNA can be detected with high sensitivity and specificity in plasma. The assay’s noninvasive nature, ability to reflect intratumoral heterogeneity, short turnaround time, and ability to obtain serial samples make it an attractive option compared with traditional tissue biopsy tumor sequencing. Currently, this technology is mostly being used for the detection of EGFR mutations in patients with advanced non–small-cell lung cancer where tissue is inadequate to detect EGFR mutations that drive acquired resistance, most notably EGFR T790M. Emerging uses include the incorporation of ctDNA testing into primary diagnosis, treatment monitoring, detection of minimal residual disease, and detection of early-stage disease in screening populations. This review summarizes both validated and evolving uses of ctDNA testing in non–small-cell lung cancer in the context of oncologists’ daily practice and some of its potential challenges in the era of targeted therapy and immunotherapy.

Review of the clinical applications and technological advances of circulating tumor DNA in cancer monitoring

Circulating cell-free DNA (cfDNA) released by tumor cells, termed ctDNA, closely reflects the heterogeneity of primary cancers and their metastases. As a noninvasive, real-time monitoring biomarker, ctDNA is a promising tool for detecting driver gene mutations, assessing tumor burden and acquired resistance, and early diagnosis. However, isolation and enrichment of cfDNA is a big challenge due to the high degree of DNA fragmentation and its relatively low abundance in the bloodstream. This review aims to provide insights into the recent technological advances in acquisition of optimal quality cfDNA, the use of preservatives, isolation methods, processing timelines, and detection techniques. It also describes clinical applications of ctDNA in cancer patient management.

Urine test for EGFR analysis in patients with non-small cell lung cancer

Precision medicine approaches in oncology are reliant on the accurate genomic characterization of tumors. While tissue remains the mainstay specimen for molecular testing, tumor biopsies are riddled with challenges and limitations due to their invasive and site-specific nature. Tumor inaccessibility and intratumoral heterogeneity, in particular, represent significant obstacles to the identification of actionable genetic alterations and hence effective mono- and combination therapy strategies. Proof-of-concept studies indicate that circulating tumor DNA (ctDNA) released from multiple tumor regions and anatomical locations is more reflective of intra- and intertumoral heterogeneity. Non-invasive liquid biopsy approaches that allow for the analysis of ctDNA are thus being increasingly implemented in routine patient care for the detection and monitoring of cancer-associated mutations. Indeed, the use of plasma testing to screen for epidermal growth factor receptor (EGFR) T790M mutant positive non-small cell lung cancer (NSCLC) patients eligible for treatment with third-generation EGFR inhibitors was recently approved by the U.S. Food and Drug Administration and is incorporated into the most recent version of the National Comprehensive Cancer Center guidelines as an alternative to tissue biopsy. Urine represents another liquid biopsy specimen that is distinguished by its ease of collection, option for home collection, and lack of temporal and volumetric collection restrictions. Importantly, there is an accumulating body of evidence supporting the clinical validity of urinary EGFR mutant testing for the identification and stratification of patients likely to benefit from EGFR-directed therapies and as a means to assess patient response, the presence of residual disease, and emergence of resistant tumor cell populations.

New insights in non-small-cell lung cancer: circulating tumor cells and cell-free DNA

Lung cancer is the second most frequent tumor and the leading cause of death by cancer in both men and women. Increasing knowledge about the cancer genome and tumor environment has led to a new setting in which morphological and molecular characterization is needed to treat patients in the most personalized way in order to achieve better outcomes. Since tumor products can be detected in body fluids, the liquid biopsy, particularly, peripheral blood, has emerged as a new source for lung cancer biomarker's analysis. A variety of tumor components can be used for this purpose. Among them, circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) should be especially considered. Different detection methods for both CTCs and ctDNA have been and are being developed to improve the sensitivity and specificity of these tests. This would lead to better characterization and would solve some clinical doubts at different disease evolution times, e.g., intratumoral or temporal heterogeneity, difficulty in the obtaining a tumor sample, etc., and would also avoid the side effects of very expensive and complicated tumor obtaining interventions. CTCs and ctDNA are useful in different lung cancer settings. Their value has been shown for the early diagnosis, prognosis, prediction of treatment efficacy, monitoring responses and early detection of lung cancer relapse. CTCs have still not been validated for use in clinical settings in non-small-cell lung cancer (NSCLC), while ctDNA has been approved by the Food and Drug Administration (FDA) and European Medical Association (EMA), and the main clinical guidelines used for detect different epidermal growth factor receptor (EGFR) mutations and the monitoring and treatment choice of mutated patients with tyrosine kinase inhibitors (TKIs). This review, describes how ctDNA seem to be winning the race against CTCs from the laboratory bench to clinical practice due to easier obtaining methods, manipulation and its implementation into clinical practice.

Possible application of circulating free tumor DNA in non-small cell lung cancer patients

Liquid biopsies have been heralded as a game changer in cancer management. Blood tests offer a minimally invasive, safe and sensitive complementary (or even alternative) approach for tissue biopsies. With lung cancer being the second most commonly diagnosed cancer and the leading cause of cancer deaths worldwide, due to the limitations of tissue sampling, liquid biopsies must urgently materialize in the clinic. In this short review, we will present the current applications of cell-free DNA (cfDNA) in lung cancer management, emphasizing on our own experience and previous work. We will also shortly comment on the challenges and need for a coordinated collaboration combining disciplines and sectors (from academia to health economies) in order to accelerate liquid biopsy development in lung cancer and other cancers.

Liquid biopsy genotyping in lung cancer: ready for clinical utility?

Liquid biopsy is a blood test that detects evidence of cancer cells or tumor DNA in the circulation. Despite complicated collection methods and the requirement for technique-dependent platforms, it has generated substantial interest due, in part, to its potential to detect driver oncogenes such as epidermal growth factor receptor (EGFR) mutants in lung cancer. This technology is advancing rapidly and is being incorporated into numerous EGFR tyrosine kinase inhibitor (EGFR-TKI) development programs. It appears ready for integration into clinical care. Recent studies have demonstrated that biological fluids such as saliva and urine can also be used for detecting EGFR mutant DNA through application other user-friendly techniques. This review focuses on the clinical application of liquid biopsies to lung cancer genotyping, including EGFR and other targets of genotype-directed therapy and compares multiple platforms used for liquid biopsy.

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.

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

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

CT characteristics in pulmonary adenocarcinoma with epidermal growth factor receptor mutation

Comprehensively investigate the association of CT morphology and clinical findings of adenocarcinoma with EGFR mutation status. Retrospectively included 282 patients who was pathologically proved as lung adenocarcinoma with known EGFR mutation status (mutations: 138 patients, female: 86, median age: 66 years; wildtype: 144 patients, female: 67, median age: 62 years) and their pre-treatment CT scans were analyzed. CT findings and clinical information were collected. Univariate and multivariable logistic regression analysis were performed. Adjusted for age, gender and smoking history of two groups, significantly more patients with pleural tags, pleural and liver metastases were found in the EGFR mutated group (P = 0.007, 0.004, and 0.043, respectively). Multivariable logistic regression analysis found that the model included age, gender, smoking history, air bronchogram, pleural tags, pleural and liver metastasis had a moderate predictive value for EGFR mutation status (AUC = 0.741, P < .0001). Exon-19 deletion was associated with air bronchogram which adjusted for age, gender and smoking history (P = 0.007, OR: 2.91, 95%CI: 1.25–7.79). The evidence of pleural tags, pleural and liver metastases go along with a higher probability of EGFR mutation in adenocarcinoma patients and air bronchogram is positively associated with Exon-19 deletion mutation.

Circulating tumor DNA shows variable clonal response of breast cancer during neoadjuvant chemotherapy

Circulating tumor DNA (ctDNA) correlates with tumor burden and provides early detection of treatment response and tumor genetic alterations in breast cancer (BC). In this study, we aimed to identify genetic alterations during the process of tumor clonal evolution and examine if ctDNA level well indicated clinical response to neoadjuvant chemotherapy (NAC) and BC recurrence.

We performed targeted ultra-deep sequencing of plasma DNAs, matched germline DNAs and tumor DNAs from locally advanced BC patients. Serial plasma DNAs were collected at diagnosis, after the 1^st cycle of NAC and after curative surgery. For the target enrichment, we designed RNA baits covering a total of ∼202kb regions of the human genome including a total of 82 cancer-related genes.

For ctDNA, 15 serial samples were collected and 87% of plasma SNVs were detected in 13 BC samples that had somatic alterations in tumor tissues. The TP53 mutation was most commonly detected in primary tumor tissues and plasma followed by BRCA1 and BRCA2. At BC diagnosis, the amount of plasma SNVs did not correlate with clinical stage at diagnosis. With respect to the therapeutic effects of NAC, we found two samples in which ctDNA disappeared after the 1^st NAC cycle achieved a pathologic complete response (pCR). In addition, the amount of ctDNA correlated with residual cancer volume detected by breast MRI.

This targeted ultra-deep sequencing for ctDNA analysis would be useful for monitoring tumor burden and drug resistance. Most of all, we suggest that ctDNA could be the earliest predictor of NAC response.

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.

Utility of Genomic Assessment of Blood-Derived Circulating Tumor DNA (ctDNA) in Patients with Advanced Lung Adenocarcinoma

Purpose: Genomic alterations in blood-derived circulating tumor DNA (ctDNA) from patients with non-small cell lung adenocarcinoma (NSCLC) were ascertained and correlated with clinical characteristics and therapeutic outcomes.Experimental Design: Comprehensive plasma ctDNA testing was performed in 88 consecutive patients; 34 also had tissue next-generation sequencing; 29, other forms of genotyping; and 25 (28.4%) had no tissue molecular tests because of inadequate tissue or biopsy contraindications.Results: Seventy-two patients (82%) had ≥1 ctDNA alteration(s); among these, 75% carried alteration(s) potentially actionable by FDA-approved (61.1%) or experimental drug(s) in clinical trials (additional 13.9%). The most frequent alterations were in the TP53 (44.3% of patients), EGFR (27.3%), MET (14.8%), KRAS (13.6%), and ALK (6.8%) genes. The concordance rate for EGFR alterations was 80.8% (100% vs. 61.5%; ≤1 vs. >1 month between ctDNA and tissue tests; P = 0.04) for patients with any detectable ctDNA alterations. Twenty-five patients (28.4%) received therapy matching ≥1 ctDNA alteration(s); 72.3% (N = 16/22) of the evaluable matched patients achieved stable disease ≥6 months (SD) or partial response (PR). Five patients with ctDNA-detected EGFR T790M were subsequently treated with a third generation EGFR inhibitor; all five achieved SD ≥ 6 months/PR. Patients with ≥1 alteration with ≥5% variant allele fraction (vs. < 5%) had a significantly shorter median survival (P = 0.012).Conclusions: ctDNA analysis detected alterations in the majority of patients, with potentially targetable aberrations found at expected frequencies. Therapy matched to ctDNA alterations demonstrated appreciable therapeutic efficacy, suggesting clinical utility that warrants future prospective studies. Clin Cancer Res; 23(17); 5101-11. ©2017 AACR.

Accuracy and clinical influence of plasma EGFR mutation detection in management of advanced lung adenocarcinoma

This study aimed to investigate the accuracy of plasma EGFR status detecting according to tissue EGFR status, and further explore the correlation of plasma EGFR status with clinicopathological features and progression-free survival (PFS) in patients with advanced lung adenocarcinoma. 157 patients with advanced lung adenocarcinoma were recruited. Paired tissue and plasma samples were collected before any prior treatments, EGFR gene mutation detection was performed using the amplification refractory mutation system (ARMS) method. EGFR mutations were detected in 81 tissue samples and the mutation rate was 51.6%, while in 50 plasma samples and the mutation rate was 31.8%. The overall concordance rate of EGFR mutations between tissue and plasma samples was 76.4%. And the sensitivity, specificity, positive predictive value and negative predictive value of the EGFR detection using plasma samples were 94.0%, 68.2%, 58.0 and 96.1% respectively. Patients with no-smoking (P = 0.039) and more number of metastatic sites (P = 0.012) presented a higher EGFR mutation frequency in plasma, but no association of plasma EGFR mutation with other clinicopathological features and PFS by targeted therapy was discovered. This study revealed that plasma EGFR mutation detection might be regarded as a good alternative biomarker for lung adenocarcinoma management, especially for patients who were not tolerant with obtainment of tissue samples, but further prognostic value needs to be investigated.

Circulating DNA in EGFR-mutated lung cancer

Circulating tumor DNA (ctDNA) consists of short double stranded DNA fragments that are released by tumors including non-small cell lung cancer (NSCLC). With the identification of driver mutations in the epidermal growth factor receptor (EGFR) gene and development of targeted tyrosine kinase inhibitors (TKIs), the clinical outcome of NSCLC patients in this subgroup has improved tremendously. The gold standard to assess EGFR mutation is through tissue biopsy, which can be limited by difficulty in accessing the tumor, inability of patients to tolerate invasive procedures, insufficient sample for molecular testing and inability to capture intratumoral heterogeneity. The great need for rapid and accurate identification of activating EGFR mutations in NSCLC patients paves the road for ctDNA technology. Studies have demonstrated ctDNA to be a reliable complement to tumor genotyping. Platforms like digital polymerase chain reaction (PCR) and next-generation sequencing based analyses have made it possible to identify EGFR mutations in plasma with high sensitivity and specificity. This article will provide an overview on ctDNA in the context of EGFR mutated NSCLC, especially its emerging applications in diagnosis, disease surveillance, treatment monitoring and detection of resistance mechanisms.

EGFR mutation prevalence in Asia-Pacific and Russian patients with advanced NSCLC of adenocarcinoma and non-adenocarcinoma histology: The IGNITE study

OBJECTIVES

Limited understanding exists of epidermal growth factor receptor (EGFR) mutation frequency in less common subgroups of advanced non-small-cell lung cancer (aNSCLC) (e.g. squamous cell carcinoma [SCC]), and to what extent local practices exclude patients from EGFR testing based on their clinical characteristics.

MATERIALS AND METHODS

IGNITE (non-comparative/-interventional; NCT01788163) was conducted in 90 centres (Asia-Pacific/Russia). Eligible patients: local/metastatic aNSCLC; chemotherapy-naïve, newly-diagnosed/recurrent disease after resection; ineligible for curative treatment. Patients provided a tissue/cytology (all) and a blood plasma (China/Russia/South Korea/Taiwan) sample. Primary endpoint: EGFR mutation frequency in aNSCLC patients (adenocarcinoma [ADC]/non-ADC), as per local practices.

RESULTS

3382 patients were enrolled. EGFR mutation frequencies for evaluable tissue/cytology samples in Asia-Pacific and Russian patients: 49.3% (862/1749) and 18.0% (90/500) for ADC tumours; 14.1% (74/525) and 3.7% (15/402) for non-ADC; 9.9% (40/403) and 3.7% (13/349) for SCC. Of Russian patients with SCC tumours harbouring common, activating EGFR mutations, 6/9 were never-/former-smokers. Mutation status concordance between 2581 matched tissue/cytology and plasma samples: 80.5% (sensitivity 46.9%, specificity 95.6%).

CONCLUSION

EGFR mutation testing should be considered in all Asian aNSCLC patients. Also, as activating EGFR mutations were observed in a small number of Caucasian squamous NSCLC patients, testing here may be appropriate, particularly in those with no/remote smoking history. Circulating free tumour-derived DNA is feasible for mutation analysis employing well-validated and sensitive methods, when tumour samples are unavailable.

Clinical validation of a highly sensitive assay to detect EGFR mutations in plasma cell-free DNA from patients with advanced lung adenocarcinoma

BACKGROUND

Circulating tumor DNA (ctDNA) is a promising biomarker for noninvasive epidermal growth factor receptor (EGFR) mutations detection in lung cancer patients, but the existing methods have limitations in sensitivity or in availability. In this study, we evaluated the performance of a novel assay called ADx-SuperARMS in detecting EGFR mutations in plasma cell-free DNA from patients with advanced lung adenocarcinoma.

METHODS

A total of 109 patients with metastatic advanced adenocarcinoma were recruited who provided both blood samples and matched tumor tissue samples. EGFR mutation status in plasma samples were tested with ADx-SuperARMS EGFR assay and tumor tissue samples were tested with ADx-ARMS EGFR assay. The clinical sensitivity, specificity, positive prediction value (PPV), and negative prediction value (NPV) of ADx-SuperARMS EGFR assay were calculated by using EGFR mutation status in tumor tissue as standard reference. A receiver operating characteristic (ROC) analysis was implemented and an area under the curve (AUC) was calculated to evaluate sensitivity and specificity of exon 19 deletion (E19Del) and L858R mutation detection. The objective response rate (ORR) were calculated according to the EGFR mutation status determined by ADx-superARMS as well.

RESULTS

0.2% analytical sensitivity and 100% specificity of the ADx-SuperARMS EGFR assays for EGFR E19Del, L858R, and T790M mutants were confirmed by using a series of diluted cell line DNA. In the clinical study, EGFR mutations were detected in 45.9% (50/109) of the plasma samples and in 56.9% (62/109) of the matched tumor tissue samples. The sensitivity, specificity, PPV and NPV of the ADx-SuperARMS EGFR assay for plasma EGFR mutation detection were 82.0% (50/61), 100% (48/48), 100% (50/50), and 81.4% (48/59), respectively. In ROC analysis, ADx-SuperARMS achieved sensitivity and specificity of 88% and 99% in E19Dels as well as sensitivity and specificity of 89% and 100% in L858R, respectively. Among the 35 patients who were plasma EGFR mutation positive and treated with first generation of EGFR-tyrosine kinase inhibitors (TKIs), 23 (65.7%) achieved partial response, 11 (31.4%) sustained disease, and 1 (2.9%) progressive disease. The ORR and disease control rate (DCR) were 65.7% and 97.1%, respectively.

CONCLUSIONS

ADx-SuperARMS EGFR assay is likely to be a highly sensitive and specific method to noninvasively detect plasma EGFR mutations of patients with advanced lung adenocarcinoma. The EGFR mutations detected by ADx-SuperARMS EGFR assay could predict the efficacy of the treatment with first generation of EGFR-TKIs. Hence, EGFR blood testing with ADx-SuperARMS could address the unmet clinical needs.

Crystal digital droplet PCR for detection and quantification of circulating EGFR sensitizing and resistance mutations in advanced non-small cell lung cancer

Over the past years, targeted therapies using tyrosine kinase inhibitors (TKI) have led to an increase in progression-free survival and response rate for a subgroup of non-small cell lung cancer (NSCLC) patients harbouring specific gene abnormalities compared with chemotherapy. However long-lasting tumor regression is rarely achieved, due to the development of resistant tumoral subclones, which requires alternative therapeutic approaches. Molecular profile at progressive disease is a challenge for making adaptive treatment decisions. The aim of this study was to monitor EGFR-mutant tumors over time based on the quantity of mutant DNA circulating in plasma (ctDNA), comparing two different methods, Crystal™ Digital™ PCR and Massive Parallel Sequencing (MPS). In plasma circulating cell free DNA (cfDNA) of 61 advanced NSCLC patients we found an overall correlation of 78% between mutated allelic fraction measured by Crystal Digital PCR and MPS. 7 additional samples with sensitizing mutations and 4 additional samples with the resistance mutation were detected with Crystal Digital PCR, but not with MPS. Monitoring levels of both mutation types over time showed a correlation between levels and trends of mutated ctDNA detected and clinical assessment of disease for the 6 patients tested. In conclusion, Crystal Digital PCR exhibited good performance for monitoring mutational status in plasma cfDNA, and also appeared as better suited to the detection of known mutations than MPS in terms of features such as time to results.

Estimation of cell-free circulating EGFR mutation concentration predicts outcomes in NSCLC patients treated with EGFR-TKIs

Detection of circulating tumor DNA using droplet digital polymerase chain reaction (ddPCR) is a highly-sensitive, minimally invasive alternative to serial biopsies for assessment and management of cancer. We used ddPCR to assess the utility of measuring plasma concentrations of common epidermal growth factor receptor (EGFR) mutations (L858R, exon 19 deletion, and T790M) in 57 non-small cell lung cancer (NSCLC) patients treated with EGFR tyrosine kinase inhibitors (EGFR-TKIs). High baseline plasma EGFR mutation (pEGFRmut) concentrations were associated with shorter progression-free survival (8.43 months) than low baseline pEGFRmut (16.23 months; p = 0.0019). By contrast, there were no differences in tumor shrinkage or overall survival between groups. During EGFR-TKI treatment, pEGFRmut levels decreased to zero in 89.58% of patients. Twenty-five of the 27 patients who progressed had basal pEGFRmut, and 18 also had circulating T790M. All 20 patients with dramatic progression (according to a categorization system for EGFR-TKIs failure) had basal pEGFRmut, and 13 had T790M mutation at progression. These results support the use of ddPCR for analysis of plasma EGFR mutations for prediction of PFS and to monitor clinical responses to EGFR-TKIs in NSCLC patients.