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

Clinical Utility and Application of Liquid Biopsy Genotyping in Lung Cancer: A Comprehensive Review

Precision medicine has revolutionized the therapeutic management of cancer patients with a major impact on non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma, where advances have been remarkable. Tissue biopsy, required for tumor molecular testing, has significant limitations due to the difficulty of the biopsy site or the inadequacy of the histological specimen. In this context, liquid biopsy, consisting of the analysis of tumor-released materials circulating in body fluids, such as blood, is increasingly emerging as a valuable and non-invasive biomarker for detecting circulating tumor DNA (ctDNA) carrying molecular tumor signatures. In advanced/metastatic NSCLC, liquid biopsy drives target therapy by monitoring response to treatment and identifying eventual genomic mechanisms of resistance. In addition, recent data have shown a significant ability to detect minimal residual disease in early-stage lung cancer, underlying the potential application of liquid biopsy in the adjuvant setting, in early detection of recurrence, and also in the screening field. In this article, we present a review of the currently available data about the utility and application of liquid biopsy in lung cancer, with a particular focus on the approach to different techniques of analysis for liquid biopsy and a comparison with tissue samples as well as the potential practical uses in early and advanced/metastatic NSCLC.

Circulating EGFR Mutations in Patients with Lung Adenocarcinoma by Circulating Tumor Cell Isolation Systems: A Concordance Study

Background: We developed a hybrid platform using a negative combined with a positive selection strategy to capture circulating tumor cells (CTCs) and detect epidermal growth factor receptor (EGFR) mutations in patients with metastatic lung adenocarcinoma. Methods: Blood samples were collected from patients with pathology-proven treatment-naïve stage IV lung adenocarcinoma. Genomic DNA was extracted from CTCs collected for EGFR mutational tests. The second set of CTC-EGFR mutational tests were performed after three months of anti-cancer therapy. Results: A total of 80 samples collected from 28 patients enrolled between July 2016 and August 2018. Seventeen patients had EGFR mutations, including Exon 19 deletion (n = 11), L858R (n = 5), and de-novo T790 and L858R (n = 1). Concordance between tissue and CTCs before treatment was 88.2% in EGFR- mutant patients and 90.9% in non-mutant patients. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of EGFR mutation tests for CTCs were 89.3%, 88.2%, 90.9%, 93.8%, and 83.3%, respectively. Conclusions: CTCs captured by a hybrid platform using a negative and positive selection strategy may serve as a suitable and reliable source of lung cancer tumor DNA for detecting EGFR mutations, including T790M.

The Presence of EGFR T790M in TKI-Naïve Lung Cancer Samples of Patients Who Developed a T790M-Positive Relapse on First or Second Generation TKI Is Rare

EGFR-mutated non-small cell lung cancer (NSCLC) patients can be effectively treated with tyrosine kinase inhibitors (TKI) but frequently present with an EGFR T790M resistance mutation at relapse. We aimed to screen for T790M in pre-treatment formalin-fixed and paraffin-embedded (FFPE) tissue samples of patients with a confirmed T790M mutation at progression. We analyzed 33 pre-treatment DNA samples of NSCLC patients who progressed upon TKI between 2013 to 2019. To establish storage-time dependent formalin fixation-induced background levels for C>T mutations, we analyzed DNA isolated from archival (stored >1 year, n = 22) and recently generated (stored <1 month, n = 11) FFPE samples and included DNA isolated from white blood cells (WBC) (n = 24) as controls. DNA samples were analyzed by droplet digital (dd)PCR, and positivity was defined by outlier detection according to Grubb’s criterion. The T790M background allele frequency levels were 0.160% in DNA isolated from archival-FFPE, 0.100% in fresh FFPE, and 0.035% in WBC. Progression-free survival (PFS) time of the single T790M positive patient was 9 months, while T790M negative patients had a median PFS of 10 months (range 2−27). Proper storage time matched FFPE control samples are essential for reliable detection of T790M mutation at low VAF. The presence of EGFR T790M mutations in pre-TKI samples is rare, even in patients who progressed with EGFR T790M mutations.

Association between squamous cell carcinoma antigen level and EGFR mutation status in Chinese lung adenocarcinoma patients

Background

To investigate the association between squamous cell carcinoma antigen (SCCAg) level and epidermal growth factor receptor (EGFR) mutation status in Chinese lung adenocarcinoma patients.

Methods

We retrospectively analyzed 293 patients with lung adenocarcinoma, divided into EGFR mutant group (n = 178) and EGFR wild‐type group (n = 115). The general data and laboratory parameters of the two groups were compared. We used univariable and multivariable logistic regression to analyze the association between SCCAg level and EGFR mutation. Generalized additive model was used for curve fitting, and a hierarchical binary logistic regression model was used for interaction analysis.

Results

Squamous cell carcinoma antigen level in the EGFR wild‐type group was significantly higher than that in the mutant group (p < 0.001). After adjusting for confounding factors, we found that elevated SCCAg was associated with a lower probability of EGFR mutation, with an OR of 0.717 (95% CI: 0.543–0.947, p = 0.019). For the tripartite SCCAg groups, the increasing trend of SCCAg was significantly associated with the decreasing probability of EGFR mutation (p for trend = 0.015), especially for Tertile 3 versus Tertile 1 (OR = 0.505; 95% CI: 0.258–0.986; p = 0.045). Curve fitting showed that there was an approximate linear negative relationship between continuous SCCAg and EGFR mutation probability (p = 0.020), which was first flattened and then decreased (p < 0.001). The association between the two was consistent among different subgroups, suggesting no interaction (all p > 0.05).

Conclusion

There is a negative association between SCCAg level and EGFR mutation probability in Chinese lung adenocarcinoma patients.

Using All Our Genomes: Blood-based Liquid Biopsies for the Early Detection of Cancer

The pursuit of highly sensitive and specific cancer diagnostics based on cell-free (cf) nucleic acids isolated from minimally invasive liquid biopsies has been an area of intense research and commercial effort for at least two decades. Most of these tests detect cancer-specific mutations or epigenetic modifications on circulating DNA derived from tumor cells (ctDNA). Although recent FDA approvals of both single and multi-analyte liquid biopsy companion diagnostic assays are proof of the tremendous progress made in this domain, using ctDNA for the diagnosis of early-stage (stage I/II) cancers remains challenging due to several factors, such as low mutational allele frequency in circulation, overlapping profiles in genomic alterations among diverse cancers, and clonal hematopoiesis. This review discusses these analytical challenges, interim solutions, and the opportunity to complement ctDNA diagnostics with microbiome-aware analyses that may mitigate several existing ctDNA assay limitations.

Study of patient characteristics, treatment patterns, EGFR testing patterns and outcomes in real-world patients with EGFRm+ non-small cell lung cancer

OBJECTIVE

This retrospective, observational study examined patient characteristics, treatment patterns, testing patterns, and outcomes of US patients receiving first-/second- or third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs).

METHODS

This study used an electronic health record-derived de-identified database. Eligible patients had advanced EGFRm⁺ non-small cell lung cancer. Descriptive statistics were used to describe demographic, clinical, and treatment characteristics. Logistic regression models were used to identify patient characteristics that were associated with the use of osimertinib vs. a first-/second-generation EGFR TKI. Kaplan-Meier methods were used for survival analysis.

RESULTS

Of the 782 patients who received first-line (1L) therapy with first-/second-generation EGFR TKIs in cohort A, erlotinib was the most common (58%), and osimertinib was the most widely prescribed second-line (2L) therapy (52%). Of the patients who received 1L therapy with osimertinib, a greater range of treatments were prescribed in 2L. A third of patients treated with first-/second-generation EGFR TKIs underwent EGFR testing near the end of 1L, and 44% of these patients had T790M positive disease. The median time on targeted therapy (TTT) of the cohort was 11.1 months (95% confidence interval [CI] 9.7, 12.3), and the median overall survival from the start of 1L therapy was 23.5 months (95% CI 20.7, 24.8).

CONCLUSIONS

The majority of patients treated with first-/second-generation EGFR TKIs went on to receive osimertinib in the 2L setting, but overall, only a third of patients had received molecular testing at progression. Improved testing frequency is vital to inform treatment decisions.

The value of cell-free circulating tumour DNA profiling in advanced non-small cell lung cancer (NSCLC) management

Liquid biopsy (LB) has boosted a remarkable change in the management of cancer patients by contributing to tumour genomic profiling. Plasma circulating cell-free tumour DNA (ctDNA) is the most widely searched tumour-related element for clinical application. Specifically, for patients with lung cancer, LB has revealed valuable to detect the diversity of targetable genomic alterations and to detect and monitor the emergence of resistance mechanisms. Furthermore, its non-invasive nature helps to overcome the difficulty in obtaining tissue samples, offering a comprehensive view about tumour diversity. However, the use of the LB to support diagnostic and therapeutic decisions still needs further clarification. In this sense, this review aims to provide a critical view of the clinical importance of plasma ctDNA analysis, the most widely applied LB, and its limitations while anticipating concepts that will intersect the present and future of LB in non-small cell lung cancer patients.

Graphical Abstract

EGFR-plasma mutations in prognosis for non-small cell lung cancer treated with EGFR TKIs: A meta-analysis

BACKGROUND

The plasma-based epidermal growth factor receptor (EGFR) mutation testing is approved recently to use in clinical practice. However, it has not been used as a prognostic marker yet because of contradictory results.

AIM

This meta-analysis aims to clarify the role of the EGFR-plasma test in prognosis for non-small cell lung cancer (NSCLC) who have mutant tumors and receive EGFR tyrosine kinase inhibitors (TKIs).

METHODS AND RESULTS

The PubMed/MEDLINE, Web of Science, Cochrane Library, and Google Scholar databases were searched for relevant studies by April 10, 2021. The hazard ratio (HR) from reports was extracted and used to assess the correlation of EGFR-plasma status with progression-free survival (PFS) and overall survival (OS). A total of 35 eligible studies with 4106 patients were enrolled in the final analysis. Patients with concurrent EGFR mutations in pretreatment plasma have shorter PFS (HR = 2.00, 95% confidence interval [CI]: 1.73-2.31, p < .001) and OS time (HR = 2.31, 95% CI: 1.89-2.83, p < .001) compared to the tumor-only mutation cases. Besides, the persistence of EGFR-activating mutations in post-treatment plasma is associated with worse PFS (HR = 3.84, 95% CI: 2.96-4.99, p < .001) and OS outcome (HR = 3.22, 95% CI: 2.35-4.42, p < .001) compared to others. Notably, the prognostic value of the EGFR-plasma test is also validated in treatment with third-generation EGFR TKI and significance regardless of different detection methods.

CONCLUSION

The presence of EGFR-plasma mutations at pretreatment and after EGFR TKI initiation is the worse prognostic factor for PFS and OS in NSCLC.

Circulating tumor DNA in lung cancer: real-time monitoring of disease evolution and treatment response

Lung cancer is one of the leading causes of all cancer-related deaths. Circulating tumor DNA (ctDNA) is released from apoptotic and necrotic tumor cells. Several sensitive techniques have been invented and adapted to quantify ctDNA genomic alterations. Applications of ctDNA in lung cancer include early diagnosis and detection, prognosis prediction, detecting mutations and structural alterations, minimal residual disease, tumor mutational burden, and tumor evolution tracking. Compared to surgical biopsy and radiographic imaging, the advantages of ctDNA are that it is a non-invasive procedure, allows real-time monitoring, and has relatively high sensitivity and specificity. Given the massive research on non-small cell lung cancer, attention should be paid to small cell lung cancer.

Understanding barriers to the introduction of precision medicine in non-small cell lung cancer: a qualitative interview study

Background: While treatments targeting genetic mutations and alterations in non-small cell lung cancer (NSCLC) have been available since 2010, the adoption of such examples of precision medicine into clinical practice has historically been slow. This means that patients with NSCLC may not have received life improving and extending treatments which should have been available to them. The purpose of this qualitative interview study was to identify the barriers to the provision of examples of precision medicine for NSCLC. Methods: This study used semi-structured telephone interviews with clinicians, test providers and service commissioners to identify the perceived barriers to providing historical, current, and future examples of precision medicine in NSCLC. Participants were identified through mailing list advertisements and snowball sampling. The qualitative data was analysed using a framework analysis. Results: Interviews were conducted with 11 participants including: five oncologists; three pathologists; two clinical geneticists; and one service commissioner. A total of 17 barriers to the introduction of precision medicine for NSCLC were identified and these were grouped into five themes: the regulation of precision medicine and tests; the commissioning and reimbursement of tests and the testing process; the complexity of the logistics around providing tests; centralisation or localisation of test provision; and opinions about future developments in precision medicine for NSCLC. Conclusions: A number of barriers exist to the introduction of precision medicine in NSCLC. Addressing these barriers may improve access to novel life improving and extending treatments for patients.

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.

A circulating tumor cell-based digital assay for the detection of EGFR T790M mutation in advanced non-small cell lung cancer

Determining the status of epidermal growth factor receptor (EGFR) T790M mutation is crucial for guiding further treatment intervention in advanced non-small cell lung cancer (NSCLC) patients who develop acquired resistance to initial EGFR tyrosine kinase inhibitor (TKI) treatment. Circulating tumor cells (CTCs) which contain plentiful copies of well-preserved RNA offer an ideal source for noninvasive detection of T790M mutation in NSCLC. We developed a CTC-based digital assay which synergistically integrates NanoVelcro Chips for enriching NSCLC CTCs and reverse-transcription droplet digital PCR (RT-ddPCR) for quantifying T790M transcripts in the enriched CTCs. We collected 46 peripheral arterial and venous blood samples from 27 advanced NSCLC patients for testing this CTC-based digital assay. The results showed that the T790M mutational status observed by the CTC-based digital assay matched with those observed by tissue-based diagnostic methods. Furthermore, higher copy numbers of T790M transcripts were observed in peripheral arterial blood than those detected in the matched peripheral venous blood. In short, our results demonstrated the potential of the NanoVelcro CTC-digital assay for noninvasive detection of the T790M mutation in NSCLC, and suggested that peripheral arterial blood sampling may offer a more abundant CTC source than peripheral venous blood in advanced NSCLC patients.

Liquid biopsy mutation panel for non-small cell lung cancer: analytical validation and clinical concordance

Molecular testing for genomic variants is recommended in advanced non-small cell lung cancer (NSCLC). Standard tissue biopsy is sometimes infeasible, procedurally risky, or insufficient in tumor tissue quantity. We present the analytical validation and concordance study of EGFR variants using a new 17-gene liquid biopsy assay (NCT02762877). Of 144 patients enrolled with newly diagnosed or progressive stage IV nonsquamous NSCLC, 140 (97%) had liquid assay results, and 117 (81%) had both EGFR blood and tissue results. Alterations were detected in 58% of liquid samples. Overall tissue-liquid concordance for EGFR alterations was 94.0% (95% CI 88.1%, 97.6%) with positive percent agreement of 76.7% (57.7%, 90.1%) and negative percent agreement of 100% (95.8%, 100%). Concordance for ALK structural variants was 95.7% (90.1%, 98.6%). This assay detected alterations in other therapeutically relevant genes at a rate similar to tissue analysis. These results demonstrate the analytical and clinical validity of this 17-gene assay.

Presence of mEGFR ctDNA predicts a poor clinical outcome in lung adenocarcinoma

Background

Circulating tumor DNA (ctDNA) is a biomarker for the selection of target agents in various malignancies. In this study, we examined the effect of ctDNA presence on the response to EGFR‐tyrosine kinase inhibitor (TKI) and on the prognosis in lung adenocarcinoma.

Methods

ctDNA of EGFR‐TKI sensitizing mutations (mEGFR), L858R substitution and Exon 19 deletion (E19d) mutation, was evaluated using droplet digital PCR (ddPCR) in 81 patients with lung adenocarcinoma which harbored mEGFR in the corresponding tumor tissues.

Results

The study recruited lung cancer patients at various stages, and the sensitivity, specificity, and area under the curve (AUC) of mEGFR ctDNA detection by ddPCR were 40.0%, 88.5%, and 0.68, respectively. It showed higher sensitivity (75.0% vs. 10.0%) and AUC (0.83 vs. 0.49) in the advanced stages of lung adenocarcinoma compared with the early stages and the number of metastases and the fractional abundance of mEGFR ctDNA showed a strong correlation (σ = 0.516; P < 0.001, Spearman correlation test). There was a significantly shorter progression‐free survival and duration of disease control by EGFR‐TKIs in the ctDNA‐positive group than the negative group (14.0 vs. 41.0 months, P = 0.02 and 12.0 vs. 23.0 months, P = 0.02, log‐rank test, respectively). There was a trend for overall survival time to be shorter in patients with mEGFR ctDNA than for patients without mEGFR ctDNA (35.6 vs. 67.1 months, P = 0.06, log‐rank test).

Conclusions

These data showed that mEGFR ctDNA detection using ddPCR is useful in the advanced stages and its presence predicted distant metastasis and poor clinical outcome in lung adenocarcinoma.

The Prediction Of Epidermal Growth Factor Receptor Mutation And Prognosis Of EGFR Tyrosine Kinase Inhibitor By Serum Ferritin In Advanced NSCLC

Purpose

To investigate the association between level of serum ferritin (SF) and epidermal growth factor receptor (EGFR) mutations and to analyse the impact of SF level on survival times in advanced non-small-cell lung cancer (NSCLC) patients taking EGFR tyrosine kinase inhibitors (EGFR-TKIs).

Methods

A total of 301 patients who were admitted to the Chinese PLA general hospital from August 2015 to August 2017 were enrolled. The association between tumour markers, including SF, CEA, and EGFR mutation, and their impact on the prognosis of patients taking EGFR-TKIs was investigated.

Results

In all patients, the percentage of patients with EGFR mutations was 52.5% (158/301). EGFR mutations were more likely to be detected in younger (<60 years old), adenocarcinoma patients, non-smokers, women, CEA≥5 µg/L and serum ferritin ≥129 µg/L for females or ≥329 µg/L for males (p<0.05). Increased serum ferritin was an independent factor for predicting EGFR mutations (odds ratio (OR)=4.593, 95% CI (2.673–7.890); P <0.001), and an area under curve (AUC) of 0.711 was shown to predict EGFR mutations with a sensitivity of 81.7% and a specificity of 65.2% in women. Sensitivity increased to 91.1% when combining SF and CEA in all patients. SF was also an independent factor (HR=3.531, 95% CI (2.288–5.448); P<0.001) for predicting progression-free survival (PFS) of patients on EGFR-TKIs, analysed by a Cox proportional hazard model, as PFS was shorter in patients with higher SF (15.0 mo. (SF < 129 µg/L for females or <329 for males) vs 10.0 mo. (129–258 µg/L for females or 329–658 µg/L for males) vs 7.3 mo. (>258 µg/L (>258 µg/L for females or >658 µg/L for males) p<0.001).

Conclusion

SF was a significant predictor of EGFR mutation with moderate diagnostic accuracy, and combining SF and CEA increased the diagnostic sensitivity and specificity for EGFR mutations. SF was also useful for predicting survival in EGFR-TKIs.

Liquid Biopsy in Tumor Genetic Diagnosis

BACKGROUND

Liquid biopsy involves the analysis of cell-free nucleic acids, mainly circulating free DNA (cfDNA), in bodily fluids such as blood. The obtaining of specimens is easier for patients and less invasive than tissue biopsy, but the method has certain limitations.

METHODS

This review is based on pertinent publications retrieved by a selective literature search.

RESULTS

Because the concentration of cfDNA in plasma is less than 0.001%, special amplifying techniques must be used to enable a search for specific mutations. Liquid biopsy can be used in patients with non-small cell lung cancer (NSCLC) if no tissue is available for biopsy; when performed for this indication, it has 67% sensitivity and 94% specificity. If liquid biopsy does not reveal a mutation, this may be due either to the absence of the mutation in the tumor or to the inadequate sensitivity of the measuring technique. This uncertainty associated with negative findings can be reduced by the simultaneous demonstration of reference mutations derived from a primary tumor tissue analysis. In comparison to tissue studies, the search for tumor-specific mutations by liquid biopsy is 70% sensitive and 69% specific; this corresponds to a positive predictive value of 86% and a negative predictive value of 46%.

CONCLUSION

Liquid biopsy and tumor tissue analysis are complementary, rather than alternative, techniques for therapeutically relevant genetic investigation of tumors. Comparative studies are needed so that further indications can be determined for liquid biopsy in the diagnostic evaluation of cancer.

Circulating Cell-Free DNA-Diagnostic and Prognostic Applications in Personalized Cancer Therapy

Genomic analyses in oncologic care allow for the development of more precise clinical laboratory tests that will be critical for personalized pharmacotherapy. Traditional biopsy-based approaches are limited by the availability of sequential tissue specimens to detect resistance. Blood-based genomic profiling ("liquid biopsy") is useful for longitudinal monitoring of tumor genomes and can complement biopsies. Tumor-associated mutations can be identified in cell-free tumor DNA (ctDNA) from patient blood samples and used for monitoring disease activity. The US Food and Drug Administration approved a liquid biopsy test for EGFR-activating mutations in patients with non-small-cell lung cancer as a companion diagnostic for therapy selection. ctDNA also allows for the identification of mutations selected by treatment such as EGFR T790M in non-small-cell lung cancer. ctDNA can also detect mutations such as KRAS G12V in colorectal cancer and BRAF V600E/V600K in melanoma. Chromosomal aberration pattern analysis by low-coverage whole genome sequencing is a new, broader approach. Genomic imbalances detected in cell-free DNA (cfDNA) can be used to compute a copy number instability (CNI) score. In clinical studies, it was demonstrated that the change in CNI score can serve as an early predictor of therapeutic response to chemotherapy/immunotherapy of many cancer types. In multivariable models, it could be shown that the CNI score was superior to clinical parameters for prediction of overall survival in patients with head and neck cancer. There is emerging evidence for the clinical validity of ctDNA testing regarding identification of candidates for targeted therapies, prediction of therapeutic response, early detection of recurrence, resistance mutation detection, measuring genetic heterogeneity, tumor burden monitoring, and risk stratification. Improvement of sensitivity to detect tumors at very early stages is difficult due to insufficient mutant DNA fraction of ≤0.01%. Further developments will include validation in prospective multicenter interventional outcome studies and the development of digital platforms to integrate diagnostic data.

Evaluation of EGFR mutations in NSCLC with highly sensitive droplet digital PCR assays

Targeted drugs have been widely used in the treatment of patients with lung cancer, particularly for those with non-small cell lung cancer (NSCLC). Plasma cell-free DNA is an emerging clinical tool for the detection of epidermal growth factor receptor (EGFR) gene mutation in patients with lung cancer. Detection of circulating tumor (ct) DNA by droplet digital PCR (ddPCR) is a highly sensitive and minimally invasive alternative for the assessment and management of cancer. In the present study, four ddPCR systems were developed to detect the 19DELs, L858R, T790M and C797S mutations of the EGFR gene in plasma ctDNA samples, and all exhibited higher sensitivity compared with the amplification refractory mutation system (ARMS)-PCR assays. The results revealed that the sensitivity of the ddPCR assays for the four major types of EGFR mutant reached 0.04%. In total, 50 plasma ctDNA samples were collected from patients with NSCLC to detect the 19DELs, L858R, T790M and C797S mutations by ddPCR and ARMS-PCR. All the mutations except for C797S were detected and the concordance rates between ddPCR and ARMS-PCR were 96% (19DELs), 98% (L858R) and 100% (T790M). The fraction of EGFR mutation ranged from 0.43 to 68.07% using the ddPCR method. Therefore, the present study suggests that the four ddPCR testing systems could be used for early detection of EGFR mutations in plasma samples, so that patients can better select the targeted drugs according to the EGFR mutation.

Pleural effusion as a substitute for tumor tissue in detecting EGFR/ALK mutations in non-small cell lung cancer: A systematic review and meta-analysis

BACKGROUND

Pleural effusion (PE) has been reported useful in many studies for testing epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) with variable results. This systematic review and meta-analysis was performed to elucidate whether PE could be used as a surrogate for tumor tissue to detect EGFR mutations.

METHODS

We extracted 2 × 2 diagnostic table from each included study and calculated data on specificity, sensitivity, negative likelihood ratio (NLR), positive likelihood ratio (PLR) ,and diagnostic odds ratio (DOR). We used the area under curve (AUC) and summary receiver operating characteristic curve (SROC) to summarize the overall diagnostic performance and assessed publication bias by Deeks' funnel plot.

RESULTS

Our meta-analysis included 15 eligible publications. The following summary estimates for diagnostic parameters of the EGFR mutations detection in PE were made: sensitivity, 0.86 (95%CI 0.83-0.89); specificity, 0.93 (95%CI 0.91-0.95); PLR, 8.53 (95%CI 5,94-12.25); NLR, 0.18 (95%CI 0.13-0.25); DOR, 63.40 (95%CI 38.83-103.51); and AUC, 0.94. Funnel plot indicated publication bias insignificant.

CONCLUSIONS

The meta-analysis suggests that EGFR mutation detecting in PE, especially supernatants, is a promising surrogate for tumor tissue in EGFR mutations testing of patients with NSCLC.

Liquid Biopsy in Solid Malignancy

The clinical utility of tissue biopsies in cancer management will continue to expand, especially with the evolving role of targeted therapies. "Liquid biopsy" refers to testing a patient's biofluid samples such as blood or urine to detect tumor-derived molecules and cells that can be used diagnostically and prognostically in the assessment of cancer. Many proof-of-concept and pilot studies have shown the clinical potential of liquid biopsies as diagnostic and prognostic markers which would provide a surrogate for the conventional "solid biopsy". In this review, we focus on three methods of liquid biopsy-circulating tumor cells, extracellular vesicles, and circulating tumor DNA-to provide a landscape view of their clinical applicability in cancer management and research.

Promising clinical application of ctDNA in evaluating immunotherapy efficacy

An increasing number of promising immunotherapies and related clinical trials have led to several major breakthroughs in multiple cancers, but a reliable and precise biomarker for evaluating efficacy and prognosis has not yet been established. As a typical representation of a liquid biopsy, circulating cell-free DNA (ctDNA) possesses the functions and advantages of tissue biopsy but its distinct advantages of convenience, real-time nature, non-invasiveness and homogeneity make it superior to tissue biopsy. Indeed, compared with routine imaging and tumor markers, ctDNA offers an earlier indication and provides more precise information. ctDNA is reportedly able to identify immunotherapy responders, evaluate efficacy and survival time, screen immune checkpoint inhibitor resistance and pseudo-progress and predict tumor recurrence and metastasis. Thus, ctDNA can act as an "Eagle Eye" by comprehensively monitoring both macro- and micro-changes in the immunotherapy process. Although ctDNA has become a research topic of interest, its limitations cannot be ignored, and improvements in its sensitivity and standardization are urgently needed. This review reveals the advantages and limitations of ctDNA as a precise biomarker and supports the feasibility of using ctDNA detection for common monitoring during immunotherapy.

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.

ctDNA assessment of EGFR mutation status in Chinese patients with advanced non-small cell lung cancer in real-world setting

Background

The prevalence of EGFR mutations in circulating free tumor-derived DNA (ctDNA) was still unknown in China. This large-scale study (NCT02623257) aimed to explore the prevalence of epidermal growth factor receptor (EGFR) mutations and determine the correlation of EGFR mutation status with clinical characteristics.

Methods

Plasma DNA samples from 1,001 patients with stage III/IV NSCLC who received ≤1st line chemotherapy were collected from 65 hospitals. EGFR mutations were tested by amplification refractory mutation system (ARMS) method. The EGFR mutation rate was calculated and the associations between EGFR status and patients' demographic data, disease status as well as treatment pattern were explored.

Results

EGFR mutations were detected in 251 of 1,001 (25.1%) patients, 26.8% in adenocarcinoma and 11.7% in squamous carcinoma. A total of 189 harbored sensitizing mutations alone, 28 had resistance mutations alone, 3 had a combination of activating mutations, and 31 had a combination of activating and resistance mutations. Higher detection rate was observed in chemotherapy-naïve patients than those received 1st line chemotherapy (27.0% vs. 18.0%; P=0.006). Of which, the mutation rate of exon 19 deletion was 9.31% for naïve patients and 7.37% for the 1st chemotherapy patients; while the mutation rate of L858R decreased obviously from 10.20% (naïve) to 3.69% (1st line). We also noticed the mutation rate was 37.1% in patients with ≥2 organ metastases. Multivariate analysis showed female, chemotherapy-naïve, or ≥2 metastatic organs patients had higher EGFR mutation rate.

Conclusions

ctDNA based EGFR mutation test is feasible and could be a surrogate when tissue biopsy is not available.

Large scale, prospective screening of EGFR mutations in the blood of advanced NSCLC patients to guide treatment decisions

Background

In a significant percentage of advanced non-small-cell lung cancer (NSCLC) patients, tumor tissue is unavailable or insufficient for genetic analyses. We prospectively analyzed if circulating-free DNA (cfDNA) purified from blood can be used as a surrogate in this setting to select patients for treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs).

Patients and methods

Blood samples were collected in 119 hospitals from 1138 advanced NSCLC patients at presentation (n = 1033) or at progression to EGFR-TKIs (n = 105) with no biopsy or insufficient tumor tissue. Serum and plasma were sent to a central laboratory, cfDNA purified and EGFR mutations analyzed and quantified using a real-time PCR assay. Response data from a subset of patients (n = 18) were retrospectively collected.

Results

Of 1033 NSCLC patients at presentation, 1026 were assessable; with a prevalence of males and former or current smokers. Sensitizing mutations were found in the cfDNA of 113 patients (11%); with a majority of females, never smokers and exon 19 deletions. Thirty-one patients were positive only in plasma and 11 in serum alone and mutation load was higher in plasma and in cases with exon 19 deletions. More than 50% of samples had <10 pg mutated genomes/µl with allelic fractions below 0.25%. Patients treated first line with TKIs based exclusively on EGFR positivity in blood had an ORR of 72% and a median PFS of 11 months. Of 105 patients screened after progression to EGFR-TKIs, sensitizing mutations were found in 56.2% and the p.T790M resistance mutation in 35.2%.

Conclusions

Large-scale EGFR testing in the blood of unselected advanced NSCLC patients is feasible and can be used to select patients for targeted therapy when testing cannot be done in tissue. The characteristics and clinical outcomes to TKI treatment of the EGFR-mutated patients identified are undistinguishable from those positive in tumor.

Exosome-Based Detection of EGFR T790M in Plasma from Non-Small Cell Lung Cancer Patients

Purpose: About 60% of non-small cell lung cancer (NSCLC) patients develop resistance to targeted epidermal growth factor receptor (EGFR) inhibitor therapy through the EGFR T790M mutation. Patients with this mutation respond well to third-generation tyrosine kinase inhibitors, but obtaining a tissue biopsy to confirm the mutation poses risks and is often not feasible. Liquid biopsies using circulating free tumor DNA (cfDNA) have emerged as a noninvasive option to detect the mutation; however, sensitivity is low as many patients have too few detectable copies in circulation. Here, we have developed and validated a novel test that overcomes the limited abundance of the mutation by simultaneously capturing and interrogating exosomal RNA/DNA and cfDNA (exoNA) in a single step followed by a sensitive allele-specific qPCR.Experimental Design: ExoNA was extracted from the plasma of NSCLC patients with biopsy-confirmed T790M-positive (N = 102) and T790M-negative (N = 108) samples. The T790M mutation status was determined using an analytically validated allele-specific qPCR assay in a Clinical Laboratory Improvement Amendment laboratory.Results: Detection of the T790M mutation on exoNA achieved 92% sensitivity and 89% specificity using tumor biopsy results as gold standard. We also obtained high sensitivity (88%) in patients with intrathoracic disease (M0/M1a), for whom detection by liquid biopsy has been particularly challenging.Conclusions: The combination of exoRNA/DNA and cfDNA for T790M detection has higher sensitivity and specificity compared with historical cohorts using cfDNA alone. This could further help avoid unnecessary tumor biopsies for T790M mutation testing. Clin Cancer Res; 24(12); 2944-50. ©2018 AACR.

Prognostic value of EGFR and KRAS in circulating tumor DNA in patients with advanced non-small cell lung cancer: a systematic review and meta-analysis

EGFR (exon 19 and exon 21) mutations in patients with advanced non-small cell lung cancer (NSCLC) treated by EGFR-TKIs are associated with a better survival; while KRAS mutations predict a worse prognosis. However, there are divergent findings regarding the prognostic value of EGFR and KRAS mutations in circulating tumor DNA (ctDNA). We aimed to summarize the evidence for the use of circulating EGFR and KRAS mutations as prognostic factors in advanced NSCLC patients.We searched the network databases for studies reporting progression-free survival (PFS) and overall survival (OS) stratified by EGFR or KRAS mutations in ctDNA in advanced NSCLC patients. Thirteen studies enrolling 2,293 patients were reviewed. Correlation of circulating EGFR or KRAS mutations with patients' prognosis was assessed by meta-analysis.The pooled analyses showed that EGFR mutations in ctDNA significantly prolong PFS (HR=0.64,95% CI 0.51-0.81, I2=0%, p=0.0002), namely, in patients treated by EGFR-TKIs. There is a trend to have a prolonged OS for advanced NSCLC patients with circulating EGFR mutations who were treated by EGFR-TKIs (HR=0.79, 95% CI 0.52-1.21, I2=0, p=0.28). KRAS mutations detected in ctDNA predict a worse PFS (HR=1.83, 95% CI 1.40-2.40, p<0.0001) and OS (HR=2.07, 95% CI 1.54-2.78, p<0.00001) in advanced NSCLC patients treated by chemotherapy. Sensitivity analyses and subgroup analyses demonstrated the stability of our conclusion.Our analysis showed that EGFR mutations in ctDNA predicted a better PFS, in particular in advanced NSCLC patients treated by EGFR-TKIs. KRAS mutations in ctDNA indicated a worse PFS and OS in patients treated by chemotherapy.

Liquid Biopsy in Clinical Management of Breast, Lung, and Colorectal Cancer

Examination of tumor molecular characteristics by liquid biopsy is likely to greatly influence personalized cancer patient management. Analysis of circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and tumor-derived exosomes, all collectively referred to as “liquid biopsies,” are not only a modality to monitor treatment efficacy, disease progression, and emerging therapy resistance mechanisms, but they also assess tumor heterogeneity and evolution in real time. We review the literature concerning the examination of ctDNA and CTC in a diagnostic setting, evaluating their prognostic, predictive, and monitoring capabilities. We discuss the advantages and limitations of various leading ctDNA/CTC analysis technologies. Finally, guided by the results of clinical trials, we discuss the readiness of cell-free DNA and CTC as routine biomarkers in the context of various common types of neoplastic disease. At this moment, one cannot conclude whether or not liquid biopsy will become a mainstay in oncology practice.

Effective assessment of low times MET amplification in pleural effusion after epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) acquired resistance: Cases report

RATIONALE

The mechanism of the first-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) acquired resistance included T790M mutation, cellular-mesenchymal to epithelial transition factor (MET) or EGFR amplification, PIK3CA mutation, and transformation to small cell lung cancer. MET amplification accounted for only about 5% of the resistance cases.

PATIENTS CONCERNS

Few report detected MET amplification in pleural effusion. Here, we reported 2 lung adenocarcinoma cases with MET amplification in pleural effusion rapidly responded to crizotinib after EGFR-TKIs acquired resistance.

DIAGNOSES

Biopsy via bronchoscopy, next-generation sequencing (NGS) in pleural effusion.

INTERVENTIONS

EGFR-TKIs (Icotinib), MET inhibitor crizotinib.

OUTCOMES

After a progression-free survival of 9 months and 23months, respectively, both cases progressed accompanying with pleural effusion. Results of NGS in pleural effusion showed MET amplification (2-3 times) in both cases. The 2 patients were treated with a MET inhibitor crizotinib and rapidly responded.

CONCLUSION

MET amplification in pleural effusion could predict a perfect response to crizotinib after EGFR-TKIs acquired resistance, even only a low times gene amplification.

A comparison of ARMS-Plus and droplet digital PCR for detecting EGFR activating mutations in plasma

In this study, we introduce a novel amplification refractory mutation system (ARMS)-based assay, namely ARMS-Plus, for the detection of epidermal growth factor receptor (EGFR) mutations in plasma samples. We evaluated the performance of ARMS-Plus in comparison with droplet digital PCR (ddPCR) and assessed the significance of plasma EGFR mutations in predicting efficacy of EGFR-tyrosine kinase inhibitor (TKI) regimen. A total of 122 advanced non-small cell lung cancer (NSCLC) patients were enrolled in this study. The tumor tissue samples from these patients were evaluated by conventional ARMS PCR method to confirm their EGFR mutation status. For the 116 plasma samples analyzed by ARMS-Plus, the sensitivity, specificity, and concordance rate were 77.27% (34/44), 97.22% (70/72), and 89.66% (104/116; κ=0.77, P<0.0001), respectively. Among the 71 plasma samples analyzed by both ARMS-Plus and ddPCR, ARMS-Plus showed a higher sensitivity than ddPCR (83.33% versus 70.83%). The presence of EGFR activating mutations in plasma was not associated with the response to EGFR-TKI, although further validation with a larger cohort is required to confirm the correlation. Collectively, the performance of ARMS-Plus and ddPCR are comparable. ARMS-Plus could be a potential alternative to tissue genotyping for the detection of plasma EGFR mutations in NSCLC patients.

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.

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.

Biomarkers for early diagnosis, prognosis, prediction, and recurrence monitoring of non-small cell lung cancer

Despite advances in the management of non-small cell lung cancer, it remains to be the leading cause of cancer-related deaths worldwide primarily because of diagnosis at a late stage with an overall 5-year survival rate of 17%. A reduction in mortality was achieved by low-dose computed tomography screening of high-risk patients. However, the benefit was later challenged by the high false positive rate, resulting in unnecessary follow-ups, thus entailing a burden on both the health care system and the individual. The diagnostic dilemma imposed by imaging modalities has created a need for the development of biomarkers capable of differentiating benign nodules from malignant ones. In the past decade, with the advancements in high-throughput profiling technologies, a huge amount of work has been done to derive biomarkers to supplement clinical diagnosis. However, only a few of them have efficient sensitivity and specificity to be utilized in clinical settings. Therefore, there is an urgent need for the development of sensitive and specific means to detect and diagnose lung cancers at an early stage, when curative interventions are still possible. Due to the invasiveness of tissue biopsies and inability to capture tumor heterogeneity, nowadays enormous efforts have been invested in the development of technologies and biomarkers that enable sensitive and cost-effective testing using substrates that can be obtained in a noninvasive manner. This review, primarily focusing on liquid biopsy, summarizes all documented potential biomarkers for diagnosis, monitoring recurrence treatment response.

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 TKI as first-line treatment for patients with advanced EGFR mutation-positive non-small-cell lung cancer

After the discovery of activating mutations in EGFR, EGFR tyrosine kinase inhibitors (TKIs) have been introduced into the first-line treatment of non-small-cell lung cancer (NSCLC). A series of studies have shown that EGFR TKI monotherapy as first-line treatment can benefit NSCLC patients harbouring EGFR mutations. Besides, combination strategies based on EGFR TKIs in the first line treatment have also been proved to delay the occurrence of resistance. In this review, we summarize the scientific literature and evidence of EGFR TKIs as first-line therapy from the first-generation EGFR TKIs to conceptually proposed fourth-generation EGFR TKI, and also recommend the application of monotherapy and combination therapies of the EGFR-based targeted therapy with other agents such as chemotherapy, anti-angiogenic drugs and immunecheckpoint inhibitors.

Scientific Advances in Thoracic Oncology 2016

Lung cancer care is rapidly changing with advances in genomic testing, the development of next-generation targeted kinase inhibitors, and the continued broad study of immunotherapy in new settings and potential combinations. The International Association for the Study of Lung Cancer and the Journal of Thoracic Oncology publish this annual update to help readers keep pace with these important developments. Experts in thoracic cancer and care provide focused updates across multiple areas, including prevention and early detection, molecular diagnostics, pathology and staging, surgery, adjuvant therapy, radiotherapy, molecular targeted therapy, and immunotherapy for NSCLC, SCLC, and mesothelioma. Quality and value of care and perspectives on the future of lung cancer research and treatment have also been included in this concise review.

Osimertinib in patients with advanced epidermal growth factor receptor T790M mutation-positive non-small cell lung cancer: rationale, evidence and place in therapy

The identification of epidermal growth factor receptor (EGFR) mutations represented a fundamental step forward in the treatment of advanced non-small cell lung cancer (NSCLC) as they define a subset of patients who benefit from the administration of specifically designed targeted therapies. The inhibition of mutant EGFR through EGFR-tyrosine kinase inhibitors (TKIs), either reversible, first-generation gefitinib and erlotinib, or irreversible, second-generation afatinib, has dramatically improved the prognosis of patients harboring this specific genetic alteration, leading to unexpected clinical benefit. Unfortunately, virtually all patients who initially respond to treatment develop acquired resistance to EGFR-TKIs within 9-14 months. The EGFR T790M secondary mutation has emerged as a cause of treatment failure in approximately 60% of resistant cases. To date, several compounds designed with the aim to overcome T790M-mediated resistance are under clinical investigation. The aim of this review is to discuss emerging data regarding the third-generation EGFR-TKI, osimertinib, for the treatment of EGFR T790M mutant advanced NSCLC.

EGFR mutation testing in blood for guiding EGFR tyrosine kinase inhibitor treatment in patients with nonsmall cell lung cancer: A protocol for systematic review and meta-analysis

BACKGROUND

Epidermal growth factor receptor (EGFR) mutation testing in tumor tissue is now a common practice in selecting non-small cell lung cancer (NSCLC) patients for EGFR tyrosine kinase inhibitor (TKI) treatment. However, tumor tissues are often absent or insufficient for the testing. Blood is a potential substitute providing a noninvasive, easily accessible and repeatedly measureable source of genotypic information. However which is the best blood EGFR mutation testing method remains unclear. We undertake this study to investigate the best blood EGFR mutation testing method for selecting EGFR TKI treatment in patients with NSCLC.

METHODS

This study was registered in PROSPERO (CRD42017055263). PubMed, EMBASE, Cochrane library, and NIHR Health Technology Assessment program will be searched. Studies fulfill the following criteria will be eligible: (1) randomized controlled trials or cohort studies; (2) included patients with NSCLC; (3) reported response, progression-free survival, or overall survival for EGFR TKI by the EGFR mutation status in blood sample. Diagnostic accuracy of blood EGFR mutation tests for predicting response to TKI will be pooled. Tumor response, progression-free survival, and overall survival according to different blood EGFR mutation testing methods will be evaluated and compared.

RESULTS

Based published data and combined analysis, this study will quantitatively compare the blood EGFR mutation testing methods according to their accuracy for predicting treatment response and relationship with clinical outcome in NSCLC patients treated with EGFR TKIs.

CONCLUSION

This protocol will determine the best blood EGFR mutation testing method.

Blood-based detection of RAS mutations to guide anti-EGFR therapy in colorectal cancer patients: concordance of results from circulating tumor DNA and tissue-based RAS testing

An accurate blood‐based RAS mutation assay to determine eligibility of metastatic colorectal cancer (mCRC) patients for anti‐EGFR therapy would benefit clinical practice by better informing decisions to administer treatment independent of tissue availability. The objective of this study was to determine the level of concordance between plasma and tissue RAS mutation status in patients with mCRC to gauge whether blood‐based RAS mutation testing is a viable alternative to standard‐of‐care RAS tumor testing. RAS testing was performed on plasma samples from newly diagnosed metastatic patients, or from recurrent mCRC patients using the highly sensitive digital PCR technology, BEAMing (beads, emulsions, amplification, and magnetics), and compared with DNA sequencing data of respective FFPE (formalin‐fixed paraffin‐embedded) tumor samples. Discordant tissue RAS results were re‐examined by BEAMing, if possible. The prevalence of RAS mutations detected in plasma (51%) vs. tumor (53%) was similar, in accord with the known prevalence of RAS mutations observed in mCRC patient populations. The positive agreement between plasma and tumor RAS results was 90.4% (47/52), the negative agreement was 93.5% (43/46), and the overall agreement (concordance) was 91.8% (90/98). The high concordance of plasma and tissue results demonstrates that blood‐based RAS mutation testing is a viable alternative to tissue‐based RAS testing.

Treatment in EGFR-mutated Non-small Cell Lung Cancer: How to Block the Receptor and overcome Resistance Mechanisms

In non-small cell lung cancer (NSCLC), the identification of epidermal growth factor receptor (EGFR) mutations and the parallel development of EGFR tyrosine kinase inhibitors (TKIs) have radically changed the therapeutic management strategies. Currently, erlotinib, gefitinib, and afatinib are all approved as standard first-line treatment in EGFR-mutated NSCLC. However, despite the proven efficacy, some EGFR-mutated NSCLCs do not respond to EGFR TKIs, while some patients, after a favorable and prolonged response to EGFR TKIs, inevitably progress within about 10-14 months. Epidermal growth factor receptor-dependent mechanisms, activation of alternative pathways, or phenotypic transformation can cause the resistance to EGFR TKIs. The exon 20 p.Thr790Met point mutation (T790M) is responsible for about 60% of cases of resistance when progression occurs. A third-generation TKI, osimertinib, improved outcome in patients harboring T790M after first- and second-generation TKI treatment. However, resistance develops even after treatment with third-generation drugs. To date, the Cys797Ser (C797S) mutation in exon 20 of EGFR is the most well-known resistance mutation after osimertinib. Fourth-generation TKIs are already under development. Nevertheless, additional information is needed to better understand and effectively overcome resistance. The aim of this review is to report recent advances and future perspectives in the treatment of EGFR-mutated NSCLC, highlighting the resistance mechanisms that underlie disease progression.

Mechanisms of Resistance to Target Therapies in Non-small Cell Lung Cancer

Targeted therapies are revolutionizing the treatment of advanced non-small cell lung cancer (NSCLC). The discovery of key oncogenic events mainly in lung adenocarcinoma, like EGFR mutations or ALK rearrangements, has changed the treatment landscape while improving the prognosis of lung cancer patients. Inevitably, virtually all patients initially treated with targeted therapies develop resistance because of the emergence of an insensitive cellular population, selected by pharmacologic pressure. Diverse mechanisms of resistance, in particular to EGFR, ALK and ROS1 tyrosine-kinase inhibitors (TKIs), have now been discovered and may be classified in three different groups: (1) alterations in the target (such as EGFR T790M and ALK or ROS1 mutations); (2) activation of alternative pathways (i.e. MET amplification, KRAS mutations); (3) phenotype transformation (to small cell lung cancer, epithelial-mesenchymal transition). These basic mechanisms are informing the development of novel therapeutic strategies to overcome resistance in the clinic. Novel-generation molecules include osimertinib, for EGFR-T790M-positive patients, and new ALK-TKIs. Nevertheless, the possible concomitant presence of multiple resistance mechanisms, as well as their heterogeneity among cells and disease localizations, makes research in this field particularly arduous. In this chapter, available evidence and perspectives concerning precise mechanisms of escape to pharmacological inhibition in oncogene-addicted NSCLC are reported for single targets, including but not limited to EGFR and ALK.