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

Assessment of high-sensitive methods for the detection of EGFR mutations in circulating free tumor DNA from NSCLC patients

AIM

We assessed the ability of the Therascreen(®) kit (plasma-Therascreen) and of a peptide nucleic acids (PNA)-clamp approach to detect EGFR mutations in plasma-derived circulating-free tumor DNA (cftDNA) from non-small-cell lung cancer patients.

MATERIALS & METHODS

cftDNA from 96 patients was analyzed for exon 19 deletions and the p.L858R mutation, using both plasma-Therascreen and PNA-clamp-based assays.

RESULTS

None of the 70 EGFR wild-type patients showed EGFR mutations in cftDNA with both techniques (specificity: 100%). In 17/26 EGFR-mutant patients, plasma-Therascreen analysis confirmed the mutation identified in the primary tumor (analytical sensitivity: 65.4%). Similar results were obtained with the PNA-clamp method.

CONCLUSION

Both approaches were specific and sensitive for EGFR mutational analysis of cftDNA in non-small-cell lung cancer patients.

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

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

Diagnostic Accuracy of Noninvasive Genotyping of EGFR in Lung Cancer Patients by Deep Sequencing of Plasma Cell-Free DNA

BACKGROUND

Genotyping of EGFR (epidermal growth factor receptor) mutations is indispensable for making therapeutic decisions regarding whether to use EGFR tyrosine kinase inhibitors (TKIs) for lung cancer. Because some cases might pose challenges for biopsy, noninvasive genotyping of EGFR in circulating tumor DNA (ctDNA) would be beneficial for lung cancer treatment.

METHODS

We developed a detection system for EGFR mutations in ctDNA by use of deep sequencing of plasma DNA. Mutations were searched in >100 000 reads obtained from each exon region. Parameters corresponding to the limit of detection and limit of quantification were used as the thresholds for mutation detection. We conducted a multi-institute prospective study to evaluate the detection system, enrolling 288 non-small cell lung cancer (NSCLC) patients.

RESULTS

In evaluating the performance of the detection system, we used the genotyping results from biopsy samples as a comparator: diagnostic sensitivity for exon 19 deletions, 50.9% (95% CI 37.9%-63.9%); diagnostic specificity for exon 19 deletions, 98.0% (88.5%-100%); sensitivity for the L858R mutation, 51.9% (38.7%-64.9%); and specificity for L858R, 94.1% (83.5%-98.6%). The overall sensitivities were as follows: all cases, 54.4% (44.8%-63.7%); stages IA-IIIA, 22.2% (11.5%-38.3%); and stages IIIB-IV, 72.7% (60.9%-82.1%).

CONCLUSIONS

Deep sequencing of plasma DNA can be used for genotyping of EGFR in lung cancer patients. In particular, the high specificity of the system may enable a direct recommendation for EGFR-TKI on the basis of positive results with plasma DNA. Because sensitivity was low in early-stage NSCLC, the detection system is preferred for stage IIIB-IV NSCLC.

Cell-Free DNA Next-Generation Sequencing in Pancreatobiliary Carcinomas

Patients with pancreatic and biliary carcinomas lack personalized treatment options, in part because biopsies are often inadequate for molecular characterization. Cell-free DNA (cfDNA) sequencing may enable a precision oncology approach in this setting. We attempted to prospectively analyze 54 genes in tumor and cfDNA for 26 patients. Tumor sequencing failed in 9 patients (35%). In the remaining 17, 90.3% (95% confidence interval, 73.1%-97.5%) of mutations detected in tumor biopsies were also detected in cfDNA. The diagnostic accuracy of cfDNA sequencing was 97.7%, with 92.3% average sensitivity and 100% specificity across five informative genes. Changes in cfDNA correlated well with tumor marker dynamics in serial sampling (r = 0.93). We demonstrate that cfDNA sequencing is feasible, accurate, and sensitive in identifying tumor-derived mutations without prior knowledge of tumor genotype or the abundance of circulating tumor DNA. cfDNA sequencing should be considered in pancreatobiliary cancer trials where tissue sampling is unsafe, infeasible, or otherwise unsuccessful.

SIGNIFICANCE

Precision medicine efforts in biliary and pancreatic cancers have been frustrated by difficulties in obtaining adequate tumor tissue for next-generation sequencing. cfDNA sequencing reliably and accurately detects tumor-derived mutations, paving the way for precision oncology approaches in these deadly diseases.

Cell-Free DNA Next-Generation Sequencing in Pancreatobiliary Carcinomas

Patients with pancreatic and biliary carcinomas lack personalized treatment options, in part because biopsies are often inadequate for molecular characterization. Cell-free DNA (cfDNA) sequencing may enable a precision oncology approach in this setting. We attempted to prospectively analyze 54 genes in tumor and cfDNA for 26 patients. Tumor sequencing failed in 9 patients (35%). In the remaining 17, 90.3% (95% confidence interval, 73.1%-97.5%) of mutations detected in tumor biopsies were also detected in cfDNA. The diagnostic accuracy of cfDNA sequencing was 97.7%, with 92.3% average sensitivity and 100% specificity across five informative genes. Changes in cfDNA correlated well with tumor marker dynamics in serial sampling (r = 0.93). We demonstrate that cfDNA sequencing is feasible, accurate, and sensitive in identifying tumor-derived mutations without prior knowledge of tumor genotype or the abundance of circulating tumor DNA. cfDNA sequencing should be considered in pancreatobiliary cancer trials where tissue sampling is unsafe, infeasible, or otherwise unsuccessful.

SIGNIFICANCE

Precision medicine efforts in biliary and pancreatic cancers have been frustrated by difficulties in obtaining adequate tumor tissue for next-generation sequencing. cfDNA sequencing reliably and accurately detects tumor-derived mutations, paving the way for precision oncology approaches in these deadly diseases.

EGFR mutation status and first-line treatment in patients with stage III/IV non-small cell lung cancer in Germany: an observational study

INTRODUCTION

EGFR mutations confer sensitivity to EGFR tyrosine kinase inhibitors (TKI) in advanced non-small cell lung cancer (NSCLC). We investigated the clinicopathologic characteristics associated with EGFR mutations and their impact on real-world treatment decisions and outcomes in Caucasian patients with advanced NSCLC.

METHODS

REASON (NCT00997230) was a noninterventional multicenter study in patients (≥18 years) with stage IIIb/IV NSCLC, who were candidates for EGFR mutation testing and first-line systemic treatment, but not eligible for surgery or radiotherapy. Patients were followed up according to normal clinical practice and assessed for primary (correlation of mutation status with baseline characteristics) and secondary endpoints (first-line treatment decision).

RESULTS

Baseline data were obtained for 4,200 patients; 4,196 fulfilled the inclusion criteria; EGFR mutations were detected in 431 patients; no EGFR mutations were detected in 3,590 patients; mutation status was not evaluable in 175 patients. In multivariate analysis, the odds of EGFR mutations were significantly higher (P < 0.0001) in females versus males (odds ratio: 1.85; 95% confidence interval, 1.48-2.32), never-smokers versus smokers (3.64; 2.91-4.56), and patients with adenocarcinoma versus other histologic subtypes (2.94; 2.17-4.08). The most commonly prescribed first-line systemic treatments were: EGFR-TKIs in EGFR mutation-positive NSCLC (56.6%) and combination chemotherapy in EGFR mutation-negative NSCLC (78.5%).

CONCLUSIONS

This represents the largest dataset for EGFR mutations in Caucasian patients and shows EGFR mutations to be most prevalent in females with adenocarcinoma who had never smoked.

IMPACT

These findings add to our understanding of the prognostic and predictive factors of NSCLC, supporting future improved treatment selection.

Circulating miRNAs is a potential marker for gefitinib sensitivity and correlation with EGFR mutational status in human lung cancers

miRNA expression is deregulated in non-small cell lung cancer (NSCLC), and some miRNAs are associated with gefitinib sensitivity. Here, we investigated if circulating miRNAs could be a useful biomarker for the prediction of EGFR mutation and the patient's prognosis. The differential miRNAs related to gefitinib sensitivity were screened and identified by microRNA array. Using Taqman-based real-time RT-PCR, we analyzed the expression of selected miRNAs in tumor tissues and plasma of 150 NSCLC patients. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to determine the association between miRNAs expression and survival. Receiver operating characteristic curve analysis was also performed. Compared with PC9 cell line, 41 microRNAs detected by microarray were significantly differentially expressed in A549 and H1299 cells. The 5 selected hsa-miRNAs were all found differently expressed between wild and mutant EGFR carriers (all P<0.01). Down-regulation of 5 selected miRNAs were independently associated with lymphatic invasion (all P<0.01) and clinical stage (all P<0.01), respectively. Both down-regulation of has-miR-195 (P=0.012) and has-miR-21 (P=0.004) were associated with poor differentiation. All up-regulation of 5 has-miRNAs were associated with smoking (All P<0.05). 5 hsa-miRNAs were up-regulated both in plasma and tissue samples. A model including 4 hsa-miRNAs may predict EGFR mutational status and gefitinib-sensitivity (both AUC: 0.869). Plasma levels of has-miR-125b expression were associated with disease-free survival (P=0.033) and overall survival in the patients (P=0.028). In a word, Circulating 5 selected miRNAs may especially be useful in predicting EGFR mutation, and circulating hsa-miR-125b may have prognostic values in NSCLC patients.

The translational potential of circulating tumour DNA in oncology

The recent understanding of tumour heterogeneity and cancer evolution in response to therapy has raised questions about the value of historical or single site biopsies for guiding treatment decisions. The ability of ctDNA analysis to reveal de novo mutations (i.e., without prior knowledge), allows monitoring of clonal heterogeneity without the need for multiple tumour biopsies. Additionally, ctDNA monitoring of such heterogeneity and novel mutation detection will allow clinicians to detect resistant mechanisms early and tailor treatment therapies accordingly. If ctDNA can be used to detect low volume cancerous states, it will have important applications in treatment stratification post-surgery/radical radiotherapy and may have a role in patient screening. Mutant cfDNA can also be detected in other bodily fluids that are easily accessible and may aid detection of rare mutant alleles in certain cancer types. This article outlines recent advances in these areas.

Detection and Dynamic Changes of EGFR Mutations from Circulating Tumor DNA as a Predictor of Survival Outcomes in NSCLC Patients Treated with First-line Intercalated Erlotinib and Chemotherapy

PURPOSE

Blood-based circulating-free (cf) tumor DNA may be an alternative to tissue-based EGFR mutation testing in NSCLC. This exploratory analysis compares matched tumor and blood samples from the FASTACT-2 study.

EXPERIMENTAL DESIGN

Patients were randomized to receive six cycles of gemcitabine/platinum plus sequential erlotinib or placebo. EGFR mutation testing was performed using the cobas tissue test and the cobas blood test (in development). Blood samples at baseline, cycle 3, and progression were assessed for blood test detection rate, sensitivity, and specificity; concordance with matched tumor analysis (n = 238), and correlation with progression-free survival (PFS) and overall survival (OS).

RESULTS

Concordance between tissue and blood tests was 88%, with blood test sensitivity of 75% and a specificity of 96%. Median PFS was 13.1 versus 6.0 months for erlotinib and placebo, respectively, for those with baseline EGFR mut(+) cfDNA [HR, 0.22; 95% confidence intervals (CI), 0.14-0.33, P < 0.0001] and 6.2 versus 6.1 months, respectively, for the EGFR mut(-) cfDNA subgroup (HR, 0.83; 95% CI, 0.65-1.04, P = 0.1076). For patients with EGFR mut(+) cfDNA at baseline, median PFS was 7.2 versus 12.0 months for cycle 3 EGFR mut(+) cfDNA versus cycle 3 EGFR mut(-) patients, respectively (HR, 0.32; 95% CI, 0.21-0.48, P < 0.0001); median OS by cycle 3 status was 18.2 and 31.9 months, respectively (HR, 0.51; 95% CI, 0.31-0.84, P = 0.0066).

CONCLUSIONS

Blood-based EGFR mutation analysis is relatively sensitive and highly specific. Dynamic changes in cfDNA EGFR mutation status relative to baseline may predict clinical outcomes.

Gefitinib: a review of its use in adults with advanced non-small cell lung cancer

Gefitinib (Iressa®) is a selective small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR TKI) indicated for the treatment of adults with locally advanced or metastatic non-small cell lung cancer (NSCLC) with activating mutations of EGFR tyrosine kinase. Large phase III or IV clinical trials in patients with locally advanced or metastatic NSCLC showed that gefitinib as first- or subsequent-line treatment significantly prolonged progression-free survival (PFS) and improved objective response rates and/or health-related quality of life parameters in patients with activating EGFR mutations and in clinically selected patients (e.g., Asian patients or never-smokers) who are more likely to harbour these mutations. Overall survival did not increase significantly with gefitinib, although post-study treatments may have had a confounding effect on this outcome. Gefitinib was generally well tolerated in these studies, with mild or moderate skin reactions, gastrointestinal disturbances and elevations in liver enzymes among the most common adverse reactions in gefitinib recipients; interstitial lung disease has also been reported in <6 % of gefitinib recipients. Compared with chemotherapy, gefitinib as first- or subsequent-line therapy provided similar or greater PFS benefit and was generally associated with fewer haematological adverse events, neurotoxicity, asthenic disorders, as well as grade ≥3 adverse events. Although the position of gefitinib with respect to other EGFR TKIs is not definitively established, current evidence indicates that gefitinib monotherapy is an effective and generally well-tolerated first- or subsequent-line treatment option for patients with NSCLC and activating EGFR mutations who have not received an EGFR TKI previously.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

IMPACT

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