Detection of epidermal growth factor receptor mutation in plasma as a biomarker in Chinese patients with early-stage non-small cell lung cancer

Combination of Vismodegib and Paclitaxel Enhances Cytotoxicity via Bak-mediated Mitochondrial Damage in EGFR-Mutant Non-Small Cell Lung Cancer Cells

Half of NSCLC patients harbor epidermal growth factor receptor (EGFR) mutations, and their therapeutic responses are remarkably different from patients with wild-type EGFR (EGFR-WT) NSCLC. We previously demonstrated that the hedgehog inhibitor vismodegib (Vis) potentiates paclitaxel (PTX)-induced cytotoxicity via suppression of Bax phosphorylation, which promotes accumulation of mitochondrial damage and apoptosis in EGFR-WT NSCLC cells. In this study, we further delineated the anticancer activity and underlying mechanisms of this combination treatment in EGFR-mutant NSCLC cells. MTS/PMS activity and trypan blue exclusion assays were used to assess cell viability. Apoptosis was monitored by chromosome condensation, annexin V staining, and cleavage of PARP and caspase-3. Western blots were conducted to track proteins of interest after treatment. Reactive oxygen species (ROS) level was monitored by 2',7'-dichlorodihydrofluorescein diacetate. Mitochondrial status was analyzed by tetramethylrhodamine, ethyl ester. Hedgehog signaling was induced by PTX, which rendered H1975 and PC9 cells insensitive to PTX-induced mitochondrial apoptosis via suppression of Bak. However, Vis enhanced PTX-induced Bak activation, leading to mitochondrial damage, ROS accumulation, and subsequent apoptosis. Our findings suggest that the combination of Vis and PTX could be a potential therapeutic strategy to increase PTX sensitivity of EGFR-mutant NSCLC.

A real-world study of second or later-line osimertinib in patients with EGFR T790M-positive NSCLC: the final ASTRIS data

Aim: Report the final analysis from ASTRIS, the largest real-world study of second-/later-line osimertinib in advanced/metastatic EGFR T790M non-small-cell lung cancer (NSCLC). Methods: Patients with advanced/metastatic EGFR T790M NSCLC and prior EGFR-TKI treatment, received once-daily osimertinib 80 mg. Primary end point: overall survival (OS); secondary end points: progression-free survival (PFS), time-to-treatment discontinuation (TTD) and response rate. Safety was also recorded. Results: In 3014 patients, median OS: 22.8 months (21.6-23.8), median PFS: 11.1 months (11.0-12.0), median TTD: 13.5 months (12.6-13.9), and response rate: 57.3% (55.5-59.2). All end points reported with 95% CIs . Numerically longer median OS was observed in patients with baseline WHO performance status <2 versus 2 (24.0 vs 11.1 months) and those without versus with brain/leptomeningeal metastases (25.4 vs 18.0 months). No new safety signals were identified. Conclusion: Second-/later-line osimertinib demonstrated real-world clinical benefit and safety in advanced/metastatic EGFR T790M NSCLC. Clinical Trial Registration: NCT02474355 (ClinicalTrials.gov).

Detection of epidermal growth factor receptor (EGFR) mutations from preoperative circulating tumor DNA (ctDNA) as a prognostic predictor for stage I-III non-small cell lung cancer (NSCLC) patients with baseline tissue EGFR mutations

Background

Plasma circulating tumor DNA (ctDNA) may be a surrogate, minimally invasive approach to tissue-based epidermal growth factor receptor (EGFR) mutation detection in non-small cell lung cancer (NSCLC) patients. However, the predictive ability of preoperative ctDNA EGFR mutation test on long-term postoperative survival and tumor metastasis development has not been extensively investigated.

Methods

Stage I–III NSCLC patients with tissue EGFR mutations were enrolled in this study (n=174). The ctDNA EGFR mutations were identified in paired preoperative plasma samples. EGFR mutation testing was performed using Scorpion amplified refractory mutation system (ARMS) technology. The correlation between ctDNA EGFR mutation status and clinicopathologic parameters was analyzed. By combining at least 5 years of follow-up data, we assessed the relationship between ctDNA EGFR mutation status and disease-free survival (DFS) and overall survival (OS).

Results

Plasma-based ctDNA EGFR mutations were detected in 27 patients. The mutation types were exactly matched with those in paired tissue samples. Blood test sensitivity was closely associated with N stages, tumor-node-metastasis (TNM) stages and tumor differentiation (P<0.001). The overall 5-year survival rate was 18.5% versus 76.9% for ctDNA EGFR mutation-positive and ctDNA EGFR mutation-negative patients, respectively. For patients with ctDNA EGFR mutation positive, the median OS and DFS were 29.00±2.55 and 19.00±2.50 months, respectively, which were both significantly better than those in the ctDNA EGFR mutation-negative subgroup (P<0.001). ctDNA EGFR mutation was an independent risk factor of OS and DFS [hazard ratio (HR) 3.289, 95% confidence interval (CI), 1.816–5.956, P<0.001; HR, 4.860, 95% CI, 2.660–8.880, P<0.001]. For stage III patients with exon 19 deletion or L858R mutations in both tissue and plasma samples, tyrosine kinase inhibitor (TKI) therapy showed significantly better OS (P=0.025) and possible DFS benefit (P=0.060) than did chemotherapy.

Conclusions

EGFR mutation testing using the Scorpion-ARMS method in preoperative plasma could be a strong predictor for postoperative survival and metastasis of NSCLC patients. Thus, the subset of this population may be benefit from targeted strategies and management.

Performance comparison of commercial kits for isolating and detecting circulating tumor DNA

Circulating tumor DNA (ctDNA), a fraction of cell-free DNA (cfDNA) in the circulatory system, is released from tumor cells and thus carries tumor-specific genetic signatures. Using blood-derived ctDNA to detect somatic mutations has shown great value in guiding cancer targeted therapy. Isolation and detection efficiencies are the key factors affecting the performance of ctDNA detection. To optimize and standardize our clinical practice, in this study, we analyzed the isolation efficiency of four commercial cfDNA purification kits: QIAamp circulating nucleic acid kit, AmoyDx^® Circulating DNA kits, Microdiag^® circulating DNA isolation kit, and MagMAX cell-free DNA isolation kit; and the detection efficiency of two mainstream domestic EGFR gene mutation detection kits: MicroDiag EGFR gene mutation detection kit and Fluorometric real-time PCR Detection Kit for the analysis of EGFR gene mutations. Reference materials and plasma samples collected from lung cancer patients and healthy volunteers were used for the analysis. Our results showed that QIAamp circulating nucleic acid kit and Microdiag^® circulating DNA kit had the highest recovery rate (up to 21.25 ng/mL) for short DNA fragments of about 173 bp which is the peak length of ctDNA. For ctDNA detection, the MicroDiag^® EGFR gene mutation detection kit showed the highest detection rate and sensitivity for detecting EGFR mutations at a mutant frequency of 0.5%. This work provides a reliable choice of commercial kits for the clinical application of ctDNA.

Genome-Wide Plasma Cell-Free DNA Methylation Profiling Identifies Potential Biomarkers for Lung Cancer

As a noninvasive blood testing, the detection of cell-free DNA (cfDNA) methylation in plasma has raised an increasing interest due to diagnostic applications. Although extensively used in cfDNA methylation analysis, bisulfite sequencing is less cost-effective. In this study, we investigated the cfDNA methylation patterns in lung cancer patients by MeDIP-seq. Compared with the healthy individuals, 330 differentially methylated regions (DMRs) at gene promoters were identified in lung cancer patients with 33 hypermethylated and 297 hypomethylated regions, respectively. Moreover, these hypermethylated genes were validated with the publicly available DNA methylation data, yielding a set of ten significant differentially methylated genes in lung cancer, including B3GAT2, BCAR1, HLF, HOPX, HOXD11, MIR1203, MYL9, SLC9A3R2, SYT5, and VTRNA1-3. Our study demonstrated MeDIP-seq could be effectively used for cfDNA methylation profiling and identified a set of potential biomarker genes with clinical application for lung cancer.

Serum EGFR gene mutation status via second-generation sequencing and clinical features of patients with advanced lung cancer

Objective: To detect the serum epithelial growth factor receptor (EGFR) gene mutation status in patients with lung cancer via second-generation sequencing and to analyze its correlations with the clinical features of patients and its therapeutic effects. Methods: A total of 110 patients with non-small cell lung cancer (NSCLC) treated in our hospital were recruited as subjects of our study. The distribution of the EGFR gene mutation in patients was detected via second-generation sequencing and then patients were divided into mutant-type EGFR group (n=37) and wild-type EGFR group (n=73). The clinical features and therapeutic effects were compared between the two groups of patients. Results: A total of 5 kinds of EGFR gene mutation [19del (45.95%), L858R (43.24%), L861Q (5.41%), S768I (2.70%), and G719X (2.70%)] were detected via second-generation sequencing. In the mutant-type EGFR group, the proportions of female patients, patients with adenocarcinoma, and those with no history of smoking were high, and the differences were statistically significant (P<0.05). Moreover, there were statistically significant differences in gender, type of cancer, tumor-node-metastasis (TNM) staging, and smoking history between the mutant-type EGFR group and the wild-type EGFR group (P<0.05). Results of a multivariate logistic regression analysis showed that the EGFR gene mutation status was significantly associated with the type of cancer, gender, TNM staging, and smoking history of patients with NSCLC (P<0.05). The clinical effective rate of patients in the mutant-type EGFR group was significantly higher than that in the wild-type EGFR group (54.05% vs. 19.18%) while progression-free survival (PFS) was significantly longer than that in the wild-type EGFR group [(9.75±1.64) months vs. (5.51±0.40) months] (P<0.05). The expression level of carcinoembryonic antigen (CEA) in patients in the mutant-type EGFR group was apparently higher than that in the wild-type EGFR group, but the levels of carbohydrate antigen 125 (CA125), CY21-1 and squamous cell carcinoma-related antigen (SCC-Ag) were apparently lower than those in the wild-type EGFR group. There were statistically significant differences in the expression levels of serum tumor markers between the two groups (P<0.05). Conclusion: EGFR mutation status is closely related to the clinical features of NSCLC patients, such as gender, type of cancer, tumor staging, smoking history, and clinical effect. The second-generation sequencing is an important detection method to identify EGFR gene mutation status, which provides an applicable scaffold for the clinical treatment of patients.

Fluorometric detection of EGFR exon 19 deletion mutation in lung cancer cells using graphene oxide

Mutations in epidermal growth factor receptor (EGFR) are known as biomarkers that cause non-small cell lung cancer. Particularly, approximately 45% of non-small cell lung cancer patients possess a deletion in exon 19 of the EGFR gene. A less invasive method for detecting the EGFR mutation is required; thus, we developed a simple polymerase chain reaction (PCR)-based method for detecting EGFR exon 19 deletion by using a quencher-free fluorescent probe DNA and graphene oxide (GO). In the presence of the exon 19 deletion mutation, the fluorophore-labeled DNA probe was designed to be fully complementary to the mutant sequences. The fully annealed DNA probe was degraded by the 5' to 3' exonuclease activity of Taq DNA polymerase during PCR, releasing the fluorophore from the probe DNA. In contrast, a wild-type gene only allowed partial annealing of the probe DNA to the amplicon because of the absence of the deletion sequences, with Taq polymerase digestion releasing unannealed fragments of probe DNA. When GO was added to each reaction solution, starkly different fluorescence signals were obtained; enhanced fluorescence was observed because of the released fluorophore from the probe DNA that was not adsorbed onto GO, whereas fluorescence was quenched when the fragmented single-stranded probe DNA was readily adsorbed onto GO. Our method enabled the detection of as low as 49 pg of EGFR exon 19 deletion DNA with a detection limit of 0.1% when the mutant genomic DNA was mixed with wild-type DNA.

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.

Cell-free DNA and next-generation sequencing in the service of personalized medicine for lung cancer

Personalized medicine has emerged as the future of cancer care to ensure that patients receive individualized treatment specific to their needs. In order to provide such care, molecular techniques that enable oncologists to diagnose, treat, and monitor tumors are necessary. In the field of lung cancer, cell free DNA (cfDNA) shows great potential as a less invasive liquid biopsy technique, and next-generation sequencing (NGS) is a promising tool for analysis of tumor mutations. In this review, we outline the evolution of cfDNA and NGS and discuss the progress of using them in a clinical setting for patients with lung cancer. We also present an analysis of the role of cfDNA as a liquid biopsy technique and NGS as an analytical tool in studying EGFR and MET, two frequently mutated genes in lung cancer. Ultimately, we hope that using cfDNA and NGS for cancer diagnosis and treatment will become standard for patients with lung cancer and across the field of oncology.

The clinical significance of CXCL5 in non-small cell lung cancer

As a CXC-type chemokine, ENA78/CXCL5 is an important attractant for granulocytes by binding to its receptor CXCR2. Recent studies proved that CXCL5/CXCR2 axis plays an oncogenic role in many human cancers. However, the exact clinical significance of CXCL5 in lung cancer has not been well defined. Here, we found that the serum protein expression of CXCL5 was significantly increased in non-small cell lung cancer (NSCLC) compared with that in healthy volunteers. Immunohistochemistry staining revealed that CXCL5 protein was higher in various lung cancer tissues compared with normal tissues. Moreover, CXCL5 expression correlated with histological grade, tumor size, and TNM stage in NSCLC. Elevated CXCL5 protein abundance predicted poor overall survival in adenocarcinoma patients. Further meta-analysis demonstrated that CXCL5 mRNA expression was also positively associated with tumor stage, lymph node metastasis, and worse survival. Kaplan–Meier plot analyses indicated high CXCL5 was associated with short overall survival and progression-free survival. Together, these results indicated that CXCL5 may be a potential biomarker for NSCLC.

Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) of Yunnan in southwestern China

To investigate the Epidermal Growth Factor Receptor (EGFR) mutation status in non-small cell lung cancer (NSCLC) in Yunnan province in southwestern China, we detected EGFR mutation by Amplification Refractory Mutation System (ARMS) polymerase chain reaction (PCR) using DNA samples from 447 pathologically confirmed NSCLC specimens (175 tissue, 256 plasma and 16 cytologic samples). The relationship between EGFR mutations and demographic and clinical factors were further explored. Subgroup analyses according to sample type (tissue and plasma) and histological type (adenocarcinoma) were done. We found the mutation rate was 34.9% in overall patients (42.3%, 29.7%, and 37.5% for tissue, plasma, and cytologic samples respectively). We found female (p < 0.0001), no smoking (p = 0.001), adenocarcinoma (p < 0.0001), and tissue specimen (p = 0.026) were associated with higher EGFR mutation rate. The most common mutations were exon 19 deletions (40%) and L858R point (30%) mutation. Interestingly, NSCLC patients from Xuanwei harbored a strikingly divergent mutational pattern for EGFR when compared with non-Xuanwei patients (higher G719X, G719X+S768I mutations, but lower 19 deletion and L858R mutations). Generally, EGFR mutation rate and pattern in Yunnan province was in accord with other Asian populations. However, Xuanwei subgroup showed strikingly divergent EGFR mutation spectrum from other general population. Our analysis also indicated that cftDNA analysis for EGFR mutations detection was feasibility for the patients lacking sufficient tissue for molecular analyses.

Review of Clinical Next-Generation Sequencing

CONTEXT

- Next-generation sequencing (NGS) is a technology being used by many laboratories to test for inherited disorders and tumor mutations. This technology is new for many practicing pathologists, who may not be familiar with the uses, methodology, and limitations of NGS.

OBJECTIVE

- To familiarize pathologists with several aspects of NGS, including current and expanding uses; methodology including wet bench aspects, bioinformatics, and interpretation; validation and proficiency; limitations; and issues related to the integration of NGS data into patient care.

DATA SOURCES

- The review is based on peer-reviewed literature and personal experience using NGS in a clinical setting at a major academic center.

CONCLUSIONS

- The clinical applications of NGS will increase as the technology, bioinformatics, and resources evolve to address the limitations and improve quality of results. The challenge for clinical laboratories is to ensure testing is clinically relevant, cost-effective, and can be integrated into clinical care.

Comparison of plasma to tissue DNA mutations in surgical patients with non-small cell lung cancer

OBJECTIVE

Noninvasive liquid biopsies of circulating tumor DNA (ctDNA) can be used to assess non-small cell lung cancer (NSCLC), but previous work focused on patients with advanced-stage cancer. Thus, we evaluated the feasibility and their potential clinical application of circulating tumor DNA approached for surgical patients with NSCLC.

METHOD

Consecutive patients with suspected lung cancer who underwent curative-intent lung resection were enrolled prospectively in this study. Targeted DNA sequencing with a next-generation sequencing platform was used to identify a series of somatic mutations in matched tumor tissue DNA (tDNA) and plasma ctDNA samples. Plasma was collected before, during, and after surgery. Concordance was defined as matched tDNA and ctDNA with the same identified mutations or with no mutations.

RESULTS

In the enrolled 76 patients with lung cancer who were included, 31 had concordant mutations and 21 had no mutation in both ctDNA and tDNA, yielding an overall concordance of 68.4%. ctDNA samples obtained before and during surgery had the same mutations with a low variance in mutation frequency (1.2%) that was reduced to an average of 0.28% after surgery (P < .001). More patients were positive as assayed by ctDNA (48; 63.2%) than with serum tumor protein markers (36; 49.3%). The area under the curve was greater in ctDNA (0.887, 95% confidence interval [CI], 0.788-0.986) than for the 2 prediction models (0.803, 95% CI, 0.647-0.959; 0.69, 95% CI, 0.512-0.869) for estimating malignancy of solitary pulmonary nodules.

CONCLUSION

ctDNA mutation analysis for stage I-III surgical patients with NSCLC is feasible. More studies are needed to investigate its clinical application.

Tumor volume determines the feasibility of cell-free DNA sequencing for mutation detection in non-small cell lung cancer

Next‐generation sequencing (NGS) and digital PCR technologies allow analysis of the mutational profile of circulating cell‐free DNA (cfDNA) in individuals with advanced lung cancer. We have now evaluated the feasibility of cfDNA sequencing for mutation detection in patients with non‐small cell lung cancer at earlier stages. A total of 150 matched tumor and serum samples were collected from non‐small cell lung cancer patients at stages IA–IIIA. Amplicon sequencing with DNA extracted from tumor tissue detected frequent mutations in EGFR (37% of patients), TP53 (39%), and KRAS (10%), consistent with previous findings. In contrast, NGS of cfDNA identified only EGFR,TP53, and PIK3CA mutations in three, five, and one patient, respectively, even though adequate amounts of cfDNA were extracted (median of 4936 copies/mL serum). Next‐generation sequencing showed a high accuracy (98.8%) compared with droplet digital PCR for cfDNA mutation detection, suggesting that the low frequency of mutations in cfDNA was not due to a low assay sensitivity. Whereas the yield of cfDNA did not differ among tumor stages, the cfDNA mutations were detected in seven patients at stages IIA–IIIA and at T2b or T3. Tumor volume was significantly higher in the cfDNA mutation‐positive patients than in the negative patients at stages T2b–T4 (159.1 ± 58.0 vs. 52.5 ± 9.9 cm³, P = 0.014). Our results thus suggest that tumor volume is a determinant of the feasibility of mutation detection with cfDNA as the analyte.

The liquid biopsy in lung cancer

The incidence of lung cancer has significantly increased over the last century, largely due to smoking, and remains the most common cause of cancer deaths worldwide. This is often due to lung cancer first presenting at late stages and a lack of curative therapeutic options at these later stages. Delayed diagnoses, inadequate tumor sampling, and lung cancer misdiagnoses are also not uncommon due to the limitations of the tissue biopsy. Our better understanding of the tumor microenvironment and the systemic actions of tumors, combined with the recent advent of the liquid biopsy, may allow molecular diagnostics to be done on circulating tumor markers, particularly circulating tumor DNA. Multiple liquid biopsy molecular methods are presently being examined to determine their efficacy as surrogates to the tumor tissue biopsy. This review will focus on new liquid biopsy technologies and how they may assist in lung cancer detection, diagnosis, and treatment.

A Comparison of Cell-Free DNA Isolation Kits: Isolation and Quantification of Cell-Free DNA in Plasma

The analysis of cell-free DNA (cfDNA) as a sensitive biomarker for cancer diagnosis and monitoring has resulted in a need for efficient and standardized cfDNA isolation. In this study, we compared the isolation efficiency of the QIAamp circulating nucleic acid kit (QIA) with four other cfDNA isolation kits: the PME free-circulating DNA Extraction Kit (PME), the Maxwell RSC ccfDNA Plasma Kit (RSC), the EpiQuick Circulating Cell-Free DNA Isolation Kit (EQ), and two consecutive versions of the NEXTprep-Mag cfDNA Isolation Kit (NpM_V1/2). cfDNA was isolated from 10 plasma samples, of which five contained KRAS mutated cell-free tumor DNA (ctDNA). Digital droplet PCR was used to quantify the total cfDNA concentration as well as the KRAS mutated ctDNA fraction. cfDNA integrity was assessed with real-time quantitative PCR. The QIA and the RSC kits displayed similar isolation efficiencies of both KRAS mutated ctDNA and nonmutated cfDNA, whereas the yield generated by the PME and NpM_V2 kits was significantly lower. Real-time quantitative PCR indicated the presence of digital droplet PCR inhibiting agents in the eluates of the NpM_V1 and EQ kits. To conclude, this study presents two highly efficient isolation kits for cfDNA isolation, of which the RSC kit has the advantage of a fully automated protocol over the labor-intensive QIA kit.

Total and mutated EGFR quantification in cell-free DNA from non-small cell lung cancer patients detects tumor heterogeneity and presents prognostic value

Mutation analysis of epidermal growth factor receptor (EGFR) gene is essential for treatment selection in non-small cell lung cancer (NSCLC). Analysis is usually performed in tumor samples. We evaluated the clinical utility of EGFR analysis in plasma cell-free DNA (cfDNA) from patients under treatment with EGFR inhibitors. We selected 36 patients with NSCLC and EGFR-activating mutations. Blood samples were collected at baseline and during treatment with EGFR inhibitors. Wild-type EGFR, L858R, delE746-A750, and T790M mutations were quantified in cfDNA by droplet digital PCR. Stage IV patients had higher total circulating EGFR copy levels than stage I (3523 vs. 1003 copies/mL; p < 0.01). There was high agreement for activating mutations between baseline cfDNA and tumor samples, especially for L858R mutation (kappa index = 0.679; p = 0.001). In 34 % of advanced NSCLC patients, we detected mutations in cfDNA not previously detected in tumor samples and double mutations in 17 %. Patients with baseline total EGFR copy levels above the median presented decreased overall survival (OS) (341 vs. 870 days, p < 0.05) and progression-free survival (PFS) (238 vs. 783 days; p < 0.05) compared with those with total EGFR copy levels below the median. Patients with baseline concentrations of activating mutations above the median (94 copies/mL) had lower OS (317 vs. 805 days; p < 0.05) and PFS (195 vs. 724 days; p < 0.05). During follow-up, T790M resistance mutation was detected in 53 % of patients. Total and mutated EGFR analysis in cfDNA seems a relevant tool to characterize the molecular profile and prognosis of NSCLC patients harboring EGFR mutations.

Circulating cell-free nucleic acids and platelets as a liquid biopsy in the provision of personalized therapy for lung cancer patients

Lung cancer is the predominant cause of cancer-related mortality in the world. The majority of patients present with locally advanced or metastatic non-small-cell lung cancer (NSCLC). Treatment for NSCLC is evolving from the use of cytotoxic chemotherapy to personalized treatment based on molecular alterations. Unfortunately, the quality of the available tumor biopsy and/or cytology material is not always adequate to perform the necessary molecular testing, which has prompted the search for alternatives. This review examines the use of circulating cell-free nucleic acids (cfNA), consisting of both circulating cell-free (tumoral) DNA (cfDNA-ctDNA) and RNA (cfRNA), as a liquid biopsy in lung cancer. The development of sensitive and accurate techniques such as Next-Generation Sequencing (NGS); Beads, Emulsion, Amplification, and Magnetics (BEAMing); and Digital PCR (dPCR), have made it possible to detect the specific genetic alterations (e.g. EGFR mutations, MET amplifications, and ALK and ROS1 translocations) for which targeted therapies are already available. Moreover, the ability to detect and quantify these tumor mutations has enabled the follow-up of tumor dynamics in real time. Liquid biopsy offers opportunities to detect resistance mechanisms, such as the EGFR T790M mutation in the case of EGFR TKI use, at an early stage. Several studies have already established the predictive and prognostic value of measuring ctNA concentration in the blood. To conclude, using ctNA analysis as a liquid biopsy has many advantages and allows for a variety of clinical and investigational applications.

Coexistence of EGFR T790M mutation and common activating mutations in pretreatment non-small cell lung cancer: A systematic review and meta-analysis

OBJECTIVE

Previous studies have indicated that EGFR exon 19 deletions in non-small cell lung cancer (NSCLC) are associated with better outcomes to tyrosine kinase inhibitors (TKIs) than the L858R mutation. This study aimed to evaluate whether T790M, a resistant mutation, is more likely to coexist with L858R mutation than with exon 19 deletions in pretreatment NSCLC patients.

MATERIALS AND METHOD

We searched MEDLINE and EMBASE up to Nov 30th, 2015 to identify randomized controlled trials (RCTs) and observational studies that reported pretreatment T790M and EGFR-activating mutation. A meta-analysis was performed using a random-effects model. The primary outcome was odds ratio (OR) of pretreatment T790M mutation in NSCLC co-existing with L858R mutation and exon 19 deletions. Stratified analysis was performed based on sensitivity of mutation detection methods for T790M.

RESULTS

We identified 15 observational studies and 3 RCTs for analysis. Pretreatment T790M was more frequent in L858R than in exon 19 mutated patients. The association of T790M and L858R was statistically significant in observational studies (OR, 1.65, 95% CI, 1.17-2.32), with less precision in RCTs (OR, 1.84, 95% CI, 0.96-3.52). In the stratified analysis based on the sensitivity of the mutation detection methods, the association was observed in the studies using intermediately (detection limit <5% and ≥ 0.1%; OR, 2.23, 95% CI, 1.19-4.17) and highly sensitive methods (detection limit <0.1%; OR, 1.74, 95% CI, 1.10-2.73), but not in those using low sensitivity methods (detection limit >5%; OR, 1.28, 95% CI, 0.74-2.23).

CONCLUSIONS

Pretreatment EGFR T790M mutation is more likely to coexist with L858R mutation than with exon 19 deletions in NSCLC. This association was observed only in studies using sensitive mutation detection methods (<5%).