Cobas Epidermal Growth Factor Receptor Mutation Test Research Articles

The Advantage of Targeted Next-Generation Sequencing over qPCR in Testing for Druggable EGFR Variants in Non-Small-Cell Lung Cancer.

The emergence of targeted therapies in non-small-cell lung cancer (NSCLC), including inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase, has increased the need for robust companion diagnostic tests. Nowadays, detection of actionable variants in exons 18-21 of the EGFR gene by qPCR and direct DNA sequencing is often replaced by next-generation sequencing (NGS). In this study, we evaluated the diagnostic usefulness of targeted NGS for druggable EGFR variants testing in clinical NSCLC material previously analyzed by the IVD-certified qPCR test with respect to DNA reference material. We tested 59 NSCLC tissue and cytology specimens for EGFR variants using the NGS 'TruSight Tumor 15' assay (Illumina) and the qPCR 'cobas EGFR mutation test v2' (Roche Diagnostics). The sensitivity and specificity of targeted NGS assay were evaluated using the biosynthetic and biological DNA reference material with known allelic frequencies (VAF) of EGFR variants. NGS demonstrated a sufficient lower detection limit for diagnostic applications (VAF < 5%) in DNA reference material; all EGFR variants were correctly identified. NGS showed high repeatability of VAF assessment between runs (CV% from 0.02 to 3.98). In clinical material, the overall concordance between NGS and qPCR was 76.14% (Cohen's Kappa = 0.5933). The majority of discordant results concerned false-positive detection of EGFR exon 20 insertions by qPCR. A total of 9 out of 59 (15%) clinical samples showed discordant results for one or more EGFR variants in both assays. Additionally, we observed TP53 to be a frequently co-mutated gene in EGFR-positive NSCLC patients. In conclusion, targeted NGS showed a number of superior features over qPCR in EGFR variant detection (exact identification of variants, calculation of allelic frequency, high analytical sensitivity), which might enhance the basic diagnostic report.

The association of EGFR amplification with aberrant exon 20 insertion report using the cobas EGFR Mutation Test v2.

Determining the exact type of epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutation in lung cancer has become important. We found that not all ex20ins mutations reported by cobas EGFR test v2 could be validated by Sanger sequencing even using surgical specimens with high tumor contents. This study aimed to validate the ex20ins results reported by the cobas test and to determine whether there were clinicopathological factors associated with aberrant cobas ex20ins report. In total, 123 cobas-reported cases with ex20ins were retrospectively collected and validated by Sanger sequencing and Idylla assay. Clinicopathological features between ex20ins cobas+/Sanger+ group (n = 71) and cobas+/Sanger- group (n = 52) were compared. The Idylla assay detected ex20ins in 82.6% of cobas+/Sanger+ cases but only in 4.9% of cobas+/Sanger- cases. The cobas+/Sanger- group was significantly associated with higher tumor contents, poorly differentiated patterns, tumor necrosis, and a lower internal control cycle threshold value reported by the Idylla which suggesting the presence of increased EGFR gene copy numbers. EGFR fluorescence in situ hybridization (FISH) revealed the majority of cobas+/Sanger- group had EGFR high copy number gain (16%) or amplification (76%) according to the Colorado criteria. Among cases reported to have concomitant classic EGFR and ex20ins mutations by the cobas, the classic EGFR mutations were all detected by Sanger sequencing and Idylla, while the ex20ins mutations were undetected by Sanger sequencing (0%) or rarely reported by Idylla assay (3%). FISH revealed high EGFR copy number gain (17.9%) and amplification (79.5%) in cases reported having concomitant classic EGFR and ex20ins mutations by the cobas. This study demonstrated an unusually high frequency of EGFR amplification in cases with aberrant cobas ex20ins report which could not be validated by Sanger sequencing or Idylla assay. Ex20ins reported by the cobas test should be validated using other methods especially those reported having concomitant ex20ins and classic EGFR mutations.

Clinical Validation of the Unparalleled Sensitivity of the Novel Allele-Discriminating Priming System Technology-Based EGFR Mutation Assay in Patients with Operable Non-Small Cell Lung Cancer.

Recently, we developed allele-discriminating priming system (ADPS) technology. This method increases the sensitivity of conventional quantitative polymerase chain reaction up to 100 folds, with limit of detection, 0.01%, with reinforced specificity. This prospective study aimed to develop and validate the accuracy of ADPS epidermal growth factor receptor (EGFR) Mutation Test Kit using clinical specimens. In total 189 formalin-fixed paraffin-embedded tumor tissues resected from patients with non-small cell lung cancer were used to perform a comparative evaluation of the ADPS EGFR Mutation Test Kit versus the cobas EGFR Mutation Test v2, which is the current gold standard. When the two methods had inconsistent results, next-generation sequencing-based CancerSCAN was utilized as a referee. The overall agreement of the two methods was 97.4% (93.9%-99.1%); the positive percent agreement, 95.0% (88.7%-98.4%); and the negative percent agreement, 100.0% (95.9%-100.0%). EGFR mutations were detected at a frequency of 50.3% using the ADPS EGFR Mutation Test Kit and 52.9% using the cobas EGFR Mutation Test v2. There were 10 discrepant mutation calls between the two methods. CancerSCAN reproduced eight ADPS results. In two cases, mutant allele fraction was ultra-low at 0.02% and 0.06%, which are significantly below the limit of detection of the cobas assay and CancerSCAN. Based on the EGFR genotyping by ADPS, the treatment options could be switched in five patients. The highly sensitive and specific ADPS EGFR Mutation Test Kit would be useful in detecting the patients who have lung cancer with EGFR mutation, and can benefit from the EGFR targeted therapy.

Performance of Ultra-Rapid Idylla™ EGFR Mutation Test in Non-Small-Cell Lung Cancer and Its Potential at Clinical Molecular Screening.

The Idylla™ EGFR Mutation Test is an ultra-rapid single-gene test that detects epidermal growth factor receptor (EGFR) mutations using formalin-fixed paraffin-embedded specimens. Here, we compared the performance of the Idylla EGFR Mutation Test with the Cobas® EGFR Mutation Test v2. Surgically resected NSCLC specimens obtained at two Japanese institutions (N = 170) were examined. The Idylla EGFR Mutation Test and the Cobas EGFR Mutation Test v2 were performed independently and the results were compared. For discordant cases, the Ion AmpliSeq Colon and Lung Cancer Research Panel V2 was performed. After the exclusion of five inadequate/invalid samples, 165 cases were evaluated. EGFR mutation analysis revealed 52 were positive and 107 were negative for EGFR mutation in both assays (overall concordance rate: 96.4%). Analyses of the six discordant cases revealed that the Idylla EGFR Mutation Test was correct in four and the Cobas EGFR Mutation Test v2 was correct in two. In a trial calculation, the combination of the Idylla EGFR Mutation Test followed by a multi-gene panel test will reduce molecular screening expenses if applied to a cohort with EGFR mutation frequency >17.9%. We demonstrated the accuracy and potential clinical utility of the Idylla EGFR Mutation Test as a molecular screening platform in terms of turnaround time and molecular testing cost if applied to a cohort with a high EGFR mutation incidence (>17.9%).

Efficacy of different platforms in detecting EGFR mutations using cerebrospinal fluid cell-free DNA from non-small-cell lung cancer patients with leptomeningeal metastases.

Cell-free tumor DNA (ctDNA) obtained through liquid biopsy is useful for the molecular analysis of advanced non-small-cell lung cancer (NSCLC). Few studies have directly compared analysis platforms in terms of their diagnostic performance in analyzing ctDNA obtained from the cerebrospinal fluid (CSF) of patients with leptomeningeal metastasis (LM). We prospectively analyzed patients with epidermal growth factor receptor (EGFR)-mutant NSCLC who were subjected to CSF analysis for suspected LM. To detect EGFR mutations, CSF ctDNA was analyzed using the cobas EGFR Mutation Test and droplet digital polymerase chain reaction (ddPCR). CSF samples from osimertinib-refractory patients with LM were also subjected to next-generation sequencing (NGS). Significantly higher rates of valid results (95.1% vs. 78%, respectively, p = 0.04) and EGFR common mutation detection (94.3% vs. 77.1%, respectively, p = 0.047) were obtained through ddPCR than through the cobas EGFR Mutation Test. The sensitivities of ddPCR and cobas were 94.3% and 75.6%, respectively. The concordance rate for EGFR mutation detection through ddPCR and the cobas EGFR Mutation Test was 75.6% and that for EGFR mutation detection in CSF and plasma ctDNA was 28.1%. In osimertinib-resistant CSF samples, all original EGFR mutations were detected through NGS. MET amplification and CCDC6-RET fusion were demonstrated in one patient each (9.1%). The cobas EGFR Mutation Test, ddPCR, and NGS appear to be feasible methods for analyzing CSF ctDNA in patients with NSCLC and LM. In addition, NGS may provide comprehensive information regarding the mechanisms underlying osimertinib resistance.

Epidemiology and clinical impact of EGFR mutation in patients with lung cancer after radical surgical treatment.

8552 Background: The epidemiology of epidermal growth factor receptor (EGFR) mutation in lung adenocarcinoma and its clinical impact are well-known. However, most studies have focused on advanced-stage inoperable cancer. Data on the frequency of EGFR mutation in surgically resected lung cancer are limited. Recent studies have shown a promising effect of Osimertinib in adjuvant settings. Hence, the need to estimate the target population in the real-world data. This study aimed to assess the occurrence of EGFR mutation in patients after radical surgical treatment of lung adenocarcinoma and explore its prognostic impact compared to EGFR negative group. Methods: This single-center retrospective analysis included the group of 732 consecutive Caucasian patients with histopathologically confirmed lung adenocarcinoma, evaluated for EGFR mutations expression, who underwent anatomical resection between January 2016, and December 2020. EGFR status was assessed by cobas EGFR mutation test v2. The frequency of EGFR mutations, disease-free survival (DFS) and overall survival (OS) in EGFR positive and EGFR negative groups were analyzed. Results: EGFR mutations were found in 65 surgical patients (8.9%) and did not differ from patients with advanced stages of lung adenocarcinoma (7.9%). EGFR mutations occurred more frequently in females than males, 48 out of 344 (14%) and 17 out of 388 (4.4%), respectively. Deletions within exon 19 and the L858R mutation in exon 21 constituted 49.2% and 24.6% of all mutations, respectively, while others comprised 26.2%. One case of L858R mutation coincided with T790M in exon 20 mutation. Detailed results divided by stages are presented in the Table. The occurrence of EGFR mutation had no significant influence on DFS and OS in patients after radical resection. Conclusions: The frequency of EGFR mutation in postoperative lung cancer was comparable to the occurrence in the general lung cancer population. EGFR mutation did not affect DFS and OS in patients after radical resection. [Table: see text]

Observational study of rebiopsy in EGFR-TKI-resistant patients with EGFR mutation-positive advanced NSCLC

The identification of acquired resistance mutations has been essential in non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) active mutations. Rebiopsy plays a pivotal role in selecting the optimal treatment for patients who develop resistance to initial EGFR-tyrosine kinase inhibitors (EGFR-TKIs). This multicenter, observational study was conducted to investigate the details of rebiopsy in Japanese clinical practice. The primary endpoints were the implementation rate of rebiopsy and the concordance rate for T790M mutation detection between histological and cytological specimens using the cobas EGFR Mutation Test, version 2. One hundred ninety-four patients with EGFR-mutant NSCLC were enrolled, and 120 patients developed acquired resistance to EGFR-TKIs. The median age was 68 years (range 20–87), and 52.5% of the patients were women. Rebiopsy was performed in 109 patients, and the implementation rate of rebiopsy was 90.8%. The success rates of rebiopsy in the total, histology, cytology and liquid biopsy populations were 67.9%, 81.3%, 66.7% and 43.8%, respectively. The positive percent agreement and the negative percent agreement in the detection of the T790M mutation between the histological and cytological specimens were both 90.9%. Obtaining histological or cytological tissue samples at rebiopsy may contribute to improving the detection rate of the T790M mutation (trial registration number: UMIN000026019).

374 Therapeutic Class Labeling of EGFR Companion Diagnostics (CDxs)

OBJECTIVES/GOALS: Review all approved companion diagnostics (CDxs) labeling for therapeutic class language. Examine the regulatory pathways of CDx products whose labels contain therapeutic class labeling. Develop recommendations for pharmaceutical industry professionals on best practices in the co-development of CDxs and oncology therapeutic products. METHODS/STUDY POPULATION: Literature discussing companion diagnostics was reviewed from EBSCOhost, PubMed, and OVID. The Intended Use language within CDx labels on the Food and Drug Administrations “List of Cleared or Approved Companion Diagnostic Devices (In Vitro and Imaging Tools)” website were reviewed on November 1, 2021 for therapeutics class language. For CDx products with therapeutic class label language, the regulatory history was evaluated to determine the development approach taken to achieve the language. RESULTS/ANTICIPATED RESULTS: A total of 45 CDxs were identified, of which only 2 contained therapeutic class labeling, both of which were devices for the identification of epidermal growth factor receptor (EGFR) mutations for the treatment of non-small cell lung cancer (NSCLC). Three additional EGFR CDxs were approved; however, they did not contain therapeutic class labeling. The first CDx was the Cobas EGFR Mutation Test V2, which received therapeutic group label language as an update on October 27, 2020; however, prior to the therapeutic class labeling, three oncology products were named in the Intended Use: Tarceva (erlotinib), Tagrisso (osimertinib), and Iressa (gefitinib). The second CDx to incorporate therapeutic class labeling was the ONCO/Reveal Diagnostic Lung and Colon Cancer Assay upon initial approval on July 30, 2021. DISCUSSION/SIGNIFICANCE: EGFR CDxs are the first to shift towards therapeutic class labeling. Indication, molecular alterations, and mechanism of action of the approved therapeutic class products, number of products approved, as well as CDx analytical and clinical validation influence class label relevance. Discussions with the FDA are encouraged early in development.

Application of liquid biopsy-based targeted capture sequencing analysis to improve the precision treatment of non-small cell lung cancer by tyrosine kinase inhibitors

BackgroundTargeted therapy of patients with non-small cell lung cancer (NSCLC) who harbour sensitising mutations by tyrosine kinase inhibitors (TKIs) has been found more effective than traditional chemotherapies. However, target genes...

FP12.05 The Intrinsic Limitation and Clinical Impact of Mutant Allele-Specific Real-Time PCR-Based EGFR Mutation Assay in NSCLC

The detection of driver gene mutations, such as epidermal growth factor receptor (EGFR) mutations, plays a decisive role in the treatment of non-small cell lung cancer (NSCLC). Cobas EGFR mutation test is a mutant allele-specific real-time PCR assay that is commonly used in daily practice. It has a notable intrinsic detection limitation caused by its primer designs. Next-generation sequencing (NGS) is a comprehensive mutation assay that does not have the constraint. It will have a higher mutation detection rate but the clinical impact remains uncertain.

Detection of EGFR mutations in liquid biopsy samples using allele-specific quantitative PCR: A comparative real-world evaluation of two popular diagnostic systems

PurposeThe detection of epidermal growth factor receptor (EGFR) mutations in plasma cell-free DNA (cfDNA) is an auxiliary tool for the molecular diagnosis of non-small cell lung cancer (NSCLC), especially when an adequate tumor tissue specimen cannot be obtained. We compared the diagnostic accuracy of two commonly used in vitro diagnostic-certified allele-specific quantitative PCR assays for detecting plasma cfDNA EGFR mutations. MethodsWe analyzed EGFR mutations in plasma cfDNA from 90 NSCLC patients (stages I–IV) before treatment (n ​= ​60) and after clinical progression on EGFR tyrosine kinase inhibitors (n ​= ​30) using the cobas EGFR mutation test v2 (Roche Molecular Systems, Inc.) and therascreen EGFR Plasma RGQ PCR kit (Qiagen GmbH). ResultsThere was higher concordance between plasma cfDNA and matched tumor tissue EGFR mutations with cobas (66.67%) compared with therascreen (55.93%). The concordance rate increased to 90.00% with cobas (Cohen's kappa coefficient, κ ​= ​0.80; p ​< ​0.0001) and 73.33% with therascreen (κ ​= ​0.49; p ​= ​0.0009) in advanced NSCLC patients. In treatment-naïve patients, cobas was superior to therascreen (sensitivity: 82.35% vs. 52.94%; specificity: 100% vs. 100%). In patients with clinical progression on EGFR tyrosine kinase inhibitors, EGFR exon 20 p.T790M was detected in 30% and 23% of cfDNA samples by cobas and therascreen, respectively. ConclusionsCobas was superior to therascreen for detection of plasma EGFR mutations in advanced NSCLC. Plasma cfDNA EGFR mutation analysis is complex; therefore, the diagnostic accuracy of commercially available assays should be validated.

Lungful: An observational prospective study to assess the molecular epidemiology of EGFR mutations upon progression on or after first line EGFR-TKI therapy, in real-life clinical settings in Greece.

e21641 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the gold standard 1st line strategy for non-small-cell lung cancer (NSCLC) patients with activating EGFR mutations (EGFRm), associated with improved survival outcomes and quality of life compared to chemotherapy. Despite the high response rate with first- and second- generation TKIs, most patients develop resistance to treatment and progress. The acquisition of T790M mutation in exon 20 is considered the most common resistance mechanism. This study aims to investigate the molecular epidemiology of EGFR resistance mutations, focusing on T790M in EGFRm NSCLC patients treated with TKIs. Methods: The study included patients with locally advanced/metastatic EGFRm NSCLC who have progressed on or after 1st line treatment with first- or second- generation TKI. Samples either from plasma-based liquid biopsy and/or tissue re-biopsy were analysed using the Cobas EGFR Mutation Test v2. All patients signed informed consent and were enrolled between July 2017 and September 2019. Statistical analyses were performed using SAS software, Version 9.4. Results: Ninety-six eligible patients were enrolled. At the time of progression, T790M mutation was detected in 16.7%of the patients using plasma-based liquid biopsies. Among patients with negative T790M result, in plasma, tissue re-biopsy was performed in 22,7% with evaluable/valid results in 72.2% of them. T790M mutation was identified in 38.5% of re-biopsy samples. According to Cobas EGFR Mutation test results (combined plasma and tissue), T790M mutation was identified in 21.9% of the patients. Of T790M-positive patients 42.9% had previously received first and 57.1% second generation EGFR-TKI. Conclusions: Results from this study in real world clinical setting in Greece, show that EGFR-T790M acquired resistance positivity rate in plasma is lower compared to previous reports. Moreover, these data underline the challenges of implementing precision medicine using tissue re-biopsy in advanced/metastatic NSCLC. Clinical trial information: D133FR00126. [Table: see text]

Predictive impact of low-frequency pretreatment T790M mutation in patients with EGFR-mutated non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors

ObjectivesLow-frequency epidermal growth factor receptor (EGFR) T790M mutation could be detected by ultrasensitive methods in EGFR tyrosine kinase inhibitor (TKI)-naïve non-small cell lung cancer (NSCLC). However, the impact of pretreatment T790M (preT790M) on the efficacy of EGFR-TKIs and on resistance remains unclear. Materials and methodsTwo independent cohorts consisting of advanced EGFR-mutated NSCLC patients treated with first-line EGFR-TKIs, a derivation cohort that started treatment between August 2013 and July 2016 (cohort A, n = 44) and a validation cohort between August 2016 and December 2017 (cohort B, n = 22), were examined in this study. Among these, 28 patients underwent re-biopsy at disease progression. DNAs from pretreatment tumor biopsy samples and re-biopsy samples were assessed to detect T790M by the Cobas EGFR Mutation Test v2 (Cobas) and for quantitating T790M by droplet digital polymerase chain reaction (ddPCR). ResultsDetection rates of preT790M were 40.9% (18/44) in cohort A and 45.5% (10/22) in cohort B by ddPCR, and none by Cobas. A cutoff value of 0.3% for dividing into high- vs. low-preT790M allele frequency was determined by receiver operating characteristic curve analysis in cohort A. Progression-free survival (PFS) was significantly shorter in the high- preT790M group (n = 12) than in the low-preT790M (n = 6) and negative (n = 26) groups (combined low-preT790M) (median: 6.9 vs. 13.8 months, P = 0.00073). These observations were validated in cohort B [median: 6.2 (n = 5) vs. 15.3 months (n = 17), P = 0.0029]. In 28 paired biopsies, Cobas detected post-progression T790M in 60% (3/5) of the high-preT790M, in 57% (4/7) of the low-preT790M, and in 56% (9/16) of the negative-preT790M groups. ConclusionEGFR-mutated NSCLC with high preT790M had significantly shorter PFS on EGFR-TKIs. However, preT790M abundance may not necessarily confer post-TKI T790M resistance.

1415P - Feasibility study of a ctEGFR prototype assay on the fully automated Idylla™ platform

BackgroundTo predict the response to EGFR tyrosine kinase inhibitor (TKI) therapy in non-small cell lung cancer (NSCLC) patients, formalin-fixed paraffin-embedded (FFPE) tumor tissue is routinely tested for the presence of somatic mutations in the epidermal growth factor receptor (EGFR) gene. Sufficient tumor tissue is not always available and ctEGFR testing from plasma is an alternative approach for the detection of EGFR mutations. Therefore, a fast and fully automated ctEGFR assay with minimal hands-on time should allow laboratories to quickly generate EGFR testing results. MethodsIdyllaTM (Biocartis) is a fully integrated molecular diagnostics platform that combines speed and ease of use with high sensitivity and high multiplexing capabilities. In terms of ctDNA testing, it overcomes the time-consuming step of ctDNA extraction from plasma. After insertion of 2ml of plasma into the cartridge, the complete process of ctDNA extraction, real-time PCR, data analysis and reporting is fully automated. The ctEGFR prototype assay allows the detection of 49 mutations including insertions and deletions in exons 18, 19, 20 and 21. The results obtained by the ctEGFR prototype assay were compared with NGS (sensitivity 2-5%). ResultsSixty-four NSCLC samples were tested with both assays. Overall, 34 mutations were detected by NGS and confirmed by the ctEGFR prototype assay. In 33 samples, NGS detected no mutation. The ctEGFR prototype assay detected 7 additional mutations in this cohort. Retesting with the cobas EGFR Mutation Test v2 confirmed the presence of these mutations. Analytical sensitivity was assessed for 20 mutations using plasma spiked with synthetic targets. Analytical sensitivities ranging from 1 to 4% were obtained for the tested mutations. Inclusivity was demonstrated for 49 mutations in total. The average turnaround time of a run was <2h 40min and the hands-on time for the assay was <2min. ConclusionsThis study shows that the Idylla™ platform enables the development of a prototype ctEGFR assay with high sensitivity and ease of use combined with a fast turnaround time for the testing of 49 relevant EGFR mutations in 2ml of plasma from NSCLC patients. Legal entity responsible for the studyBiocartis. FundingBiocartis. DisclosureM. Reijans: Full / Part-time employment: Biocartis. S.V. Gestel: Full / Part-time employment: Biocartis. E.D. Haes: Full / Part-time employment: Biocartis. C. Vandesteene: Full / Part-time employment: Biocartis. J.M. Castro Gomez: Full / Part-time employment: Biocartis. C. Gouedard: Full / Part-time employment: BioPath Innovations SA. S. Patera: Full / Part-time employment: BioPath Innovations SA. S. Murray: Full / Part-time employment: BioMarker Solutions Ltd. G.G. Maertens: Full / Part-time employment: Biocartis.

Liquid biopsy for detection of EGFR T790M mutation in nonsmall cell lung cancer: An experience of proficiency testing in Taiwan.

The use of liquid biopsy to detect epidermal growth factor receptor (EGFR) T790M mutation in nonsmall cell lung cancer (NSCLC) is a promising method to screen patients eligible for third-generation EGFR inhibitors. Proficiency testing (PT) programs involving liquid biopsy are currently lacking. In this study, we conducted a PT program to assess the quality assurance of liquid biopsy tests for detecting EGFR T790M mutation in molecular pathology laboratories in Taiwan. Whole blood samples (2 mL) with various concentrations of the EGFR T790M mutation were prepared and analyzed in six participating laboratories using their clinically validated assays. For circulating cell-free DNA (cfDNA) isolation, three of the six participating laboratories used the cobas cfDNA Sample Preparation Kit, and three used the QIAamp Circulating Nucleic Acid Kit. For testing platforms, two of the six participating laboratories used mass spectrometry, three used the cobas EGFR mutation test, and one used a laboratory-developed test. There was 100% concordance in detection of all the given concentrations of EGFR T790M mutation between the participating laboratories and different testing platforms. The testing platforms used by all participating laboratories could successfully detect EGFR T790M mutation to an expected frequency of 1%. In this first PT program using liquid biopsy in Taiwan, local clinical laboratories were suitably equipped and proficient in the use of cfDNA to test for the EGFR T790M mutation. Establishing a routine PT system to ensure the reliability and accuracy of liquid biopsy in clinical practice in Taiwan would be helpful.

Determination of plasma EGFR mutations from non-small cell lung cancer patients at Bach Mai Hospital.

e13121 Background: Lung cancer patients with mutations in the epidermal growth factor receptor (EGFR) are primary candidates for EGFR-targeted therapy. Reliable analyses of such mutations have previously been possible only in tumor tissue. Here, we demonstrate that mutations can be detected in plasma samples of non-small cell lung cancer patients at Bach Mai Hospital and relation of different variables to the frequency of EGFR mutations. Methods: 193 patients with non-small cell lung cancer were identified with EGFR mutation by cobas EGFR Mutation Test v2 kit (Roche Diagnostics, USA), evaluating the EGFR mutation status with different variables. Results: The EGFR mutation rate was 43%, common in patients with adenocarcinoma, female, non-smoking, late stage disease. The rate of EGFR T790M mutation was 36.1%. Among 78 patients who was previous treated TKIs, EGFR mutation rate was 73.1% and the rate of EGFR T790M mutation was 50.8% at the time of progression. The concordance of EGFR mutation from plasma sample with tissue sample was 81%. Conclusions: EGFR mutation in plasma sample results was not different from those in tissue samples and similar with result of studies in Vietnam and worldwide.

The Dynamic Use of EGFR Mutation Analysis in Cell-Free DNA as a Follow-Up Biomarker during Different Treatment Lines in Non-Small-Cell Lung Cancer Patients.

Epidermal growth factor receptor (EGFR) mutational testing in advanced non-small-cell lung cancer (NSCLC) is usually performed in tumor tissue, although cfDNA (cell-free DNA) could be an alternative. We evaluated EGFR mutations in cfDNA as a complementary tool in patients, who had already known EGFR mutations in tumor tissue and were treated with either EGFR-tyrosine kinase inhibitors (TKIs) or chemotherapy. We obtained plasma samples from 21 advanced NSCLC patients with known EGFR tumor mutations, before and during therapy with EGFR-TKIs and/or chemotherapy. cfDNA was isolated and EGFR mutations were analyzed with the multiple targeted cobas EGFR Mutation Test v2. EGFR mutations were detected at baseline in cfDNA from 57% of patients. The semiquantitative index (SQI) significantly decreased from the baseline (median = 11, IQR = 9.5-13) to the best response (median = 0, IQR = 0-0, p < 0.01), followed by a significant increase at progression (median = 11, IQR = 11-15, p < 0.01) in patients treated with either EGFR-TKIs or chemotherapy. The SQI obtained with the cobas EGFR Mutation Test v2 did not correlate with the concentration in copies/mL determined by droplet digital PCR. Resistance mutation p.T790M was observed at progression in patients with either type of treatment. In conclusion, cfDNA multiple targeted EGFR mutation analysis is useful for treatment monitoring in tissue of EGFR-positive NSCLC patients independently of the drug received.

P3.13-03 Real-World Anaplastic Lymphoma Kinase Testing Practices: Results from a Survey in the United States

Anaplastic lymphoma kinase (ALK) translocation is a clinically validated predictive biomarker in multiple cancer types including non-small cell lung cancer, and widespread adoption of diagnostic assays permits a review of test performance. This analysis presents ALK and epidermal growth factor receptor (EGFR) testing rates, expediency, and results from 4 large national laboratories. Deidentified data from January 2013 to December 2015 were compiled from 40 states and Washington DC and included in the final analysis. ALK status was evaluated with the Vysis ALK Break Apart FISH Probe Kit; EGFR status was evaluated by therascreen EGFR RGQ PCR Kit, cobas EGFR Mutation Test, or Sanger sequencing. Results from the most recent conclusive test were used. Collection to order (time from date of biopsy to date of biomarker test order), order to results (time from date of biomarker test order to date of available results), and overall turnaround times (collection to order + order to results) were evaluated. Results were analyzed by laboratories and US regions (Northeast, Midwest, South, and West). Data were summarized with descriptive statistics. s of 59,058 ALK and 50,992 EGFR tests were collected; 50,023 patients were tested for both ALK and EGFR, 9035 had results for ALK only, and 969 for EGFR only. Mean patient ages at ALK-positive (ALK+) and EGFR-positive (EGFR+) diagnoses were 62.5 and 69.0 years, respectively. Overall ALK+ and inconclusive rates were 2.8% and 6.5%, respectively, vs 10.4% and 6.2% for EGFR testing. ALK+ (2.3–5.1%) and inconclusive (1.1–17.4%) rates varied between test centers. In the western US, the ALK+ rate (3.3%) was comparably greater than in other regions (2.4–2.7%). The median turnaround time was 15 days, with a median of 10 days for collection to order and 4 days for order to results; some regional variation was seen in turnaround time (14–18 days). No correlation was seen between age and turnaround time. EGFR+ and ALK+ rates and age distributions were consistent with prior reports. An interesting geographic difference in ALK rates was seen that warrants further investigation. The average turnaround time was longer than current guidelines recommend, suggesting an opportunity to improve current testing practices.

Lung cancer mutation testing: a clinical retesting study of agreement between a real-time PCR and a mass spectrometry test.

To investigate the clinical validity and utility of tests for detecting Epidermal Growth Factor Receptor (EGFR) gene mutations in non-squamous non-small cell lung cancer patients, tumour DNA extracts from 532 patients previously tested by the cobas EGFR Mutation Test (RT-PCR test) were retested by the Sequenom/Agena Biosciences MassArray OncoFocus mass spectrometry test (MS test). Valid results from both tests were available from 470 patients (88%) for agreement analysis. Survival data were obtained for 513 patients (96%) and 77 patients (14%) were treated with EGFR tyrosine kinase inhibitors (TKIs). Agreement analysis revealed moderately high positive (79.8%), negative (96.9%) and overall percentage agreement (93.2%) for the detection of EGFR mutations. However, EGFR mutations were detected by one test and not by the other test in 32 patients (7%). Retesting of discordant samples revealed false-positive and false-negative results generated by both tests. Despite this, treatment and survival outcomes correlated with the results of the RT-PCR and MS tests. In conclusion, this study provides evidence of the clinical validity and utility of the RT-PCR and MS tests for detection of EGFR mutations that predict prognosis and benefit from EGFR-TKI treatment. However, their false-positive and false-negative test results may have important clinical consequences.

EGFR mutation detection in ctDNA from NSCLC patient plasma: A cross-platform comparison of leading technologies to support the clinical development of AZD9291.

To assess the ability of different technology platforms to detect epidermal growth factor receptor (EGFR) mutations, including T790M, from circulating tumor DNA (ctDNA) in advanced non-small cell lung cancer (NSCLC) patients. A comparison of multiple platforms for detecting EGFR mutations in plasma ctDNA was undertaken. Plasma samples were collected from patients entering the ongoing AURA trial (NCT01802632), investigating the safety, tolerability, and efficacy of AZD9291 in patients with EGFR-sensitizing mutation-positive NSCLC. Plasma was collected prior to AZD9291 dosing but following clinical progression on a previous EGFR-tyrosine kinase inhibitor (TKI). Extracted ctDNA was analyzed using two non-digital platforms (cobas(®) EGFR Mutation Test and therascreen™ EGFR amplification refractory mutation system assay) and two digital platforms (Droplet Digital™ PCR and BEAMing digital PCR [dPCR]). Preliminary assessment (38 samples) was conducted using all four platforms. For EGFR-TKI-sensitizing mutations, high sensitivity (78-100%) and specificity (93-100%) were observed using tissue as a non-reference standard. For the T790M mutation, the digital platforms outperformed the non-digital platforms. Subsequent assessment using 72 additional baseline plasma samples was conducted using the cobas(®) EGFR Mutation Test and BEAMing dPCR. The two platforms demonstrated high sensitivity (82-87%) and specificity (97%) for EGFR-sensitizing mutations. For the T790M mutation, the sensitivity and specificity were 73% and 67%, respectively, with the cobas(®) EGFR Mutation Test, and 81% and 58%, respectively, with BEAMing dPCR. Concordance between the platforms was >90%, showing that multiple platforms are capable of sensitive and specific detection of EGFR-TKI-sensitizing mutations from NSCLC patient plasma. The cobas(®) EGFR Mutation Test and BEAMing dPCR demonstrate a high sensitivity for T790M mutation detection. Genomic heterogeneity of T790M-mediated resistance may explain the reduced specificity observed with plasma-based detection of T790M mutations versus tissue. These data support the use of both platforms in the AZD9291 clinical development program.