Ultrarapid EGFR Mutation Screening Followed by Comprehensive Next-Generation Sequencing: A Feasible, Informative Approach for Lung Carcinoma Cytology Specimens With a High Success Rate

Maximizing the clinical utility and performance of cytology samples for comprehensive genetic profiling

Comprehensive molecular profiling by next-generation sequencing has revolutionized tumor classification and biomarker evaluation. However, routine implementation is challenged by the scant nature of diagnostic material obtained through minimally invasive procedures. Here, we describe our long-term experience in profiling cytology samples with an in-depth assessment of the performance, quality metrics, biomarker identification capabilities, and potential pitfalls. We highlight the impact of several optimization strategies to maximize performance with 4,871 prospectively sequenced clinical cytology samples tested by MSK-IMPACTTM. Special emphasis is given to the use of residual supernatant cell-free DNA (ScfDNA) as a valuable source of tumor DNA. Overall, cytology samples are similar in performance to surgical samples in identifying clinically relevant genomic alterations, achieving success rates up to 93% with full optimization. While cell block (CB) samples have excellent performance overall, low-level cross-contamination is identified in a small proportion of cases (4.7%), a common pitfall intrinsic to the processing of paraffin blocks, suggesting that more stringent precautions and processing modifications should be considered in quality control initiatives. By contrast ScfDNA samples have negligible contamination. Finally, ScfDNA testing exclusively used as a rescue strategy, delivered successful results in 71% of cases where tumor tissue from CB was depleted.

Same-day molecular testing for targetable mutations in solid tumor cytopathology-The next frontier of the rapid on-site evaluation

INTRODUCTION

This study aimed to assess the feasibility of implementing the Idylla system, an ultra-rapid, cartridge-based assay, as an extension of rapid on-site evaluation (ROSE) in cytology. The authors conducted a pilot validation study on specimens from non-small cell lung carcinoma, thyroid carcinoma, and melanoma, evaluating four assays designed to detect alterations in KRAS, EGFR, BRAF, gene fusions, and expression imbalances in ALK, ROS1, RET, NTRK1/2/3, and MET exon 14 skipping transcripts. They investigated the feasibility of providing accurate biomarker molecular testing results in a cytopathology laboratory within hours of specimen collection.

METHODS

The authors evaluated the performance characteristics and turn-around-time of the Idylla system by testing a total of 144 cartridge assays across various specimen types, including fine-needle aspirate smears, formalin-fixed paraffin-embedded (FFPE) cell blocks, small tissue biopsy FFPE blocks, and control cell line FFPE scrolls.

RESULTS

The average time from specimen input to results output was 2-3 hours. Accuracy across the four cartridge types was: KRAS assay: 100%, EGFR assay: 94%, BRAF assay: 100%, and GeneFusion assay: 94%. Analytical sensitivity ranged from 1% to 5% variant allele frequency for all assays. Inter-assay precision and analytical specificity were both 100%.

CONCLUSION

Using the Idylla system, actionable genetic alterations can be reliably detected within 2-3 hours from cytology and small biopsy samples with minimal input requirements. The findings of this study demonstrate the feasibility of incorporating same-day molecular testing as part of ROSE procedures in the cytopathology laboratory, ultimately shortening the time from procedure to personalized treatment for cancer patients.

Maximizing the clinical utility and performance of cytology samples for comprehensive genetic profiling - A report on the impact of process optimization through the analysis of 4,871 cytology samples profiled by MSK-IMPACT

Comprehensive molecular profiling by next generation sequencing (NGS) has revolutionized tumor classification and biomarker evaluation. However, routine implementation is challenged by the scant nature of diagnostic material obtained through minimally invasive procedures. Here, we describe our long-term experience in profiling cytology samples with an in-depth assessment of the performance, quality metrics, biomarker identification capabilities, and potential pitfalls. We highlight the impact of several optimization strategies to maximize performance with 4,871 prospectively sequenced clinical cytology samples tested by MSK-IMPACT™. Special emphasis is given to the use of residual supernatant cell free DNA (ScfDNA) as a valuable source of tumor DNA. Overall, cytology samples were similar in performance to surgical samples in identifying clinically relevant genomic alterations, achieving success rates up to 93% with full optimization. While cell block (CB) samples had excellent performance overall, low-level cross-contamination was identified in a small proportion of cases (4.7%), a common pitfall intrinsic to the processing of paraffin blocks, suggesting that more stringent precautions and processing modifications should be considered in quality control initiatives. By contrast ScfDNA samples had negligible contamination. Finally, ScfDNA testing exclusively used as a rescue strategy delivered successful results in 71% of cases where tumor tissue from CB was depleted.

Tissue- and liquid-biopsy based NGS profiling in advanced non-small-cell lung cancer in a real-world setting: the IMMINENT study

Introduction

To date, for all non-small cell lung cancer (NSCLC) cases, it is recommended to test for driver alterations to identify actionable therapeutic targets. In this light, comprehensive genomic profiling (CGP) with next generation sequencing (NGS) has progressively gained increasing importance in clinical practice. Here, with the aim of assessing the distribution and the real-world frequency of gene alterations and their correlation with patient characteristics, we present the outcomes obtained using FoundationOne (F1CDx) and FoundationLiquid CDx (F1L/F1LCDx) NGS-based profiling in a nationwide initiative for advanced NSCLC patients.

Methods

F1CDx (324 genes) was used for tissue samples, and F1L (70 genes) or F1LCDx (324 genes) for liquid biopsy, aiming to explore the real-world occurrence of molecular alterations in aNSCLC and their relationship with patients' characteristics.

Results

Overall, 232 advanced NSCLC patients from 11 Institutions were gathered [median age 63 years; never/former or current smokers 29.3/65.9%; adenocarcinoma/squamous 79.3/12.5%; F1CDx/F1L+F1LCDx 59.5/40.5%]. Alterations were found in 170 different genes. Median number of mutated genes per sample was 4 (IQR 3-6) and 2 (IQR 1-3) in the F1CDx and F1L/F1LCDx cohorts, respectively. TP53 (58%), KRAS (22%), CDKN2A/B (19%), and STK11 (17%) alterations were the most frequently detected. Actionability rates (tier I and II) were comparable: 36.2% F1CDx vs. 34% ctDNA NGS assays (29.5% and 40.9% F1L and F1LCDx, respectively). Alterations in KEAP1 were significantly associated with STK11 and KRAS, so as TP53 with RB1. Median tumor mutational burden was 6 (IQR 3-10) and was significantly higher in smokers. Median OS from metastatic diagnosis was 23 months (IQR 18.5-19.5) and significantly lower in patients harboring ≥3 gene mutations. Conditional three-year survival probabilities increased over time for patients profiled at initial diagnosis and exceeded those of individuals tested later in their clinical history after 12 months.

Conclusion

This study confirms that NGS-based molecular profiling of aNSCLC on tissue or blood samples offers valuable predictive and prognostic insights.

Multinational proficiency tests for EGFR exon 20 insertions reveal that the assay design matters

Insertion mutations in exon 20 of the epidermal growth factor receptor gene (EGFR exon20ins) are rare, heterogeneous alterations observed in non-small cell lung cancer (NSCLC). With a few exceptions, they are associated with primary resistance to established EGFR tyrosine kinase inhibitors (TKIs). As patients carrying EGFR exon20ins may be eligible for treatment with novel therapeutics-the bispecific antibody amivantamab, the TKI mobocertinib, or potential future innovations-they need to be identified reliably in clinical practice for which quality-based routine genetic testing is crucial. Spearheaded by the German Quality Assurance Initiative Pathology two international proficiency tests were run, assessing the performance of 104 participating institutes detecting EGFR exon20ins in tissue and/or plasma samples. EGFR exon20ins were most reliably identified using next-generation sequencing (NGS). Interestingly, success rates of institutes using commercially available mutation-/allele-specific quantitative (q)PCR were below 30% for tissue samples and 0% for plasma samples. Most of these mutation-/allele-specific (q)PCR assays are not designed to detect the whole spectrum of EGFR exon20ins mutations leading to false negative results. These data suggest that NGS is a suitable method to detect EGFR exon20ins in various types of patient samples and is superior to the detection spectrum of commercially available assays.

Microfluidics-based EGFR mutation detection and its implication in the resource-limited clinical setting

Management of lung cancer today obligates a mutational analysis of the epidermal growth factor receptor (EGFR) gene particularly when Tyrosine Kinase Inhibitor (TKI) therapy is being considered as part of prognostic stratification. This study evaluates the performance of automated microfluidics-based EGFR mutation detection and its significance in clinical diagnostic settings. Formalin-fixed, paraffin-embedded (FFPE) samples from NSCLC patients (n = 174) were included in a two-phase study. Phase I: Validation of the platform by comparing the results with conventional real-time PCR and next-generation sequencing (NGS) platform. Phase II: EGFR mutation detection on microfluidics-based platform as part of routine diagnostics workup. The microfluidics-based platform demonstrates 96.5% and 89.2% concordance with conventional real-time PCR and NGS, respectively. The system efficiently detects mutations across the EGFR gene with 88.23% sensitivity and 100% specificity. Out of 144 samples analysed in phase II, the platform generated valid results in 94% with mutation detected in 41% of samples. This microfluidics-based platform can detect as low as 5% mutant allele fractions from the FFPE samples. Therefore the microfluidics-based platform is a rapid, complete walkaway, with minimum tissue requirement (two sections of 5 μ thickness) and technical skill requirement. The method can detect clinically actionable EGFR mutations efficiently and can be considered a reliable diagnostic platform in resource-limited settings. From receiving samples to reporting the results this platform provides accurate data without much manual intervention. The study helped to devise an algorithm that emphasizes effective screening of the NSCLC cases for EGFR mutations with varying tumour content. Thus it helps in triaging the cases judiciously before proceeding with multigene testing.

Pitfalls in Respiratory Tract Cytopathology

BACKGROUND

Cytopathology is integral to the investigation and diagnosis of respiratory disease, and, in the last decade or so, transbronchial needle aspiration by endobronchial ultrasound has made possible diagnosis and staging of malignant thoracic tumours at a single procedure. In addition, interventional teams increasingly include cytopathologists and cytotechnologists who, by providing rapid onsite evaluation, ensure efficient sampling of intrathoracic targets with the ultimate goal of accurate diagnosis as well as sufficient material for comprehensive predictive testing. Nonetheless, "traditional" cytological investigations such as bronchial washings, brushings, and lavages are still carried out for investigation of both suspected neoplastic and non-neoplastic conditions, and all these procedures still produce specimens in which florid benign cells mimic malignancy, while truly neoplastic cells lurk quietly in the background. Furthermore, even when neoplasia is not suspected, issues in preparation and interpretation may render a final assessment inaccurate and, therefore, clinically unhelpful or misleading. In this overview, we have tried to adopt a format partly modelled on the passage of a specimen from clinical acquisition to laboratory endpoint, thus taking in potential pitfalls in communication, clinical interaction, transport, and clinic-based preparation, as well as in morphology, immunocytochemistry, and suitability for predictive testing. It is not exhaustive but highlights areas that may frequently be encountered or are part of our personal experience.

SUMMARY

The account highlights potential pitfalls in respiratory cytopathology at key stages of the process from acquisition to reporting and presents these in both flow diagram and tabular form. We hope this is useful for the increasingly collaborative roles of cytotechnologist and cytopathologist and their wider involvement in the clinical investigative teams.

KEY MESSAGES

Correct clinical and radiological information is crucially important and promotes the correct acquisition and processing of cytopathological specimens. Cross-discipline collaborative working ensures the most efficient use of the specimen such that diagnoses and predictive tests are performed on optimal material, reducing the potential for misinterpretation. Nonetheless, even with optimal material, morphological mimics and atypical antigen expression may mislead and render accurate diagnosis challenging.

Use of cytology fluid samples for predictive biomarker testing in lung cancer patients

OBJECTIVE

To provide a method of directly using cytology fluid samples for predictive biomarker testing in lung cancer patients and to determine the efficacy of a variety of fluid sample types.

METHOD

A review of our in-house data from a range of cytology samples including endobronchial ultrasound (EBUS) fine-needle aspirate (FNA) needle washings (NW) and serous effusions tested on the Biocartis Idylla platform. All fluid samples were originally tested using Sanger sequencing.

RESULTS

Using our method for fluid samples all of our cytology samples tested for epithelial growth factor receptor (EGFR) yielded valid results on this platform and all variant cases identified. The data showed serous fluids provided the best quality DNA, and variant genotype reports were obtained within 150 minutes.

CONCLUSION

Cytology fluid samples can be used for predictive biomarker testing for lung cancer patients to provide in-house results with all fluids providing good-quality DNA.

Evaluation of the Idylla™ EGFR Mutation Test on formalin-fixed, paraffin-embedded tissue of human lung cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) mutation detection is essential for the therapy of lung cancer. A sensitive, specific, and cost-effective standardized method to quickly and accurately detect EGFR mutations is urgently needed.

METHODS

We evaluated the Idylla™ EGFR Mutation Assay for EGFR mutations in formalin-fixed, paraffin-embedded (FFPE) tumor samples from 232 lung cancer patients, and compared the results with amplification refractory mutation system (ARMS) (n=146) and next-generation sequencing (NGS) (n=86). The surgical tumor sections and cell blocks derived from the same FFPE section were compared. Overall concordance, specificity, sensitivity, cost-effectiveness and turnaround time were compared among the three methods.

RESULTS

The overall concordance between Idylla and ARMS was 89.51% [95% confidence interval (CI): 83.31% to 93.64%] and the specificity of Idylla was 88.68% (95% CI: 80.69% to 93.76%). A concordance of 97.67% (95% CI: 91.41% to 99.86%) was obtained between Idylla and NGS, the specificity of Idylla was 96.30% (95% CI: 86.16% to 99.36%). Compared to the ARMS and NGS, the Idylla™ system significantly reduces the turnaround time. Combining labor, equipment, reagents and time costs, Idylla is more affordable.

CONCLUSIONS

Clinically urgent cases with adequate cellularity, can first perform Idylla to detect critical markers, then perform NGS for a comprehensive mutation analysis. Besides, with limited molecular expertise or infrastructure, the Idylla has the potential to extend EGFR testing to more pathology laboratories in primary hospitals.

Digital Examination of LYmph node CYtopathology Using the Sydney system (DELYCYUS): An international, multi-institutional study

BACKGROUND

After a series of standardized reporting systems in cytopathology, the Sydney system was recently introduced to address the need for reproducibility and standardization in lymph node cytopathology. Since then, the risk of malignancy for the categories of the Sydney system has been explored by several studies, but no studies have yet examined the interobserver reproducibility of the Sydney system.

METHODS

The authors assessed interobserver reproducibility of the Sydney system on 85 lymph node fine-needle aspiration cytology cases reviewed by 15 cytopathologists from 12 institutions in eight different countries, resulting in 1275 diagnoses. In total, 186 slides stained with Diff-Quik, Papanicolaou, and immunocytochemistry were scanned. A subset of the cases included clinical data and results from ultrasound examinations, flow cytometry immunophenotyping, and fluorescence in situ hybridization analysis. The study participants assessed the cases digitally using whole-slide images.

RESULTS

Overall, the authors observed an almost perfect agreement of cytopathologists with the ground truth (median weighted Cohen κ = 0.887; interquartile range, κ = 0.210) and moderate overall interobserver concordance (Fleiss κ = 0.476). There was substantial agreement for the inadequate and malignant categories (κ = 0.794 and κ = 0.729, respectively), moderate agreement for the benign category (κ = 0.490), and very slight agreement for the suspicious (κ = 0.104) and atypical (κ = 0.075) categories.

CONCLUSIONS

The Sydney system for reporting lymph node cytopathology shows adequate interobserver concordance. Digital microscopy is an adequate means to assess lymph node cytopathology specimens.

X-linked hydrocephalus genes: Their proximity to telomeres and high A + T content compared to Parkinson's disease

Proximity to telomeres (i) and high adenine and thymine (A + T) content (ii) are two factors associated with high mutation rates in human chromosomes. We have previously shown that >100 human genes when mutated to cause congenital hydrocephalus (CH) meet either factor (i) or (ii) at 91% matching, while two factors are poorly satisfied in human genes associated with familial Parkinson's disease (fPD) at 59%. Using the sets of mouse, rat, and human chromosomes, we found that 7 genes associated with CH were located on the X chromosome of mice, rats, and humans. However, genes associated with fPD were in different autosomes depending on species. While the contribution of proximity to telomeres in the autosome was comparable in CH and fPD, high A + T content played a pivotal contribution in X-linked CH (43% in all three species) than in fPD (6% in rodents or 13% in humans). Low A + T content found in fPD cases suggests that PARK family genes harbor roughly 3 times higher chances of methylations in CpG sites or epigenetic changes than X-linked genes.

Updates in pathology and molecular diagnostics to inform the evolving landscape of thoracic surgery and oncology

The pathologic assessment of lung cancers provides essential guidance to the surgeon and oncologist who are considering the best treatment strategies for patients with both early and advanced-stage disease. The management of patients with lung cancer is predicated first and foremost on access to an accurate diagnosis, even when the sample size is limited, as is often the case with use of modern, minimally invasive sampling techniques. Once the diagnosis and disease stage are established, predictive biomarker testing may be essential, particularly for those patients with nonsmall cell lung carcinoma (NSCLC) being considered for immunotherapy or genomic biomarker-driven targeted therapy. This review will discuss the best practices for the diagnosis of NSCLC using morphology and immunohistochemistry, thus providing the surgeon with needed information to understand and critically evaluate pathology reports. Controversial and evolving topics including tumor spread through airspaces, evaluation of multiple tumors, and staging based on invasive tumor size will be addressed. Clinical genomic profiling in NSCLC is driven by published guidelines and reflects evidence based on clinical trials and regulatory approvals. In this fast-moving space, surgeons should be aware of the critical immunohistochemical and genomic biomarkers that drive systemic therapy decisions and anticipate when such testing will be required, both to ensure adequate sampling and to advise the pathologist when tumor material will be required for biomarker analysis. The basic approaches to and sample requirements for molecular biomarker testing will be addressed. As biomarker testing moves exclusively from advanced-stage patients into earlier stage disease, the surgeon should be aware of the relevant markers and work with the pathologist and oncologist to ensure that this information is available to facilitate timely access to therapies not just in the advanced setting, but in consideration of neoadjuvant and adjuvant care.

FACILITATE: A real-world, multicenter, prospective study investigating the utility of a rapid, fully automated real-time PCR assay versus local reference methods for detecting epidermal growth factor receptor variants in NSCLC

Accurate testing for epidermal growth factor receptor (EGFR) variants is essential for informing treatment decisions in non-small cell lung cancer (NSCLC). Automated diagnostic workflows may allow more streamlined initiation of targeted treatments, where appropriate, while comprehensive variant analysis is ongoing. FACILITATE, a real-world, prospective, multicenter, European study, evaluated performance and analytical turnaround time of the Idylla™ EGFR Mutation Test compared with local reference methods. Sixteen sites obtained formalin-fixed paraffin-embedded biopsy samples with ≥ 10% neoplastic cells from patients with NSCLC. Consecutive 5 μm sections from patient samples were tested for clinically relevant NSCLC-associated EGFR variants using the Idylla™ EGFR Mutation Test and local reference methods; performance (concordance) and analytical turnaround time were compared. Between January 2019 and November 2020, 1,474 parallel analyses were conducted. Overall percentage agreement was 97.7% [n = 1,418; 95% confidence interval (CI): 96.8-98.3], positive agreement, 87.4% (n = 182; 95% CI: 81.8-91.4) and negative agreement, 99.2% (n = 1,236; 95% CI: 98.5-99.6). There were 38 (2.6%) discordant cases. Ninety percent of results were returned with an analytical turnaround time of within 1 week using the Idylla™ EGFR Mutation Test versus ∼22 days using reference methods. The Idylla™ EGFR Mutation Test performed well versus local methods and had shorter analytical turnaround time. The Idylla™ EGFR Mutation Test can thus support application of personalized medicine in NSCLC.

Overview and update on molecular testing in non-small cell lung carcinoma utilizing endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) samples

Lung carcinoma remains one of the most frequent and aggressive human neoplasms. Fortunately, in the last decades, the increasing knowledge of the molecular mechanisms leading to cancer development has allowed the use of targeted therapies with improvement of prognosis in many patients. Clinical management has also changed after the introduction of endobronchialultrasonographic bronchoscopy that allows a conservative staging of lung tumors, avoiding the need of mediastinoscopy for lymph node staging. Lung pathologists and cytopathologists are facing the challenge of giving the more comprehensive prognostic and predictive information with ever smaller tissue or cytological samples. The aim of this review is to summarize the molecular testing for non-small cell lung carcinoma and how pathologists can contribute to the patient's outcome with a conscious management of biological samples.

The basics of commonly used molecular techniques for diagnosis, and application of molecular testing in cytology

Molecular diagnostics has expanded to become the standard of care for a variety of solid tumor types. With limited diagnostic material, it is often desirable to use cytological preparations to provide rapid and accurate molecular results. This review covers important pre-analytic considerations and limitations, and a description of common techniques that the modern cytopathologist should understand when ordering and interpreting molecular tests in practice.

Use of the Biocartis Idylla™ Platform for the Detection of Epidermal Growth Factor Receptor, BRAF and KRAS Proto-Oncogene Mutations in Liquid-Based Cytology Specimens from Patients with Non-Small Cell Lung Carcinoma and Pancreatic Adenocarcinoma

The study aimed to demonstrate rapid and effective molecular testing on liquid-based cytology (LBC) samples for EGFR, KRAS and BRAF mutations using the Biocartis Idylla™. Rapid on-site evaluation (ROSE) LBC samples for patients with non-small cell lung carcinoma (NSCLC) or pancreatic ductal adenocarcinoma (PDAC) were tested for EGFR, KRAS and BRAF mutations based on the relevance to tumour subtype. The quantification values (Cq values) and mutation detection status were compared between LBC samples and routine formalin-fixed paraffin-embedded (FFPE) clot samples. ROSE LBC samples (n = 54) showed a higher yield of well-preserved tumour and wild type (WT) DNA, demonstrated by lower quantification cycles, no false positives or false negatives, and a higher sensitivity for low allele frequency mutations when compared with FFPE clot samples. The Biocartis Idylla™ provides highly sensitive, reliable and rapid testing for LBC samples for the detection of EFGR and KRAS mutations. BRAF mutations were not detected in the participant cohort; however, all LBC WT BRAF results correlated with the results from the FFPE clot samples. Access to rapid molecular testing using LBC samples can detect the most frequent driver mutations closer to the time of diagnosis, enabling the selection of the most effective first-line targeted therapy sooner, reducing delays or side effects from suboptimal treatments, patient anxiety and costs to healthcare systems, whilst improving patient outcomes.

Contribution of the IdyllaTM System to Improving the Therapeutic Care of Patients with NSCLC through Early Screening of EGFR Mutations

Epidermal growth factor receptor (EGFR) genotyping, a critical examen for the treatment decisions of patients with non-small cell lung cancer (NSCLC), is commonly assayed by next-generation sequencing (NGS), but this global approach takes time. To determine whether rapid EGFR genotyping tests by the Idylla^TM system guides earlier therapy decisions, EGFR mutations were assayed by both the Idylla^TM system and NGS in 223 patients with NSCLC in a bicentric prospective study. Idylla^TM demonstrated agreement with the NGS method in 187/194 cases (96.4%) and recovered 20 of the 26 (77%) EGFR mutations detected using NGS. Regarding the seven missed EGFR mutations, five were not detected by the Idylla^TM system, one was assayed in a sample with insufficient tumoral cells, and the last was in a sample not validated by the Idylla^TM system (a bone metastasis). Idylla^TM did not detect any false positives. The average time between EGFR genotyping results from Idylla^TM and the NGS method was 9.2 ± 2.2 working days (wd) (12.6 ± 4.0 calendar days (cd)). Subsequently, based on the Idylla^TM method, the timeframe from tumor sampling to the initiation of EGFR-TKI was 7.7 ± 1.2 wd (11.4 ± 3.1 cd), while it was 20.3 ± 6.7 wd (27.2 ± 8.3 cd) with the NGS method (p < 0.001). We thus demonstrated here that the Idylla^TM system contributes to improving the therapeutic care of patients with NSCLC by the early screening of EGFR mutations.

Feasibility and performance of the Idylla™ NRAS/BRAF cartridge mutation assay on thyroid liquid-based fine-needle aspiration

BACKGROUND

Thyroid nodules with indeterminate cytology represent up to 30% of cases. Molecular testing is now highly recommended to improve management. This study aimed to evaluate the use of the Idylla™ NRAS/BRAF mutation test, a rapid and automated polymerase chain reaction (PCR) assay validated for fixed paraffin-embedded use, on residual thyroid liquid-based fine-needle aspiration (LB-FNA).

METHODS

Concordance between mutations detected by the Idylla™ assay and the gold-standard qPCR was assessed by splitting in two aliquots 31 BRAF or RAS mutated and 5 non-mutated LB-FNA samples. Samples were obtained either from simulated FNA after thyroidectomy or from FNA obtained during routine care. A third aliquot was used to assess the limit of detection of Idylla™ for five mutated samples.

RESULTS

The Idylla™ assay showed a sensitivity of 97% and a specificity of 83% as results were concordant for 34 out of 36 samples. One discordant sample concerned a BRAF p.K601E-mutation which is not detected by the Idylla™ cartridge. The other showed a false-positive NRAS p.A146T detection and a weak BRAF p.V600E detection. The limit of detection of the Idylla™ assay was not reached by the dilution assay.

CONCLUSION

Idylla™ NRAS/BRAF mutation testing can be performed on residual thyroid LB-FNA, using low DNA quantity input, thus not requiring a dedicated sample. The Idylla™ NRAS/BRAF assay offers a quick and easy first step for analyzing the main molecular alterations in indeterminate thyroid nodules, hence improving diagnostic management.

Short report: Performance evaluation of the Idylla™ KRAS and EGFR mutation tests on paraffin-embedded cytological NSCLC samples

BACKGROUND

Quick and reliable testing of EGFR and KRAS is needed in non-small cell lung cancer (NSCLC) to ensure optimal decision-making for targeted therapy. The Idylla™ platform was designed for Formalin-Fixed Paraffin-Embedded (FFPE) tissue sections but recently several studies were published that evaluated its potential for cytological specimens. This study aimed to validate the Idylla™ platform for the detection of EGFR/KRAS mutations in cytological NSCLC samples prepared as cytoblocks using AGAR and paraffin embedding.

MATERIAL AND METHODS

The KRAS Idylla™ test were performed on 11 specimens with a known KRAS mutation. The EGFR Idylla™ test was performed on 18 specimens with a known primary EGFR mutation and 7 specimens with a primary EGFR-EGFR T790M resistance mutation combination.

RESULTS

Concordant KRAS and primary EGFR mutations were detected for both KRAS and primary EGFR mutations. Samples with a total CQ value of < 26 could be considered negative. Samples with a total CQ value of > 26 could not be assessed (probability of false-negative). In specimens with a primary EGFR-EGFR T790M resistance mutation combination, 5/7 cases were not concordant.

CONCLUSION

Our results confirm the conclusion of recent reports that the Idylla™EGFR assay is not suitable in a resistance to EGFR TKI setting, also not in our cytological NSCLC samples prepared as cytoblocks using AGAR and paraffin embedding. KRAS and primary EGFR mutations were detected using the Idylla™ assays in virtually all cytological NSCLC samples. This analysis was rapid and time-saving compared to other mutation detection assays and may be useful if the amount of material is insufficient to perform a full set of molecular tests.

Evaluation of the Idylla ctEGFR mutation assay to detect EGFR mutations in plasma from patients with non-small cell lung cancers

The assessment of EGFR mutations is recommended for the management of patients with non-small cell lung cancer (NSCLC). Presence of EGFR mutation is associated with response or resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI). Liquid biopsy is nowadays widely used for the detection of resistance to EGFR-TKI. We evaluated here the performance of the Idylla ctEGFR mutation assay for the detection of EGFR mutations in circulating tumour DNA (ctDNA) in plasma from patients with NSCLC. Previously characterized plasma samples from 38 patients with NSCLC were analysed using 2 different analytical conditions (C1 and C2). The limit of detection (LOD) was evaluated using 2 mL of healthy donor plasma spiked with commercial DNA controls. Overall agreement, sensitivity and specificity were 92.1%, 86.7% and 95.7% for C1 condition respectively and 94.7%, 86.7% and 100% for C2 condition respectively. The T790M secondary resistance mutation was detected in two samples out of 3. The Idylla system was able to detect the exon 19 deletion from 6 copies/mL and up to 91 copies/mL for the G719S mutation. These results support that the Idylla ctEGFR mutation assay is a rapid option for the detection of EGFR hotspots mutations in plasma samples, however a particular attention is needed for its interpretation.

Testing EGFR with Idylla on Cytological Specimens of Lung Cancer: A Review

The current standard of care for advanced non-small-cell lung cancer is based on detecting actionable mutations that can benefit from targeted therapy. Comprehensive genetic tests can have long turn-around times, and because EGFR mutations are the most prevalent actionable mutation, a quick detection would enable a prompt initiation of targeted therapy. Furthermore, the scarcity of diagnostic material means that sometimes only cytologic material is available. The Idylla™ EGFR assay is a real-time PCR–based method able to detect 51 EGFR mutations in 2.5 h. Idylla is validated for use only on FFPE sections, but some researchers described their experiences with cytological material. We reviewed the relevant literature, finding four articles describing 471 cases and many types of cytological input material: smears, cell-block sections, suspensions, and extracted DNA. The sensitivity, specificity, and limit of detection appear comparable to those obtained with histological input material, with one exception: the usage of scraped stained smears as input may reduce the accuracy of the test. In conclusion, usage of cytological material as input to the Idylla EGFR test is possible. A workflow where common mutations are tested first and fast, leaving rarer mutations for subsequent comprehensive profiling, seems the most effective approach.

Performance evaluation of the Biocartis Idylla EGFR Mutation Test using pre-extracted DNA from a cohort of highly characterised mutation positive samples

AIMS

Targeted therapies for non-small cell lung carcinoma (NSCLC) rely on the detection of specific genomic lesions, such as mutations within the epidermal growth factor receptor (EGFR) gene. The Biocartis Idylla platform and single-use EGFR mutation test cartridge is CE-IVD for use with formalin-fixed paraffin embedded (FFPE) tumour material, but can also function off-scope using extracted DNA as input material. This can expand the utility of the platform and potentially conserve valuable tissue.

METHODS

We sought to evaluate the performance of this system to detect known EGFR mutations using extracted DNA at different input levels. 130 next generation sequencing-characterised NSCLC cases possessing EGFR mutations that were theoretically detectable by the Idylla system were selected. Replicate analyses were performed using the Idylla EGFR test with up to three different DNA input levels (20 ng, 50 ng and 250 ng).

RESULTS

Considering only variants within the test manufacturer's specified scope, the Idylla EGFR test generated concordant findings for 90.77% of cases at 20 ng DNA input, 98.46% at 50 ng input and 100% at 250 ng input. Analyses with discordant findings all generated control quantification cycle (CQ) values greater than 23. Very low CQ values were associated with EGFR gene amplification.

CONCLUSIONS

The Idylla EGFR Mutation Test can be used at least as well with pre-extracted DNA than with direct FFPE input. In cases with control CQ >23, reanalysis with an increased DNA input should ideally be undertaken. If this is not possible, the risk of false negative calls may be mitigated by manual review of the quantitative PCR data and/or by reflexing to alternative analysis options.