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

Efficacy of third-generation epidermal growth factor receptor-tyrosine kinase inhibitors in advanced NSCLC with different T790M statuses tested via digital droplet polymerase chain reaction ddPCR and next-generation sequencing

OBJECTIVES

We hypothesize that digital droplet polymerase chain reaction (ddPCR) would optimize the treatment strategies in epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) relapsed patients. In this study, we compared the efficacy of third-generation TKIs with various T790M statuses via ddPCR and next-generation sequencing (NGS).

METHODS

NGS was performed on blood samples of patients progressed from previous EGFR-TKIs for resistance mechanism. T790M-negative patients received further liquid biopsy using ddPCR for T790M detection.

RESULTS

A cohort of 40 patients were enrolled, with 30.0% (12/40) T790M-positive via NGS (Group A). In another 28 T790M-negative patients by NGS, 11 (39.3%) were T790M-positive (Group B) and 17 (60.7%) were T790M-negative (Group C) via ddPCR. A relatively longer progression-free survival (PFS) was observed in group A (NR) and group B (10.0 months, 95% CI 7.040-12.889) than in group C (7.0 months, 95% CI 0.000-15.219), with no significant difference across all three groups (p = 0.196), or between group B and C (p = 0.412). EGFR-sensitive mutation correlated with inferior PFS (p = 0.041) and ORR (p = 0.326), and a significantly lower DCR (p = 0.033) in T790M-negative patients via NGS (n = 28).

CONCLUSION

This study indicates that ddPCR may contribute as a supplement to NGS in liquid biopsies for T790M detection in EGFR-TKIs relapsed patients and help to optimize the treatment strategies, especially for those without coexistence of EGFR-sensitive mutation.

TRIAL REGISTRATION

www.clinicaltrials.gov identifier is NCT05458726.

Unrevealing the therapeutic benefits of radiotherapy and consolidation immunotherapy using ctDNA-defined tumor clonality in unresectable locally advanced non-small cell lung cancer

Progression occurs in approximately two-thirds of patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving chemoradiation and consolidation immunotherapy. Molecular indicators for outcome prediction are under development. A novel metric, the ratio of mean to max variant allele frequency (mmVAF), was derived from 431 pre-treatment tissue biopsies from The Cancer Genome Atlas and evaluated in serial circulating tumor DNA (ctDNA) from 70 LA-NSCLC patients receiving definitive radiotherapy/chemoradiotherapy (RT/CRT) with/without immunotherapy. High mmVAFs in pre-treatment tissue biopsies, indicating clonal predominant tumors (P < 0.01), were associated with inferior overall survival [OS, hazard ratio (HR): 1.48, 95 % confidence interval (CI): 1.11-1.98]. Similar associations of mmVAF with clonality (P < 0.01) and OS (HR: 2.24, 95 % CI: 0.71-7.08) were observed in pre-treatment ctDNA. At 1-month post-RT, ctDNA mmVAF-high patients receiving consolidation immunotherapy exhibited improved progression-free survival (PFS) compared to those who did not (HR: 0.14, 95 % CI: 0.03-0.67). From the baseline to week 4 of RT and/or 1-month post-RT, survival benefits from consolidation immunotherapy were exclusively observed in ctDNA mmVAF-increased patients (PFS, HR: 0.39, 95 % CI: 0.14-1.15), especially in terms of distant metastasis (HR: 0.11, 95 % CI: 0.01-0.95). In summary, our longitudinal data demonstrated the applicability of ctDNA-defined clonality for prognostic stratification and immunotherapy benefit prediction in LA-NSCLC.

Analytical Performance Evaluation of a 523-Gene Circulating Tumor DNA Assay for Next-Generation Sequencing-Based Comprehensive Tumor Profiling in Liquid Biopsy Samples

Next-generation sequencing (NGS)-based comprehensive tumor profiling from liquid biopsy samples can significantly improve diagnosis and monitoring of tumors when high-quality tissue material is difficult to obtain. In addition, it offers the potential to capture the entire complexity of the tumor, which is particularly important for highly heterogeneous or metastatic tumors. Here, we report the findings of an analytical performance evaluation of the TruSight Oncology 500 circulating tumor DNA (ctDNA) assay, a 523-gene NGS panel developed for ctDNA-based comprehensive genomic profiling of tumors, using reference and patient samples. Using 30 ng cell-free DNA, the assay showed high sensitivity and low variant detection variability for single-nucleotide variants, insertions and deletions, and fusions down to a variant allele frequency (VAF) of 0.5% in the reference samples and VAFs that were highly concordant with previous digital droplet PCR results in the patient samples. At reduced input amounts (20, 15, and 5 ng) and below VAFs of 0.5%, sensitivity was considerably lower and variant detection variability increased. Covering 523 tumor-associated genes, the assay demonstrated a convincing performance comparable to NGS-based ctDNA assays with smaller gene panels, highlighting its value to screen large numbers of different genes.

The efficacy and safety of chemo-free therapy in epidermal growth factor receptor tyrosine kinase inhibitor-resistant advanced non-small cell lung cancer: A single-arm, phase II study

OBJECTIVES

The purpose of this study was to explore the efficacy and safety of toripalimab combined with anlotinib in patients with advanced non-small cell lung cancer (NSCLC) who acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs).

MATERIALS AND METHODS

Patients who developed resistance after using first- or second-generation EGFR-TKIs as their first-line regimen without EGFR T790M mutation or had disease progression after being treated with third-generation EGFR-TKIs as first- or second-line therapy were enrolled. All patients received toripalimab (240 mg/day on Day 1, intravenously) combined with anlotinib (12 mg/day, Days 1-14, orally) once every 3 weeks. Treatment continued until disease progression, or if toxicity was intolerable. The primary endpoint was the objective response rate (ORR) assessed by the investigator. The secondary endpoint was the progression-free survival (PFS).

RESULTS

In total, 19 patients were enrolled between May 2020 and October 2021.The ORR was 0%, and a median PFS was 2.1 months (95% CI 0.251-3.949). Grade ≥3 treatment-related adverse events (AEs) occurred in 11% patients. Common adverse events included hypothyroidism (12/19), fatigue (9/19), and hypertension (8/19). Patients in stable disease (SD) group had lower abundance of EGFR mutation allele frequency (AF) before enrollment than those in progressive disease (PD) group (p = 0.031). Patients without detectable EGFR mutation (EGFR-) had longer PFS compared to the ones with EGFR mutations (p = 0.059). Patients with high levels of soluble programmed cell death ligand 1 (PD-L1) at baseline also tended to have longer PFS (p = 0.160).

CONCLUSION

Toripalimab combined with anlotinib was tolerable in EGFR-TKI-resistant advanced NSCLC patients not previously treated with chemotherapy. Patients without detectable EGFR mutation and high soluble PD-L1 levels may benefit from this chemotherapy-free treatment.

The Emerging Role of Liquid Biopsies in Revolutionising Cancer Diagnosis and Therapy

A potential non-invasive technique for identifying and tracking cancer is a liquid biopsy. This review article provides a comprehensive overview of the principles, applications, and challenges associated with liquid biopsies. The circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), exosomes, and microRNAs are just a few of the biomarkers we cover in this article that are discovered in liquid biopsies. The clinical application of liquid biopsies in many stages of cancer management, including early cancer identification, therapy selection and response monitoring, and minimum residual illness, is also investigated. The technical advancements in liquid biopsy techniques, including digital polymerase chain reaction (dPCR) and next-generation sequencing (NGS), have improved the sensitivity and specificity of biomarker identification. Liquid biopsies require assistance with cost-effectiveness, sensitivity, and standardisation despite the potential benefits. We talk about these restrictions and potential solutions. In conclusion, liquid biopsies revolutionise personalised therapies and cancer diagnostics by providing a real-time, non-invasive tool for characterising and monitoring tumours. It will be possible to expand the use of liquid biopsies in clinical practises by having a better understanding of their current state and predicted future developments.

Liquid Biopsy in NSCLC: An Investigation with Multiple Clinical Implications

Tissue biopsy is essential for NSCLC diagnosis and treatment management. Over the past decades, liquid biopsy has proven to be a powerful tool in clinical oncology, isolating tumor-derived entities from the blood. Liquid biopsy permits several advantages over tissue biopsy: it is non-invasive, and it should provide a better view of tumor heterogeneity, gene alterations, and clonal evolution. Consequentially, liquid biopsy has gained attention as a cancer biomarker tool, with growing clinical applications in NSCLC. In the era of precision medicine based on molecular typing, non-invasive genotyping methods became increasingly important due to the great number of oncogene drivers and the small tissue specimen often available. In our work, we comprehensively reviewed established and emerging applications of liquid biopsy in NSCLC. We made an excursus on laboratory analysis methods and the applications of liquid biopsy either in early or metastatic NSCLC disease settings. We deeply reviewed current data and future perspectives regarding screening, minimal residual disease, micrometastasis detection, and their implication in adjuvant and neoadjuvant therapy management. Moreover, we reviewed liquid biopsy diagnostic utility in the absence of tissue biopsy and its role in monitoring treatment response and emerging resistance in metastatic NSCLC treated with target therapy and immuno-therapy.

Circulating tumor DNA sequencing of pediatric solid and brain tumor patients: An institutional feasibility study

The potential of circulating tumor DNA (ctDNA) analysis to serve as a real-time "liquid biopsy" for children with central nervous system (CNS) and non-CNS solid tumors remains to be fully elucidated. We conducted a study to investigate the feasibility and potential clinical utility of ctDNA sequencing in pediatric patients enrolled on an institutional clinical genomics trial. A total of 240 patients had tumor DNA profiling performed during the study period. Plasma samples were collected at study enrollment from 217 patients and then longitudinally from a subset of patients. Successful cell-free DNA extraction and quantification occurred in 216 of 217 (99.5%) of these initial samples. Twenty-four patients were identified whose tumors harbored 30 unique variants that were potentially detectable on a commercially-available ctDNA panel. Twenty of these 30 mutations (67%) were successfully detected by next-generation sequencing in the ctDNA from at least one plasma sample. The rate of ctDNA mutation detection was higher in patients with non-CNS solid tumors (7/9, 78%) compared to those with CNS tumors (9/15, 60%). A higher ctDNA mutation detection rate was also observed in patients with metastatic disease (9/10, 90%) compared to non-metastatic disease (7/14, 50%), although tumor-specific variants were detected in a few patients in the absence of radiographic evidence of disease. This study illustrates the feasibility of incorporating longitudinal ctDNA analysis into the management of relapsed or refractory patients with childhood CNS or non-CNS solid tumors.

Clinical benefit and cost-effectiveness analysis of liquid biopsy application in patients with advanced non-small cell lung cancer (NSCLC): a modelling approach

PURPOSE

Targeted therapies are effective therapeutic approaches in advanced stages of NSCLC and require precise molecular profiling to identify oncogenic drivers. Differential diagnosis on a molecular level contributes to clinical decision making. Liquid biopsy (LB) use has demonstrated its potential to serve as an alternative to tissue biopsy (TB) particularly in cases where tissue sampling is not feasible or insufficient. We aimed at evaluating the cost-effectiveness of ctDNA-based LB use (molecular multigene testing) according to German care guidelines for metastatic NSCLC.

METHODS

A Markov model was developed to compare the costs and clinical benefits associated with the use of LB as an add-on to TB according to the guidelines for NSCLC patients. Usual care TB served as comparator. A microsimulation model was used to simulate a cohort of non-squamous NSCLC patients stage IV. The parameters used for modelling were obtained from the literature and from the prospective German CRISP registry ("Clinical Research platform Into molecular testing, treatment, and outcome of non-Small cell lung carcinoma Patients"). For each pathway, average direct medical costs, and QALYs gained per patient were used for calculating incremental cost-effectiveness ratios (ICER).

RESULTS

The use of LB as an add-on was costlier (€144,981 vs. €144,587) but more effective measured in QALYs (1.20 vs. 1.19) for the care pathway of NSCLC patients (ICER €53,909/QALY). Cost-effectiveness was shown for EGFR-mutated patients (ICER €-13,247/QALY).

CONCLUSION

Including LB as an add-on into the care pathway of advanced NSCLC has positive clinical effects in terms of QALYs accompanied by a moderate cost-effectiveness.

Intracranial efficacy and safety of furmonertinib 160 mg with or without anti-angiogenic agent in advanced NSCLC patients with BM/LM as salvage therapy

OBJECTIVES

Central nervous system (CNS) metastases including brain metastases (BM) and leptomeningeal metastases (LM) are frequent in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC), and are correlated with poor outcomes. In this study, we evaluated the efficacy of single-agent furmonertinib 160 mg or combining with anti-angiogenic agent in NSCLC patients who had developed BM/LM progression from previous tyrosine kinase inhibior (TKI) treatment.

METHODS

EGFR-mutated NSCLC patients who developed BM (the BM cohort) or LM progression (the LM cohort) were included, having received furmonertinib 160 mg daily as second-line or later treatment, with or without anti-angiogenic agents. The intracranial efficacy was evaluated by intracranial progression-free survival (iPFS).

RESULTS

Totally 12 patients in the BM cohort and 16 patients in the LM cohort were included. Almost one half of patients in the BM cohort and a majority in the LM cohort had a poor physical status, with a Eastern Cooperative Oncology Group performance status (ECOG-PS) ≥2. The administration of single-agent furmonertinib or combination treatment achieved a median iPFS of 3.6 months (95%CI 1.435-5.705) in the BM cohort, and 4.3 months (95%CI 2.094-6.486) in the LM cohort. Subgroup and univariate analysis has shown that a good ECOG-PS correlated with a favorable efficacy of furmonertinib in the BM cohort (median iPFS = 2.1 with ECOG-PS ≥ 2 vs. 14.6 months with ECOG-PS < 2, P < 0.05). Overall, any grade of adverse events (AEs) occured in 46.4% of patients (13/28). Among them, 14.3% of patients (4 of 28) had grade 3 or higher AEs, and were all under control, led to no dose reductions or suspension.

CONCLUSION

Single-agent furmonertinib 160 mg or in combination of anti-angiogenic agent is an optional salvage therapy for advanced NSCLC patients who developed BM/LM progression from prior EGFR-TKI treatment, with a promising efficacy and an acceptable safety profile, and is worth of further exploration.

Analysis of acquired resistance mechanisms to osimertinib in patients with EGFR-mutated advanced non-small cell lung cancer from the AURA3 trial

Osimertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), potently and selectively inhibits EGFR-TKI-sensitizing and EGFR T790M resistance mutations. This analysis evaluates acquired resistance mechanisms to second-line osimertinib (n = 78) in patients with EGFR T790M advanced non-small cell lung cancer (NSCLC) from AURA3 (NCT02151981), a randomized phase 3 study comparing osimertinib with chemotherapy. Plasma samples collected at baseline and disease progression/treatment discontinuation are analyzed using next-generation sequencing. Half (50%) of patients have undetectable plasma EGFR T790M at disease progression and/or treatment discontinuation. Fifteen patients (19%) have >1 resistance-related genomic alteration; MET amplification (14/78, 18%) and EGFR C797X mutation (14/78, 18%).

Can Liquid Biopsy Based on ctDNA/cfDNA Replace Tissue Biopsy for the Precision Treatment of EGFR-Mutated NSCLC?

More and more clinical trials have explored the role of liquid biopsy in the diagnosis and treatment of EGFR-mutated NSCLC. In certain circumstances, liquid biopsy has unique advantages and offers a new way to detect therapeutic targets, analyze drug resistance mechanisms in advanced patients, and monitor MRD in patients with operable NSCLC. Although its potential cannot be ignored, more evidence is needed to support the transition from the research stage to clinical application. We reviewed the latest progress in research on the efficacy and resistance mechanisms of targeted therapy for advanced NSCLC patients with plasma ctDNA EGFR mutation and the evaluation of MRD based on ctDNA detection in perioperative and follow-up monitoring.

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

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

Liquid biopsy for detecting epidermal growth factor receptor mutation among patients with non-small cell lung cancer treated with afatinib: a multicenter prospective study

Background

This study aimed to determine the effectiveness of liquid biopsy in detecting epidermal growth factor receptor (EGFR) mutations at diagnosis, disease progression, and intermediate stages.

Methods

This prospective, multicenter, observational study included 30 patients with non-small cell lung cancer treated with afatinib, harboring a major EGFR mutation confirmed by tumor tissue biopsy. We collected blood samples for liquid biopsy at diagnosis, intermediate stage, and progressive disease. Tissue and liquid biopsies were examined using Cobas ® EGFR Mutation Test v2.

Results

Liquid biopsy detected EGFR mutations in 63.6% of the patients at diagnosis. The presence of metastasis in the extrathoracic, brain, and adrenal glands correlated positively with the detection of EGFR mutations. Patients with positive EGFR mutations at diagnosis had significantly shorter overall and progression-free survival than patients with negative EGFR mutations. Four of the 18 patients (22.2%) who reached progressive disease had positive EGFR T790M mutations. Three of 10 patients (30.0%) with progressive disease were positive and negative for T790M using tumor re-biopsy and liquid biopsy, respectively. The results of EGFR mutation by tissue re-biopsy were the same as those of liquid biopsy in the three patients who were positive for significant EGFR mutations but negative for the T790M mutation using liquid biopsy at progressing disease. Only two patients were positive for major EGFR mutations at intermediate levels.

Conclusions

Liquid biopsy can be a prognostic factor in EGFR-tyrosine kinase inhibitor treatments at diagnosis. Tumor re-biopsy can be omitted in patients with positive EGFR mutations by liquid biopsy at PD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10135-z.

Bioplatforms in liquid biopsy: advances in the techniques for isolation, characterization and clinical applications

Tissue biopsy analysis has conventionally been the gold standard for cancer prognosis, diagnosis and prediction of responses/resistances to treatments. The existing biopsy procedures used in clinical practice are, however, invasive, painful and often associated with pitfalls like poor recovery of tumor cells and infeasibility for repetition in single patients. To circumvent these limitations, alternative non-invasive, rapid and economical, yet sturdy, consistent and dependable, biopsy techniques are required. Liquid biopsy is an emerging technology that fulfills these criteria and potentially much more in terms of subject-specific real-time monitoring of cancer progression, determination of tumor heterogeneity and treatment responses, and specific identification of the type and stages of cancers. The present review first briefly revisits the state-of-the-art technique of liquid biopsy and then proceeds to address in detail, the advances in the potential clinical applications of four major biological agencies present in liquid biopsy samples (circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), exosomes and tumor-educated platelets (TEPs)). Finally, the authors conclude with the limitations that need to be addressed in order for liquid biopsy to effectively replace the conventional invasive biopsy methods in the clinical settings.

Liquid Biopsy: A Multi-Parametric Analysis of Mutation Status, Circulating Tumor Cells and Inflammatory Markers in EGFR-Mutated NSCLC

The liquid biopsy has the potential to improve patient care in the diagnostic and therapeutic setting in non-small cell lung cancer (NSCLC). Consented patients with epidermal growth factor receptor (EGFR) positive disease (n = 21) were stratified into two cohorts: those currently receiving EGFR tyrosine kinase inhibitor (TKI) therapy (n = 9) and newly diagnosed EGFR TKI treatment-naïve patients (n = 12). Plasma genotyping of cell-free DNA was carried out using the FDA-approved cobas® EGFR mutation test v2 and compared to next generation sequencing (NGS) cfDNA panels. Circulating tumor cell (CTC) numbers were correlated with treatment response and EGFR exon 20 p.T790M. The prognostic significance of the neutrophil to lymphocyte ratio (NLR) and lactate dehydrogenase (LDH) was also investigated. Patients in cohort 1 with an EGFR exon 20 p.T790M mutation progressed more rapidly than those with an EGFR sensitizing mutation, while patients in cohort 2 had a significantly longer progression-free survival (p = 0.04). EGFR exon 20 p.T790M was detected by liquid biopsy prior to disease progression indicated by computed tomography (CT) imaging. The cobas® EGFR mutation test detected a significantly greater number of exon 20 p.T790M mutations (p = 0.05). High NLR and derived neutrophil to lymphocyte ratio (dNLR) were associated with shorter time to progression and worse survival outcomes (p < 0.05). High LDH levels were significantly associated with shorter time to disease progression (p = 0.03). These data support the use of liquid biopsy for monitoring EGFR mutations and inflammatory markers as prognostic indicators in NSCLC.

Liquid Biopsy Analysis as a Tool for TKI-Based Treatment in Non-Small Cell Lung Cancer

The treatment of non-small cell lung cancer (NSCLC) has recently evolved with the introduction of targeted therapy based on the use of tyrosine kinase inhibitors (TKIs) in patients with certain gene alterations, including EGFR, ALK, ROS1, BRAF, and MET genes. Molecular targeted therapy based on TKIs has improved clinical outcomes in a large number of NSCLC patients with advanced disease, enabling significantly longer progression-free survival (PFS). Liquid biopsy is an increasingly popular diagnostic tool for treating TKI-based NSCLC. The studies presented in this article show that detection and analysis based on liquid biopsy elements such as circulating tumor cells (CTCs), cell-free DNA (cfDNA), exosomes, and/or tumor-educated platelets (TEPs) can contribute to the appropriate selection and monitoring of targeted therapy in NSCLC patients as complementary to invasive tissue biopsy. The detection of these elements, combined with their molecular analysis (using, e.g., digital PCR (dPCR), next generation sequencing (NGS), shallow whole genome sequencing (sWGS)), enables the detection of mutations, which are required for the TKI treatment. Despite such promising results obtained by many research teams, it is still necessary to carry out prospective studies on a larger group of patients in order to validate these methods before their application in clinical practice.

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

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

Comparison of EGFR mutations detected by LNA-ARMS PCR in plasma ctDNA samples and matched tissue sample in non-small cell lung cancer patients

BACKGROUND

Screening for epidermal growth factor receptor (EGFR) mutations is the key to select suitable patients with non-small cell lung cancer (NSCLC) for EGFR-TKI therapy in clinical practice. Nevertheless, tumor tissue that needed for mutation analysis is frequently unavailable, especially for patients with recurrence after operation. Therefore, detection of EGFR from circulating tumor DNA (ctDNA) in patients with NSCLC is a sensitive and convenient method to direct patient sequential treatment strategy.

METHODS

One hundred and seventy-nine NSCLC patients with both tumor tissue samples and paired plasma samples were recruited. EGFR mutations were detected in 68 tumor tissue samples and 179 plasma samples using Anlongen Locked Nucleic Acid-Amplification Refractory Mutation System (LNA-ARMS) EGFR Mutation Detection Kit. The remaining 111 tumor tissue samples were detected with the use of multiplex PCR-Based NGS sequence. We calculated the sensitivity, specificity, positive prediction value (PPV) and negative prediction value (NPV) of LAN-ARMS PCR. The objective response rate (ORR) of patients received TKIs therapy was calculated.

RESULTS

Of the 179 patients, EGFR mutations were detected in 77 of the 179 tumor tissue samples, with a positive rate of 43.01% (77/179). In addition, EGFR mutations were detected in 42 of the 179 plasma samples. The sensitivity and specificity of LAN-ARMS in detecting EGFR mutations were 57.18% and 98.04% respectively compared to tissue results. The PPV was 95.24%, and NPV was 72.99%. Of the 179 pair of samples, EGFR mutations were inconsistent in 39 pairs of tissue and plasma. The overall agreement of EGFR mutation detection was 78.21% (140/179). The ORR was higher in patients with both tissue and plasma EGFR mutations compared with that in patients with only tissue EGFR mutations (73.33% vs. 68.29%), but the difference was not significant. It was suggested that tissue detection combined with plasma detection could improve the mutation rate.

CONCLUSION

In plasma samples, Anlongen LAN-ARMS EGFR Mutation Detection Kit had a high sensitivity and specificity for the detection of EGFR mutations. Anlongen LAN-ARMS EGFR Mutation Detection Kit had the advantages of easy-to-operate and high sensitivity in clinical application.

Changes in Circulating Tumor DNA Reflect Clinical Benefit Across Multiple Studies of Patients With Non-Small-Cell Lung Cancer Treated With Immune Checkpoint Inhibitors

PURPOSE

As immune checkpoint inhibitors (ICI) become increasingly used in frontline settings, identifying early indicators of response is needed. Recent studies suggest a role for circulating tumor DNA (ctDNA) in monitoring response to ICI, but uncertainty exists in the generalizability of these studies. Here, the role of ctDNA for monitoring response to ICI is assessed through a standardized approach by assessing clinical trial data from five independent studies.

PATIENTS AND METHODS

Patient-level clinical and ctDNA data were pooled and harmonized from 200 patients across five independent clinical trials investigating the treatment of patients with non-small-cell lung cancer with programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1)-directed monotherapy or in combination with chemotherapy. CtDNA levels were measured using different ctDNA assays across the studies. Maximum variant allele frequencies were calculated using all somatic tumor-derived variants in each unique patient sample to correlate ctDNA changes with overall survival (OS) and progression-free survival (PFS).

RESULTS

We observed strong associations between reductions in ctDNA levels from on-treatment liquid biopsies with improved OS (OS; hazard ratio, 2.28; 95% CI, 1.62 to 3.20; P < .001) and PFS (PFS; hazard ratio 1.76; 95% CI, 1.31 to 2.36; P < .001). Changes in the maximum variant allele frequencies ctDNA values showed strong association across different outcomes.

CONCLUSION

In this pooled analysis of five independent clinical trials, consistent and robust associations between reductions in ctDNA and outcomes were found across multiple end points assessed in patients with non-small-cell lung cancer treated with an ICI. Additional tumor types, stages, and drug classes should be included in future analyses to further validate this. CtDNA may serve as an important tool in clinical development and an early indicator of treatment benefit.

Results of a worldwide external quality assessment of cfDNA testing in lung Cancer

BACKGROUND

Circulating cell free DNA (cfDNA) testing of plasma for EGFR somatic variants in lung cancer patients is being widely implemented and with any new service, external quality assessment (EQA) is required to ensure patient safety. An international consortium, International Quality Network for Pathology (IQNPath), has delivered a second round of assessment to measure the accuracy of cfDNA testing for lung cancer and the interpretation of the results.

METHODS

A collaboration of five EQA provider organisations, all members of IQNPath, have delivered the assessment during 2018-19 to a total of 264 laboratories from 45 countries. Bespoke plasma reference material containing a range of EGFR mutations at varying allelic frequencies were supplied to laboratories for testing and reporting according to routine procedures. The genotyping accuracy and clinical reporting was reviewed against standardised criteria and feedback was provided to participants.

RESULTS

The overall genotyping error rate in the EQA was found to be 11.1%. Low allelic frequency samples were the most challenging and were not detected by some testing methods, resulting in critical genotyping errors. This was reflected in higher false negative rates for samples with variant allele frequencies (VAF) rates less than 1.5% compared to higher frequencies. A sample with two different EGFR mutations gave inconsistent detection of both mutations. However, for one sample, where two variants were present at a VAF of less than 1% then both mutations were correctly detected in 145/263 laboratories. Reports often did not address the risk that tumour DNA may have not been tested and limitations of the methodologies provided by participants were insufficient. This was reflected in the average interpretation score for the EQA being 1.49 out of a maximum of 2.

CONCLUSIONS

The variability in the standard of genotyping and reporting highlighted the need for EQA and educational guidance in this field to ensure the delivery of high-quality clinical services where testing of cfDNA is the only option for clinical management.

Longitudinal monitoring by next-generation sequencing of plasma cell-free DNA in ALK rearranged NSCLC patients treated with ALK tyrosine kinase inhibitors

Background

Patients with ALK‐rearranged non‐small cell lung cancer (ALK+ NSCLC) inevitably acquire resistance to ALK inhibitors. Longitudinal monitoring of cell‐free plasma DNA (cfDNA) next‐generation sequencing (NGS) could predict the response and resistance to tyrosine kinase inhibitor (TKI) therapy in ALK+ NSCLC.

Methods

Patients with ALK+ NSCLC determined by standard tissue testing and planned to undergo TKI therapy were prospectively recruited. Plasma was collected at pretreatment, 2 months‐post therapy, and at progression for cfDNA‐NGS analysis, Guardant 360.

Results

Among 92 patients enrolled, circulating tumor DNA (ctDNA) was detected in 69 baseline samples (75%): 43 ALK fusions (62.3%) and two ALK mutations without fusion (2.8%). Two patients showed ALK‐resistance mutations after ceritinib; G1202R, and co‐occurring G1202R and T1151R. Eight patients developed ALK resistance mutations after crizotinib therapy; L1196M (n = 5), G1269A (n = 1), G1202R (n = 1), and co‐occurring F1174L, G1202R, and G1269A (n = 1). Absence of ctDNA at baseline was significantly associated with longer progression‐free survival (PFS; median 36.1 vs. 11.4 months, p = 0.0049) and overall survival (OS; not reached vs. 29.3 months, p = 0.0200). ctDNA clearance at 2 months (n = 29) was associated with significantly longer PFS (25.4 vs. 11.6 months, p = 0.0012) and OS (not reached vs. 26.1 months, p = 0.0307) than those without clearance (n = 22). Patients with co‐occurring TP53 alterations and ALK fusions at baseline (n = 16) showed significantly shorter PFS (7.28 vs. 13.0 months, p = 0.0307) than those without TP53 alterations (n = 25).

Conclusions

cfDNA‐NGS facilitates detection of ALK fusions and resistance mutations, assessment of prognosis, and monitoring dynamic changes of genomic alterations in ALK+ NSCLC treated with ALK‐TKI.

Concordance of Epidermal Growth Factor Receptor Mutation from Tissue Biopsy and Plasma Circulating Tumor DNA in Treatment-Naïve Lung Adenocarcinoma Patients

Background: Prevalence of Epidermal Growth Factor Receptor (EGFR) mutation in ctDNA in treatment-naïve individuals are not well established in Indonesia. In recent years, ctDNA as a specific and sensitive blood-based biomarker had been developed to detect the mutation. The study was done to understand the concordance and acceptance levels of ctDNA in detecting the gene mutation in lung adenocarcinoma patients.    Methods: This study used cross-sectional approach with purposive sampling design in 100 treatment-naïve NSCLC, adenocarcinoma patients. Samples were obtained from bronchoscopy, and blood, which were examined to detect the mutation in formalin-fixed, paraffin-embedded (FFPE) specimens or plasma samples using QIAampDNA Micro Kit. Mutation was calculated by droplet digital PCR (ddPCR).   Results: A hundred subjects with primary tumor tissue samples were compared with the plasma samples and mutation was detected in 20 patients (20.0%), 12 (12.0%) on exon 19, 7 (7.0%) on exon 21 and 1 (1.0%) on both exon 19 and 21. Within the plasma samples, mutation was found in 15 patients (15%) with mutation on exon 19 and 21 in 12 (12.0%) and 3 (3.0%) patients, respectively.  Within the two samples, concordance of EGFR mutation was 83.0% (83/100, P<0.001; correlation index: 0.42). Assuming presence of mutation as the benchmark, the accuracy of mutation presence in plasma DNA was 60.0% (9/15). Kappa test showed a weak agreement between the mutation in tissues and plasma, with a coefficient of 0.414 (95% CI).   Conclusion: Tissue biopsy was still considered as the main option to detect EGFR mutation in lung cancer. More research on ctDNA as the standardized tools to detect the mutation are required.   

Randomised, open-label, multicentric phase III trial to evaluate the safety and efficacy of palbociclib in combination with endocrine therapy, guided by ESR1 mutation monitoring in oestrogen receptor-positive, HER2-negative metastatic breast cancer patients: study design of PADA-1

INTRODUCTION

The combination of a CDK4/6 inhibitor with an aromatase inhibitor (AI) has recently become the gold standard for AI-sensitive first line treatment of oestrogen receptor-positive (ER+) HER2-negative (HER2-) advanced breast cancer. However, most patients receiving this combination will ultimately progress and require further therapies.Several studies have demonstrated that the onset of a ESR1 gene mutation lead to AIs resistance in the advanced setting. ESR1 mutations can be detected in circulating tumour DNA (ctDNA) using a digital PCR assay. Our study aims to prove the clinical efficacy of periodic monitoring for emerging or rise of ESR1 mutations in ctDNA to trigger an early change from AI plus palbociclib to fulvestrant plus palbociclib treatment while assessing global safety.

METHODS

PADA-1 is a randomised, open-label, multicentric, phase III trial conducted in patients receiving AI and palbociclib as first line therapy for metastatic ER +HER2- breast cancer. 1000 patients will be included and treated with palbociclib in combination with an AI. Patients will be screened for circulating blood ESR1 mutation detection at regular intervals. Patients for whom a rising circulating ESR1 mutation is detected without tumour progression (up to N=200) will be randomised (1:1) between (1) Arm A: no modification of therapy; and (2) Arm B: palbociclib in combination with fulvestrant, a selective ER down-regulator. At tumour progression, an optional crossover will be offered to patients randomised in arm A. The coprimary endpoints are (1) Grade ≥3 haematological toxicities and their associations with baseline characteristics and (2) progression-free survival in randomised patients.

ETHICS AND DISSEMINATION

The study has been approved by the French medicines agency (ANSM) and by an ethics committee (ref 01/17_1 CPP Ouest-IV Nantes) in January 2017. The trial results will be published in academic conference presentations and international peer-reviewed journals.

TRIAL REGISTRATION NUMBERS

EudraCT: 2016-004360-18; NCT03079011.

Monitoring of the presence of EGFR-mutated DNA during EGFR-targeted therapy may assist in the prediction of treatment outcome

The aim of our trial was to evaluate the prognostic significance of qualitative ctDNA analysis on different stages of EGFR mutated non-small cell lung cancer (NSCLC) treatment. We included 99 patients amendable for the first line treatment with either gefitinib/erlotinib (n = 87), afatinib (n = 10) or osimertinib (n = 2). Sequential qualitative analysis of ctDNA with cobas® EGFR Mutation Test v2 were performed before first dose, after 2 and 4 months of treatment, and on progression. Our analysis showed clinically significant heterogeneity of EGFR-mutated NSCLC treated with 1st line tyrosine kinase inhibitors (TKIs) in terms of progression-free and overall survival. When treated with conventional approach, i.e. monotherapy with TKIs, the patients falls into three subgroups based on ctDNA analysis before and after 2 months of treatment. Patients without detectable ctDNA at baseline (N = 32) possess the best prognosis on duration of treatment (PFS: 24.07 [16.8-31.3] and OS: 56.2 [21.8-90.7] months). Those who achieve clearance after two months of TKI (N = 42) have indistinguishably good PFS (19.0 [13.7 - 24.2]). Individuals who retain ctDNA after 2 months (N = 25) have the worst prognosis (PFS: 10.3 [7.0 - 13.5], p = 0.000). 9/25 patients did not develop ctDNA clearance at 4 months with no statistical difference in PFS from those without clearance at 2 months. Prognostic heterogeneity of EGFR-mutated NSCLC should be taken into consideration in planning further clinical trials and optimizing the outcome of patients.

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

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

Graphical Abstract

Emerging role of exosomes as biomarkers in cancer treatment and diagnosis

Cancer is a leading cause of death worldwide and cancer incidence and mortality are rapidly growing. These massive amounts of cancer patients require rapid diagnosis and efficient treatment strategies. However, the currently utilized methods are invasive and cost-effective. Recently, the effective roles of exosomes as promising diagnostic, prognostic, and predictive biomarkers have been revealed. Exosomes are membrane-bound extracellular vesicles containing RNAs, DNAs, and proteins, and are present in a wide array of body fluids. Exosomal cargos have shown the potential to detect various types of cancers at early stages with high sensitivity and specificity. They can also delivery therapeutic agents efficiently. In this article, an overview of recent advances in the research of exosomal biomarkers and their applications in cancer diagnosis and treatment has been provided. Furthermore, the advantages and challenges of exosomes as liquid biopsy targets are discussed and the clinical implications of using exosomal miRNAs have been revealed.

Recent advances in lung cancer genomics: Application in targeted therapy

Genomic characterization of lung cancer has not only improved our understanding of disease biology and carcinogenesis but also revealed several therapeutic opportunities. Targeting tumor dependencies on specific genomic alterations (oncogene addiction) has accelerated the therapeutic developments and significantly improved the outcomes even in advanced stage of disease. Identification of genomic alterations predicting response to specific targeted treatment is the key to success for this "personalized treatment" approach. Availability of multiple choices of therapeutic options for specific genomic alterations highlight the importance of optimum sequencing of drugs. Multiplex gene testing has become mandatory in view of constantly increasing number of therapeutic targets and effective treatment options. Influence of genomic characteristics on response to immunotherapy further makes comprehensive genomic profiling necessary before therapeutic decision making. A comprehensive elucidation of resistance mechanisms and directed treatments have made the continuum of care possible and transformed this deadly disease into a chronic condition. Liquid biopsy-based approach has made the dynamic monitoring of disease possible and enabled treatment optimizations accordingly. Current lung cancer management is the perfect example of "precision-medicine" in clinical oncology.

Selective KRAS G12C inhibitors in non-small cell lung cancer: chemistry, concurrent pathway alterations, and clinical outcomes

Cancers harboring mutations in the Kirsten rat sarcoma homolog (KRAS) gene have been associated with poor prognosis and lack of targeted therapies. KRAS mutations occur in approximately one in four patients diagnosed with non-small cell lung cancer (NSCLC) with KRAS G12C mutations harbored at approximately 11-16%. Research into KRAS-driven tumors and analytical chemistry have borne a new class of selective small molecules against the KRAS G12C isoform. Phase II data for sotorasib (AMG510) has demonstrated a 37.1% overall response rate (ORR). Adagrasib (MRTX849) has demonstrated a 45% ORR in an early study. While single agent efficacy has been seen, initial data suggest combination approaches are an opportunity to improve outcomes. Here, we present perspectives on the initial progress in targeting KRAS G12C, examine co-mutations evident in KRAS G12C NSCLC, and comment on potential future combinatorial approaches including SHP2, SOS1, MEK, EGFR, mTOR, CDK, and checkpoint blockade which are currently being evaluated in clinical trials. As of May 28, 2021, sotorasib has achieved US FDA approval for patients with KRAS G12C mutant lung cancer after one line of a prior therapy.

Combined multimodal ctDNA analysis and radiological imaging for tumor surveillance in Non-small cell lung cancer

BACKGROUND

Radiology is the current standard for monitoring treatment responses in lung cancer. Limited sensitivity, exposure to ionizing radiations and related sequelae constitute some of its major limitation. Non-invasive and highly sensitive methods for early detection of treatment failures and resistance-associated disease progression would have additional clinical utility.

METHODS

We analyzed serially collected plasma and paired tumor samples from lung cancer patients (61 with stage IV, 48 with stages I-III disease) and 61 healthy samples by means of next-generation sequencing, radiological imaging and droplet digital polymerase chain reaction (ddPCR) mutation and methylation assays.

RESULTS

A 62% variant concordance between tumor-reported and circulating-free DNA (cfDNA) sequencing was observed between baseline liquid and tissue biopsies in stage IV patients. Interestingly, ctDNA sequencing allowed for the identification of resistance-mediating p.T790M mutations in baseline plasma samples for which no such mutation was observed in the corresponding tissue. Serial circulating tumor DNA (ctDNA) mutation analysis by means of ddPCR revealed a general decrease in ctDNA loads between baseline and first reassessment. Additionally, serial ctDNA analyses only recapitulated computed tomography (CT) -monitored tumor dynamics of some, but not all lesions within the same patient. To complement ctDNA variant analysis we devised a ctDNA methylation assay (^methcfDNA) based on methylation-sensitive restriction enzymes. cfDNA methylation showed and area under the curve (AUC) of > 0.90 in early and late stage cases. A decrease in ^methcfDNA between baseline and first reassessment was reflected by a decrease in CT-derive tumor surface area, irrespective of tumor mutational status.

CONCLUSION

Taken together, our data support the use of cfDNA sequencing for unbiased characterization of the molecular tumor architecture, highlights the impact of tumor architectural heterogeneity on ctDNA-based tumor surveillance and the added value of complementary approaches such as cfDNA methylation for early detection and monitoring.

Monitoring cfDNA in Plasma and in Other Liquid Biopsies of Advanced EGFR Mutated NSCLC Patients: A Pilot Study and a Review of the Literature

Simple Summary

In advanced non-small cell lung cancer (NSCLC) patients, tumor tissue biopsy represents the gold standard for molecular analysis procedures. However, to achieve the necessary information, both at the time of diagnosis and progressive disease, is sometimes challenging, considering the small cancer material available. Liquid biopsy consists of a non-invasive alternative approach that owns the potential to provide useful information for molecular diagnostic. We aimed to prove the worth of liquid biopsy as plasma but also as urine and exhaled breath condensate (EBC) as the best surrogate to tumor tissue as well as to explore the molecular mechanisms that underlying the resistance to second-line osimertinib in advanced EGFR mutated NSCLC. We believe that our findings, with the PLUREX study and the review of literature, may add another brick in the wall on the use of liquid biopsy in the clinical practice in the setting of EGFR-mutated NSCLC disease.

Abstract

In order to study alternatives at the tissue biopsy to study EGFR status in NSCLC patients, we evaluated three different liquid biopsy platforms (plasma, urine and exhaled breath condensate, EBC). We also reviewed the literature of the cfDNA biological sources other than plasma and compared our results with it about the sensitivity to EGFR mutation determination. Twenty-two EGFR T790M-mutated NSCLC patients in progression to first-line treatment were enrolled and candidate to osimertinib. Plasma, urine and EBC samples were collected at baseline and every two months until progression. Molecular analysis of cfDNA was performed by ddPCR and compared to tissue results. At progression NGS analysis was performed. The EGFR activating mutation detection reached a sensitivity of 58 and 11% and for the T790M mutation of 45 and 10%, in plasma and urine samples, respectively. Any DNA content was recovered from EBC samples. Considering the plasma monitoring study, the worst survival was associated with positive shedding status; both plasma and urine molecular progression anticipated the radiological worsening. Our results confirmed the role of plasma liquid biopsy in testing EGFR mutational status, but unfortunately, did not evidence any improvement from the combination with alternative sources, as urine and EBC.

Plasma Cell-Free DNA Genotyping: From an Emerging Concept to a Standard-of-Care Tool in Metastatic Non-Small Cell Lung Cancer

Plasma cell-free DNA (cfDNA) genotyping is an alternative to tissue genotyping, particularly when tissue specimens are insufficient or unavailable, and provides critical information that can be used to guide treatment decisions in managing patients with non-small cell lung cancer (NSCLC). In this article, we review the evolution of plasma cfDNA genotyping from an emerging concept, through development of analytical methods, to its clinical applications as a standard-of-care tool in NSCLC. The number of driver or resistance mutations recommended for testing in NSCLC continues to increase. Because of the expanding list of therapeutically relevant variants, comprehensive testing to investigate larger regions of multiple genes in a single run is often preferable and saves on time and cost, compared with performing serial single-gene assays. Recent advances in nucleic acid next-generation sequencing have led to a rapid expansion in cfDNA genotyping technologies. Analytic assays that have received regulatory approval are now routinely used as diagnostic companions in the setting of metastatic NSCLC. As the demand for plasma-based technologies increases, more regulatory approvals of cfDNA genotyping assays are expected in the future. Plasma cfDNA genotyping is currently aiding oncologists in the delivery of personalized care by facilitating matching of patients with targeted therapy and monitoring emergence of resistance to therapy in NSCLC. Further advances currently underway to increase assay sensitivity and specificity will potentially expand the use of plasma cfDNA genotyping in early cancer detection, monitoring response to therapy, detection of minimal residual disease, and measurement of tumor mutational burden in NSCLC. IMPLICATIONS FOR PRACTICE: Plasma cell-free DNA (cfDNA) genotyping offers an alternative to tissue genotyping, particularly when tissue specimens are insufficient or unavailable. Advances in cfDNA genotyping technologies have led to analytic assays that are now routinely used to aid oncologists in the delivery of personalized care by facilitating matching of patients with targeted therapy and monitoring emergence of resistance to therapy. Further advances underway to increase assay sensitivity and specificity will potentially expand the use of plasma cfDNA genotyping in early cancer detection, monitoring response to therapy, detection of minimal residual disease, and evaluation of tumor mutational burden in non-small cell lung cancer.

Liquid Biopsy for Advanced NSCLC: A Consensus Statement From the International Association for the Study of Lung Cancer

Although precision medicine has had a mixed impact on the clinical management of patients with advanced-stage cancer overall, for NSCLC, and more specifically for lung adenocarcinoma, the advances have been dramatic, largely owing to the genomic complexity and growing number of druggable oncogene drivers. Furthermore, although tumor tissue is historically the "accepted standard" biospecimen for these molecular analyses, there are considerable innate limitations. Thus, liquid biopsy represents a practical alternative source for investigating tumor-derived somatic alterations. Although data are most robust in NSCLC, patients with other cancer types may also benefit from this minimally invasive approach to facilitate selection of targeted therapies. The liquid biopsy approach includes a variety of methodologies for circulating analytes. From a clinical point of view, plasma circulating tumor DNA is the most extensively studied and widely adopted alternative to tissue tumor genotyping in solid tumors, including NSCLC, first entering clinical practice for detection of EGFR mutations in NSCLC. Since the publication of the first International Association for the Study of Lung Cancer (IASLC) liquid biopsy statement in 2018, several additional advances have been made in this field, leading to changes in the therapeutic decision-making algorithm for advanced NSCLC and prompting this 2021 update. In view of the novel and impressive technological advances made in the past few years, the growing clinical application of plasma-based, next-generation sequencing, and the recent Food and Drug and Administration approval in the United States of two different assays for circulating tumor DNA analysis, IASLC revisited the role of liquid biopsy in therapeutic decision-making in a recent workshop in October 2020 and the question of "plasma first" versus "tissue first" approach toward molecular testing for advanced NSCLC. Moreover, evidence-based recommendations from IASLC provide an international perspective on when to order which test and how to interpret the results. Here, we present updates and additional considerations to the previous statement article as a consensus from a multidisciplinary and international team of experts selected by IASLC.

Comparison of Different EGFR Gene Mutation Status in Patients with Metastatic Non-Small Lung Cancer After First-Line EGFR-TKIs Therapy and Analyzing Its Relationship with Efficacy and Prognosis

Purpose

The purpose of this study is to compare the different EGFR mutation status in patients with metastatic non-small cell lung cancer (NSCLC) after first-line EGFR-TKIs therapy and analyze its relationship with efficacy and prognosis.

Patients and Methods

This study retrospectively analyzed the data of patients with metastatic NSCLC harboring EGFR mutation in the Affiliated Tumor Hospital of Guangxi Medical University from June 2016 to December 2020. Samples were collected before treatment and at the time of disease progression after first-line EGFR-TKIs therapy. Amplification refractory mutation system (ARMS) PCR and next-generation sequencing (NGS) were used to detect EGFR mutation. ORR, DCR, and PFS of different EGFR mutation groups were compared.

Results

The EGFR mutation rate of re-biopsy was 60.23%. The inconsistency rate of EGFR mutations in the same and different simple types was 72.22% (26/36) and 92.31% (48/52), respectively. Alterations in terms of EGFR mutations were divided into four groups: Group A: EGFR-sensitive mutation negative and T790M negative (39.77%); Group B: EGFR-sensitive mutation positive and T790M negative (18.19%); Group C: EGFR-sensitive mutation negative and T790M positive (36.36%); Group D: EGFR-sensitive mutation positive and T790M positive (5.68%). The differences between the four groups in ORR and DCR were not statistically significant (P>0.05). The median PFS of all patients was 10.65 months. PFS of Group A, B, C, and D was 12.26, 7.96, 10.55, and 13.81 months, respectively, with statistical significance (Log rank P = 0.014).

Conclusion

EGFR mutation status in metastatic NSCLC patients receiving the first- and second-generation TKIs after disease progression show diversity. Monitoring the EGFR mutation changes is of great importance for subsequent clinical decision-making and exploring the underlying mechanisms of acquired resistance.

The Predictive Values of Advanced Non-Small Cell Lung Cancer Patients Harboring Uncommon EGFR Mutations-The Mutation Patterns, Use of Different Generations of EGFR-TKIs, and Concurrent Genetic Alterations

Introduction

Epidermal growth factor receptor (EGFR) 19del and L858R mutation are known as “common mutations” in non-small cell lung cancer (NSCLC) and predict sensitivities to EGFR tyrosine kinase inhibitors (TKIs), whereas 20ins and T790M mutations confer drug-resistance to EGFR-TKIs. The role of the remaining uncommon EGFR mutations remains elusive.

Methods

We retrospectively screened a group of NSCLC patients with uncommon EGFR mutations other than 20ins and T790M. The mutation patterns, use of different generations of EGFR-TKIs, and concurrent genetic alterations were analyzed. Meanwhile, a cohort of patients with single 19del or L858R were included for comparison.

Results

A total of 180/1,300 (13.8%) patients were identified. There were 102 patients with advanced or recurrent NSCLC that received first-line therapy of gefitinib/erlotinib/icotinib and afatinib and were eligible for analysis. The therapeutic outcomes among patients with common mutations (EGFRcm, n = 97), uncommon mutation plus common mutations (EGFRum+EGFRcm, n = 52), complex uncommon mutations (complex EGFRum, n = 22), and single uncommon mutations (single EGFRum, n = 28) were significantly different (ORRs: 76.3%, 61.5%, 54.5%, and 50.0%, respectively, p = 0.023; and mPFS: 13.3, 14.7, 8.1, and 6.0 months, respectively, p = 0.004). Afatinib showed superior efficacy over gefitinib/erlotinib/icotinib in EGFRcm (ORR: 81.0% vs. 75.0%, p = 0.773; mPFS: 19.1 vs. 12.0m, p = 0.036), EGFRum+EGFRcm (ORR: 100% vs. 54.5%, p = 0.017; mPFS: NE vs. 13.6m, p = 0.032), and single EGFRum (ORR: 78.6% vs. 21.4%, p = 0.007; mPFS: 10.1 vs. 3.0m, p = 0.025) groups. Comprehensive genomic profiling by Next Generation Sequencing encompassing multiple cancer-related genes was performed on 51/102 patients; the mPFS of patients without co-mutation (n = 16) and with co-mutations of tumor-suppressor genes (n = 31) and driver oncogenes (n = 4) were 31.1, 9.2, and 12.4 months, respectively (p = 0.046). TP53 mutation was the most common co-alteration and showed significantly shorter mPFS than TP53 wild-type patients (7.0 vs. 31.1m, p < 0.001). Multivariate analysis revealed that concurrent 19del/L858R and tumor-suppressor gene alterations independently predicted better and worse prognosis in patients with uncommon mutations, respectively.

Conclusions

Uncommon EGFR mutations constitute a highly heterogeneous subgroup of NSCLC that confer different sensitivities to EGFR-TKIs with regard to the mutation patterns. Afatinib may be a better choice for most uncommon EGFR mutations. Concurrent 19del/L858R and tumor-suppressor gene alterations, especially TP53, can be established as prognostic biomarkers.

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.

Application of Circulating Tumor DNA as a Biomarker for Non-Small Cell Lung Cancer

Background

Non-small cell lung cancer (NSCLC) is one of the most prevalent causes of cancer-related death worldwide. Recently, there are many important medical advancements on NSCLC, such as therapies based on tyrosine kinase inhibitors and immune checkpoint inhibitors. Most of these therapies require tumor molecular testing for selecting patients who would benefit most from them. As invasive biopsy is highly risky, NSCLC molecular testing based on liquid biopsy has received more and more attention recently.

Objective

We aimed to introduce liquid biopsy and its potential clinical applications in NSCLC patients, including cancer diagnosis, treatment plan prioritization, minimal residual disease detection, and dynamic monitoring on the response to cancer treatment.

Method

We reviewed recent studies on circulating tumor DNA (ctDNA) testing, which is a minimally invasive approach to identify the presence of tumor-related mutations. In addition, we evaluated potential clinical applications of ctDNA as blood biomarkers for advanced NSCLC patients.

Results

Most studies have indicated that ctDNA testing is critical in diagnosing NSCLC, predicting clinical outcomes, monitoring response to targeted therapies and immunotherapies, and detecting cancer recurrence. Moreover, the changes of ctDNA levels are associated with tumor mutation burden and cancer progression.

Conclusion

The ctDNA testing is promising in guiding the therapies on NSCLC patients.

Liquid Biopsy for Disease Monitoring in Non-Small Cell Lung Cancer: The Link between Biology and the Clinic

INTRODUCTION

Cell-free DNA (cfDNA) analysis offers a non-invasive method to identify sensitising and resistance mutations in advanced Non-Small Cell Lung Cancer (NSCLC) patients. Next-generation sequencing (NGS) of circulating free DNA (cfDNA) is a valuable tool for mutations detection and disease's clonal monitoring.

MATERIAL AND METHODS

An amplicon-based targeted gene NGS panel was used to analyse 101 plasma samples of advanced non-small cell lung cancer (NSCLC) patients with known oncogenic mutations, mostly EGFR mutations, serially collected at different clinically relevant time points of the disease.

RESULTS

The variant allelic frequency (VAF) monitoring in consecutive plasma samples demonstrated different molecular response and progression patterns. The decrease in or the clearance of the mutant alleles was associated with response and the increase in or the emergence of novel alterations with progression. At the best response, the median VAF was 0% (0.0% to 3.62%), lower than that at baseline, with a median of 0.53% (0.0% to 9.9%) (p = 0.004). At progression, the VAF was significantly higher (median 4.67; range: 0.0-36.9%) than that observed at the best response (p = 0.001) and baseline (p = 0.006). These variations anticipated radiographic changes in most cases, with a median time of 0.86 months. Overall, the VAF evolution of different oncogenic mutations predicts clinical outcomes.

CONCLUSION

The targeted NGS of circulating tumour DNA (ctDNA) has clinical utility to monitor treatment response in patients with advanced lung adenocarcinoma.

Primary Pleural Squamous Cell Carcinoma, Highly Positive PD-L1, Shows Marked Response to Camrelizumab: A Case Report

Here, we reported the rare case of primary pleural squamous cell carcinoma (PPSCC) in a 71-year-old male patient. After chemo and targeted therapies, the patient showed continuous tumor progression and clinical deterioration. Fortunately, the patient had a high expression level of PD-L1 (80%) in the tumor tissues. Ultimately, the patient survived for additional 6 months with camrelizumab treatment. In summary, camrelizumab may be a good candidate for the treatment of PPSCC, especially in tumors with high PD-L1 expression.

Liquid biopsy as an option for predictive testing and prognosis in patients with lung cancer

BACKGROUND

The aim of this study was to investigate the clinical value of liquid biopsy as a primary source for variant analysis in lung cancer. In addition, we sought to characterize liquid biopsy variants and to correlate mutational load to clinical data.

METHODS

Circulating cell-free DNA was extracted from plasma from patients with lung cancer (n = 60) and controls with benign lung disease (n = 16). Variant analysis was performed using the AVENIO ctDNA Surveillance kit and the results were correlated to clinical and variant analysis data from tumor tissue or cytology retrieved from clinical routine diagnostics.

RESULTS

There were significantly more variants detected in lung cancer cases compared to controls (p = 0.011), but no difference between the histological subgroups of lung cancer was found (p = 0.465). Furthermore, significantly more variants were detected in patients with stage IIIb-IV disease compared to patients with stage I-IIIa (median 7 vs 4, p = 0.017). Plasma cfDNA mutational load was significantly associated with overall survival (p = 0.010). The association persisted when adjusted for stage and ECOG performance status (HR: 3.64, 95% CI 1.37-9.67, p = 0.009). Agreement between tumor and plasma samples significantly differed with stage; patients with stage IIIb-IV disease showed agreement in 88.2% of the cases with clinically relevant variants, compared to zero cases in stage I-IIIa (p = 0.004). Furthermore, one variant in EGFR, two in KRAS, and one in BRAF were detected in plasma but not in tumor samples.

CONCLUSION

This study concludes that in the vast majority of advanced NSCLC patients a reliable variant analysis can be performed using liquid biopsy from plasma. Furthermore, we found that the number of variants in plasma is associated with prognosis, possibly indicating a strategy for closer follow up on this crucial patient group.

A new sensitive and fast assay for the detection of EGFR mutations in liquid biopsies

BACKGROUND

A major perspective for the use of circulating tumor DNA (ctDNA) in the clinical setting of non-small cell lung cancer (NSCLC) is expected as predictive factor for resistance and response to EGFR TKI therapy and, especially, as a non-invasive alternative to tissue biopsy. However, ctDNA is both highly fragmented and mostly low concentrated in plasma and serum. On this basis, it is important to use a platform characterized by high sensitivity and linear performance in the low concentration range. This motivated us to evaluate the newly developed and commercially available SensiScreen® EGFR Liquid assay platform (PentaBase) with regard to sensitivity, linearity, repeatability and accuracy and finally to compare it to our already implemented methods. The validation was made in three independent European laboratories using two cohorts on a total of 68 unique liquid biopsies.

RESULTS

Using artificial samples containing 1600 copies of WT DNA spiked with 50% - 0.1% of mutant copies across a seven-log dilution scale, we assessed the sensitivity, linearity, repeatability and accuracy for the p.T790M, p.L858R and exon 19 deletion assays of the SensiScreen® EGFR Liquid assay platform. The lowest value detectable ranged from 0.5% to 0.1% with R2≥0,97 indicating good linearity. High PCR efficiency was shown for all three assays. In 102 single PCRs each containing theoretical one copy of the mutant at initiating, assays showed repeatable positivity in 75.5% - 80.4% of reactions. At low ctDNA levels, as in plasma, the SensiScreen® EGFR Liquid assay platform showed better sensitivity than the Therascreen® EGFR platform (Qiagen) and equal performance to the ctEGFR Mutation Detection Kit (EntroGen) and the IOT® Oncomine cell-free nucleic acids assay (Thermo Fisher Scientific) with 100% concordance at the sequence level.

CONCLUSION

For profiling clinical plasma samples, characterized by low ctDNA abundance, the SensiScreen® EGFR Liquid assay is able to identify down to 1 copy of mutant alleles and with its high sensitivity, linearity and accuracy it may be a competitive platform of choice.

Enhanced specificity of clinical high-sensitivity tumor mutation profiling in cell-free DNA via paired normal sequencing using MSK-ACCESS

Circulating cell-free DNA from blood plasma of cancer patients can be used to non-invasively interrogate somatic tumor alterations. Here we develop MSK-ACCESS (Memorial Sloan Kettering - Analysis of Circulating cfDNA to Examine Somatic Status), an NGS assay for detection of very low frequency somatic alterations in 129 genes. Analytical validation demonstrated 92% sensitivity in de-novo mutation calling down to 0.5% allele frequency and 99% for a priori mutation profiling. To evaluate the performance of MSK-ACCESS, we report results from 681 prospective blood samples that underwent clinical analysis to guide patient management. Somatic alterations are detected in 73% of the samples, 56% of which have clinically actionable alterations. The utilization of matched normal sequencing allows retention of somatic alterations while removing over 10,000 germline and clonal hematopoiesis variants. Our experience illustrates the importance of analyzing matched normal samples when interpreting cfDNA results and highlights the importance of cfDNA as a genomic profiling source for cancer patients.

Liquid biopsies allow the non-invasive detection of somatic mutations from tumours. Here, the authors develop and test MSK-ACCESS, an NGS-based clinical assay for identifying low frequency mutations in 129 genes and describe how it benefits patients in the clinic.

Clinical Application of Next-Generation Sequencing of Plasma Cell-Free DNA for Genotyping Untreated Advanced Non-Small Cell Lung Cancer

Simple Summary

Plasma ctDNA is a material source for molecular analysis particularly useful when tissue is not available or sufficient. NGS-based plasma genotyping should be integrated into the clinical workup of newly diagnosed advanced NSCLC.

Abstract

Background: Analysis of circulating tumor DNA (ctDNA) has remarkable potential as a non-invasive lung cancer molecular diagnostic method. This prospective study addressed the clinical value of a targeted-gene amplicon-based plasma next-generation sequencing (NGS) assay to detect actionable mutations in ctDNA in patients with newly diagnosed advanced lung adenocarcinoma. Methods: ctDNA test performance and concordance with tissue NGS were determined, and the correlation between ctDNA findings, clinical features, and clinical outcomes was evaluated in 115 patients with paired plasma and tissue samples. Results: Targeted-gene NGS-based ctDNA and NGS-based tissue analysis detected 54 and 63 genomic alterations, respectively; 11 patients presented co-mutations, totalizing 66 hotspot mutations detected, 51 on both tissue and plasma, 12 exclusively on tissue, and 3 exclusively on plasma. NGS-based ctDNA revealed a diagnostic performance with 81.0% sensitivity, 95.3% specificity, 94.4% PPV, 83.6% NPV, test accuracy of 88.2%, and Cohen’s Kappa 0.764. PFS and OS assessed by both assays did not significantly differ. Detection of ctDNA alterations was statistically associated with metastatic disease (p = 0.013), extra-thoracic metastasis (p = 0.004) and the number of organs involved (p = 0.010). Conclusions: This study highlights the potential use of ctDNA for mutation detection in newly diagnosed NSCLC patients due to its high accuracy and correlation with clinical outcomes.

Detection of rare variant alleles using the AsCas12a double-stranded DNA trans-cleavage activity

The sensitive and accurate detection of rare mutations has profound clinical implications; however, current methods require expensive instrumentation and are laborious and time-consuming. Thus, there is a need for a probe-based alternative that can effectively discriminate single-base mutations. Recently, several groups have shown the potential of the CRISPR/Cas12a system for sensitive and selective DNA detection but its application on single nucleotide variants (SNVs) detection is limited by the requirement of a protospacer adjacent motif (PAM) directly upstream to the SNV site and the amplification of non-specific signals due to the rapid and indiscriminate trans cleavage activity. Here, we report an ultra-selective Cas12a-based system that eliminates the need for the PAM sequence in the target with lower noise from the wild-type sequence by using its non-canonical double-stranded trans-cleavage activity. We show that our strategy can allow the detection of an EGFR gene mutation in sub-femtomolar concentrations up to 0.1% variant allele frequency using either fluorescence or electrochemical readouts.

Clinical Applications of Liquid Biopsy in Non-Small Cell Lung Cancer Patients: Current Status and Recent Advances in Clinical Practice

Recent advances in targeted and immune therapies have enabled tailored treatment strategies for advanced lung cancer. Identifying and understanding the genomic alterations that arise in the course of tumor evolution has become hugely valuable, but tissue biopsies are often insufficient for representing the whole cancer genome due to tumor heterogeneity. A liquid biopsy refers to the isolation and analysis of any tumor-derived material in the blood, and recent studies of this material have mostly focused on cell-free tumor DNA (ctDNA) in plasma. Indeed, liquid biopsy analysis is now expected to expand in utility and scope in clinical practice. In this review, we assess the biology and technical aspects of ctDNA analysis and discuss how it is currently applied in the clinic. Key points: Liquid biopsy is a potentially powerful tool in the era of personalized medicine for guiding targeted therapies in non-small cell lung cancer.

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

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

Circulating Tumor DNA Analyses Predict Disease Recurrence in Non-Muscle-Invasive Bladder Cancer

Circulating tumor DNA (ctDNA) can be a prognostic biomarker for non-muscle-invasive bladder cancer (NMIBC); however, targeted sequencing has not been performed to detect ctDNA in NMIBC. We applied targeted sequencing based on an 861-gene panel to determine mutations in tumor tissue DNA and plasma ctDNA in 82 NMIBC patients receiving transurethral resection (TUR) of bladder followed by immunotherapy. We detected 476 and 165 somatic variants in tumor DNA from 82 NMIBC patients (100%) and ctDNA from 54 patients (65.85%), respectively. Patients with high heterogeneity in tumor DNA had a significantly shorter disease-free survival than those with low heterogeneity. Tumor-derived alterations were detectable in plasma of 43 patients (52.44%). The concordance of somatic variants between tumor DNA and plasma ctDNA were higher in patients with T1 stage (p < 0.0001) and tumor size ≥3 cm (p = 0.0002). Molecular tumor burden index (mTBI) in ctDNA positively correlated with larger tumor size (p = 0.0020). A higher mTBI was an independent predictor of recurrence after TUR of bladder followed by immunotherapy. Analysis of ctDNA based on targeted sequencing is a promising approach to predict disease recurrence for NMIBC patients receiving TUR of bladder followed by immunotherapy.

Liquid Biopsies in Solid Cancers: Implementation in a Nordic Healthcare System

Simple Summary

We here review liquid biopsy methods and their use in the diagnostics and treatment of patients with solid cancers. More specifically, circulating tumor DNA, circulating tumor cells, and their current and future clinical applications are considered. Important factors for further integration of liquid biopsy methods in clinical practice are discussed, with a special focus on a Nordic Healthcare system.

Abstract

Liquid biopsies have emerged as a potential new diagnostic tool, providing detailed information relevant for characterization and treatment of solid cancers. We here present an overview of current evidence supporting the clinical relevance of liquid biopsy assessments. We also discuss the implementation of liquid biopsies in clinical studies and their current and future clinical role, with a special reference to the Nordic healthcare systems. Our considerations are restricted to the most established liquid biopsy specimens: circulating tumor DNA (ctDNA) and circulating tumor cells (CTC). Both ctDNA and CTCs have been used for prognostic stratification, treatment choices, and treatment monitoring in solid cancers. Several recent publications also support the role of ctDNA in early cancer detection. ctDNA seems to provide more robust clinically relevant information in general, whereas CTCs have the potential to answer more basic questions related to cancer biology and metastasis. Epidermal growth factor receptor-directed treatment of non-small-cell lung cancer represents a clinical setting where ctDNA already has entered the clinic. The role of liquid biopsies in treatment decisions, standardization of methods, diagnostic performance and the need for further research, as well as cost and regulatory issues were identified as factors that influence further integration in the clinic. In conclusion, substantial evidence supports the clinical utility of liquid biopsies in cancer diagnostics, but further research is still required for a more general application in clinical practice.

Future Perspectives in Detecting EGFR and ALK Gene Alterations in Liquid Biopsies of Patients with NSCLC

Non-small-cell lung cancer (NSCLC) is a major cause of death worldwide. Alterations in such genes as EGFR and ALK are considered important biomarkers in NSCLC due to the existence of targeted therapies with specific tyrosine kinase inhibitors (TKIs). However, specific resistance-related mutations can occur during TKI treatment, which often result in therapy inefficacy. Liquid biopsies arise as a reliable tool for the early detection of these types of alterations, allowing a non-invasive follow-up of the patients. Furthermore, they can be essential for cancer screening, initial diagnosis and to check surgery success. Despite the great advantages of liquid biopsies in NSCLC and the high input that next-generation sequencing (NGS) approaches can provide in this field, its use in oncology is still limited. With improvement of assay sensitivity and the establishment of clinical guidelines for liquid biopsy analysis, it is expected that they will be used in routine procedures. This review focuses on the usefulness of liquid biopsies of NSCLC patients as a means to detect alterations in EGFR and ALK genes and in disease management, highlighting the impact of NGS methods.

Detection of Microsatellite Instability: State of the Art and Future Applications in Circulating Tumour DNA (ctDNA)

Simple Summary

Microsatellite instability (MSI) is a molecular fingerprint for defects in the mismatch repair system (dMMR) and is associated with higher risks of cancers. MSI/dMMR tumours are characterized by the accumulation of mutations throughout the genome, and particularly in microsatellite (MS) DNA repeat sequences. MSI stands as a major biomarker for familial cancer risk assessment, cancer prognosis, and therapeutic choices. Standard-of-care classification of MSI/dMMR tumours is most frequently achieved using immunohistochemistry or PCR-based assay directed against a set of five MS regions. However, novel molecular methods based on tumour tissue or plasma samples have been developed and could enter in the future trends of MSI testing. Here, we provide insights into these emerging approaches and discuss their advantages and limitations.

Abstract

Microsatellite instability (MSI) is a molecular scar resulting from a defective mismatch repair system (dMMR) and associated with various malignancies. MSI tumours are characterized by the accumulation of mutations throughout the genome and particularly clustered in highly repetitive microsatellite (MS) regions. MSI/dMMR status is routinely assessed in solid tumours for the initial screening of Lynch syndrome, the evaluation of cancer prognosis, and treatment decision-making. Currently, pentaplex PCR-based methods and MMR immunohistochemistry on tumour tissue samples are the standard diagnostic methods for MSI/dMMR. Other tissue methods such as next-generation sequencing or real-time PCR-based systems have emerged and represent viable alternatives to standard MSI testing in specific settings. The evolution of the standard molecular techniques has offered the opportunity to extend MSI determination to liquid biopsy based on the analysis of cell-free DNA (cfDNA) in plasma. This review aims at synthetizing the standard and emerging techniques used on tumour tissue samples for MSI/dMMR determination. We also provide insights into the MSI molecular techniques compatible with liquid biopsy and the potential clinical consequences for patients with solid cancers.