Multiplex Digital Methylation-Specific PCR for Noninvasive Screening of Lung Cancer

Simultaneous detection of eight cancer types using a multiplex droplet digital PCR assay

DNA methylation biomarkers have emerged as promising tools for cancer detection. Common methylation patterns across tumor types allow multi-cancer detection. Droplet digital PCR (ddPCR) has gained considerable attention for methylation detection. However, multi-cancer detection using multiple targets in ddPCR has never been performed before. Therefore, we developed a multiplex ddPCR assay for multi-cancer detection. Based on previous data analyses using The Cancer Genome Atlas (TCGA), we selected differentially methylated targets for eight frequent tumor types (lung, breast, colorectal, prostate, pancreatic, head and neck, liver, and esophageal cancer). Three targets were validated using ddPCR in 103 tumor and 109 normal adjacent fresh frozen samples. Two distinct ddPCR assays were successfully developed. Output data from both assays is combined to obtain a read-out from the three targets together. Our overall ddPCR assay has a cross-validated area under the curve (cvAUC) of 0.948. Performance between distinct cancer types varies, with sensitivities ranging from 53.8% to 100% and specificities ranging from 80% to 100%. Compared to previously published single-target parameters, we show that combining targets can drastically increase sensitivity and specificity, while lowering DNA input. In conclusion, we are the first to report a multi-cancer methylation ddPCR assay, which allows for highly accurate tumor predictions.

Value of circulating tumor cell assisting low-dose computed tomography in screening pulmonary nodules based on existing liquid biopsy techniques: a systematic review with meta-analysis and trial sequential analysis

OBJECTIVE

This study aims to assess the diagnostic utility of circulating tumor cells (CTCs) in conjunction with low-dose computed tomography (LDCT) for differentiating between benign and malignant pulmonary nodules and to substantiate the foundation for their integration into clinical practice.

METHODS

A systematic literature review was performed independently by two researchers utilizing databases including PubMed, Web of Science, The Cochrane Library, Embase, and Medline, to collate studies up to September 15, 2023, that investigated the application of CTCs in diagnosing pulmonary nodules. A meta-analysis was executed employing Stata 15.0 and Revman 5.4 to calculate the pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), and the area under the receiver operating characteristic curve (AUC). Additionally, trial sequential analysis was conducted using dedicated TSA software.

RESULTS

The selection criteria identified 16 studies, encompassing a total of 3409 patients. The meta-analysis revealed that CTCs achieved a pooled sensitivity of 0.84 (95% CI 0.80 to 0.87), specificity of 0.80 (95% CI 0.73 to 0.86), PLR of 4.23 (95% CI 3.12 to 5.72), NLR of 0.20 (95% CI 0.16 to 0.25), DOR of 20.92 (95% CI 13.52 to 32.36), and AUC of 0.89 (95% CI 0.86 to 0.93).

CONCLUSIONS

Circulating tumor cells demonstrate substantial diagnostic accuracy in distinguishing benign from malignant pulmonary nodules. The incorporation of CTCs into the diagnostic protocol can significantly augment the diagnostic efficacy of LDCT in screening for malignant lung diseases.

Multiplex digital profiling of DNA methylation heterogeneity for sensitive and cost-effective cancer detection in low-volume liquid biopsies

Molecular alterations in cancerous tissues exhibit intercellular genetic and epigenetic heterogeneity, complicating the performance of diagnostic assays, particularly for early cancer detection. Conventional liquid biopsy methods have limited sensitivity and/or ability to assess epigenetic heterogeneity of rare epiallelic variants cost-effectively. We report an approach, named REM-DREAMing (Ratiometric-Encoded Multiplex Discrimination of Rare EpiAlleles by Melt), which leverages a digital microfluidic platform that incorporates a ratiometric fluorescence multiplex detection scheme and precise digital high-resolution melt analysis to enable low-cost, parallelized analysis of heterogeneous methylation patterns on a molecule-by-molecule basis for the detection of cancer in liquid biopsies. We applied the platform to simultaneously assess intermolecular epigenetic heterogeneity in five methylation biomarkers for improved, blood-based screening for early-stage non-small cell lung cancer. In a cohort of 48 low-volume liquid biopsy specimens from patients with indeterminant pulmonary nodules, we show that assessment of intermolecular methylation density distributions can notably improve the performance of multigene methylation biomarker panels for the early detection of cancer.

Electrochemical sensing technology based on a ligation-initiated LAMP-assisted CRISPR/Cas12a system for high-specificity detection of EGFR E746-A750 deletion mutation

Epidermal growth factor receptor (EGFR) mutation status is pivotal in predicting the efficacy of tyrosine kinase inhibitor treatments against tumors. Among EGFR mutations, the E746-A750 deletion is particularly common and accurately quantifying it can guide targeted therapies. This study introduces a novel visual sensing technology using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a system guided by ligation-initiated loop-mediated isothermal amplification (LAMP) to detect the del E746-A750 mutation in EGFR. Conventional LAMP primers were simplified by designing a pair of target-specific stem-loop DNA probes, enabling selective amplification of the target DNA. The CRISPR/Cas12a system was employed to identify the target nucleic acid and activate Cas12a trans-cleavage activity, thereby enhancing the specificity of the assay. Furthermore, the biosensor utilized high-performance nanomaterials such as triangular gold nanoparticles and graphdiyne, known for their large specific surface area, to enhance sensitivity effectively as a sensing platform. The proposed biosensor demonstrated outstanding specificity, achieving a low detection limit of 17 fM (S/N = 3). Consequently, this innovative strategy not only expands the application scope of CRISPR/Cas12a technology but also introduces a promising approach for clinical diagnostics in modern medicine.

The Evidence Base for Circulating Tumor DNA-Methylation in Non-Small Cell Lung Cancer: A Systematic Review and Meta-Analysis

Background: Non-Small Cell Lung Cancer (NSCLC) remains a challenging disease to manage with effectiveness. Early detection and precise monitoring are crucial for improving patient outcomes. Circulating tumor DNA (ctDNA) offers a non-invasive cancer detection and monitoring method. Emerging biomarkers, such as ctDNA methylation, have shown promise in enhancing diagnostic accuracy and prognostic assessment in NSCLC. In this review, we examined the current evidence regarding ctDNA methylation's role in NSCLC detection through a systematic review of the existing literature and meta-analysis. Methods: We systematically searched PubMed, Medline, Embase, and Web of Science databases up to 26 June 2024 for studies on the role of ctDNA methylation analysis in NSCLC patients. We included studies from 2010 to 2024 on NSCLC patients. We excluded case reports, non-English articles, studies on cell lines or artificial samples, those without cfDNA detection, prognostic studies, and studies with non-extractable data or mixed cancer types. Funnel plots were visually examined for potential publication bias, with a p value < 0.05 indicating bias. Meta-analysis was conducted using R packages (meta, forestplot, and mada). Combined sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), positive and negative predictive values, diagnostic odds ratio (DOR), and 95% confidence intervals (95% CI) were calculated. A summary receiver operating characteristic curve (SROC) and area under the curve (AUC) with related Standard Error (SE) were used to evaluate the overall diagnostic performance. Additionally, RASSF1A, APC, SOX17, SEPT9, and RARβ2 were analyzed, since their methylation was assessed in two or more studies. Results: From 38 candidate papers, we finally identified 12 studies, including 472 NSCLC patients. The pooled sensitivity was 0.62 (0.47-0.77) and the specificity was 0.90 (0.85-0.94). The diagnostic odds ratio was 15.6 (95% CI 9.36-26.09) and the area under the curve was 0.249 (SE = 0.138). The positive and negative predictive values were 5.38 (95% CI 3.89-7.44) and 0.34 (95% CI 0.22-0.54), respectively. For single genes, the specificity reached 0.83~0.96, except for RARβ2, but the sensitivity was relatively low for each gene. Significant heterogeneity across the included studies, the potential publication bias for specificity (p = 0.0231), and the need to validate the clinical utility of ctDNA methylation for monitoring treatment response and predicting outcomes in NSCLC patients represent the main limitations of this study. Conclusions: These results provide evidence of the significant potential of ctDNA methylation as a valuable biomarker for improving the diagnosis of NSCLC, advocating for its integration into clinical practice to enhance patient management.

Analysis of urine cell-free DNA in bladder cancer diagnosis by emerging bioactive technologies and materials

Urinary cell-free DNA (UcfDNA) is gaining recognition as an important biomarker for diagnosing bladder cancer. UcfDNA contains tumor derived DNA sequences, making it a viable candidate for non-invasive early detection, diagnosis, and surveillance of bladder cancer. The quantification and qualification of UcfDNA have demonstrated high sensitivity and specificity in the molecular characterization of bladder cancer. However, precise analysis of UcfDNA for clinical bladder cancer diagnosis remains challenging. This review summarizes the history of UcfDNA discovery, its biological properties, and the quantitative and qualitative evaluations of UcfDNA for its clinical significance and utility in bladder cancer patients, emphasizing the critical role of UcfDNA in bladder cancer diagnosis. Emerging bioactive technologies and materials currently offer promising tools for multiple UcfDNA analysis, aiming to achieve more precise and efficient capture of UcfDNA, thereby significantly enhancing diagnostic accuracy. This review also highlights breakthroughs in detection technologies and substrates with the potential to revolutionize bladder cancer diagnosis in clinic.

Liquid biopsy: An arsenal for tumour screening and early diagnosis

Cancer has become the second leading cause of death in the world, and more than 50% of cancer patients are diagnosed at an advanced stage. Early diagnosis of tumours is the key to improving patient quality of life and survival time and reducing the socioeconomic burden. However, there is still a lack of reliable early diagnosis methods in clinical practice. In recent years, liquid biopsy technology has developed rapidly. It has the advantages of noninvasiveness, easy access to sample sources, and reproducibility. It has become the main focus of research on the early diagnosis methods of tumours. This review summarises the research progress of existing liquid biopsy markers, such as circulating tumour DNA, circulating viral DNA, DNA methylation, circulating tumour cells, circulating RNA, exosomes, and tumour education platelets in early diagnosis of tumours, and analyses the current advantages and limitations of various markers, providing a direction for the application and transformation of liquid biopsy research in early diagnosis of clinical tumours.

Single-molecule epiallelic profiling of DNA derived from routinely collected Pap specimens for noninvasive detection of ovarian cancer

Recent advances in molecular analyses of ovarian cancer have revealed a wealth of promising tumour-specific biomarkers, including protein, DNA mutations and methylation; however, reliably detecting such alterations at satisfactorily high sensitivity and specificity through low-cost methods remains challenging, especially in early-stage diseases. Here we present PapDREAM, a new approach that enables detection of rare, ovarian-cancer-specific aberrations of DNA methylation from routinely-collected cervical Pap specimens. The PapDREAM approach employs a microfluidic platform that performs highly parallelized digital high-resolution melt to analyze locus-specific DNA methylation patterns on a molecule-by-molecule basis at or near single CpG-site resolution at a fraction (< 1/10th) of the cost of next-generation sequencing techniques. We demonstrate the feasibility of the platform by assessing intermolecular heterogeneity of DNA methylation in a panel of methylation biomarker loci using DNA derived from Pap specimens obtained from a cohort of 43 women, including 18 cases with ovarian cancer and 25 cancer-free controls. PapDREAM leverages systematic multidimensional bioinformatic analyses of locus-specific methylation heterogeneity to improve upon Pap-specimen-based detection of ovarian cancer, demonstrating a clinical sensitivity of 50% at 99% specificity in detecting ovarian cancer cases with an area under the receiver operator curve of 0.90. We then establish a logistic regression model that could be used to identify high-risk patients for subsequent clinical follow-up and monitoring. The results of this study support the utility of PapDREAM as a simple, low-cost screening method with the potential to integrate with existing clinical workflows for early detection of ovarian cancer. KEY POINTS: We present a microfluidic platform for detection and analysis of rare, heterogeneously methylated DNA within Pap specimens towards detection of ovarian cancer. The platform achieves high sensitivity (fractions <0.00005%) at a suitably low cost (∼$25) for routine screening applications. Furthermore, it provides molecule-by-molecule quantitative analysis to facilitate further study on the effect of heterogeneous methylation on cancer development.

Digitized Kinetic Analysis Enhances Genotyping Capacity of CRISPR-Based Biosensing

CRISPR/Cas systems have been widely employed for nucleic acid biosensing and have been further advanced for mutation detection by virtue of the sequence specificity of crRNA. However, existing CRISPR-based genotyping methods are limited by the mismatch tolerance of Cas effectors, necessitating a comprehensive screening of crRNAs to effectively distinguish between wild-type and point-mutated sequences. To circumvent the limitation of conventional CRISPR-based genotyping, here, we introduce Single-Molecule kinetic Analysis via a Real-Time digital CRISPR/Cas12a-assisted assay (SMART-dCRISPR). SMART-dCRISPR leverages the differential kinetics of the signal increase in CRISPR/Cas systems, which is modulated by the complementarity between crRNA and the target sequence. It employs single-molecule digital measurements to discern mutations based on kinetic profiles that could otherwise be obscured by variations in the target concentrations. We applied SMART-dCRISPR to genotype notable mutations in SARS-CoV-2, point mutation (K417N) and deletion (69/70DEL), successfully distinguishing wild-type, Omicron BA.1, and Omicron BA.2 SARS-CoV-2 strains from clinical nasopharyngeal/nasal swab samples. Additionally, we introduced a portable digital real-time sensing device to streamline SMART-dCRISPR and enhance its practicality for point-of-care settings. The combination of a rapid and sensitive isothermal CRISPR-based assay with single-molecule kinetic analysis in a portable format significantly enhances the versatility of CRISPR-based nucleic acid biosensing and genotyping.

All-In-One OsciDrop Digital PCR System for Automated and Highly Multiplexed Molecular Diagnostics

Digital PCR (dPCR) holds immense potential for precisely detecting nucleic acid markers essential for personalized medicine. However, its broader application is hindered by high consumable costs, complex procedures, and restricted multiplexing capabilities. To address these challenges, an all-in-one dPCR system is introduced that eliminates the need for microfabricated chips, offering fully automated operations and enhanced multiplexing capabilities. Using this innovative oscillation-induced droplet generation technique, OsciDrop, this system supports a comprehensive dPCR workflow, including precise liquid handling, pipette-based droplet printing, in situ thermocycling, multicolor fluorescence imaging, and machine learning-driven analysis. The system's reliability is demonstrated by quantifying reference materials and evaluating HER2 copy number variation in breast cancer. Its multiplexing capability is showcased with a quadruplex dPCR assay that detects key EGFR mutations, including 19Del, L858R, and T790M in lung cancer. Moreover, the digital stepwise melting analysis (dSMA) technique is introduced, enabling high-multiplex profiling of seven major EGFR variants spanning 35 subtypes. This innovative dPCR system presents a cost-effective and versatile alternative, overcoming existing limitations and paving the way for transformative advances in precision diagnostics.

Fluorogenic RNA Aptamer-Based Amplification and Transcription Strategy for Label-free Sensing of Methyltransferase Activity in Complex Matrixes

DNA methyltransferase is significant in cellular activities and gene expression, and its aberrant expression is closely linked to various cancers during initiation and progression. Currently, there is a great demand for reliable and label-free techniques for DNA methyltransferase evaluation in tumor diagnosis and cancer therapy. Herein, a low-background fluorescent RNA aptamer-based sensing approach for label-free quantification of cytosine-guanine (CpG) dinucleotides methyltransferase (M.SssI) is reported. The fluorogenic light-up RNA aptamers-based strategy exhibits high selectivity via restriction endonuclease, padlock-based recognition, and RNA transcription. By combining rolling circle amplification (RCA), and RNA transcription with fluorescence response of RNA aptamers of Spinach-dye compound, the proposed platform exhibited efficiently ultrahigh sensitivity toward M.SssI. Eventually, the detection can be achieved in a linear range of 0.02-100 U mL-1 with a detection limit of 1.6 × 10-3 U mL-1. Owing to these superior features, the method is further applied in serum samples spiked M.SssI, which delivers a recovery ranging from 92.0 to 107.0% and a relative standard deviation <7.0%, providing a promising and practical tool for determining M.SssI in complex biological matrices.

Hypermethylation Loci of ZNF671, IRF8, and OTX1 as Potential Urine-Based Predictive Biomarkers for Bladder Cancer

Bladder cancer (BCa) is a significant health issue and poses a healthcare burden on patients, highlighting the importance of an effective detection method. Here, we developed a urine DNA methylation diagnostic panel for distinguishing between BCa and non-BCa. In the discovery stage, an analysis of the TCGA database was conducted to identify BCa-specific DNA hypermethylation markers. In the validation phase, DNA methylation levels of urine samples were measured with real-time quantitative methylation-specific PCR (qMSP). Comparative analysis of the methylation levels between BCa and non-BCa, along with the receiver operating characteristic (ROC) analyses with machine learning algorithms (logistic regression and decision tree methods) were conducted to develop practical diagnostic panels. The performance evaluation of the panel shows that the individual biomarkers of ZNF671, OTX1, and IRF8 achieved AUCs of 0.86, 0.82, and 0.81, respectively, while the combined yielded an AUC of 0.91. The diagnostic panel using the decision tree algorithm attained an accuracy, sensitivity, and specificity of 82.6%, 75.0%, and 90.9%, respectively. Our results show that the urine-based DNA methylation diagnostic panel provides a sensitive and specific method for detecting and stratifying BCa, showing promise as a standard test that could enhance the diagnosis and prognosis of BCa in clinical settings.

Endonuclease IV and T4 ligase enhanced detection of mutations in low abundance

We propose a mutant detection approach based on endonuclease IV and DNA ligase in combination with qPCR. The enzymes functioned cooperatively to facilitate PCR for low abundance DNA detection. We demonstrate that our approach can distinguish mutations as low as 0.01%, indicating the potential application of this strategy in early cancer diagnosis.

Circulating Tumor DNA Is a Variant of Liquid Biopsy with Predictive and Prognostic Clinical Value in Breast Cancer Patients

This paper introduces the reader to the field of liquid biopsies and cell-free nucleic acids, focusing on circulating tumor DNA (ctDNA) in breast cancer (BC). BC is the most common type of cancer in women, and progress with regard to treatment has been made in recent years. Despite this, there remain a number of unresolved issues in the treatment of BC; in particular, early detection and diagnosis, reliable markers of response to treatment and for the prediction of recurrence and metastasis, especially for unfavorable subtypes, are needed. It is also important to identify biomarkers for the assessment of drug resistance and for disease monitoring. Our work is devoted to ctDNA, which may be such a marker. Here, we describe its main characteristics and potential applications in clinical oncology. This review considers the results of studies devoted to the analysis of the prognostic and predictive roles of various methods for the determination of ctDNA in BC patients. Currently known epigenetic changes in ctDNA with clinical significance are reviewed. The possibility of using ctDNA as a predictive and prognostic marker for monitoring BC and predicting the recurrence and metastasis of cancer is also discussed, which may become an important part of a precision approach to the treatment of BC.

Utility of peripheral blood macrophage factor Apo10 and TKTL1 as markers in distinguishing malignant from benign lung nodules: a protocol for a prospective cohort study in Southern China

INTRODUCTION

Lung nodules are one of the most prevalent diseases. Medical imaging methods have a high false positive rate for distinguishing malignant nodules from benign nodules. Therefore, developing new technologies with high accuracy for screening malignant nodules is of great importance for lung nodule surveillance. Use of flow cytometry to detect biomarkers in blood macrophages (epitop detect in macrophages/macrophages) has opened a new era for early and noninvasive diagnosis of cancer. This planned study aims to examine whether the peripheral blood macrophage factors Apo10 and TKTL1 accurately distinguish malignant nodules from benign nodules.

METHODS AND ANALYSES

We plan to enrol in this study 3825 participants with lung nodules who will attend their annual physical examination at Sun Yat-sen University Cancer Center. Apo10 and TKTL1 levels in all patients will be tested at 60 min after their last meal every 6 months during their 3-year follow-up. Biopsy or surgical pathology results will be collected as the gold standard to assess the accuracy of Apo10 and TKTL1 in distinguishing malignant nodules from benign nodules. The sensitivity, specificity, positive predictive value, negative predictive value and area under the receiving operating characteristic curve will also be evaluated.

ETHICS AND DISSEMINATION

The study is approved by the medical ethics committee of Sun Yat-sen University (SL-G2022-005-02). The results of this study will be disseminated in peer-reviewed publications and presentations at international scientific meetings and will also be disseminated to the participants.

TRIAL REGISTRATION NUMBER

ChiCTR2300073823; Pre-results.

The Clinical Significance of Circulating Tumor DNA for Minimal Residual Disease Identification in Early-Stage Non-Small Cell Lung Cancer

Lung cancer (LC) is the deadliest malignancy worldwide. In an operable stage I-III patient setting, the detection of minimal residual disease (MRD) after curative treatment could identify patients at higher risk of relapse. In this context, the study of circulating tumor DNA (ctDNA) is emerging as a useful tool to identify patients who could benefit from an adjuvant treatment, and patients who could avoid adverse events related to a more aggressive clinical management. On the other hand, ctDNA profiling presents technical, biological and standardization challenges before entering clinical practice as a decisional tool. In this paper, we review the latest advances regarding the role of ctDNA in identifying MRD and in predicting patients' prognosis, with a particular focus on clinical trials investigating the potential of ctDNA, the technical challenges to address and the biological parameters that influence the MRD detection.