Clinical Practice Guidelines for Pre-Analytical Procedures of Plasma Epidermal Growth Factor Receptor Variant Testing

Liquid biopsy: paving a new avenue for cancer research

The current constraints associated with cancer diagnosis and molecular profiling, which rely on invasive tissue biopsies or clinical imaging, have spurred the emergence of the liquid biopsy field. Liquid biopsy involves the extraction of circulating tumor cells (CTCs), circulating free or circulating tumor DNA (cfDNA or ctDNA), circulating cell-free RNA (cfRNA), extracellular vesicles (EVs), and tumor-educated platelets (TEPs) from bodily fluid samples. Subsequently, these components undergo molecular characterization to identify biomarkers that are critical for early cancer detection, prognosis, therapeutic assessment, and post-treatment monitoring. These innovative biosources exhibit characteristics analogous to those of the primary tumor from which they originate or interact. This review comprehensively explores the diverse technologies and methodologies employed for processing these biosources, along with their principal clinical applications.

Liquid biopsy for renal cell carcinoma

Liquid biopsies offer a less invasive alternative to tissue biopsies for diagnosis, prognosis, and determining therapeutic potential in renal cell carcinoma (RCC). Unfortunately, clinical studies using liquid biopsy biomarkers in RCC are limited. Accordingly, we examine RCC biomarkers, derived from urine, plasma, serum and feces of potential impact and clinical outcome in these patients. A PRISMA checklist was used to identify valuable liquid biopsy biomarkers for diagnosis (plasma cfDNA, serum- or urine-derived circulating RNAs, exosomes and proteins), prognosis (plasma cfDNA, plasma- or serum-derived RNAs, and proteins), and therapeutic response (plasma- and serum-derived proteins). Although other analytes have been identified, their application for routine clinical use remains unclear. In general, panels appear more effective than single biomarkers. Important considerations included proof of reproducibility. Unfortunately, many of the examined studies were insufficiently large and lacked multi-center rigor. Cost-effectiveness was also not available. Accordingly, it is clear that more standardized protocols need to be developed before liquid biopsies can be successfully integrated into clinical practice in RCC.

Decoding the Dynamics of Circulating Tumor DNA in Liquid Biopsies

Circulating tumor DNA (ctDNA), a fragment of tumor DNA found in the bloodstream, has emerged as a revolutionary tool in cancer management. This review delves into the biology of ctDNA, examining release mechanisms, including necrosis, apoptosis, and active secretion, all of which offer information about the state and nature of the tumor. Comprehensive DNA profiling has been enabled by methods such as whole genome sequencing and methylation analysis. The low abundance of the ctDNA fraction makes alternative techniques, such as digital PCR and targeted next-generation exome sequencing, more valuable and accurate for mutation profiling and detection. There are numerous clinical applications for ctDNA analysis, including non-invasive liquid biopsies for minimal residual disease monitoring to detect cancer recurrence, personalized medicine by mutation profiling for targeted therapy identification, early cancer detection, and real-time evaluation of therapeutic response. Integrating ctDNA analysis into routine clinical practice creates promising avenues for successful and personalized cancer care, from diagnosis to treatment and follow-up.

Optimization of a Protocol for Isolating Cell-free DNA From Cerebrospinal Fluid

A standardized protocol for the isolation of cell-free DNA (cfDNA) from cerebrospinal fluid (CSF) is lacking. Therefore, we established a cfDNA isolation protocol optimized for clinical CSF specimens, integrating acceptable modifications and using artificial CSF generated from remnant CSF spiked with reference cell-free tumor DNA (ctDNA). We compared the isolation yields of in vitro diagnostic (IVD)-certified column-based (CB) and magnetic bead-based (MB) isolation. Furthermore, we modified both methods, including pre- and post-elution steps. To confirm ctDNA integrity and quantify the variant allele frequency after isolation, we performed droplet digital PCR (ddPCR) targeting IDH1 R132C in the reference ctDNA. MB isolation had a higher yield than CB isolation (P<0.0001), and post-isolation vacuum increased the final concentration in both methods, with little effect on cfDNA integrity. Our study provides a protocol to maximize CSF-ctDNA concentrations in IVD testing and future studies.

Clinical Practice Guideline for Blood-based Circulating Tumor DNA Assays

Circulating tumor DNA (ctDNA) has emerged as a promising tool for various clinical applications, including early diagnosis, therapeutic target identification, treatment response monitoring, prognosis evaluation, and minimal residual disease detection. Consequently, ctDNA assays have been incorporated into clinical practice. In this review, we offer an in-depth exploration of the clinical implementation of ctDNA assays. Notably, we examined existing evidence related to pre-analytical procedures, analytical components in current technologies, and result interpretation and reporting processes. The primary objective of this guidelines is to provide recommendations for the clinical utilization of ctDNA assays.

Extraction of Cell-Free DNA: Evaluation of Efficiency, Quantity, and Quality

Cell-free DNA (cfDNA) serves as a valuable biomarker for early disease detection and monitoring. However, the use of cfDNA for analysis faces challenges owing to general low but variable abundance and fragmentation. Preanalytical factors, including cfDNA extraction, impact cfDNA quality and quantity. Efficient and robust cfDNA extraction is essential for reliable results in downstream applications, and various commercial extraction methods exist, each with trade-offs. To aid researchers and clinicians in choosing the proper cfDNA extraction method, manual, semiautomated, and automated methods were evaluated, including the QIAamp Circulating Nucleic Acid Kit (manual and QIAcube), QIAamp MinElute ccfDNA Kit (QIAcube), and QIAsymphony DSP Circulating DNA Kit (QIAsymphony). For each extraction method, cfDNA was extracted on two separate days, using samples obtained from 18 healthy donors. This study assessed extraction efficiency, quantity, and quality using droplet digital PCR and TapeStation. The QIAamp Circulating Nucleic Acid Kit, both manual and semiautomated, outperformed the QIAamp MinElute ccfDNA Kit (QIAcube) and QIAsymphony DSP Circulating DNA Kit (QIAsymphony), showing higher recovery rates and cfDNA quantity. All methods were reproducible, with no day-to-day variability and no contamination by high-molecular-weight DNA. The QIAamp Circulating Nucleic Acid Kit offers high yield without compromising quality. Implementation of the method should consider specific study and clinical needs, taking into account each method's advantages and limitations for optimal outcomes.

Identification of Potential Genomic Alterations Using Pan-Cancer Cell-Free DNA Next-Generation Sequencing in Patients With Gastric Cancer

Background

Molecular cancer profiling may lead to appropriate trials for molecularly targeted therapies. Cell-free DNA (cfDNA) is a promising diagnostic and/or prognostic biomarker in gastric cancer (GC). We characterized somatic genomic alterations in cfDNA of patients with GC.

Methods

Medical records and cfDNA data of 81 patients diagnosed as having GC were reviewed. Forty-nine and 32 patients were tested using the Oncomine Pan-Cancer Cell-Free Assay on the Ion Torrent platform and AlphaLiquid 100 kit on the Illumina platform, respectively.

Results

Tier I or II alterations were detected in 64.2% (52/81) of patients. Biomarkers for potential targeted therapy were detected in 55.6% of patients (45/81), and clinical trials are underway. ERBB2 amplification is actionable and was detected in 4.9% of patients (4/81). Among biomarkers showing potential for possible targeted therapy, TP53 mutation (38.3%, 35 variants in 31 patients, 31/81) and FGFR2 amplification (6.2%, 5/81) were detected the most.

Conclusions

Next-generation sequencing of cfDNA is a promising technique for the molecular profiling of GC. Evidence suggests that cfDNA analysis can provide accurate and reliable information on somatic genomic alterations in patients with GC, potentially replacing tissue biopsy as a diagnostic and prognostic tool. Through cfDNA analysis for molecular profiling, it may be possible to translate the molecular classification into therapeutic targets and predictive biomarkers, leading to personalized treatment options for patients with GC in the future.

Liquid biopsies and minimal residual disease in lymphoid malignancies

Minimal residual disease (MRD) assessment using peripheral blood instead of bone marrow aspirate/biopsy specimen or the biopsy of the cancerous infiltrated by lymphoid malignancies is an emerging technique with enormous interest of research and technological innovation at the current time. In some lymphoid malignancies (particularly ALL), Studies have shown that MRD monitoring of the peripheral blood may be an adequate alternative to frequent BM aspirations. However, additional studies investigating the biology of liquid biopsies in ALL and its potential as an MRD marker in larger patient cohorts in treatment protocols are warranted. Despite the promising data, there are still limitations in liquid biopsies in lymphoid malignancies, such as standardization of the sample collection and processing, determination of timing and duration for liquid biopsy analysis, and definition of the biological characteristics and specificity of the techniques evaluated such as flow cytometry, molecular techniques, and next generation sequencies. The use of liquid biopsy for detection of minimal residual disease in T-cell lymphoma is still experimental but it has made significant progress in multiple myeloma for example. Recent attempt to use artificial intelligence may help simplify the algorithm for testing and may help avoid inter-observer variation and operator dependency in these highly technically demanding testing process.

Liquid biopsies and minimal residual disease in myeloid malignancies

Minimal residual disease (MRD) assessment through blood component sampling by liquid biopsies (LBs) is increasingly being investigated in myeloid malignancies. Blood components then undergo molecular analysis by flow cytometry or sequencing techniques and can be used as a powerful tool for prognostic and predictive purposes in myeloid malignancies. There is evidence and more is evolving about the quantification and identification of cell-based and gene-based biomarkers in myeloid malignancies to monitor treatment response. MRD based acute myeloid leukemia protocol and clinical trials are currently incorporating LB testing and preliminary results are encouraging for potential widespread use in clinic in the near future. MRD monitoring using LBs are not standard in myelodysplastic syndrome (MDS) but this is an area of active investigation. In the future, LBs can replace more invasive techniques such as bone marrow biopsies. However, the routine clinical application of these markers continues to be an issue due to lack of standardization and limited number of studies investigating their specificities. Integrating artificial intelligence (AI) could help simplify the complex interpretation of molecular testing and reduce errors related to operator dependency. Though the field is rapidly evolving, the applicability of MRD testing using LB is mostly limited to research setting at this time due to the need for validation, regulatory approval, payer coverage, and cost issues. This review focuses on the types of biomarkers, most recent research exploring MRD and LB in myeloid malignancies, ongoing clinical trials, and the future of LB in the setting of AI.

Analytical and Clinical Validation of Cell-Free Circulating Tumor DNA Assay for the Estimation of Tumor Mutational Burden

Background

Ultra-deep sequencing to detect low-frequency mutations in circulating tumor-derived DNA (ctDNA) increases the diagnostic value of liquid biopsy. The demand for large ctDNA panels for comprehensive genomic profiling and tumor mutational burden (TMB) estimation is increasing; however, few ctDNA panels for TMB have been validated. Here, we designed a ctDNA panel with 531 genes, named TMB500, along with a technical and clinical validation.

Methods

Synthetic reference cell-free DNA materials with predefined allele frequencies were sequenced in a total of 92 tests in 6 batches to evaluate the precision, linearity, and limit of detection of the assay. We used clinical samples from 50 patients with various cancers, 11 healthy individuals, and paired tissue samples. Molecular barcoding and data analysis were performed using customized pipelines.

Results

The assay showed high precision and linearity (coefficient of determination, r2 = 0.87) for all single nucleotide variants, with a limit of detection of 0.24%. In clinical samples, the TMB500 ctDNA assay detected most variants present and absent in tissues, showing that ctDNA could assess tumor heterogeneity in different tissues and metastasis sites. The estimated TMBs correlated well between tissue and blood, except in 4 cases with extreme heterogeneity that showed very high blood TMBs compared to tissue TMBs. A pilot evaluation showed that the TMB500 assay could be used for disease monitoring.

Conclusions

The TMB500 assay is an accurate and reliable ctDNA assay for many clinical purposes. It may be useful for guiding the treatment of cancers with diverse genomic profiles, estimating TMB in immune therapy, and disease monitoring.

Circulating Tumor DNA Characteristics Based on Next Generation Sequencing and Its Correlation With Clinical Parameters in Patients With Lymphoma

Background

Lymphoma is a heterogeneous group of tumors in terms of morphological subtypes, molecular alterations, and management. However, data on circulating tumor DNA (ctDNA) mutated genes are limited. The purpose of this study was to investigate the features of the ctDNA mutated genes, the prognosis, and the association between the ctDNA mutated genes and the clinical parameters in lymphoma.

Methods

Differences in the ctDNA between the mutated genes and the prognosis of 59 patients with Hodgkin’s lymphoma (HL) (10.2%), germinal center B-cell–like lymphoma (GCB) (28.8%), nongerminal center B-cell–like lymphoma (non-GCB) (50.8%), and marginal zone lymphoma (MZL) (10.2%) were analyzed by next generation sequencing (NGS) targeting 121 lymphoma-relevant genes.

Results

Genetic alterations were identified in the ctDNA samples with a median of 6 variants per sample. The genetic variation of the ctDNA in the plasma was found to be significantly correlated with the clinical indices in lymphoma. The genetic heterogeneity of different lymphoma subtypes was clearly observed in the ctDNAs from HL, GCB, non-GCB, and MZL, confirming that distinct molecular mechanisms are involved in the pathogenesis of different lymphomas.

Conclusion

Our findings suggest that NGS-based ctDNA mutation analysis reveals genetic heterogeneity across lymphoma subtypes, with potential implications for discovering therapeutic targets, exploring genomic evolution, and developing risk-adaptive therapies.

Outstanding prognostic value of novel ferroptosis-related genes in chemoresistance osteosarcoma patients

Osteosarcoma (OS) is the most common bone-derived tumor, and chemoresistance is a pivotal factor in the poor prognosis of patients with OS. Ferroptosis, as an emerging modality of regulated cell death, has demonstrated potential value in tumor chemoresistance studies. Through the gene expression omnibus database in conjunction with the FerrDb database, we identified novel ferroptosis-related differentially expressed genes (DEGs) involving chemoresistance in OS patients. Subsequently, enrichment analysis, protein-protein interaction network analysis and survival analysis were performed sequentially to recognize the hub genes and ultimately to construct a predictive model. The model constructed from the TARGET database was exhibited in a nomogram and assessed by calibration curves. The prognostic value of the model and hub genes was validated separately by an independent cohort. Twenty-two ferroptosis-related DEGs were identified, including 16 up-regulated and 6 down-regulated. Among them, expressions of CBS, COCS1, EGFR, as hub genes, were significantly associated with the prognosis of OS patients and were evidenced as independent prognostic factors. An efficient prognostic model covering hub gene expressions and clinical variables was developed and validated. Combining the results of hub genes in differential analysis, the actions of hub genes in ferroptosis, and the prognostic relevance of hub genes in patients, we revealed that CBS, SOCS1 and EGFR might play essential roles in OS and its chemoresistance with potential research and clinical value.

The Minimal Residual Disease Using Liquid Biopsies in Hematological Malignancies

The study of cell-free DNA (cfDNA) and other peripheral blood components (known as "liquid biopsies") is promising, and has been investigated especially in solid tumors. Nevertheless, it is increasingly showing a greater utility in the diagnosis, prognosis, and response to treatment of hematological malignancies; in the future, it could prevent invasive techniques, such as bone marrow (BM) biopsies. Most of the studies about this topic have focused on B-cell lymphoid malignancies; some of them have shown that cfDNA can be used as a novel way for the diagnosis and minimal residual monitoring of B-cell lymphomas, using techniques such as next-generation sequencing (NGS). In myelodysplastic syndromes, multiple myeloma, or chronic lymphocytic leukemia, liquid biopsies may allow for an interesting genomic representation of the tumor clones affecting different lesions (spatial heterogeneity). In acute leukemias, it can be helpful in the monitoring of the early treatment response and the prediction of treatment failure. In chronic lymphocytic leukemia, the evaluation of cfDNA permits the definition of clonal evolution and drug resistance in real time. However, there are limitations, such as the difficulty in obtaining sufficient circulating tumor DNA for achieving a high sensitivity to assess the minimal residual disease, or the lack of standardization of the method, and clinical studies, to confirm its prognostic impact. This review focuses on the clinical applications of cfDNA on the minimal residual disease in hematological malignancies.