Circulating DNA and Survival in Solid Tumors

The emerging role of liquid biopsy in oral squamous cell carcinoma detection: advantages and challenges

INTRODUCTION

Oral Squamous Cell Carcinoma (OSCC), the sixth most widespread malignancy in the world, accounts for 90% of all cases of oral cancer. The primary risk factors are tobacco chewing, alcohol consumption, viral infection, and genetic modifications. OSCC has a high morbidity rate due to the lack of early diagnostic methods. Nowadays, liquid biopsy plays a vital role in the initial diagnosis of oral cancer. ctNAs extracted from saliva and serum/plasma offer meaningful insights into tumor genetics and dynamics. The interplay of these elements in saliva and serum/plasma showcases their significance in advancing noninvasive, effective OSCC detection and monitoring.

AREAS COVERED

This review mainly focused on the role of liquid biopsy as an emerging point in the diagnosis and prognosis of OSCC and the current advancements and challenges associated with liquid biopsy.

EXPERT OPINION

Liquid biopsy is regarded as a new, minimally invasive, real-time monitoring tool for cancer diagnosis and prognosis. Many biomolecules found in bodily fluids, including ctDNA, ctRNA, CTCs, and EVs, are significant biomarkers to identify cancer in its early stages. Despite these groundbreaking strides, challenges persist. Standardization of sample collection, isolation, processing, and detection methods is imperative for ensuring result reproducibility across diverse studies.

Exploring Circulating Tumor DNA (CtDNA) and Its Role in Early Detection of Cancer: A Systematic Review

There is a significant increase in the need for an efficient screening method that might identify cancer at an early stage and could improve patients' long-term survival due to the continued rise in cancer incidence and associated mortality. One such effort involved using circulating tumor DNA (ctDNA) as a rescue agent for a non-invasive blood test that may identify many tumors. A tumor marker called ctDNA is created by cells with the same DNA alterations. Due to its shorter half-life, it may be useful for both early cancer detection and real-time monitoring of tumor development, therapeutic response, and tumor outcomes. We obtained 156 papers from PUBMED using the MeSH approach in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) criteria and ten articles from additional online resources. After removing articles with irrelevant titles and screening the abstract and full text of the articles that contained information unrelated to or not specific to the title query using inclusion and exclusion criteria, 18 out of 166 articles were chosen for the quality check. Fourteen medium to high-quality papers were chosen out of the 18 publications to be included in the study design. The reviewed literature showed no significant utility of ctDNA in detecting early-stage tumors of size less than 1 cm diameter. Still, the ideal screening test would require the assay to detect a size <5 mm tumor, which is nearly impossible with the current data. The sensitivity and specificity of the assay ranged from 69% to 98% and 99%, respectively. Furthermore, CancerSEEK achieves tumor origin localization in 83% of cases, while targeted error correction sequencing (TEC-Seq) assays demonstrate a cancer detection rate ranging from 59% to 71%, depending on the type of cancer. However, it could be of great value as a prognostic indicator, and the levels are associated with progression-free survival (PFS) and overall survival (OS) rates, wherein the positive detection of ctDNA is associated with worse OS compared to the tumors detected through standard procedures, with an odds ratio (OS) of 4.83. We conclude that ctDNA could be better applied in cancer patients for prognosis, disease progression monitoring, and treatment outcomes compared to its use in early cancer detection. Due to its specific feature of recognizing the tumor-related mutations, it could be implemented as a supplemental tool to assess the nature of the tumor, grade, and size of the tumor and for predicting the outcomes by pre-operative and post-operative evaluation of the tumor marker, ctDNA, and thereby estimating PFS and OS depending on the level of marker present. A vast amount of research is required in early detection to determine the sensitivity, specificity, false positive rates, and false negative rates in evaluating its true potential as a screening tool. Even if the test could detect the mutations, an extensive workup for the search of tumor is required as the assay could only detect but cannot localize the disease. Establishing the clinical validity and utility of ctDNA is imperative for its implementation in future clinical practice.

Impact of Circulating Cell-Free DNA (cfDNA) as a Biomarker of the Development and Evolution of Periodontitis

In the last few decades, circulating cell-free DNA (cfDNA) has been shown to have an important role in cell apoptosis or necrosis, including in the development and evolution of several tumors and inflammatory diseases in humans. In this regard, periodontitis, a chronic inflammatory disease that can induce the destruction of supporting components of the teeth, could represent a chronic inflammatory stimulus linked to a various range of systemic inflammatory diseases. Recently, a possible correlation between periodontal disease and cfDNA has been shown, representing new important diagnostic-therapeutic perspectives. During the development of periodontitis, cfDNA is released in biological fluids such as blood, saliva, urine and other body fluids and represents an important index of inflammation. Due to the possibility of withdrawing some of these liquids in a non-invasive way, cfDNA could be used as a possible biomarker for periodontal disease. In addition, discovering a proportional relationship between cfDNA levels and the severity of periodontitis, expressed through the disease extent, could open the prospect of using cfDNA as a possible therapeutic target. The aim of this article is to report what researchers have discovered in recent years about circulating cfDNA in the development, evolution and therapy of periodontitis. The analyzed literature review shows that cfDNA has considerable potential as a diagnostic, therapeutic biomarker and therapeutic target in periodontal disease; however, further studies are needed for cfDNA to be used in clinical practice.

Changes in circulating tumor DNA and outcomes in solid tumors treated with immune checkpoint inhibitors: a systematic review

BACKGROUND

Quantification of circulating tumor DNA (ctDNA) levels is a reliable prognostic tool in several malignancies. Dynamic changes in ctDNA levels in response to treatment may also provide prognostic information. Here, we explore the value of changes in ctDNA levels in response to immune checkpoint inhibitors (ICIs).

METHODS

We searched MEDLINE (host: PubMed) for trials of ICIs in advanced solid tumors in which outcomes were reported based on change in ctDNA levels. ctDNA reduction was defined as reported in individual trials. Typically, this was either >50% reduction or a reduction to undetectable levels. We extracted HRs and related 95% CIs and/or p values comparing ctDNA reduction versus no reduction for progression-free survival (PFS) and/or overall survival (OS). Data were then pooled in a meta-analysis. Variation in effect size was examined using subgroup analyses.

RESULTS

Eighteen trials were included in the meta-analysis. ctDNA levels were detectable in all participants in all studies prior to initiation of ICIs. A reduction in ctDNA measured 6-16 weeks after starting treatment was associated with significantly better PFS (HR 0.20; 95% CI, 0.14 to 0.28; p<0.001). Similarly, OS was superior in patients with reduced ctDNA levels (HR 0.18; 95% CI, 0.12 to 0.26; p<0.001). The results were consistent across all disease sites, lines of treatment, magnitude of change (to undetectable vs >50% reduction) and whether treatment exposure comprised single or combination ICIs.

CONCLUSIONS

In advanced solid tumors, a reduction in ctDNA levels in response to ICIs is associated with substantial improvements in outcome. ctDNA change is an early response biomarker which may allow for de-escalation of cross-sectional imaging in patients receiving ICIs or support treatment de-escalation strategies.

Evaluation of cell-free DNA approaches for multi-cancer early detection

In the Circulating Cell-free Genome Atlas (NCT02889978) substudy 1, we evaluate several approaches for a circulating cell-free DNA (cfDNA)-based multi-cancer early detection (MCED) test by defining clinical limit of detection (LOD) based on circulating tumor allele fraction (cTAF), enabling performance comparisons. Among 10 machine-learning classifiers trained on the same samples and independently validated, when evaluated at 98% specificity, those using whole-genome (WG) methylation, single nucleotide variants with paired white blood cell background removal, and combined scores from classifiers evaluated in this study show the highest cancer signal detection sensitivities. Compared with clinical stage and tumor type, cTAF is a more significant predictor of classifier performance and may more closely reflect tumor biology. Clinical LODs mirror relative sensitivities for all approaches. The WG methylation feature best predicts cancer signal origin. WG methylation is the most promising technology for MCED and informs development of a targeted methylation MCED test.

NPY Gene Methylation in Circulating Tumor DNA as an Early Biomarker for Treatment Effect in Metastatic Colorectal Cancer

Despite several limitations, the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) are still the gold standard in response evaluation of metastatic colorectal cancer (mCRC). The aim of the present study was to investigate hypermethylated neuropeptide Y circulating tumor DNA (meth-NPY) as an early biomarker for treatment effect and monitoring in 70 mCRC patients receiving first-line treatment in the FOLFOXIRI-Toco trial. Meth-NPY was analyzed using droplet digital PCR, and the response rate was defined as the fraction of patients converting from a baseline detectable level to an undetectable level after the first treatment cycle (responders). A significant increase in meth-NPY was defined as a value with no overlap between the 95% CI of the current and preceding measurement. Progression-free survival (PFS) was significantly longer in meth-NPY responders compared to non-responders, 10.1 and 7.6 months, respectively (p = 0.02, HR = 0.43). Patients with response according to RECIST 1.1 had a PFS of 10.1 compared to 7.3 months for non-responders (p = 0.17, HR = 0.65). A significant increase in meth-NPY was found with a median of 49 days before radiological progression. In conclusion, early meth-NPY response proved superior to response according to RECIST 1.1 with respect to predicting improved PFS. Meth-NPY is an early indicator of progression, allowing treatment reorientation at an earlier timepoint.

The Prognostic Value of Circulating Tumor DNA in Ovarian Cancer: A Meta-Analysis

Background: Studies have shown that circulating tumor DNA (ctDNA) indicates a poor prognosis in ovarian cancer. In this study, meta-analysis was used to assess the relationship between ctDNA and the prognosis of patients with epithelial ovarian cancer. Methods: The clinical trials included in this study were obtained via a search of PubMed, the Cochrane Library, the Web of Science and Embase between the period of establishment and March 2020. We selected clinical studies using qualitative or quantitative ctDNA methods to analyse the prognosis of ovarian epithelial cancer, screened the studies according to the determined inclusion and exclusion criteria, and used the modified JADAD score scale and NOS scale for evaluation, with OS (overall survival) and PFS (progression-free survival) as end events. The Cochrane Evaluation Tool was used to evaluate the quality of the randomized controlled trials. Stata 15.0 software was used to combine the effect ratio (hazard ratio, HR) and its 95% confidence interval (CI). In addition, a source analysis of ctDNA specimens, an analysis of ctDNA detection methods and a subgroup and sensitivity analysis of FIGO staging were performed. Results: A total of 8 studies were included in this meta-analysis, and ctDNA was found to be an independent risk factor for patients with epithelial ovarian cancer (OS: HR = 2.36, 95% CI [1.76,3.17], P < .001; PFS: HR = 2.51, 95% CI [1.83,3.45]). Conclusions: The results of our analysis suggested that ctDNA is a potential biomarker that can be used to evaluate the prognosis of patients with ovarian cancer.

Assessment of Circulating Nucleic Acids in Cancer: From Current Status to Future Perspectives and Potential Clinical Applications

Current approaches for cancer detection and characterization are based on radiological procedures coupled with tissue biopsies, despite relevant limitations in terms of overall accuracy and feasibility, including relevant patients' discomfort. Liquid biopsies enable the minimally invasive collection and analysis of circulating biomarkers released from cancer cells and stroma, representing therefore a promising candidate for the substitution or integration in the current standard of care. Despite the potential, the current clinical applications of liquid biopsies are limited to a few specific purposes. The lack of standardized procedures for the pre-analytical management of body fluids samples and the detection of circulating biomarkers is one of the main factors impacting the effective advancement in the applicability of liquid biopsies to clinical practice. The aim of this work, besides depicting current methods for samples collection, storage, quality check and biomarker extraction, is to review the current techniques aimed at analyzing one of the main circulating biomarkers assessed through liquid biopsy, namely cell-free nucleic acids, with particular regard to circulating tumor DNA (ctDNA). ctDNA current and potential applications are reviewed as well.

The prognostic value of longitudinal circulating tumor DNA profiling during osimertinib treatment

Background

Serial profiling of circulating tumor DNA (ctDNA) could reflect dynamic molecular changes in response to treatment and potentially predict impending disease progression (PD). Herein, we investigated the molecular factors and dynamic changes in ctDNA that can serve as predictors of survival outcomes of patients with epidermal growth factor receptor (EGFR)-mutated advanced non-small cell lung cancer (NSCLC) who received osimertinib therapy after progression from prior EGFR inhibitor regimen.

Methods

Capture-based targeted sequencing was performed on the baseline and longitudinal plasma samples collected from 72 and 57 patients, respectively, using a 168-gene panel.

Results

Analysis revealed that inferior overall survival (OS) was correlated with various baseline molecular features including high allelic fraction (AF) of EGFR sensitizing mutations (P=0.045), high maximum AF (maxAF, P=0.060), or harboring concurrent genomic alterations such as copy number amplification (CNA) in EGFR (P=0.026) or in other genes (P=0.026), and genes involved in the cell cycle (P=0.004) or TP53 signaling pathway (P=0.032). Moreover, ctDNA clearance at first follow-up after 6 weeks of osimertinib therapy was correlated with significantly longer progression-free survival (PFS) (P=0.022) and OS (P=0.009). Molecular PD, reflected by the emergence of new mutation or increased AF of existing mutations, was detected at an average lead time of 2.5 months prior to radiological PD. Patients with molecular PD were more likely to harbor CNA (P=0.035) and TP53 mutations (P=0.023).

Conclusions

Molecular factors derived from serial ctDNA profiling can serve as predictive and prognostic markers, which could allow early detection of PD, preceding imaging modalities by 2.5 months.

Expanding Uses of HIPEC for Locally Advanced Colorectal Cancer: A European Perspective

Locally advanced colorectal cancer is a challenge for surgeons and medical oncologist; 10 to 20% colorectal cancer debut as locally advanced disease, with tumors extending through the colon wall with perforation and/or invasion of adjacent organs or structures. Those locally advanced tumors have a worse prognostic at any stage due not only to systemic dissemination but also in a high percentage of patients, to locoregional recurrence, in fact, peritoneal carcinomatosis of colorectal origin is so predictable that we can assess the risk for each patient according to some histopathological and clinical features: small peritoneal nodules resected in the first surgery (70% probability), ovarian metastases (60%), perforated tumor onset or intraoperative tumor rupture (50%), positive cytology (40%), and pT4/mucinous pT3 up to 40%. Prophylactic or adjuvant hyperthermic intraperitoneal chemotherapy seems to be a promising strategy for patients with advanced colorectal cancer to prevent the development of peritoneal recurrence and improve prognosis of this group of patients.

Total Number of Alterations in Liquid Biopsies Is an Independent Predictor of Survival in Patients With Advanced Cancers

PURPOSE

Studies have demonstrated an association between quantity of circulating tumor DNA (ctDNA) and poorer survival. We investigated the relationship between percent ctDNA (%ctDNA), total number of ctDNA alterations, and overall survival (OS) in liquid biopsies.

MATERIALS AND METHODS

Overall, 418 patients with blood-based next-generation sequencing (54 to 73 genes) were analyzed. Eligible patients included those who had advanced/metastatic solid tumor malignancies and never received immunotherapy treatment, which may alter the survival curve in patients with high mutational burden.

RESULTS

Patients with a high (≥ 5%) %ctDNA had significantly shorter OS versus those with intermediate (≥ 0.4% to < 5%) or low (< 0.4%) values (median OS, 7.0 v 14.1 v not reached [NR] months, respectively; P < .0001). Patients with a high (≥ 5) total number of alterations had significantly shorter OS versus those with intermediate (≥ 1.46 to < 5), low (< 1.46), or no alterations (median OS, 4.6 v 11.7 v 21.3 v NR months, respectively; P < .0001). The total number of alterations correlated with %ctDNA (r = 0.85; 95% CI, 0.81 to 0.87; P < .0001). However, only an intermediate to high total number of alterations (≥ 1.46) was an independent predictor of worse OS (hazard ratio, 1.96; 95% CI, 1.30 to 2.96; P = .0014; multivariate analysis).

CONCLUSION

We demonstrate that the total number of alterations and %ctDNA have prognostic value and correlate with one another, but only the total number of alterations was independently associated with survival outcomes. Our findings suggest that the total number of alterations in plasma may be an indicator of more aggressive tumor biology and therefore poorer survival.

Circulating tumor DNA analysis in the era of precision oncology

The spatial and temporal genomic heterogeneity of various tumor types and advances in technology have stimulated the development of circulating tumor DNA (ctDNA) genotyping. ctDNA was developed as a non-invasive, cost-effective alternative to tumor biopsy when such biopsy is associated with significant risk, when tumor tissue is insufficient or inaccessible, and/or when repeated assessment of tumor molecular abnormalities is needed to optimize treatment. The role of ctDNA is now well established in the clinical decision in certain alterations and tumors, such as the epidermal growth factor receptor (EGFR) mutation in non-small cell lung cancer and the v-Ki-ras2 kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in colorectal cancer. The role of ctDNA analysis in other tumor types remains to be validated. Evolving data indicate the association of ctDNA level with tumor burden, and the usefulness of ctDNA analysis in assessing minimal residual disease, in understanding mechanisms of resistance to treatment, and in dynamically guiding therapy. ctDNA analysis is increasingly used to select therapy. Carefully designed clinical trials that use ctDNA analysis will increase the rate of patients who receive targeted therapy, will elucidate our understanding of evolution of tumor biology and will accelerate drug development and implementation of precision medicine. In this article we provide a critical overview of clinical trials and evolving data of ctDNA analysis in specific tumors and across tumor types.

Clearing of circulating tumour DNA predicts clinical response to first line tyrosine kinase inhibitors in advanced epidermal growth factor receptor mutated non-small cell lung cancer

OBJECTIVES

Epidermal growth factor receptor (EGFR) mutations confer sensitivity to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). However, a subset of patients has limited or no response. We investigated the initial dynamics of EGFR mutations detected in circulating tumour DNA (ctDNA) during treatment as a predictive marker of outcome.

METHODS

A total of 225 patients with advanced EGFR mutated NSCLC were included for consecutive blood sampling in this prospective multicentre study. Out of these, 146 patients received first line TKI and had a baseline blood sample available for EGFR mutation testing with the Cobas® EGFR mutation test V2. For examinations on clearing and clinical outcome, 98 patients who had detectable ctDNA at baseline and at least one follow-up blood sample were included.

RESULTS

For patients with EGFR mutations present in plasma at baseline, clearing of mutations from the blood during first line TKI served as a positive predictor for objective response rate (p = 0.0008), progression-free survival (PFS) (p < 0.0001) and overall survival (OS) (p < 0.0001). This was seen both for patients who cleared the ctDNA within the first 7 weeks of treatment and patients who cleared the ctDNA at a slower pace. Baseline mutation presence was a negative predictor for PFS (p = 0.0069) and OS (p = 0.0340).

CONCLUSION

The current study is the first to confirm, in a sizeable Caucasian cohort, that clearing of EGFR mutations predict outcome to first line TKI in patients with EGFR mutated NSCLC.

Circulating Tumor DNA Analysis: Clinical Implications for Colorectal Cancer Patients. A Systematic Review

Background

Liquid biopsies could improve diagnosis, prognostication, and monitoring of colorectal cancer (CRC). Mutation, chromosomal copy number alteration, and methylation analysis in circulating tumor DNA (ctDNA) from plasma or serum has gained great interest. However, the literature is inconsistent on preferred candidate markers, hampering a clear direction for further studies and clinical translation. This review assessed the potential of ctDNA analysis for clinical utility.

Methods

A systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines was conducted up to December 3, 2018, followed by methodological quality assessment. Primary endpoints were accuracy for detection, prognostication, and monitoring.

Results

Eighty-four studies were included. For CRC detection, sensitivity was 75% using ctDNA mutation analysis and up to 96% using copy number analysis. Septin 9 (SEPT9) hypermethylation analysis showed sensitivities of 100% and specificities of 97%. Regarding prognostication, ctDNA KRAS mutations were associated with oncological outcome and could predict response to anti-epidermal growth factor receptor therapy. For monitoring, sequential ctDNA KRAS mutation analysis showed promise for detection of relapses or therapy resistance.

Conclusions

This comprehensive overview of ctDNA candidate markers demonstrates SEPT9 methylation analysis to be promising for CRC detection, and KRAS mutation analysis could assist in prognostication and monitoring. Prospective evaluation of marker panels in clinical decision making should bring ctDNA analysis into practice.

Association of clinical outcomes in metastatic breast cancer patients with circulating tumour cell and circulating cell-free DNA

BACKGROUND

Both circulating tumour cell (CTC) and total circulating cell-free DNA (ccfDNA) predict cancer patient prognosis. However, no study has explored the prognostic value of the combined use of CTC and ccfDNA. We aimed to investigate individual and joint effects of CTC and ccfDNA on clinical outcomes of metastatic breast cancer (MBC) patients.

METHODS

We collected 227 blood samples from 117 MBC patients. CTCs were enumerated using the CellSearch System. ccfDNAs were quantified by quantitative real-time polymerase chain reaction and Qubit fluorometer. The individual and joint effects of CTC and ccfDNA levels on patient progression-free survival (PFS) and overall survival (OS) were analysed using Cox proportional hazards models.

RESULTS

Compared to patients with <5 CTCs, patients with ≥5 CTCs had a 2.58-fold increased risk of progression and 3.63-fold increased risk of death. High level of ccfDNA was associated with a 2.05-fold increased risk of progression and 3.56-fold increased risk of death. These associations remained significant after adjusting for other important clinical covariates and CTC/ccfDNA levels. CTC and ccfDNA levels had a joint effect on patient outcomes. Compared to patients with low levels of both CTC and ccfDNA, those with high levels of both markers exhibited a >17-fold increased death risk (P < 0.001). Moreover, longitudinal analysis of 132 samples from 22 patients suggested that the inconsistency between CTC level and outcome in some patients could possibly be explained by ccfDNA level.

CONCLUSIONS

CTC and total ccfDNA levels were individually and jointly associated with PFS and OS in MBC patients.

Increased Plasma Circulating Cell-Free DNA Could Be a Potential Marker for Oral Cancer

Background: Oral squamous cell carcinoma (OSCC) is a disease that affects patients worldwide. DNA of dead cells is released into the blood stream and may be isolated from plasma or serum samples. This DNA is termed cell-free DNA (cfDNA). cfDNA is increased in several types of malignancies. We investigated if there was a correlation between cfDNA levels and the progression of OSCC. Methods: Using quantitative spectrometry, we measured plasma cfDNA in 121 patients with OSCC and 50 matched controls. Mann Whitney and Wilcoxon tests were used to compare differences among various clinical variants. Receiver operating characteristic (ROC) analysis was used to obtain levels suitable for the separation of the clinical subsets. Kaplan-Meier analysis was used to assess correlation with survival. Results: Plasma cfDNA was significantly elevated in patients with OSCC relative to controls. Plasma cfDNA levels correlated with larger tumor size, cervical lymph node metastasis and late stage. Higher plasma cfDNA levels were associated with a poor prognosis of OSCC, which is a new finding. Conclusion: Plasma cfDNA could serve as a novel and easily accessible biomarker in OSCC, providing diagnostic and prognostic value.

Prognostic value of various subtypes of extracellular DNA in ovarian cancer patients

Background

Patients with ovarian cancer represent a heterogeneous population with a variable prognosis and response to chemotherapy. Plasma DNA has been shown to have a prognostic value in different types of cancer including ovarian carcinoma. Whether total circulating DNA, which can be assessed much easier without knowing the tumor-specific mutations, has similar informative value is currently unknown. The aim of this study was to evaluate the prognostic value of extracellular DNA in advanced ovarian cancer.

Methods

This prospective study included 67 patients (pts) with ovarian cancer treated with 1st line paclitaxel and carboplatin (25 pts) and paclitaxel, carboplatin and bevacizumab (42 pts). Thirty-five patients had optimal surgical debulking before chemotherapy. Extracellular DNA was quantified using real time PCR before administration of chemotherapy (67 pts) and after 6 cycles of chemotherapy (44 pts).

Results

Total extracellular DNA (ecDNA), as well as extracellular DNA of nuclear (nDNA) and mitochondrial origin (mtDNA) significantly (p < 0.05) decreased after 6 cycles of chemotherapy (by 54%, 63% and 52%, respectively. Patients with stage I disease had significantly lower mtDNA compared to patients with stage II-IV (8604 vs. 16, 984 ge/mL, p = 0.03). Patients with lower baseline nDNA had superior progression-free (HR = 0.35 (0.14–0.86)) and overall survival (HR = 0.18 (0.04–0.77). The prognostic value of nDNA was confirmed independent of tumor stage and confirmed in multivariate analysis.

Conclusions

Our data suggest that ecDNA of both, nuclear and mitochondrial origin could be added to prognostic markers in ovarian cancer. Analysis of ecDNA does not require the knowledge of tumor-specific mutations in contrast to the quantification of tumor-derived ecDNA. Study of the dynamics and cell type-specific source of the ecDNA could shed light on its biology in cancer and might help to direct the treatment of ovarian cancer.

Liquid Biopsy to Identify Actionable Genomic Alterations

Liquid biopsy has been used extensively in solid malignancies to detect actionable driver mutations, to monitor treatment response, to detect recurrence, to identify resistance mechanisms, and to prognosticate outcome. Although many liquid biopsy sequencing platforms are being used, only five test kits have received government approval. We review representative literature on these government-approved liquid biopsy kits, which are primarily used to detect EGFR mutation in lung cancer and RAS ( KRAS, NRAS, BRAF) mutations in colorectal carcinoma. Another emerging use of single-gene liquid biopsy is to detect PIK3CA mutations and to understand resistance to hormonal blockade in breast and prostate cancers. The two most commonly used next-generation sequencing (NGS) liquid biopsy tests (Guardant 360, Guardant Health; FoundationACT, Foundation Medicine Inc.) are discussed. The ability and the applicability of NGS platform to detect tumor mutation burden are also addressed. Finally, the use of circulating tumor DNA (ctDNA) to detect minimal residual disease may be the most important use of ctDNA in the setting of tumor heterogeneity. The ability to identify "shedders" and "nonshedders" of ctDNA may provide important insight into the clinicopathologic characteristics of the tumor and portend important prognostic significance regarding survival.

Genomic alterations of plasma cell-free DNAs in small cell lung cancer and their clinical relevance

OBJECTIVES

To identify genomic variations in cell-free DNA (cfDNA) and evaluate their clinical utility in small cell lung cancer (SCLC).

MATERIALS AND METHODS

We performed whole genome sequencing using plasma cfDNAs derived from 24 SCLC patients for copy number variation (CNV) analysis, and targeted sequencing using 17 pairs of plasma cfDNA and their matched gDNA for mutation analysis. We defined somatic mutations by comparing cfDNA to its matched gDNA with 5% variant alleles as the cutoff for mutation calls. We applied Kaplan-Meier to correlate the genomic alterations with overall survival (OS) and progression-free survival (PFS).

RESULTS

We observed widespread somatic copy-number alterations and mutations, including amplification of MYC at 8q24, FGF10 at 5p13, SOX2 at 3q26 and FGFR1 at 8p12, as well as deletion of TP53 at 17p13, RASSF1 at 3p21.3, RB1 at 13q14.2, FHIT at 3p14, and PTEN at 10q23. The most frequent mutations were genes involved in chromatin regulation (KMT2D, ARID1A, SETBP1 and PBRM1), PI3K/MTOR pathway(MTOR,PIK13G), Notch1 signalling pathway (NOTCH1), and DNA repair related gene ATRX. Kaplan-Meier analysis revealed poor OS and PFS in patients with somatic mutations in gene SETBP1 (P = 0.0061/0.0264, HR = 4.785/3.841, 95% CI = 2.014-28.25/1.286-16.58) and PBRM1 (P = 0.0276/0.0286, HR = 3.532/3.506, 95% CI = 1.275 to 25.34/1.26-24.87). Poor OS was also associated with somatic mutations in ATRX (P = 0.0099, HR = 4.024, 95% CI = 1.926-42.95), EP300 (P = 0.025/0.0622, HR = 3.382/2.891, 95% CI = 1.448-27.76/1.013-17.29), while poor PFS was associated with ATM mutation (P = 0.0038, HR = 4.604, 95% CI = 2.211-40.93). The mutation index produced by summing up the number of mutations in the five genes was significantly associated with the poor OS/PFS (P = 0.0185/0.0294) after adjusting the effect of the stage.

CONCLUSIONS

Our result supports blood plasma as a promising sample source for the genomic analysis in SCLC patients whose tumor tissues are scarcely available and demonstrates potential clinical utilities of cfDNA-based liquid biopsy for clinical management of this deadly disease.

Monitoring the effect of first line treatment in RAS/RAF mutated metastatic colorectal cancer by serial analysis of tumor specific DNA in plasma

BACKGROUND

Precision medicine calls for an early indicator of treatment efficiency. Circulating tumor DNA (ctDNA) is a promising marker in this setting. Our prospective study explored the association between disease development and change of ctDNA during first line chemotherapy in patients with RAS/RAF mutated metastatic colorectal cancer (mCRC).

METHODS

The study included 138 patients with mCRC receiving standard first line treatment. In patients with RAS/RAF mutated tumor DNA the same mutation was quantified in the plasma using droplet digital PCR. The fractional abundance of ctDNA was assessed in plasma before treatment start and at every treatment cycle until radiologically defined progressive disease.

RESULTS

RAS/RAF mutations were detected in the plasma from 77 patients. Twenty patients progressed on treatment and 57 stopped treatment without progression. The presence of mutated DNA in plasma was correlated with poor overall survival. A low level of ctDNA after the first cycle of chemotherapy was associated with a low risk of progression. On the other hand, a significant increase of ctDNA at any time during the treatment course was associated with a high risk of progression on continuous treatment. The first increase in ctDNA level occurred at a median of 51 days before radiologically confirmed progression.

CONCLUSIONS

The results indicate that the ctDNA level holds potential as a clinically valuable marker in first line treatment of mCRC. A rapid decrease was associated with a prolonged progression free interval, whereas a significant increase gave notice of early progression with a relevant lead time.

Incorporating blood-based liquid biopsy information into cancer staging: time for a TNMB system?

Tissue biopsy is the standard diagnostic procedure for cancer. Biopsy may also provide material for genotyping, which can assist in the diagnosis and selection of targeted therapies but may fall short in cases of inadequate sampling, particularly from highly heterogeneous tumors. Traditional tissue biopsy suffers greater limitations in its prognostic capability over the course of disease, most obviously as an invasive procedure with potential complications, but also with respect to probable tumor clonal evolution and metastasis over time from initial biopsy evaluation. Recent work highlights circulating tumor DNA (ctDNA) present in the blood as a supplemental, or perhaps an alternative, source of DNA to identify the clinically relevant cancer mutational landscape. Indeed, this noninvasive approach may facilitate repeated monitoring of disease progression and treatment response, serving as a means to guide targeted therapies based on detected actionable mutations in patients with advanced or metastatic solid tumors. Notably, ctDNA is heralding a revolution in the range of genomic profiling and molecular mechanisms to be utilized in the battle against cancer. This review will discuss the biology of ctDNA, current methods of detection and potential applications of this information in tumor diagnosis, treatment, and disease prognosis. Conventional classification of tumors to describe cancer stage follow the TNM notation system, heavily weighting local tumor extent (T), lymph node invasion (N), and detectable metastasis (M). With recent advancements in genomics and bioinformatics, it is conceivable that routine analysis of ctDNA from liquid biopsy (B) may make cancer diagnosis, treatment, and prognosis more accurate for individual patients. We put forward the futuristic concept of TNMB tumor classification, opening a new horizon for precision medicine with the hope of creating better outcomes for cancer patients.

Variations in transrenal DNA and comparison with plasma DNA as a diagnostic marker for colorectal cancer

BACKGROUND

Transrenal DNA can potentially be useful in the disease management of colorectal cancer (CRC) and has potential diagnostic utility. Our study aimed to conduct preoperative and postoperative analysis of KRAS-positive patients, using transrenal DNA compared with plasma DNA. This is critically needed for disease diagnostics and treatment response monitoring.

METHODS

CRC patients at different stages of the disease and with different molecular profiles were recruited for serial time-point analysis. Preoperative and postoperative urine specimens were extracted and compared with tumor tissues and plasma DNA.

RESULTS

Our analysis demonstrated that transrenal DNA offered comparable sensitivity and specificity to plasma DNA analysis. Collection of transrenal DNA, being noninvasive, is an attractive assay and easily allows serial monitoring of the disease. Results from preoperative detection showed a close correlation to tumor tissue profiling and demonstrated close associations to the disease. We also observed significant decreases in mutant KRAS DNA concentration after surgery, which confirmed transrenal DNA's sensitivity to treatment response.

CONCLUSIONS

The use of transrenal DNA offers a possible alternative method of disease profiling, detection and tracking. Our study is one of the first to systematically analyze a relatively large number of different CRC patients using transrenal DNA. The positive correlation with disease demonstrates the assay's viability in the clinical setting, and our method further opens up the possibility to use transrenal DNA for clinical intervention investigations.

Detection of somatic mutations in cell-free DNA in plasma and correlation with overall survival in patients with solid tumors

A suitable clinical-grade platform is required for detection of somatic mutations with high sensitivity in cell-free DNA (cfDNA) of patients with solid tumors. In this study, we evaluated in parallel ultra-deep NGS with MassARRAY and allele-specific droplet digital PCR (ddPCR) for cfDNA genotyping and correlated cfDNA yield and mutation status with overall survival (OS) of patients. We assessed plasma samples from 46 patients with various advanced metastatic solid tumors and known mutations by deep sequencing using an Ampliseq cancer hotspot panel V2 on Ion Proton. A subset of these samples with DNA availability was tested by ddPCR and UltraSEEK MassARRAY for mutation detection in 5 genes (IDH1, PIK3CA, KRAS, BRAF, and NRAS). Sixty one of 104 expected tissue mutations and 6 additional mutations not present in the tissue were detected in cfDNA. ddPCR and MassARRAY showed 83% and 77% concordance with NGS for mutation detection with 100% and 79% sensitivity, respectively. The median OS of patients with lower cfDNA yield (74 vs 50 months; P < 0.03) and cfDNA negative for mutations (74.2 vs 53 months; p < 0.04) was significantly longer than in patients with higher cfDNA yield and positive for mutations. A limit-of-detection of 0.1% was demonstrated for ddPCR and MassARRAY platforms using a serially diluted positive cfDNA sample. The MassARRAY and ddPCR systems enable fast and cost-effective genotyping for a targeted set of mutations and can be used for single gene testing to guide response to chemotherapy or for orthogonal validation of NGS results.

The clinical use of the platelet/lymphocyte ratio and lymphocyte/monocyte ratio as prognostic predictors in colorectal cancer: a meta-analysis

BACKGROUND

Conflicting evidence exists regarding the effects of platelet/lymphocyte ratio (PLR) and lymphocyte/monocyte ratio(LMR) on the prognosis of colorectal cancer (CRC) patients. This study aimed to evaluate the roles of the PLR and LMR in predicting the prognosis of CRC patients via meta-analysis.

METHODS

Eligible studies were retrieved from the PubMed, Embase,andChina National Knowledge Infrastructure (CNKI) databases, supplemented by a manual search of references from retrieved articles. Pooled hazard ratios (HR) with 95% confidence intervals (95% CI) were calculated using the generic inverse variance and random-effect model to evaluate the association of PLR and LMR with prognostic variables in CRC, including overall survival (OS), cancer-specific survival (CSS) and disease-free survival (DFS).

RESULTS

Thirty-three studies containing 15,404 patients met criteria for inclusion. Pooled analysis suggested that elevated PLR was associated with poorer OS (pooled HR = 1.57, 95% CI: 1.41 - 1.75, p< 0.00001, I2=26%) and DFS (pooled HR = 1.58, 95% CI: 1.31 - 1.92, p< 0.00001, I2=66%). Conversely, high LMR correlated with more favorable OS (pooled HR = 0.59, 95% CI: 0.50 - 0.68, p< 0.00001, I2=44%), CSS (pooled HR = 0.54, 95% CI: 0.40 - 0.72, p< 0.00001, I2=11%) and DFS (pooled HR = 0.82, 95% CI: 0.71- 0.94,p=0.005, I2=29%).

CONCLUSIONS

Elevated PLR was associated with poor prognosis, while high LMR correlated with more favorable outcomes in CRC patients. Pretreatment PLR and LMR could serve as prognostic predictors in CRC patients.

Circulating mutational portrait of cancer: manifestation of aggressive clonal events in both early and late stages

BACKGROUND

Solid tumors residing in tissues and organs leave footprints in circulation through circulating tumor cells (CTCs) and circulating tumor DNAs (ctDNA). Characterization of the ctDNA portraits and comparison with tumor DNA mutational portraits may reveal clinically actionable information on solid tumors that is traditionally achieved through more invasive approaches.

METHODS

We isolated ctDNAs from plasma of patients of 103 lung cancer and 74 other solid tumors of different tissue origins. Deep sequencing using the Guardant360 test was performed to identify mutations in 73 clinically actionable genes, and the results were associated with clinical characteristics of the patient. The mutation profiles of 37 lung cancer cases with paired ctDNA and tumor genomic DNA sequencing were used to evaluate clonal representation of tumor in circulation. Five lung cancer cases with longitudinal ctDNA sampling were monitored for cancer progression or response to treatments.

RESULTS

Mutations in TP53, EGFR, and KRAS genes are most prevalent in our cohort. Mutation rates of ctDNA are similar in early (I and II) and late stage (III and IV) cancers. Mutation in DNA repair genes BRCA1, BRCA2, and ATM are found in 18.1% (32/177) of cases. Patients with higher mutation rates had significantly higher mortality rates. Lung cancer of never smokers exhibited significantly higher ctDNA mutation rates as well as higher EGFR and ERBB2 mutations than ever smokers. Comparative analysis of ctDNA and tumor DNA mutation data from the same patients showed that key driver mutations could be detected in plasma even when they were present at a minor clonal population in the tumor. Mutations of key genes found in the tumor tissue could remain in circulation even after frontline radiotherapy and chemotherapy suggesting these mutations represented resistance mechanisms. Longitudinal sampling of five lung cancer cases showed distinct changes in ctDNA mutation portraits that are consistent with cancer progression or response to EGFR drug treatment.

CONCLUSIONS

This study demonstrates that ctDNA mutation rates in the key tumor-associated genes are clinical parameters relevant to smoking status and mortality. Mutations in ctDNA may serve as an early detection tool for cancer. This study quantitatively confirms the hypothesis that ctDNAs in circulation is the result of dissemination of aggressive tumor clones and survival of resistant clones. This study supports the use of ctDNA profiling as a less-invasive approach to monitor cancer progression and selection of appropriate drugs during cancer evolution.

Post surgery circulating free tumor DNA is a predictive biomarker for relapse of lung cancer

Cancer cells release DNA fragments into plasma as circulating free DNA (cfDNA). However, quantitative measurement of tumor-derived DNA in cfDNA remains challenge. The purpose of this study was to quantitatively assess tumor-derived DNA in lung cancer patients. By optimizing competitive allele-specific TaqMan PCR (CAST-PCR), we assessed the copy number of mutated Kirsten rat sarcoma viral oncogene homolog (KRAS) and epidermal growth factor receptor (EGFR) alleles in the pre/post surgery plasma of 168 lung cancer patients. An absolute quantitative PCR method was developed to assess the number of total cfDNA. All mutations detected in tumors were also found in the plasma after surgery. At the time of 30 days after surgery, EGFR mutation of circulating cell-free DNA was detected only in two patients who recurred in 4 months after surgery. Compared to that of normal control at 30 days after surgery, five patients who recurred in 4 months had significantly higher circulating cell-free DNA (P < 0.001), whereas six patients who recurred after 4 months (P = 0.207) and five patients without recurrence (P = 0.901) demonstrated significantly lower circulating cell-free DNA. Our findings suggest that cfDNA analysis in plasma is an alternative and supplement to tissue analysis and hold promise for clinical application. Stratification of patients according to cfDNA levels at 30 days after surgery might be helpful in selecting lung cancer patients for adjuvant therapy after surgery.

Circulating Cell-Free DNA Levels Could Predict Oncological Outcomes of Patients Undergoing Esophagectomy for Esophageal Squamous Cell Carcinoma

Circulating cell-free DNA (cfDNA) is a potential biomarker for cancer progression but its role is unclear in patients with esophageal squamous cell carcinoma (ESCC) after esophagectomy. We investigated relationships between plasma cfDNA levels and clinicopathological parameters in ESCC patients. Eighty-one ESCC patients who received esophagectomy were enrolled. Plasma samples from these patients and 95 normal controls were collected. DNA copy numbers were measured by real-time quantitative PCR. Subjects were divided into two groups by cfDNA level. Clinicopathological data were collected retrospectively and relationships between cfDNA levels and clinical parameters were evaluated. The cfDNA level in normal controls ranged from 0–4157 copies/mL. The cfDNA level of 96.3% ESCC patients was higher than the cutoff value (2447.26 copies/mL) with a specificity of 94.1%. The mean cfDNA concentration was 5918 copies/mL in lower and 53,311 copies/mL in higher cfDNA groups. No correlations were found between clinicopathological factors and cfDNA levels except for lymphovascular invasion. Higher cfDNA levels were associated with tumor relapse (p = 0.018). Five-year disease-free survival (DFS) and overall survival (OS) rates were 34.7% and 33.8%, respectively. Patients with higher cfDNA levels had poorer DFS (p = 0.013). Patients with higher cfDNA levels had poorer OS, but not significantly (p = 0.164). Circulating cfDNA could be a biomarker for tumor relapse of ESCC with high sensitivity and specificity. Higher cfDNA levels were associated with tumor relapse and shorter DFS after esophagectomy in ESCC patients.

Clinical applications of liquid biopsies in gastrointestinal oncology

"Liquid biopsies" are blood based assays used to detect and analyze circulating tumor products, including circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating messenger RNA (mRNA), circulating microRNA (miRNA), circulating exosomes, and tumor educated platelets (TEP). For patients with gastrointestinal (GI) malignancies, blood based biopsies may offer several advantages. First, tumor tissue samples are often challenging to procure, and when obtainable, are often insufficient for genomic profiling. Second, blood based assays offer a real-time overview of the entire tumor burden, and allow anatomically unbiased genomic profiling. Third, given the convenience and relative safety of liquid biopsies, this technology may facilitate identification of genomic alterations that confer sensitivity and resistance to targeted therapeutics. This review will assess the clinical applications of circulating tumor products for patients with GI tumors.

Circulating Cell Free DNA as the Diagnostic Marker for Ovarian Cancer: A Systematic Review and Meta-Analysis

Background

Quantitative analyses of circulating cell-free DNA (cfDNA) are potential methods for the detection of ovarian cancer. Many studies have evaluated these approaches, but the results were too inconsistent to be conclusive. This study is the first to systematically evaluate the accuracy of circulating cfDNA for the diagnosis of ovarian cancer by conducting meta-analysis.

Methods

We searched PubMed, Embase, Cochrane Library and the Chinese National Knowledge Infrastructure (CNKI) databases systematically for relevant literatures up to December 10, 2015. All analyses were conducted using Meta-DiSc1.4 and Stata 12.0 software. Sensitivity, specificity and other measures of accuracy of circulating cfDNA for the diagnosis of ovarian cancer were pooled. Meta-regression was performed to identify the sources of heterogeneity.

Results

This meta-analysis included a total of 9 studies, including 462 ovarian cancer patients and 407 controls. The summary estimates for quantitative analysis of circulating cfDNA in ovarian cancer screen were as follows: sensitivity, 0.70 (95% confidence interval (CI), 0.65–0.74); specificity, 0.90 (95% CI, 0.87–0.93); positive likelihood ratio, 6.60 (95% CI, 3.90–11.17); negative likelihood ratio, 0.34 (95% CI, 0.25–0.47); diagnostic odds ratio, 26.05 (95% CI, 14.67–46.26); and area under the curve, 0.89 (95% CI, 0.83–0.95), respectively. There was no statistical significance for the evaluation of publication bias.

Conclusions

Current evidence suggests that quantitative analysis of cfDNA has unsatisfactory sensitivity but acceptable specificity for the diagnosis of ovarian cancer. Further large-scale prospective studies are required to validate the potential applicability of using circulating cfDNA alone or in combination with conventional markers as diagnostic biomarker for ovarian cancer and explore potential factors that may influence the accuracy of ovarian cancer diagnosis.