The Level of Preoperative Plasma KRAS Mutations and CEA Predict Survival of Patients Undergoing Surgery for Colorectal Cancer Liver Metastases

Colorectal cancer (CRC) belongs to the most common cancers. The liver is a predominant site of CRC dissemination. Novel biomarkers for predicting the survival of CRC patients with liver metastases (CLM) undergoing metastasectomy are needed. We examined KRAS mutated circulating cell-free tumor DNA (ctDNA) in CLM patients as a prognostic biomarker, independently or in combination with carcinoembryonic antigen (CEA). Thereby, a total of 71 CLM were retrospectively analyzed. Seven KRAS G12/G13 mutations was analyzed by a ddPCR™ KRAS G12/G13 Screening Kit on QX200 Droplet Digital PCR System (Bio-Rad Laboratories, Hercules, CA, USA) in liver metastasis tissue and preoperative and postoperative plasma samples. CEA were determined by an ACCESS CEA assay with the UniCel DxI 800 Instrument (Beckman Coulter, Brea, CA, USA). Tissue KRAS positive liver metastases was detected in 33 of 69 patients (47.8%). Preoperative plasma samples were available in 30 patients and 11 (36.7%) were KRAS positive. The agreement between plasma- and tissue-based KRAS mutation status was 75.9% (22 in 29; kappa 0.529). Patients with high compared to low levels of preoperative plasma KRAS fractional abundance (cut-off 3.33%) experienced shorter overall survival (OS 647 vs. 1392 days, p = 0.003). The combination of high preoperative KRAS fractional abundance and high CEA (cut-off 3.33% and 4.9 µg/L, resp.) best predicted shorter OS (HR 13.638, 95%CI 1.567–118.725) in multivariate analysis also (OS HR 44.877, 95%CI 1.59–1266.479; covariates: extend of liver resection, biological treatment). KRAS mutations are detectable and quantifiable in preoperative plasma cell-free DNA, incompletely overlapping with tissue biopsy. KRAS mutated ctDNA is a prognostic factor for CLM patients undergoing liver metastasectomy. The best prognostic value can be reached by a combination of ctDNA and tumor marker CEA.

Circulating Tumor DNA in KRAS positive colorectal cancer patients as a prognostic factor - a systematic review and meta-analysis

BACKGROUND

Liquid biopsy is a novel tool in oncology. It provides minimally invasive detection of tumor specific DNA. This review summarizes data on presence of circulating tumor DNA in serum or plasma of CRC patients as a potential negative prognostic factor.

MATERIALS AND METHODS

The systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The search was performed using PubMed, Web of Science and Scopus.

RESULTS

In total 18 articles with a total of 1779 patients met the inclusion criteria. Six out of 8 studies found that presence of ctDNA in plasma/serum was associated with inferior overall survival. All 6 studies found that high concentrations of ctDNA in plasma/serum was associated with inferior overall survival.

CONCLUSIONS

Presence or high concentrations of KRAS mutation in plasma or serum were associated with inferior prognosis. Establishing cut-off concentrations is warranted for further clinical implementation of liquid biopsy.

Cell-Free DNA in the Management of Colorectal Cancer

Colorectal cancer is one of the leading cause of death by cancer worldwide in both men and women. Liquid biopsy belongs nowadays to the landscape of cancer management biological tools. In this chapter, we will describe and discuss the actual, potential and future applications of cfDNA analysis in plasma of patients with colorectal cancer in early or metastatic stage. During the last decade, the development of molecular biology assays like digital PCR or next-generation sequencing made the analysis of cfDNA in plasma possible with an excellent sensitivity and applications like early detection, diagnosis, prognosis, response to treatment, monitoring of an emerging resistance, mapping of the disease molecular landscape or evaluation of the residual disease are now feasible. cfDNA detection has several promising applications in the management of patients with colorectal cancer, but prospective randomised clinical trials are still lacking to make liquid biopsy ready for prime-time.

Circulating cell-free nucleic acids as biomarkers in colorectal cancer screening and diagnosis - an update

Introduction: Screening methods for one of the most frequently diagnosed malignancy, colorectal cancer (CRC), have limitations. Circulating cell-free nucleic acids (cfNA) hold clinical relevance as screening, prognostic and therapy monitoring markers. Area covered: In this review, we summarize potential CRC-specific cfNA biomarkers, the recently developed sample preparation techniques, their applications, and pitfalls. Expert opinion: Automated extraction of cfDNA is highly reproducible, however, cfDNA yield is less compared to manual isolation. Quantitative and highly sensitive detection techniques (e.g. digital PCR, NGS) can be applied to analyze genetic and epigenetic changes. Detection of DNA mutations or methylation in cfDNA and related altered levels of mRNA, miRNA, and lncRNA may improve early cancer recognition, based on specific, CRC-related patterns. Detection of cfDNA mutations (e.g. TP53, KRAS, APC) has limited diagnostic sensitivity (40-60%), however, methylated DNA including SEPT9, SFRP1, SDC2 can be applied with higher sensitivity (up to 90%) for CRC. Circulating miRNAs (e.g. miR-21, miR-92, miR-141) provide comparably high sensitivity for CRC as the circulating tumor cell mRNA markers (e.g. EGFR, CK19, CK20, CEA). Automation of cfNA isolation coupled with quantitative analysis of CRC-related, highly sensitive biomarkers may enhance CRC screening and early detection in the future.

The diagnostic accuracy of circulating free DNA for the detection of KRAS mutation status in colorectal cancer: A meta-analysis

KRAS mutations have been reported as a reliable biomarker for epidermal growth factor receptor (EGFR) targeted therapy and are also associated with poor prognosis in colorectal cancer (CRC) patients. However, limitations of detecting KRAS mutations in tissues are obvious. KRAS mutations in the peripheral blood can be detected as an alternative to tissue analysis. The objective of this meta‐analysis was to evaluate the diagnostic value of cfDNA (circulating free DNA) compared with tissues and to investigate the prognostic potential of cfDNA KRAS mutations in CRC patients. Searches were performed in PubMed, Embase, and Cochrane Library for published studies. We extracted true‐positive (TP), false‐positive (FP), false‐negative (FN), true‐negative (TN) values, survival rate of CRC patients with mutant and wild‐type KRAS and calculated pooled sensitivity and specificity, positive/negative likelihood ratios [PLRs/NLRs], diagnostic odds ratios [DORs], and corresponding 95% confidence intervals [95% CIs]. We also generated a summary receiver operating characteristic (SROC) curve to evaluate the overall diagnostic potential. Totally, 31 relevant studies were recruited and used for the meta‐analysis on the efficacy of cfDNA testing in detecting KRAS mutations. The pooled sensitivity, specificity, PLR, NLR, and DOR were 0.637 (95% CI: 0.607‐0.666), 0.943 (95% CI: 0.930‐0.954), 10.024 (95% CI: 6.912‐14.535), 0.347 (95% CI: 0.269‐0.447), and 37.882 (95% CI: 22.473‐63.857), respectively. The area under the SROC curve was 0.9392. Together, the results suggest that detecting KRAS mutations in cfDNA has adequate diagnostic efficacy in terms of specificity. There is a promising role for cfDNA in the detection of KRAS mutations in CRC patients. However, prospective studies with larger patient cohorts are still required before definitive conclusions of the prognostic potential of cfDNA KRAS mutations in CRC patients were drawn.

Clinical Interest of Circulating Tumor DNA in Oncology

Genetic alterations in tumors, as predictor of response to targeted-therapies or as prognostic markers, are clinically relevant to determine adequate therapeutic management. Tumor biopsy is currently the golden standard for somatic alterations assessment, but this approach is invasive and does not consider tumor heterogeneity. In various body fluids like plasma, somatic mutations have been identified. Circulating tumor DNA (ctDNA) holds promises in tumor burden monitoring or malignancies early detection. Since allele frequencies of circulating somatic mutations are low, highly sensitive novel assays have been developed to allow the investigation of the tumor genome, leading to the emergence of the "liquid biopsy" concept. Despite these technological advances, other assays for identifying intratumor and intermetastases heterogeneity need to be developed. Before being applied to clinic, ctDNA analyses need to be harmonized and validated with well-powered, well-designed studies. One of the primary prerequisite to incorporation of ctDNA analysis in the follow-up strategy of malignancies is the checking of the concordance with golden standard detection methods, imaging, circulating proteins and biopsy. This review focuses on the clinical interest of ctDNA in solid tumors and hematological malignancies.

Assessing the Impact of Circulating Tumor DNA (ctDNA) in Patients With Colorectal Cancer: Separating Fact From Fiction

Significant advances and increased awareness have been in made in the field of non-invasive liquid biopsies for cancer, spanning several malignancies from gastrointestinal, pulmonary, and other etiologies. Broadly, the genetic source material for liquid biopsies includes circulating tumor cells, cell-free circulating tumor DNA (ctDNA), or cell-free circulating tumor microRNA (mRNA). In this review, we specifically focus on ctDNA and its current role in colorectal cancer. While there are several commercially available assays that detect ctDNA, the utility of these products is still variable and therefore the clinical applications of ctDNA in the management of patients with cancer has yet to be determined. This is reflected by the recent joint review set forth by the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP), clarifying and somewhat tempering the present role of ctDNA in patients with cancer. This review provides additional detail regarding ctDNA in the limited setting of colorectal cancer. The increasing importance and promise of ctDNA remains an area of active research, and further prospective studies may enhance the clinical utility of ctDNA in the future.

Diagnostic and Prognostic Utility of Serum Receptor-Binding Cancer Antigen Expressed on SiSo Cells (RCAS1) Levels in Colon Cancer Patients

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a human tumor-associated antigen that induces cell-cycle arrest and/or apoptosis in cells bearing the RCAS1 receptor. The aim of the present study was to elucidate the diagnostic and prognostic utility of RCAS1 levels in colon cancer patients. Serum RCAS1 levels were determined using a sandwich enzyme-linked immunosorbent assay in 97 colon cancer patients and 20 healthy individuals. The levels were significantly increased in colon cancer patients compared to healthy individuals (p<0.0001). Increased RCAS1 levels were significantly associated with advanced Dukes’ stage (p=0.0079) and high histopathological tumor grade (p=0.0028). Univariate analysis revealed that colon cancer patients with elevated RCAS1 levels had significantly shorter overall survival times (log-rank test, p=0.027). By multivariate analysis, serum RCAS1 was identified as an independent prognostic factor (Cox regression analysis, p=0.033). In conclusion, colon cancer patients with advanced disease stage and grade and poor prognosis showed elevated serum RCAS1 levels. Assessment of serum RCAS1 levels could therefore be considered as a diagnostic and prognostic marker in colon neoplasia.

Future perspectives of circulating tumor DNA in colorectal cancer

Tumor biopsy is currently the gold standard for diagnosis and in determining cell signaling pathways involved in the development of treatment resistance. However, there are major challenges with this technique, including the need for serial sampling to monitor treatment resistance, which is invasive and also has the potential for selection bias due to intra-tumoral and inter-tumoral heterogeneity. These challenges highlight the need for more effective methods for obtaining Tumor samples. Liquid biopsy analyzes genetic material or tumor cells shed into the blood from the primary tumor and metastatic sites and consequently provides a comprehensive, real-time picture of the tumor burden in an individual patient. Indeed, liquid biopsy has the potential to revolutionize cancer management. Here, we review recent studies on the potential clinical applications of liquid biopsy using circulating tumor DNA in colorectal cancer, including screening, diagnosis, detection of minimal residual disease after surgery, detection of recurrence, prognosis, predicting treatment response, monitoring tumor burden or response during treatment, and tracking resistance. We also discuss recent data demonstrating the utility of detecting KRAS-mutated circulating tumor DNA, both at diagnosis to determine an appropriate treatment strategy and during anti-epidermal growth factor receptor therapy to predict treatment resistance. The future integration of liquid biopsy into clinical practice is discussed, together with alternative approaches and key questions that need to be answered in future clinical studies before this technology can be implemented and used routinely.

Prognostic value of circulating tumor DNA in patients with colon cancer: Systematic review

The application of circulating tumor DNA(ctDNA) represents a non-invasive method for tumor detection. Its prognostic significance in patients with colorectal cancer is controversial. We performed a systematic review of data from published studies to assess the prognostic values of ctDNA in patients with colorectal cancer. We searched Medline, Embase, Web of Science, the Cochrane Library, and Scopus databases to identify eligible studies reporting disease-free survival (DFS) and overall survival (OS) stratified by ctDNA prior to December 6, 2016. We evaluated the quality and design of these studies. A total of 22 studies were eligible for systematic review. Among them, 11 studies investigated the prognostic value of ctDNA on disease-free survival (DFS). Seven of 11 studies showed that ctDNA was an independent variable to estimate the probability of DFS by multivariate analyses. Thirteen studies assessed the relationship between ctDNA and overall survival (OS). Eight of 13 studies showed that ctDNA was an independent predictor of worse OS through the use of multivariate analyses. This analysis provides evidence that ctDNA may be a prognostic biomarker, negatively correlated with the survival of patients with colorectal cancer.

Utility of KRAS mutation detection using circulating cell-free DNA from patients with colorectal cancer

In this study, we evaluated the clinical utility of detecting KRAS mutations in circulating cell-free (ccf)DNA of metastatic colorectal cancer patients. We prospectively recruited 94 metastatic colorectal cancer patients. Circulating cell-free DNA was extracted from plasma samples and analyzed for the presence of seven KRAS point mutations. Using the Invader Plus assay with peptide nucleic acid clamping method and digital PCR, KRAS mutations were detected in the ccfDNA in 35 of 39 patients previously determined to have primary tumors containing KRAS mutations using the Luminex method, and in 5 of 55 patients with tumors containing wild-type KRAS. Curative resection was undertaken in 7 of 34 patients with primary and ccfDNA KRAS mutations, resulting in the disappearance of the mutation from the cell-free DNA in five of seven patients. Three of these patients had tumor recurrence and KRAS mutations in their ccfDNA reappeared. Epidermal growth factor receptor blockade was administered to 24 of the KRAS tumor wild-type patients. Of the 24 patients with wild-type KRAS in their primary tumors, three patients had KRAS mutations in their ccfDNA and did not respond to treatment with epidermal growth factor receptor (EGFR) blockade. We also detected a new KRAS mutation in five patients during chemotherapy with EGFR blockade, before disease progression was detectable with imaging. The detection of KRAS mutations in ccfDNA is an attractive approach for predicting both treatment response and acquired resistance to EGFR blockade, and for detecting disease recurrence.

Circulating DNA and Survival in Solid Tumors

BACKGROUND

The ability to undertake molecular analysis to inform on prognosis and predictors of response to therapy is limited by accessibility of tissue. Measurement of total circulating free DNA (cfDNA) or circulating tumor DNA (ctDNA) in peripheral blood may allow easier access to tumor material and help to predict clinical outcomes.

METHODS

A systematic review of electronic databases identified publications exploring the association between cfDNA or ctDNA and overall survival (OS) in solid tumors. HRs for OS were extracted from multivariable analyses and included in a meta-analysis. Pooled HRs were computed and weighted using generic inverse variance and random-effect modeling. For studies not reporting multivariable analyses, univariable ORs were estimated from Kaplan-Meier curves for OS at 1 and 3 years.

RESULTS

Thirty-nine studies comprising 4,052 patients were included in the analysis. Detection of ctDNA was associated with a significantly worse OS in multivariable analyses [HR, 2.70; 95% confidence interval (CI), 2.02-3.61; P < 0.001). Similar results were observed in the univariable analyses at 3 and 1 year (OR, 4.83; 95% CI, 3.20-7.28; P < 0.001).There was also a statistically significant association between high total cfDNA and worse OS for studies reporting multivariable and univariate data at 3 years (HR, 1.91; 95% CI, 1.59-2.29; P < 0.001 and OR, 2.82; 95% CI, 1.93-4.13; P < 0.001, respectively).

CONCLUSIONS

High levels of total cfDNA and presence of ctDNA are associated with worse survival in solid tumors.

IMPACT

Circulating DNA is associated with worse outcome in solid tumors.

Clinical validation of the detection of KRAS and BRAF mutations from circulating tumor DNA

Assessment of KRAS status is mandatory in patients with metastatic colorectal cancer (mCRC) before applying targeted therapy. We describe here a blinded prospective study to compare KRAS and BRAF mutation status data obtained from the analysis of tumor tissue by routine gold-standard methods and of plasma DNA using a quantitative PCR-based method specifically designed to analyze circulating cell-free DNA (cfDNA). The mutation status was determined by both methods from 106 patient samples. cfDNA analysis showed 100% specificity and sensitivity for the BRAF V600E mutation. For the seven tested KRAS point mutations, the method exhibited 98% specificity and 92% sensitivity with a concordance value of 96%. Mutation load, expressed as the proportion of mutant alleles in cfDNA, was highly variable (0.5-64.1%, median 10.5%) among mutated samples. CfDNA was detected in 100% of patients with mCRC. This study shows that liquid biopsy through cfDNA analysis could advantageously replace tumor-section analysis and expand the scope of personalized medicine for patients with cancer.

CA19-9 level as a prognostic and predictive factor of bevacizumab efficacy in metastatic colorectal cancer patients undergoing oxaliplatin-based chemotherapy

PURPOSE

The prognostic and predictive values of carbohydrate antigen 19-9 (CA19-9) levels in metastatic colorectal cancer (mCRC) remain unclear. We reviewed all mCRC patients at a single institution to evaluate the relationship between CA19-9 levels and survival.

METHODS

Two hundred and fifty-two patients underwent first-line chemotherapy using oxaliplatin-based regimens between April 2005 and December 2009. The relationship between baseline CA19-9 levels and survival was analyzed. Moreover, we evaluated the relationship between baseline CA19-9 levels and clinicopathological factors.

RESULTS

One hundred and fifty patients had elevated baseline CA19-9 levels (elevated group), and 79 patients had normal baseline CA19-9 (normal group) levels. Both KRAS and BRAF mutation rates were higher in the elevated group than in the normal group. Elevated CA19-9 level was a poor prognostic factor compared with normal CA19-9 levels (P = 0.0021). In the elevated group, the median survival time with bevacizumab was significantly longer with bevacizumab than without it (median OS, 27.8 vs. 15.3 months, P = 0.0019). However, the median survival time was not different with or without bevacizumab in the normal group (median OS, 36.5 vs. 38.0 months, P = 0.9515).

CONCLUSION

Our results suggest that baseline CA19-9 level is an independent prognostic factor in mCRC patients, and it correlated with the KRAS/BRAF mutation status. Bevacizumab exhibits clinical activity only for high CA19-9 levels in mCRC.

Monitoring tumor-derived cell-free DNA in patients with solid tumors: clinical perspectives and research opportunities

Circulating cell-free DNA represents a non-invasive biomarker, as it can be isolated from human plasma, serum and other body fluids. Circulating tumor DNA shed from primary and metastatic cancers may allow the non-invasive analysis of the evolution of tumor genomes during treatment and disease progression through 'liquid biopsies'. The serial monitoring of tumor genotypes, which are instable and prone to changes under selection pressure, is becoming increasingly possible. The "liquid biopsy" provide novel biological insights into the process of metastasis and may elucidate signaling pathways involved in cell invasiveness and metastatic competence. This review will focus on the clinical utility of circulating cell free DNA in main solid tumors, including genetic and epigenetic alterations that can be detected.

The clinical utilization of circulating cell free DNA (CCFDNA) in blood of cancer patients

Qualitative and quantitative testing of circulating cell free DNA (CCFDNA) can be applied for the management of malignant and benign neoplasms. Detecting circulating DNA in cancer patients may help develop a DNA profile for early stage diagnosis in malignancies. The technical issues of obtaining, using, and analyzing CCFDNA from blood will be discussed.

Detection of KRAS mutations and their associations with clinicopathological features and survival in Chinese colorectal cancer patients

OBJECTIVE

Mutation of the KRAS (v-Kiras2 Kirsten rat sarcoma viral oncogene homologue) gene plays an important role in colorectal tumorigenesis. This study examined associations between KRAS gene mutations and clinicopathological and survival data in Chinese patients with colorectal cancer (CRC).

METHODS

CRC patients were recruited for the detection of KRAS gene mutations using polymerase chain reaction and DNA sequencing. Data on clinicopathological features and survival times were collected.

RESULTS

The study included 78 CRC patients. The overall mutation frequency of the KRAS gene at codons 12 and 13 was 33.3% (26/78). KRAS gene mutations were significantly associated with poor tumour differentiation and liver metastasis. Patients with the wild-type KRAS gene had significantly higher median survival times than patients with KRAS gene mutations (35.05 months versus 25.72 months). Those with KRAS gene mutations at codons 12 or 13 did not have significantly different median survival times (25.69 months versus 20.67 months, respectively).

CONCLUSIONS

These findings suggest that a high frequency of KRAS gene mutations exists in Chinese patients with CRC, and that such mutations are associated with poor survival, tumour differentiation and liver metastasis in CRC patients.

Prognostic and predictive roles for circulating biomarkers in gastrointestinal cancer

Circulating tumor cells (CTCs) and circulating free DNA (cfDNA) have been studied as promising prognostic and predictive tumor-derived biomarkers in the bloodstream of patients with gastrointestinal malignancies because they may be an alternative noninvasive tool to tumor tissue biopsies. Quantification and molecular characterization of CTCs and cfDNA may provide additional insights into cancer biology, potentially revealing novel targets to individualize cancer care. The present article aims to review the biology and current methods to assess CTCs and cfDNA, and the efforts to establish both tumor-derived biomarkers as prognostic and predictive factors in esophageal, gastric and colorectal cancer.

Cell-free nucleic acids as biomarkers in cancer patients

DNA, mRNA and microRNA are released and circulate in the blood of cancer patients. Changes in the levels of circulating nucleic acids have been associated with tumour burden and malignant progression. In the past decade a wealth of information indicating the potential use of circulating nucleic acids for cancer screening, prognosis and monitoring of the efficacy of anticancer therapies has emerged. In this Review, we discuss these findings with a specific focus on the clinical utility of cell-free nucleic acids as blood biomarkers.

K-RAS mutation in the screening, prognosis and treatment of cancer

The potential use of K-RAS mutation as a cancer screening biomarker has been investigated for many years. Numerous associations between K-RAS mutation and various cancers have been established, but these associations have not been translated into effective, cost-efficient cancer screening strategies. This lack of progress may be due to the existence of K-RAS mutation in nontumor tissues and/or using detection, rather than quantitation, of K-RAS mutation as the endpoint for cancer risk categorization. K-RAS mutation appears to be a useful prognostic biomarker for colon cancer. Recent progress toward sensitive and quantitative mutation characterization and the successful use of K-RAS mutation in a personalized medicine approach to targeted biological therapy selection are likely to re-direct and expand the use of K-RAS mutation as a cancer biomarker in the near future.

Prognostic value of circulating mutant DNA in unresectable metastatic colorectal cancer

OBJECTIVE

No validated biologic prognostic marker is presently available in metastatic colorectal cancer (MCRC). We prospectively evaluated the prognostic value of circulating mutant DNA in 31 patients presenting an unresectable MCRC treated by chemotherapy, and we used, as tumor markers, KRAS mutations and methylation of the RASSF2A promoter.

METHODS

Detection in the serum of KRAS mutation and RASSF2A methylation were performed using sensitive methods, respectively, real-time polymerase chain reaction (PCR) performed in the presence of a peptide nucleic acid specific of the wild-type sequence and methyl-specific PCR after bisulfite treatment.

RESULTS

Among 29 MCRC patients for whom DNA from the primary tumor was available, 23 (79%) presented at least one of the markers in their primary tumor, and 12 of them presented the same alteration in serum. For the 2 remaining patients, RASSF2A methylation was detected in serum indicating that this alteration was present in the primary tumor. These 14 patients with a detectable tumor marker in their serum were designed sDNA+ patients. After 6 months of follow-up, 11/14 (79%) sDNA+ and 1/11 (9%) sDNA- patients presented a progressive disease (P = 0.001). The median progression free survival was 5 months in sDNA+ patients versus 14 months in sDNA- patients (P = 0.004). After 1 year of follow-up, 2 of 14 (14%) sDNA+ and 8 of 11 (73%) sDNA- patients presented no signs of disease progression (P = 0.005).

CONCLUSIONS

This study suggests that the presence of circulating mutant DNA in unresectable MCRC patients, which can be detected using simple methods such as methylation-specific PCR or real-time PCR, is highly predictive of clinical outcome.