Improvement of oligonucleotide separation using a repetto high-performance liquid chromatography recycling approach.

A new approach for the improvement of separation of oligonucleotides by recycling ion-pairing chromatography is described. In the so-called repetto process, segments of separated compounds are sequentially returned to the inlet for multiple passages through the column without a need to pass a pump and with the possibility of detecting the level of separation between individual passages. Unlike in the recently described twin-column recycle approach in which eluents are repeatedly transferred between two separation columns, with the repetto method a single column is sufficient, and the detector is not exposed to high back pressure. The repetto principle was used for the separation of synthetic oligonucleotides, resulting in a multi-fold improvement in single nt resolution of long (> 50 nt) synthetic oligonucleotide fragments with high gas chromatography (guanine-cytosine) content > 40% and their separation from impurities of the original synthesis.

Capillary electrophoresis, a method for the determination of nucleic acid ligands covalently attached to quantum dots representing a donor of Förster resonance energy transfer.

The synthesis and determination of the structure of a Förster resonance energy transfer probe intended for the detection of specific nucleic acid sequences are described here. The probe is based on the hybridization of oligonucleotide modified quantum dots with a fluorescently labeled nucleic acid sample resulting in changes of the fluorescence emission due to the energy transfer effect. The stoichiometry distribution of oligonucleotides conjugated to quantum dots was determined by capillary electrophoresis separation. The results indicate that one to four molecules of oligonucleotide are conjugated to the surface of a single nanoparticle. This conclusion is confirmed by the course of the dependence of Förster resonance energy transfer efficiency on the concentration of fluorescently labeled complementary single-stranded nucleic acid, showing saturation. While the energy transfer efficiency of the probe hybridized with complementary nucleic acid strands was 30%, negligible efficiency was observed with a noncomplementary strand.

Application of denaturing capillary electrophoresis for the detection of prognostic mutations in isocitrate dehydrogenase 1 and isocitrate dehydrogenase 2 genes in brain tumors.

Malignant transformation in gliomas is frequently supplemented by somatic mutations in isocitrate dehydrogenase 1 and isocitrate dehydrogenase 2 genes. It has recently emerged that mutations in these genes are associated with prolonged survival and should be used as prognostic factor in management of brain cancer patients. There are several approaches in use for the detection of isocitrate dehydrogenase 1 and 2 mutations; however, these often exhibit shortcomings such as convoluted protocols with long processing time, complex (and costly) dedicated fluorescent probes, and/or demand on amounts of input DNA. Therefore, a simple and rapid method would be highly desired. Here, we present development and validation of simple and reliable isocitrate dehydrogenase 1 and 2 mutation detection assay using denaturing capillary electrophoresis. The detection sensitivity in terms of the limiting mutated allele fraction detectable estimated from a series of dilution runs was 2.9%. The method was validated by comparing to results obtained by a widely accepted detection technique, the multiplex ligation-dependent probe amplification, on a set of 85 brain tumors. The concordance of both methods was 100%, but denaturing capillary electrophoresis assay required fivefold lower input of DNA (1 versus 5 µL of DNA at concentrations typically between 10 and 30 ng/µL).

[Patient with Three EGFR Mutations - Gradual Development of Resistance to Previous Targeted Treatment]. / Pacientka se tremi EGFR mutacemi - postupný rozvoj rezistence na predchozí cílenou lécbu.

BACKGROUND: Patients with sensitive EGFR mutations are already being treated with first and second generation tyrosine kinase inhibitors (TKIs). However, resistance to these drugs occurs over time, and over half of all cases is caused by a mutation (T790M) in the EGFR kinase domain. Osimertinib offers a new treatment option that overcomes this problem. Unfortunately, resistance to this drug also develops after several months of treatment and is caused by another mutation (C797S) in EGFR. CASE REPORT: Our case report provides evidence for the progressive development of EGFR-TKI resistance in a patient with a deletion of exon 19 in the EGFR gene. First, based on a mutation (T790M) identified after afatinib treatment and a subsequent mutation (C797S) mutation identified after osimertinib treatment. We mention overcoming this resistance (C797S) mutation by using 4th generation EGFR-TKI and other alternative procedures (chemotherapy, immunotherapy, and combinations of older EGFR-TKI generations). We also mention a rare case of peritoneal metastasis that occurred after previous treatment with osimertinib that we attempted to ameliorate by using erlotinib because the impaired condition of the patient did not allow treatment by chemotherapy. There are documented cases in which erlotinib has been successfully given to patients with peritoneal metastases and patients with the EGFR mutation C797S following progression to afatinib. This was not the case in our patient, probably because of the remaining EGFR mutation T790M. CONCLUSION: In our case report, erlotinib did not show efficacy after progression to osimetinib. Nowadays, chemotherapy is the only possible treatment in patients with good a performance status. The next-generation of TKIs are undergoing promising developments.Key words: EGFR - deletion on exon 19 - mutation T790M - mutation C797S - afatinib - osimertinibSubmitted: 12. 9. 2017Accepted: 12. 10. 2017 This project was supported by grant AZV 17-30 748A. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.

The first European family with gastric adenocarcinoma and proximal polyposis of the stomach: case report and review of the literature.

BACKGROUND AND AIMS: Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) has to date been recognized in only 8 families worldwide. Recently, different point mutations within the Ying Yang 1 (YY1) binding motif in promoter 1B of the APC gene were assigned as causal in 6 families with GAPPS. METHODS: We diagnosed GAPPS across 3 generations in a Czech white family. RESULTS: The proband's mother died of gastric cancer at 49 years of age. The proband died of gastric cancer at 56 years of age. All 3 of the proband's daughters inherited polyposis, involving exclusively the gastric fundus and body, with relative sparing of the lesser curve. The daughters have all been regularly surveyed endoscopically. Polyposis progressed rapidly with intestinal differentiated low-grade and high-grade dysplasia present on polypectomy specimens 5 years after the original diagnosis. On this basis, all 3 of the proband's daughters were scheduled for prophylactic total gastrectomy. Unfortunately, the middle daughter presented with generalized gastric adenocarcinoma and died at the age of 26 years. The other 2 daughters (aged 30 and 23 years) underwent total gastrectomy within 6 weeks of their sister's death; histology of surgical specimens showed gastric adenocarcinoma stage IA (pT1a, N0, M0) in both cases. Bi-directional Sanger sequencing of promoter 1B revealed a point mutation (c.-191 T>C) in all 3 daughters of the proband. CONCLUSIONS: Atypical endoscopic progression of the fundic gland polyposis, with the presence of dysplasia on polypectomy specimens and genetic testing with recently discovered mutations in promoter 1B of the APC gene might help clinicians to decide whether prophylactic gastrectomy should be performed.

[KRAS mutation assay on EUS-FNA specimens from pacients with pancreatic mass]. / Vysetrení mutace KRAS v EUS-FNA preparátech pacientu s tumorem pankreatu.

Differential diagnosis of solid pancreatic masses using EUS FNA is in 1015 % of cases still challenging. Promising method, which helps to distinguish between chronic pancreatitis and cancer, is point mutations of the proto-oncogene KRAS test. This method is not established in routine clinical practice yet.Objectives were the determination of the sensitivity of the KRAS assay using various kinds of samples of patients with pancreatic mass and testing the effect of the presence of KRAS mutations on the prognosis of survival. 147 patients underwent EUS-FNA examination of pancreatic mass, accompanied by blood sampling with subsequent separation of plasma for the detection of circulating tumor DNA. Part of biopsy sample was left native in a stabilizing solution and part as cytological smear. Samples (native aspirates, cytological smears, plasma) were examined for the presence of KRAS mutation by heteroduplex analysis, denaturing capillary electrophoresis.Among 147 patients with pancreatic masses, 118 were diagnosed as a cancer, 26 chronic pancreatitis, 3 neuroendocrine tumor. In total 147 native aspirates, 118 cytological smears and 94 plasma samples were examined. The highest sensitivity of KRAS mutation was reached in the group of pancreatic cancer patients using cytology, in which 90 % of KRAS mutation was detected (106/118 of the samples). When using the native cellular aspirates, mutation was detected in 78 % (92/118 samples), and examination of plasma was positive in 27 % (24/90 samples). In four patients with chronic pancreatitis KRAS mutations was detected, although none has been cytologically confirmed as a cancer. Two of these four patients were confirmed in the course of the disease as a cancer, one patient died because of alcoholic delirium and the last one was indicated for surgery recently.Examination of KRAS mutations can be performed in all patients undergoing EUS-FNA, with the cytology being the most reliable type of sample for genetic tests. KRAS examination would be reasonable to introduce into routine clinical practice in a group of patients with unclear differential diagnosis of chronic pancreatitis, especially in those with suspicion of cancer in inflammatory terrain.Kexwords: pancreatic cancer, chronic pancreatitis, KRAS mutation , EUS-FNA.

Statins augment efficacy of EGFR-TKIs in patients with advanced-stage non-small cell lung cancer harbouring KRAS mutation.

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) represent novel effective agents approved for the treatment of patients with advanced-stage NSCLC. KRAS mutations have been reported as a negative prognostic and predictive factor in patients with NSCLC treated with EGFR-TKIs. Several studies have recently shown that statins can block tumour cell growth, invasion and metastatic potential. We analysed clinical data of 67 patients with locally advanced (IIIB) or metastatic stage (IV) NSCLC harbouring Kirsten rat sarcoma viral oncogene (KRAS) mutation treated with erlotinib or gefitinib. Twelve patients were treated with combination of EGFR-TKI and statin and 55 patients were treated with EGFR-TKI alone. Comparison of patients' survival (progression-free survival (PFS) and overall survival (OS)) according to the treatment used was performed using the Gehan-Wilcoxon test. The median of PFS and OS for patients treated with EGFR-TKI alone was 1.0 and 5.4 months compared to 2.0 and 14.0 months for patients treated with combination of EGFR-TKI and statin (p = 0.025, p = 0.130). In conclusion, the study results suggest significant improvement of PFS for patients treated with combination of statin and EGFR-TKI, and the difference in OS was not significant.

High serum level of C-reactive protein is associated with worse outcome of patients with advanced-stage NSCLC treated with erlotinib.

Erlotinib is a low molecular weight tyrosine kinase inhibitor (TKI) directed at epidermal growth factor receptor (EGFR), widely used in the treatment of locally advanced or metastatic-stage non-small cell lung cancer (NSCLC). Although introduction of EGFR-TKIs have significantly extended survival of advanced-stage NSCLC patients, their efficacy in the entire patient population is relatively low. Aside from activating EGFR mutations, no reliable biochemical or molecular predictors of response to erlotinib have been established. The aim of our retrospective study was to evaluate the association of baseline serum levels of C-reactive protein (CRP) with outcomes in patients with advanced-stage NSCLC treated with erlotinib. We retrospectively analyzed clinical data of 595 patients with advanced-stage NSCLC (IIIB or IV) treated with erlotinib. Serum CRP was measured using an immunoturbidimetric method. High baseline levels of CRP (≥10 mg/l) were measured in 387 (65 %) patients, and normal levels (<10 mg/l) were measured in 208 (35 %) patients. The median progression-free survival (PFS) and overall survival (OS) for patients with high CRP was 1.8 and 7.7 compared to 2.8 and 14.4 months for patients with low CRP (p < 0.001 and p < 0.001). The multivariable Cox proportional hazards model revealed that CRP was significantly associated with PFS and also with OS (hazard ratio (HR) = 1.57, p < 0.001, and HR = 1.63, p < 0.001, respectively). In conclusion, the results of the conducted retrospective study suggest that high baseline level of CRP was independently associated with worse outcome of patients with advanced-stage NSCLC treated with erlotinib. CRP is a commonly used biomarker which is simple and easy to detect, and thus, it is feasible for the use in the routine clinical practice.

Variants in miRNA regulating cardiac growth are not a common cause of hypertrophic cardiomyopathy.

OBJECTIVES: A substantial proportion of patients with hypertrophic cardiomyopathy (HCM) do not have causative mutations in the genes for heart sarcomere. The purpose of this study was to evaluate the association between microRNA (miRNA) sequence variants and HCM. METHODS: We performed genetic testing on 56 HCM patients who had previously been found to be negative for mutations in the 4 major genes for sarcomeric proteins. The coding and adjacent regions (120-220 nt) of selected miRNAs were analyzed for the presence of sequence variants. The testing was based on PCR amplification of DNA-encoding miRNAs and subsequent denaturing capillary electrophoresis. RESULTS: A total of 3 different variants were detected in the 11 selected miRNAs. These included polymorphisms rs45489294 in miRNA 208b, rs13136737 in miRNA 367 and rs9989532 in miRNA 1-2. In the patient group, the most frequent polymorphism was in miRNA 208b (10 times) followed by miRNA 367 (7 times). Both polymorphisms were found to occur with similar frequencies in the group of healthy controls. The remaining detected variant was not present in the control group, but was not connected with the HCM phenotype in the children of the probands. CONCLUSION: Sequence variants in miRNAs of patients with HCM are not frequent and the contribution of these variants to the development of this disease was not demonstrated.

Lack of association between clopidogrel responsiveness tested using point-of-care assay and prognosis of patients with coronary artery disease.

Dual antiplatelet therapy is important treatment modality across the spectrum of coronary artery disease manifestations. However, a significant number of patients do not have a completely effective response to clopidogrel. This study assessed the impact of response after clopidogrel with Verify Now device on prognosis on patients undergoing coronary interventions. Consecutive patients following percutaneous coronary intervention were prospectively enrolled. A loading dose of 600 mg of clopidogrel was administered before or during PCI. Blood samples were drawn within 24 h after clopidogrel administration. The effect of clopidogrel was measured using VerifyNow. All patients were evaluated at 6 months. The primary end-point was the combination of death, MI and stroke. 378 patients (69.3 % men and 30.7 % women) were enrolled. The mean age was 67.2 ± 12.8 years, BMI 28.9 ± 17.7, and 116 patients had diabetes (30.7 %). During the 6-months follow-up 30 patients (7.94 %) experienced a monitored end-point: 12 patients (3.17 %) had MI; five patients (1.32 %) strokes and 15 patients (3.97 %) died. The remaining 248 patients (71.26 %) were end-point free. Factors associated with a poor prognosis were: leukocytes (OR 1.7 [1.2-2.4], p < 0.01), creatinine (OR 1.4 [1.1-2.5], p < 0.05) and at a borderline level the presence of AA allele of gene CYP2C19*2 (OR 2.5 [0.99-4.1], p = 0.052). The results using VerifyNow were similar between both groups (Group End-point: 208.5 ± 85.5, group No end-point 203.1 ± 91.3) and failed to show any prognostic value (OR 1.00 [0.992-1.007], p = 0.9). The measurement of clopidogrel efficacy using VerifyNow had no prognostic value for our unselected cohort of patients after PCI.

Circulating Tumor DNA correlates with Lactate Dehydrogenase, CYFRA 21-1, and CRP levels in patients with advanced NSCLC.

Purpose: To investigate potential association between selected tumor markers and laboratory parameters (lactate dehydrogenase [LDH], neutrophils, hemoglobin, neutrophils, lymphocytes, C-reactive protein, albumin, carcinoembryonic antigen, and cytokeratin 19 fragment 21-1 [CYFRA 21-1]) and circulating tumor DNA (ctDNA) with survival in patients with advanced non-small cell lung cancer (NSCLC). Patients and Methods: The study encompassed 82 patients from a single center. All patients had (localy-) advanced adenocarcinomas. ctDNA was determined before starting therapy and at 6 weeks follow-up. Laboratory parameters were measured before each cycle of therapy and oncomarkers before starting the therapy as standard clinical practice. Mann-Whitney U test, Cox proportional hazards model, Fisher's exact test, and Kaplan-Meier survival estimation with Gehan-Wilcoxon test were used for statistical analysis of the corresponding variables. Results: We have confirmed predictive or prognostic significance for some of the selected laboratory markers and oncomarkers. Above all, we demonstrate a significant relationship between the levels of LDH and the oncomarker CYFRA 21-1 and the presence or absence of ctDNA at the time of diagnosis. We also demonstrate significantly lower CRP levels in patients within whom the ctDNA disappeared during treatment. A similar but statistically insignificant trend was observed for LDH. Conclusions: CYFRA 21-1, LDH and probably CRP correlate with ctDNA levels in NSCLC. Repeated measurement of these markers could thus help in early detection of disease progression in the same way as does ctDNA monitoring.

Rapid testing of clopidogrel resistance by genotyping of CYP2C19 and CYP2C9 polymorphisms using denaturing on-chip capillary electrophoresis.

Antiplatelet therapy is a cornerstone of cardiovascular treatment in patients with coronary artery disease and after myocardial infarction. Clopidogrel has become a popular antiplatelet agent due to its fast action and low frequency of adverse effects. Kinetics of clopidogrel metabolism is driven by enzymatic activity of the Cytochrome P450 system. Genotyping of CYP2C19 and CYP2C9 polymorphisms allows to identify slow metabolizers showing resistance to clopidogrel therapy. Today, a number of PCR-based techniques for single nucleotide polymorphism genotyping directed at clopidogrel resistance polymorphisms are in use. Here, we describe a new alternative genotyping approach combining the separation power of denaturing capillary electrophoresis with the analysis speed and ease of use of Bioanalyzer chipCE platform. Using an upgraded heater control, we present an optimization for allele separation of CYP2C19 I331V, CYP2C9 R144C, and CYP2C9 I359L polymorphisms employing run temperatures of up to 55°C. We demonstrate rapid and accessible approach to reproducible clopidogrel resistance with feasibility and low cost.

Spectrum and clinical manifestations of mutations in genes responsible for hypertrophic cardiomyopathy.

INTRODUCTION: Hypertrophic cardiomyopathy (HCM) is a cardiovascular disease with autosomal dominant inheritance. It is caused by mutations in the genes coding for structural and/or regulatory proteins found in the sarcomere of cardiomyocytes. A group of genes, including the heavy chain of beta-myosin (MYH7), myosin binding protein C (MYBPC3), cardiac troponin I (TNNI3) and cardiac troponin T (TNNT2) are frequently affected by causal mutations. While exact mutation frequency data has been obtained for various populations, no screening has been reported for Central European populations. PATIENTS AND METHODS: We performed a complete sequencing of MYH7, MYBPC3, TNNI3 and TNNT2 genes in 100 HCM patients. RESULTS: We discovered mutations in a total of 40 patients (40%), including 4 patients with double mutations. A total of 35 different mutation types were detected, of which 17 were novel. The contributions from individual genes were: 24 mutations in MYBPC3 (54.5%), 14 in MYH7 (31.8%), 4 in TNNI3 (9%) and 2 mutations in TNNT2 (4.5%). We have observed a wide variability in disease manifestation across the different genes/mutation types. In addition, we have discovered differences in both frequency and distribution of mutations of the two most common genes (MYBPC3 and MYH7) compared to other populations. CONCLUSION: The most common gene responsible for HCM in our study population was MYBPC3, followed by MYH7, TNNI3 and TNNT2. Phenotypic heterogeneity, as well as the dissimilarity to other populations, prevents effective use of a pre-screening test, which would be directed at the most common mutation hotspots, in our population.

Detection and Quantification of ctDNA for Longitudinal Monitoring of Treatment in Non-Small Cell Lung Cancer Patients Using a Universal Mutant Detection Assay by Denaturing Capillary Electrophoresis.

Background: Observation of anticancer therapy effect by monitoring of minimal residual disease (MRD) is becoming an important tool in management of non-small cell lung cancer (NSCLC). The approach is based on periodic detection and quantification of tumor-specific somatic DNA mutation in circulating tumor DNA (ctDNA) extracted from patient plasma. For such repetitive testing, complex liquid-biopsy techniques relying on ultra-deep NGS sequencing are impractical. There are other, cost-effective, methods for ctDNA analysis, typically based on quantitative PCR or digital PCR, which are applicable for detecting specific individual mutations in hotspots. While such methods are routinely used in NSCLC therapy prediction, however, extension to cover broader spectrum of mutations (e.g., in tumor suppressor genes) is required for universal longitudinal MRD monitoring. Methods: For a set of tissue samples from 81 NSCLC patients we have applied a denaturing capillary electrophoresis (DCE) for initial detection of somatic mutations within 8 predesigned PCR amplicons covering oncogenes and tumor suppressor genes. Mutation-negative samples were then subjected to a large panel NGS sequencing. For each patient mutation found in tissue was then traced over time in ctDNA by DCE. Results: In total we have detected a somatic mutation in tissue of 63 patients. For those we have then prospectively analyzed ctDNA from collected plasma samples over a period of up to 2 years. The dynamics of ctDNA during the initial chemotherapy therapy cycles as well as in the long-term follow-up matched the clinically observed response. Conclusion: Detection and quantification of tumor-specific mutations in ctDNA represents a viable complement to MRD monitoring during therapy of NSCLC patients. The presented approach relying on initial tissue mutation detection by DCE combined with NGS and a subsequent ctDNA mutation testing by DCE only represents a cost-effective approach for its routine implementation.

Somatic Mutations in Exon 7 of the TP53 Gene in Index Colorectal Lesions Are Associated with the Early Occurrence of Metachronous Adenoma.

(1) Background: this prospective study was focused on detailed analysis of the mutation heterogeneity in colorectal lesions removed during baseline (index) colonoscopy to identify patients at high risk of early occurrence of metachronous adenomas. (2) Methods: a total of 120 patients after endoscopic therapy of advanced colorectal neoplasia size ≥10 mm (index lesion) with subsequent surveillance colonoscopy after 10-18 months were included. In total, 143 index lesions and 84 synchronous lesions in paraffin blocks were divided into up to 30 samples. In each of them, the detection of somatic mutations in 11 hot spot gene loci was performed. Statistical analysis to correlate the mutation profiles and the degree of heterogeneity of the lesions with the risk of metachronous adenoma occurrence was undertaken. (3) Results: mutation in exon 7 of the TP53 gene found in the index lesion significantly correlated with the early occurrence of metachronous adenoma (log-rank test p = 0.003, hazard ratio 2.73, 95% confidence interval 1.14-6.56). We did not find an association between the risk of metachronous adenomas and other markers monitored. (4) Conclusions: the findings of this study could lead to an adjustment of existing recommendations for surveillance colonoscopies in a specific group of patients with mutations in exon 7 of the TP53 gene in an index lesion, where a shortening of surveillance interval may be warranted.

Combination of Circulating Tumour DNA and 18F-FDG PET/CT for Precision Monitoring of Therapy Response in Patients With Advanced Non-small Cell Lung Cancer: A Prospective Study.

BACKGROUND/AIM: Circulating tumour DNA (ctDNA) represents an emerging biomarker in non-small cell lung cancer (NSCLC). We focused on the combination of ctDNA and positron emission tomography/computed tomography (PET/CT) in the follow-up monitoring of advanced-stage NSCLC patients treated with chemotherapy. PATIENTS AND METHODS: Eighty-four patients were enrolled in this study. 18F-fluorodeoxyglucose PET/CT and ctDNA assessments were performed at baseline and after two cycles of chemotherapy (follow-up). RESULTS: There was a correlation of ctDNA with metabolic tumour volume (MTV), total lesion glycolysis (TLG), and iodine concentration (IC) at baseline (p=0.001, p=0.001, p=0.003) and at follow-up (p=0.006, p=0.002, p=0.001). The objective response was associated with follow-up ctDNA (p<0.001) and the change of all PET/CT parameters. ROC analyses showed that the combination of follow-up ctDNA with changes in SUVmax is very promising for the estimation of objective response and progression-free survival. CONCLUSION: The combination of ctDNA assessment with PET/CT is a promising approach for the follow-up monitoring of therapy response and prognosis estimation of advanced-stage NSCLC patients.

A novel high-resolution chipCE assay for rapid detection of EGFR gene mutations and amplifications in lung cancer therapy by a combination of fragment analysis, denaturing CE and MLPA.

There is a growing interest in evaluating molecular markers as predictors of response to new generation of targeted cancer therapies. One of such areas is biological therapy targeting epidermal growth factor receptor gene (EGFR) in lung cancer. The testing of tumor tissue is focused on specific EGFR mutations and EGFR gene amplification, since tumors exhibiting positivity of either of the two marker types are highly sensitive towards the treatment. Although traditional methods of DNA sequencing and fluorescence in situ hybridization are still in use for the detection of EGFR mutations and gene amplification, respectively, there is a need for new dedicated techniques with the primary emphasis on simplicity, sensitivity, speed and cost effectiveness. The main purpose of this work was to integrate diverse assays for both EGFR tests onto a single platform to eliminate the need for different instruments and separate processing. We demonstrate a chip capillary electrophoresis (chipCE) application for EGFR mutation detection by a combination of fragment analysis and denaturing CE along with multiplex ligation-dependent probe amplification (MLPA) for evaluation of EGFR amplification. All separations are carried out in denaturing sieving polymer on a modified Bioanalyzer 2100 chipCE instrument running at temperatures of up to 65°C. The main strength of the resulting high-resolution chipCE application is in its simplicity, speed of analysis and minimal amount of sample required for complete testing of EGFR status. Such an approach could potentially fit medium throughput laboratories providing molecular pathology services for clinical oncologists with fast turnaround times and limited consumption of tissue material.

Denaturing capillary electrophoresis for automated detection of L858R mutation in exon 21 of the epidermal growth factor receptor gene in prediction of the outcome of lung cancer therapy.

The presence of activating mutations within the tyrosine kinase domain of the epidermal growth factor receptor gene has been attributed to a positive response to biological therapy of lung cancer by small-molecular tyrosine kinase inhibitors, gefitinib and erlotinib. Among the two most significant mutation types are deletions in exon 19 and a single point substitution in exon 21 (termed L858R). The exon 19 deletions can readily be examined by fragment analysis, due to the characteristic length difference between the normal and mutated PCR product. Analysis of the L858R point mutation, however, presents a greater challenge. The current paper is aimed at developing a sensitive, yet simple, low-cost mutation detection assay directed at the L858R mutation using a method based on CE of heteroduplexes under partial denaturing conditions. We perform optimization of separation conditions on different commercial instruments including ones equipped with 8, 16 and 96 capillaries. We present normalized migration reproducibility in the range from 1 (8 and 16) to 5% (96) RSD. A reliable distinction of the R836R silent polymorphism from a potential presence of the L858R mutation is also demonstrated. In its implementation, the presented assay is just another application running on a conventional CE platform without the need of dedicated instrumentation.

Comparison of Native Aspirates and Cytological Smears Obtained by EUS-Guided Biopsies for Effective DNA/RNA Marker Testing in Pancreatic Cancer.

We compare two types of pancreatic carcinoma samples obtained by EUS-guided fine needle biopsy (EUS-FNB) in terms of the success rates and clinical validity of analysis of two most commonly investigated DNA/RNA pancreatic cancer markers, KRAS mutations and miR-21 expression. 118 patients with pancreatic ductal adenocarcinoma underwent EUS-FNB. The collected sample was divided, one part was stored in a stabilizing solution as native aspirate (EUS-FNA) and second part was processed into the cytological smear (EUS-FNC). DNA/RNA extraction was followed by analysis of KRAS mutations and miR-21 expression. For both sample types, the yields of DNA/RNA extraction and success rates of KRAS mutation and miRNA expression were evaluated. Finally, the resulting KRAS mutation frequency and miR-21 prognostic role were compared to literature data from tissue resections. The overall amount of isolated DNA/RNA from EUS-FNC was lower compared to the EUS-FNA, average yield 10 ng vs 147 ng for DNA and average yield 164 vs. 642 ng for RNA, but the success rates for KRAS and miR-21 analysis was 100% for both sample types. The KRAS-mutant detection frequency in EUS-FNC was 12% higher than in EUS-FNA (90 vs 78%). The prognostic role of miR-21 was confirmed in EUS-FNC (p = 0.02), but did not reach statistical significance in EUS-FNA (p = 0.06). Although both types of EUS-FNB samples are suitable for DNA/RNA extraction and subsequent DNA mutation and miRNA expression analysis, reliable results with clinical validity were only obtained for EUS-FNC.

Monitoring of Early Changes of Circulating Tumor DNA in the Plasma of Rectal Cancer Patients Receiving Neoadjuvant Concomitant Chemoradiotherapy: Evaluation for Prognosis and Prediction of Therapeutic Response.

Introduction: Patients with locally advanced rectal cancer (LARC) are undergoing neoadjuvant chemoradiotherapy (NCRT) prior to surgery. Although in some patients the NCRT is known to prevent local recurrence, it is also accompanied by side effects. Accordingly, there is an unmet need to identify predictive markers allowing to identify non-responders to avoid its adverse effects. We monitored circulating tumor DNA (ctDNA) as a potential liquid biopsy-based biomarker. We have investigated ctDNA changes plasma during the early days of NCRT and its relationship to the overall therapy outcome. Methods and Patients: The studied cohort included 36 LARC patients (stage II or III) undergoing NCRT with subsequent surgical treatment. We have detected somatic mutations in tissue biopsies taken during endoscopic examination prior to the therapy. CtDNA was extracted from patient plasma samples prior to therapy and at the end of the first week. In order to optimize the analytical costs of liquid-biopsy testing, we have utilized a two-level approach in which first a low-cost detection method of denaturing capillary electrophoresis was used followed by examination of initially negative samples by a high-sensitivity BEAMING assay. The ctDNA was related to clinical parameters including tumor regression grade (TRG) and TNM tumor staging. Results: We have detected a somatic mutation in 33 out of 36 patients (91.7%). Seven patients (7/33, 21.2%) had ctDNA present prior to therapy. The ctDNA positivity before treatment reduced post-operative disease-free survival and overall survival by an average of 1.47 and 1.41 years, respectively (p = 0.015, and p = 0.010). In all patients, ctDNA was strongly reduced or completely eliminated from plasma by the end of the first week of NCRT, with no correlation to any of the parameters analyzed. Conclusions: The baseline ctDNA presence represented a statistically significant negative prognostic biomarker for the overall patient survival. As ctDNA was reduced indiscriminately from circulation of all patients, dynamics during the first week of NCRT is not suited for predicting the outcome of LARC. However, the general effect of rapid ctDNA disappearance apparently occurring during the initial days of NCRT is noteworthy and should further be studied.