Digital next-generation sequencing of cell-free DNA for pancreatic cancer

Detection of the BRAFV600E Mutation in Circulating Free Nucleic Acids as a Biomarker of Thyroid Cancer: A Review

Background: Liquid biopsy is a method that could potentially improve the management of thyroid cancer (TC) by enabling the detection of circulating tumor DNA and RNA (ctDNA, ctRNA). The BRAFV600E mutation appears to be the most representative example of a biomarker in liquid biopsy, as it is the most specific mutation for TC and a target for molecular therapeutics. The aim of this review is to summarize the available data on the detection of the BRAFV600E mutation in liquid biopsy in patients with TC. Methods: A comprehensive analysis of the available literature on the detection of the BRAFV600E mutation in liquid biopsy in TC was performed. Thirty-three papers meeting the inclusion criteria were selected after full-text evaluation. Results: Eleven papers discussed correlations between BRAF mutation and clinicopathological characteristics. Nine studies tested the utility of BRAFV600E detection in the assessment of residual or recurrent disease. Seven studies investigated BRAF-mutated circulating tumor nucleic acids (ctNA) as a marker of response to targeted therapy. In seven studies the method did not detect the BRAFV600E mutation. Conclusions: This review shows the potential of BRAFV600E-mutated ctNA detection in monitoring disease progression, particularly in advanced TC. The diagnostic value of BRAFV600E-mutated ctNA detection appears to be limited to advanced TC. The choice of the molecular method (quantitative PCR [qPCR], droplet digital polymerase chain reaction [ddPCR], and next-generation sequencing [NGS]) should be made based on the turnaround time, sensitivity of the test, and the clinical indications. Despite the promising outcomes of some studies, there is a need to verify these results on larger cohorts and to unify the molecular methods.

Impact of Smad4 and p53 mutations on the prognosis of patients with pancreatic ductal adenocarcinoma undergoing chemotherapy

BACKGROUND

This prospective cohort study evaluated the feasibility of using endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) samples for comprehensive mutational analysis of cancer-related genes using microtissues.

METHODS

Fifty patients with suspected pancreatic cancer presenting consecutively at the Kindai University Hospital between January 2018 and January 2019 were enrolled. Cancerous tissues from EUS-FNB were obtained from each tumor and subjected to histological examination and mutational analysis. The primary endpoint was the collection rate of EUS-FNB specimens suitable for comprehensive cancer panels using deep sequencing. Clinical history and genetic variations between the disease control and progressive disease groups of patients on chemotherapy were evaluated as secondary endpoints.

RESULTS

The collection rate of EUS-FNB specimens suitable for comprehensive cancer panels using deep sequencing was 93.6%. The cancer panel was sequenced for 25 patients with pancreatic cancer treated initially with systemic chemotherapy. Mutation in p53 and Smad4 were positively and negatively associated, respectively, with disease control at the initial evaluation. The median time to progression in 15 patients with p53 and without Smad4 mutations was 182.0 days; whereas, it was 92.5 days in other 10 patients; this difference was significant (p = 0.020).

CONCLUSIONS

Tissue samples from EUS-FNB were suitable for mutational analysis. Pancreatic cancers with p53 and without Smad4 mutations responded better to chemotherapy and had a better prognosis than those others.

Molecular assessment of endoscopically collected pancreatic juice and duodenal fluid from patients with pancreatic diseases

One concern associated with pancreatic diseases is the poor prognosis of pancreatic cancer. Even with advances in diagnostic modalities, risk stratification of premalignant lesions and differentiation of pancreatic cysts are challenging. Pancreatic lesions of concern include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystadenomas, pseudocysts, and retention cysts, as well as cystic degeneration of solid tumors such as solid pseudopapillary neoplasms and pancreatic neuroendocrine neoplasms. Pancreatic juice obtained during endoscopic retrograde cholangiopancreatography has previously been used for the detection of KRAS mutation. Recently, duodenal fluid, which can be obtained during the relatively minimally invasive procedures of endoscopic ultrasound (EUS) and esophagogastroduodenoscopy, and cyst fluid collected by EUS-guided fine-needle aspiration (FNA) were used for molecular biological analysis. Furthermore, advanced analytic methods with high sensitivity were used for the detection of single and multiple markers. Early detection of malignant pancreatic tumors and risk stratification of premalignant tumors can be performed using duodenal fluid samples with a single marker with high sensitivity. Technological advances in simultaneous detection of multiple markers allow for the differentiation of cystic pancreatic tumors. One thing to note is that the clinical guidelines do not recommend pancreatic cyst fluid and pancreatic juice (PJ) sampling by EUS-FNA and endoscopic retrograde cholangiopancreatography, respectively, in actual clinical practice, but state that they be performed at experienced facilities, and duodenal fluid sampling is not mentioned in the guidelines. With improved specimen handling and the combination of markers, molecular markers in PJ samples may be used in clinical practice in the near future.

Rapid Multiplex Strip Test for the Detection of Circulating Tumor DNA Mutations for Liquid Biopsy Applications

In the era of personalized medicine, molecular profiling of patient tumors has become the standard practice, especially for patients with advanced disease. Activating point mutations of the KRAS proto-oncogene are clinically relevant for many types of cancer, including colorectal cancer (CRC). While several approaches have been developed for tumor genotyping, liquid biopsy has been gaining much attention in the clinical setting. Analysis of circulating tumor DNA for genetic alterations has been challenging, and many methodologies with both advantages and disadvantages have been developed. We here developed a gold nanoparticle-based rapid strip test that has been applied for the first time for the multiplex detection of KRAS mutations in circulating tumor DNA (ctDNA) of CRC patients. The method involved ctDNA isolation, PCR-amplification of the KRAS gene, multiplex primer extension (PEXT) reaction, and detection with a multiplex strip test. We have optimized the efficiency and specificity of the multiplex strip test in synthetic DNA targets, in colorectal cancer cell lines, in tissue samples, and in blood-derived ctDNA from patients with advanced colorectal cancer. The proposed strip test achieved rapid and easy multiplex detection (normal allele and three major single-point mutations) of the clinically relevant KRAS mutations in ctDNA in blood samples of CRC patients with high specificity and repeatability. This multiplex strip test represents a minimally invasive, rapid, low-cost, and promising diagnostic tool for the detection of clinically relevant mutations in cancer patients.