Introduction: The discovery of driver mutations in non-small cell lung cancer (NSCLC) has led to the development of genome-based personalized medicine. Fifteen to 20% of adenocarcinomas harbor an epidermal growth factor receptor (EGFR) activating mutation associated with responses to EGFR tyrosine kinase inhibitors (TKIs). Individual laboratories’ expertise and the availability of appropriate equipment are valuable assets in predictive molecular pathology, although the choice of methods should be determined by the nature of the samples to be tested and whether the detection of only well-characterized EGFR mutations or rather, of all detectable mutations, is required. Areas covered: The EGFR mutation testing landscape is manifold and includes both screening and targeted methods, each with their own pros and cons. Here we review one of these companion tests, the Roche cobas® EGFR mutation test v2, from a methodological point of view, also exploring its liquid-biopsy applications. Expert commentary: The Roche cobas® EGFR mutation test v2, based on real time RT-PCR, is a reliable option for testing EGFR mutations in clinical practice, either using tissue-derived DNA or plasma-derived cfDNA. This application will be valuable for laboratories with whose purpose is purely diagnostic and lacking high-throughput technologies.

Background: When tumour tissue is unavailable, cell-free DNA (cfDNA)can serve as a surrogate for genetic analyses. Because mutated alleles in cfDNA are usually below 1%, next-generation sequencing (NGS)must be narrowed to target only clinically relevant genes. In this proof-of-concept study, we developed a panel to use in ultra-deep sequencing to identify such mutations in cfDNA. Methods: Our panel (‘SiRe’) covers 568 mutations in six genes (EGFR, KRAS, NRAS, BRAF, cKIT and PDGFRα)involved in non-small-cell lung cancer (NSCLC), gastrointestinal stromal tumour, colorectal carcinoma and melanoma. We evaluated the panel performance in three steps. First, we analysed its analytical sensitivity on cell line DNA and by using an artificial reference standard with multiple mutations in different genes. Second, we analysed cfDNA from cancer patients at presentation (n=42), treatment response (n=12) and tumour progression (n=11); all patients had paired tumour tissue and cfDNA previously genotyped with a Taqman-derived assay (TDA). Third, we tested blood samples prospectively collected from NSCLC patients (n=79) to assess the performance of SiRe in clinical practice. Results: SiRe had a high analytical performance and a 0.01% lower limit of detection. In the retrospective series, SiRe detected 40 EGFR, 11 KRAS, 1 NRAS and 5 BRAF mutations (96.8% concordance with TDA). In the baseline samples, SiRe had 100% specificity and 79% sensitivity relative to tumour tissue. Finally, in the prospective series, SiRe detected 8.7% (4/46) of EGFR mutations at baseline and 42.9% (9/21) of EGFR p.T790M in patients at tumour progression. Conclusions: SiRe is a feasible NGS panel for cfDNA analysis in clinical practice.

Although appreciable attempts in screening and diagnostic approaches have been achieved, prostate cancer (PCa) remains a widespread malignancy, representing the second leading cause of cancer-related death in men. Drugs currently used in PCa therapy initially show a potent anti-tumor effect, but frequently induce resistance and PCa progresses toward metastatic castration-resistant forms (mCRPC), virtually incurable. Liquid biopsy has emerged as an attractive and promising strategy complementary to invasive tissue biopsy to guide PCa diagnosis and treatment. Liquid biopsy shows the ability to represent the tumor microenvironment, allow comprehensive information and follow-up the progression of the tumor, enabling the development of different treatment strategies as well as permitting the monitoring of therapy response. Liquid biopsy, indeed, is endowed with a significant potential to modify PCa management. Several blood biomarkers could be analyzed for diagnostic, prognostic and predictive purposes, including circulating tumor cells (CTCs), extracellular vesicles (EVs), circulating tumor DNA (ctDNA) and RNA (ctRNA). In addition, several other body fluids may be adopted (i.e., urine, sperm, etc.) beyond blood. This review dissects recent advancements and future perspectives of liquid biopsies, highlighting their strength and weaknesses in PCa management.

The identification of non-small cell lung cancer (NSCLC) patients potentially responsive to targeted therapies relies on a number of relevant biomarkers, including EGFR, ALK, ROS-1, and PD-L1. Biomarker identification is most commonly based on surgical sample collection. However, when tissues are difficult to reach or when multiple analyses are necessary to monitor tumor progression and treatment response, liquid biopsy is a valid noninvasive alternative. This analysis, which is preferentially performed on circulating tumor DNA (ctDNA) extracted from plasma samples, has the major advantage of reducing the inherent risks and discomfort of tissue biopsy. However, a major disadvantage is that it yields only a low number of ctDNA targets. Thus, to avoid false-positive and false-negative results, it is important to adopt and validate technologies with high sensitivity and specificity in the pre-analytical phase of sampling. This review succinctly addresses the principal methodologies for analyzing plasma-derived ctDNA in NSCLC patients.

The advent of genomic based personalized medicine has led to multiple advances in the molecular characterization of many tumor types, such as non-small cell lung cancer (NSCLC). NSCLC is diagnosed in most cases on small tissue samples that may be not always sufficient for EGFR mutational assessment to select patients for first and second generations’ tyrosine kinase inhibitors (TKIs) therapy. In patients without tissue availability at presentation, the analysis of cell free DNA (cfDNA) derived from liquid biopsy samples, in particular from plasma, represent an established alternative to provide EGFR mutational testing for treatment decision making. In addition, a new paradigm for TKIs resistance management was recently approved by Food and Drug Administration, supporting the liquid biopsy based genotyping prior to tissue based genotyping for the detection of T790M mutation to select patients for third generation TKIs. In these settings, real time PCR (RT-PCR) and digital PCR ’targeted’ methods, which detect known mutations by specific probes, have extensively been adopted. Taking into account the restricted reference range and the limited multiplexing power of these targeted methods, the performance of liquid biopsy analyses may be further improved by next generation sequencing (NGS). While most tissue based NGS genotyping is well established, liquid biopsy NGS application is challenging, requiring a careful validation of the whole process, from blood collection to variant calling. Here we review this evolving field, highlighting those methodological points that are crucial to accurately select NSCLC patients for TKIs treatment administration by NGS on cfDNA.