BRAF mutational status is associated with survival outcomes in locally advanced resectable and metastatic NSCLC.

BACKGROUND: Immunotherapy-based treatments have demonstrated high efficacy in patients with advanced and locally advanced non-small-cell lung cancer (NSCLC). BRAF mutations affect a small but significant fraction of NSCLC. The efficacy of these therapies in this subgroup of patients is unknown. MATERIALS AND METHODS: Plasma and tissue samples from 116 resectable stage IIIA/B NSCLC patients, included in NADIM and NADIM II clinical trials (NADIM cohort), and from a prospective academic cohort with 84 stage IV NSCLC patients (BLI-O cohort), were analyzed by next-generation sequencing. RESULTS: The p.G464E, p.G466R, p.G466V, p.G469V, p.L597Q, p.T599I, p.V600E (n = 2) BRAF mutations, were identified in four (3.45 %) samples from the NADIM cohort, all of which were cases treated with neoadjuvant chemoimmunotherapy (CH-IO), and four (4.76 %) samples from the BLI-O cohort, corresponding to cases treated with first-line immunotherapy (n = 2) or CH-IO (n = 2). All these patients were alive and had no evidence of disease at data cut-off. Conversely, patients with BRAF wild-type (wt) tumors in the BLI-O cohort had a median progression-free survival (PFS) of 5.49 months and a median overall survival (OS) of 12.00 months (P-LogRank = 0.013 and 0.046, respectively). Likewise, PFS and OS probabilities at 36 months were 60.5 % and 76.1 % for patients with BRAF-wt tumors in the NADIM cohort. The pathological complete response (pCR) rate after neoadjuvant CH-IO in patients with BRAF-positive tumors (n = 4) was 100 %, whereas the pCR rate in the BRAF-wt population was 44.3 % (RR: 2.26; 95 % CI: 1.78-2.85; P < 0.001). CONCLUSION: BRAF mutations may be a good prognostic factor for advanced and locally advanced NSCLC patients undergoing immunotherapy-based treatments.

Detecting ALK, ROS1, and RET fusions and the METΔex14 splicing variant in liquid biopsies of non-small-cell lung cancer patients using RNA-based techniques.

ALK, ROS1, and RET fusions and MET∆ex14 variant associate with response to targeted therapies in non-small-cell lung cancer (NSCLC). Technologies for fusion testing in tissue must be adapted to liquid biopsies, which are often the only material available. In this study, circulating-free RNA (cfRNA) and extracellular vesicle RNA (EV-RNA) were purified from liquid biopsies. Fusion and MET∆ex14 transcripts were analyzed by nCounter (Nanostring) and digital PCR (dPCR) using the QuantStudio® System (Applied Biosystems). We found that nCounter detected ALK, ROS1, RET, or MET∆ex14 aberrant transcripts in 28/40 cfRNA samples from positive patients and 0/16 of control individuals (70% sensitivity). Regarding dPCR, aberrant transcripts were detected in the cfRNA of 25/40 positive patients. Concordance between the two techniques was 58%. Inferior results were obtained when analyzing EV-RNA, where nCounter often failed due to a low amount of input RNA. Finally, results of dPCR testing in serial liquid biopsies of five patients correlated with response to targeted therapy. We conclude that nCounter can be used for multiplex detection of fusion and MET∆ex14 transcripts in liquid biopsies, showing a performance comparable with next-generation sequencing platforms. dPCR could be employed for disease follow-up in patients with a known alteration. cfRNA should be preferred over EV-RNA for these analyses.

Cancer as an infective disease: the role of EVs in tumorigenesis.

Cancer is conventionally considered an evolutionary disease where tumor cells adapt to the environment and evolve eventually leading to the formation of metastasis through the seeding and growth of metastasis-initiating cells in distant organs. Tumor cell and tumor-stroma communication via soluble factors and extracellular vesicles (EVs) are essential for the success of the metastatic process. As the field of EVs advances, growing data support the role of tumor-derived EVs not only in modifying the microenvironment to facilitate tumor progression but also in inducing changes in cells outside the primary tumor that may lead to a malignant transformation. Thus, an alternative hypothesis has emerged suggesting the conceptualization of cancer as an 'infective' disease. Still, tackling EVs as a possible cancer treatment has not been widely explored. A major understanding is needed to unveil possible additional contributions of EVs in progression and metastasis, which may be essential for the development of novel approaches to treat cancer patients. Here, we review the contribution of EVs to cancer progression and the possible implication of these factors in the oncogenic transformation of indolent cells.

Molecular Divergence upon EGFR-TKI Resistance Could Be Dependent on the Exon Location of the Original EGFR-Sensitizing Mutation.

Tumor molecular profiling upon disease progression enables investigations of the tumor evolution. Next-generation sequencing (NGS) of liquid biopsies constitutes a noninvasive readily available source of tumor molecular information. In this study, 124 plasma samples from advanced EGFR-positive NSCLC patients, treated with a first-line EGFR tyrosine kinase inhibitor (EGFR-TKI) were collected upon disease progression. The circulating cell-free DNA (cfDNA) was sequenced using the Oncomine Pan-Cancer Cell-Free Assay™. Excluding EGFR mutations, the most frequently mutated gene was TP53 (57.3%), followed by APC (11.3%), FGFR3 (7.3%), and KRAS (5.6%). Different molecular alterations were observed upon disease progression depending on the location of the original EGFR-sensitizing mutation. Specifically, the detection of the p.T790M mutation was significantly associated with the presence of exon 19 mutations in EGFR (Fisher p-value: 0.028). All KRAS activating mutations (n = 8) were detected in tumors with EGFR mutations in exons 18 and 21 (Fisher p-value < 0.001). Similarly, mutations in NRAS and HRAS were more frequently detected in samples from tumors harboring mutations in exons 18 or 21 (Fisher p-value: 0.050 and Fisher p-value: 0.099, respectively). In conclusion, our data suggest that the mechanisms underlying EGFR-TKI resistance could be dependent on the exon location of the original EGFR-sensitizing mutation.

Circulating Tumor DNA as a Cancer Biomarker: An Overview of Biological Features and Factors That may Impact on ctDNA Analysis.

Cancer cells release nucleic acids, freely or associated with other structures such as vesicles into body fluids, including blood. Among these nucleic acids, circulating tumor DNA (ctDNA) has emerged as a minimally invasive biomarker for tumor molecular profiling. However, certain biological characteristics of ctDNA are still unknown. Here, we provide an overview of the current knowledge about ctDNA biological features, including size and structure as well as the mechanisms of ctDNA shedding and clearance, and the physio-pathological factors that determine ctDNA levels. A better understanding of ctDNA biology is essential for the development of new methods that enable the analysis of ctDNA.

ALK-Fusion Transcripts Can Be Detected in Extracellular Vesicles (EVs) from Nonsmall Cell Lung Cancer Cell Lines and Patient Plasma: Toward EV-Based Noninvasive Testing.

BACKGROUND: ALK rearrangements are present in 5% of nonsmall cell lung cancer (NSCLC) tumors and identify patients who can benefit from ALK inhibitors. ALK fusions testing using liquid biopsies, although challenging, can expand the therapeutic options for ALK-positive NSCLC patients considerably. RNA inside extracellular vesicles (EVs) is protected from RNases and other environmental factors, constituting a promising source for noninvasive fusion transcript detection. METHODS: EVs from H3122 and H2228 cell lines, harboring EML4-ALK variant 1 (E13; A20) and variant 3 (E6a/b; A20), respectively, were successfully isolated by sequential centrifugation of cell culture supernatants. EVs were also isolated from plasma samples of 16 ALK-positive NSCLC patients collected before treatment initiation. RESULTS: Purified EVs from cell cultures were characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry. Western blot and confocal microscopy confirmed the expression of EV-specific markers as well as the expression of EML4-ALK-fusion proteins in EV fractions from H3122 and H2228 cell lines. In addition, RNA from EV fractions derived from cell culture was analyzed by digital PCR (dPCR) and ALK-fusion transcripts were clearly detected. Similarly, plasma-derived EVs were characterized by NTA, flow cytometry, and the ExoView platform, the last showing that EV-specific markers captured EV populations containing ALK-fusion protein. Finally, ALK fusions were identified in 50% (8/16) of plasma EV-enriched fractions by dPCR, confirming the presence of fusion transcripts in EV fractions. CONCLUSIONS: ALK-fusion transcripts can be detected in EV-enriched fractions. These results set the stage for the development of EV-based noninvasive ALK testing.

Tumour-adipose tissue crosstalk: fuelling tumour metastasis by extracellular vesicles.

During metastasis, tumour cells must communicate with their microenvironment by secreted soluble factors and extracellular vesicles. Different stromal cell types (e.g. bone marrow-derived cells, endothelial cells and fibroblasts) influence the growth and progression of tumours. In recent years, interest has extended to other cell types in the tumour microenvironment such as adipocytes and adipose tissue-derived mesenchymal stem cells. Indeed, obesity is becoming pandemic in some developing countries and it is now considered to be a risk factor for cancer progression. However, the true impact of obesity on the metastatic behaviour of tumours is still not yet fully understood. In this 'Perspective' article, we will discuss the potential influence of obesity on tumour metastasis, mainly in melanoma, breast and ovarian cancer. We summarize the main mechanisms involved with special attention to the role of extracellular vesicles in this process. We envisage that besides having a direct impact on tumour cells, obesity systemically preconditions the tumour microenvironment for future metastasis by favouring the formation of pro-inflammatory niches.This article is part of the discussion meeting issue 'Extracellular vesicles and the tumour microenvironment'.