A New Horizon of Liquid Biopsy in Thymic Epithelial Tumors: The Potential Utility of Circulating Cell-Free DNA

Abstract

BackgroundThymic epithelial tumors (TETs) are rare thoracic malignancies, commonly divided into two different histopathological entities, thymoma (T) and thymic carcinoma (TC). To date, there are no specific biomarkers for monitoring the biological course of these rare tumors. We carried out a single center study aiming at the detection of circulating cell-free DNA (ccfDNA) and the correlation of its levels with metastatic dissemination and histological subtype in patients with TETs.MethodsFrom July 2018 to January 2020, 5-ml blood samples from 26 patients with advanced TET (aTET) (11 patients with TC and 15 patients with T) and from six patients with completely resected TET (cr-TET), were prospectively obtained before the initiation of systemic therapy. Blood samples from 10 healthy donors were used as control. The QIAamp MinElute ccfDNA Kits was used for ccfDNA isolation from plasma; real-time PCR was used for cfDNA quantification.ResultsWe found significantly higher ccfDNA amount in patients with T and TC compared to controls, with median ccfDNA level of 3.3 ng/µl, 11.4 ng/µl and 25.6 ng/µl, for healthy donors, T and TC patients, respectively (p<0.001). No significant difference was found between cr-TET and controls (p = 0.175). ccfDNA concentrations were higher in metastatic (M1a and M1b) compared to non-metastatic (M0) TETs (25.6 ng/µl versus 7.2 ng/µl; p= 0.037). No significant correlation was found either between ccfDNA and disease stage, according to both the Masaoka-Koga (p= 0.854) and the TNM 8th edition staging systems (p = 0.66), or between ccfDNA levels and overall tumor burden, estimated according RECIST 1.1 criteria (r = 0.07, p = 0.725).ConclusionsTo the best of our knowledge, this is the first study that prospectively explores detection and quantification of ccfDNA in TETs. Higher baseline cfDNA levels have been observed in both advanced T and TC comparing to the control group.

Cell-Free DNA Analysis within the Challenges of Thyroid Cancer Management

“…The main limit of qPCR is the low accuracy for ctDNA characterization. Therefore, due to the introduction of more accurate techniques (see below), the optimal application of such an approach should be the analysis of cfDNA quantitative and qualitative features [ 30 ].…”

Liquid Biopsies for Molecular Biology-Based Radiotherapy

“…In the metastatic setting, many commercial liquid biopsies have been approved for non-invasive tumor genotyping to identify candidates for targeted therapies [ 10 ]. Furthermore, there is a growing body of literature leveraging ctDNA analysis to screen for cancer where each patient’s mutations are unknown at the time of testing [ 104 , 105 , 106 , 107 , 108 ]. However, sensitive detection of ctDNA in localized disease or after curative-intent therapy most commonly tracks mutations identified from the sequencing of tumor tissue to minimize multiple hypothesis testing and to attain optimal limits of detection [ 12 , 99 , 100 , 109 , 110 ].…”

Impact of Preanalytical and Analytical Methods on Cell-Free DNA Diagnostics

“…In the blood of healthy individuals cfDNA quantity ranges from 1.8 to 44 ng/ml ( Draškovič, 2017 ; Streleckiene et al, 2019 ), mostly originating from hematopoietic cells ( Aucamp et al, 2016 ; Somen et al, 2019 ; Lampignano et al, 2020 ). Its quantity and fragment size can be increased by conditions such as physical activity, pregnancy, and various other states ( Warton and Samimi, 2015 ; Cook et al, 2018 ; Barták et al, 2019 ; Johansson et al, 2019 ; Ottaviano et al, 2021 ). Disease-derived cfDNA primarily originates from necrotic and phagocytotic processes, such as in inflammation, sepsis, trauma, or cancer, and is elevated in quantity ( Aucamp et al, 2016 ; Ponti et al, 2019 ; Somen et al, 2019 ; Yu et al, 2019 ; Li S. et al, 2020 ; Ottaviano et al, 2021 ).…”

“…Its quantity and fragment size can be increased by conditions such as physical activity, pregnancy, and various other states ( Warton and Samimi, 2015 ; Cook et al, 2018 ; Barták et al, 2019 ; Johansson et al, 2019 ; Ottaviano et al, 2021 ). Disease-derived cfDNA primarily originates from necrotic and phagocytotic processes, such as in inflammation, sepsis, trauma, or cancer, and is elevated in quantity ( Aucamp et al, 2016 ; Ponti et al, 2019 ; Somen et al, 2019 ; Yu et al, 2019 ; Li S. et al, 2020 ; Ottaviano et al, 2021 ). Among these cfDNA fractions, circulating tumor DNA (ctDNA), which originates from cancer cells, is of great interest as a novel oncological biomarker ( Solassol et al, 2018 ; Keup et al, 2020 ; Ponti et al, 2020 ).…”