Identification of mutated KRAS gene in cell free circulating DNA and its transcriptome in platelets isolated from patients with colorectal cancer and investigation of their clinical utility in disease monitoring (Doctoral thesis)

Ζαρκαβέλης, Γεώργιος

BACKGROUND: Liquid biopsies are emerging as attractive alternatives to classic tumor tissue biopsyproviding access to the molecular signature of the tumor while avoiding interventional techniques and their accompanying possible complications. AIM: The aim of this study was to investigate the role of liquid biopsies in patients with metastatic colorectal cancer. More specifically, the concordance of the results provided through tissue biopsy with the results of liquid biopsy based on circulating tumor DNA using NGS and digital PCR BEAMing were investigated. PATIENTS AND METHODS: In total 56 patients with diagnosed metastatic colorectal cancer consented to participate in this study. Tissue was processed using NGS technique aiming at the identification of mutations in 23 genes. At the same time NGS was also applied in circulating tumor DNA isolated from patient’s plasma aiming at identification of possible mutations in a broad gene panel and furthermore investigation of KRAS mutations using digital PCR BEAMing was also performed. During disease progression NGS was again applied in circulating tumor DNA. RESULTS: Metastatic colorectal cancers carry mutations in genes apart from RAS and BRAF, such as TP53, PIK3CA, FBXW7, APC with an incidence of approximately 20%. With the application of NGS in tumor tissue and circulating tumor DNA, the concordance of the incidence of KRAS mutations was estimated at 80% while for BRAF mutations it was found to be 100%. Overall agreement for KRAS, NRAS and BRAF mutations was 94%. Using digital PCR BEAMing in circulating tumor DNA RAS mutations were identified in 47,4 % while the use of NGS resulted in identification of RAS mutations in 55% of the cases. When comparing the results of tumor tissue processing with the application of both NGS and digital PCR BEAMing , total agreement for the three method was approximately 74%. When comparing NGS and digital PCR BEAMing application in circulating tumor DNA, total agreement for the identification of RAS mutations was high, reaching 93%. When NGS was applied in circulating tumor DNA at disease progression, the molecular signature of the tumor was different compared to baselinetesting. CONCLUSION: The overall agreement between tissue profiling and circulating tumor DNA profiling is encouraging regarding the possible application of liquid biopsies in colorectal cancer cases. The ability to monitor disease evolution in real time under the selective pressure of applied therapy further broadens the potential of liquid biopsies in colorectal cancer management and therapeutics.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής
Subject classification: Καρκίνος -- Παχέος Εντέρου
Keywords: Υγρές βιοψίες,καρκίνος παχέος εντέρου,κυκλοφορούν καρκινικό DNA,liquid biopsies,colorectal cancer,circulating tumor DNA
URI: https://olympias.lib.uoi.gr/jspui/handle/123456789/29631
http://dx.doi.org/10.26268/heal.uoi.9633
Appears in Collections:Διδακτορικές Διατριβές

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