title: Clinical Application of Liquid Biopsy in Targeted Therapy of Metastatic Colorectal Cancer.
abstract: Background.Colorectal cancers (CRC) shed DNA into blood circulation. There is growing evidence that the analysis of circulating tumor DNA can be effectively used for monitoring of disease, to track tumor heterogeneity and to evaluate response to treatment.Case Presentation.Here, we describe two cases of patients with advanced CRC. The first case is about a patient with no available tissue for analysis of RAS mutation status. Liquid biopsy revealed RAS-wild-type and the therapy with anti-EGFR (epidermal growth factor receptor) monoclonal antibody cetuximab could be initiated. In the second case, the mutational profile of a patient with initial wild-type RAS-status was continually tracked during the course of treatment. An acquired KRAS exon 3 mutation was detected. The number of KRAS mutated fragments decreased continuously after the discontinuation of the therapy with EGFR-specific antibodies.Conclusion. Liquid biopsy provides a rapid genotype result, which accurately reproduces the current mutation status of tumor tissue. Furthermore, liquid biopsy enables close monitoring of the onset of secondary resistance to anti-EGFR therapy.
authors.affiliation: Gastroenterology, Department of Medicine, Goethe University Frankfurt, Frankfurt, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Trojan
authors.affiliation: IMBL Medical Clinic, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Klein-Scory
authors.affiliation: Gastroenterology, Department of Medicine, Goethe University Frankfurt, Frankfurt, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Koch
authors.affiliation: IMBL Medical Clinic, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany; Department of Medicine, Hematology, and Oncology, Ruhr-University of Bochum, Bochum, Germany.
authors.forename: Wolff
authors.initials: W
authors.lastname: Schmiegel
authors.affiliation: IMBL Medical Clinic, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany; Department of Medicine, Hematology, and Oncology, Ruhr-University of Bochum, Bochum, Germany.
authors.forename: Alexander
authors.identifier: 0000-0002-0408-1552
authors.initials: A
authors.lastname: Baraniskin