title: Nanofluidic Digital PCR and Extended Genotyping of RAS and BRAF for Improved Selection of Metastatic Colorectal Cancer Patients for Anti-EGFR Therapies.
abstract: The clinical significance of low-frequent RAS pathway-mutated alleles and the optimal sensitivity cutoff value in the prediction of response to anti-EGFR therapy in metastatic colorectal cancer (mCRC) patients remains controversial. We aimed to evaluate the added value of genotyping an extended RAS panel using a robust nanofluidic digital PCR (dPCR) approach. A panel of 34 hotspots, including RAS (KRAS and NRAS exons 2/3/4) and BRAF (V600E), was analyzed in tumor FFPE samples from 102 mCRC patients treated with anti-EGFR therapy. dPCR was compared with conventional quantitative PCR (qPCR). Response rates, progression-free survival (PFS), and overall survival (OS) were correlated to the mutational status and the mutated allele fraction. Tumor response evaluations were not available in 9 patients and were excluded for response rate analysis. Twenty-two percent of patients were positive for one mutation with qPCR (mutated alleles ranged from 2.1% to 66.6%). Analysis by dPCR increased the number of positive patients to 47%. Mutated alleles for patients only detected by dPCR ranged from 0.04% to 10.8%. An inverse correlation between the fraction of mutated alleles and radiologic response was observed. ROC analysis showed that a fraction of 1% or higher of any mutated alleles offered the best predictive value for all combinations of RAS and BRAF analysis. In addition, this threshold also optimized prediction both PFS and OS. We conclude that mutation testing using an extended gene panel, including RAS and BRAF with a threshold of 1% improved prediction of response to anti-EGFR therapy. Mol Cancer Ther; 15(5); 1106-12. ©2016 AACR.
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Azuara
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. Department of Medical Oncology, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Santos
authors.affiliation: Unit of Biomarkers and Susceptibility, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Lopez-Doriga
authors.affiliation: Department of Medical Oncology, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. Department of Medical Oncology, Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Julieta
authors.initials: J
authors.lastname: Grasselli
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Marga
authors.initials: M
authors.lastname: Nadal
authors.affiliation: Department of Pathology, University Hospital Bellvitge (HUB-IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Sanjuan
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Fátima
authors.initials: F
authors.lastname: Marin
authors.affiliation: Department of Medical Oncology, Hospital Universitari del Mar, Barcelona, Spain.
authors.forename: Joana
authors.initials: J
authors.lastname: Vidal
authors.affiliation: Department of Medical Oncology, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Robert
authors.initials: R
authors.lastname: Montal
authors.affiliation: Unit of Biomarkers and Susceptibility, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Moreno
authors.affiliation: Department of Pathology, Hospital Universitari del Mar, Barcelona, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Bellosillo
authors.affiliation: Department of Medical Oncology, Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Guillem
authors.initials: G
authors.lastname: Argiles
authors.affiliation: Department of Medical Oncology, Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Elez
authors.affiliation: Department of Medical Oncology, Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Dienstmann
authors.affiliation: Department of Medical Oncology, Hospital Universitari del Mar, Barcelona, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Montagut
authors.affiliation: Department of Medical Oncology, Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Tabernero
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. ramonsalazar@iconcologia.net gcapella@iconcologia.net.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Capellá
authors.affiliation: Translational Research Laboratory, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. Department of Medical Oncology, Catalan Insitute of Oncology (ICO), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain. ramonsalazar@iconcologia.net gcapella@iconcologia.net.
authors.forename: Ramon
authors.initials: R
authors.lastname: Salazar
mesh_terms: D000328:Adult; D000368:Aged; D020533:Angiogenesis Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality; D004252:DNA Mutational Analysis; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D005091:Exons; D005260:Female; D005787:Gene Frequency; D011905:Genes, ras; D006801:Humans; D008297:Male; D008875:Middle Aged; D058990:Molecular Targeted Therapy; D058889:Molecular Typing; D009154:Mutation; D036103:Nanotechnology; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction / Q000379:methods; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D019233:Retreatment; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D066246:ErbB Receptors; D048493:Proto-Oncogene Proteins B-raf