Detection of PIK3CA Mutations in Plasma Tumor DNA Circulating in Peripheral Blood of Breast Cancer Patients

breast cancer;early stage breast cancer;PIK3CA mutations;cell-free DNA;plasma tumor DNA;cancer biomarkers;cancer therapies;cancer genetics;droplet digital PCR;Human Genetics and Molecular Biology

Valda Toro, Patricia Lourdes

Johns Hopkins University

关键词: breast cancer;    early stage breast cancer;    PIK3CA mutations;    cell-free DNA;    plasma tumor DNA;    cancer biomarkers;    cancer therapies;    cancer genetics;    droplet digital PCR;    Human Genetics and Molecular Biology;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/37105/VALDATORO-THESIS-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Tumor-specific mutations are used as genetic biomarkers for breast cancerdiagnosis and prognosis. The detection and quantification of mutations in tumor DNAcirculating in peripheral blood offers a non-invasive approach for measuring the presenceof cancer in patients and for evaluating individual responses to targeted therapies. Westudied the feasibility of detecting two common mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) gene, in circulating plasmatumor DNA (ptDNA) of early stage breast cancer patients. We used two PolymeraseChain Reaction platforms, BEAMing and droplet digital PCR (ddPCR), and showed thatboth platforms detect PIK3CA mutations in ptDNA with high specificity and differentialsensitivity (30% for BEAMing, and 93.3% for ddPCR). Additionally, we showed that thesensitivity of ddPCR for ptDNA detection decreased in blood stored at room temperaturefor one week in tubes that do not prevent blood lysis. Our results provide a novel andnon-invasive alternative for clinically detecting and quantifying breast cancer biomarkersin blood, and suggest the use of blood collection tubes that prevent lymphocyte lysis forblood storage and transportation. The method presented herein, can allow physicians tomeasure tumor burden in breast cancer patients in response to targeted therapies, and tomake more informed decisions regarding the administration of toxic systemic therapies.