PIK 3 CA hotspot mutations in circulating tumor cells and paired circulating tumor DNA in breast cancer: a direct comparison study

• Published in: Molecular oncology Vol. 13; no. 12; pp. 2515 - 2530
• Main Authors: Tzanikou, Eleni, Markou, Athina, Politaki, Eleni, Koutsopoulos, Anastasios, Psyrri, Amanda, Mavroudis, Dimitris, Georgoulias, Vassilis, Lianidou, Evi
• Format: Journal Article
• Language: English
• Published: 01.12.2019
• ISSN: 1574-7891; 1878-0261
• DOI: 10.1002/1878-0261.12540

Liquid biopsy analysis, mainly based on circulating tumor cells ( CTC s) and circulating tumor DNA (ct DNA ), provides an extremely powerful tool for the molecular profiling of cancer patients in real time. In this study, we directly compared PIK 3 CA hotspot mutations (E545K, H1047R) in Ep CAM ‐positive CTC s and paired plasma‐ct DNA in breast cancer (BrCa). PIK 3 CA hotspot mutations in CTC s and ct DNA were analyzed using our previously developed highly sensitive (0.05%), specific, and validated assay in plasma‐ct DNA from 77 early and 73 metastatic BrCa patients and 40 healthy donors. We further analyzed and directly compared PIK 3 CA hotspot mutations in DNA s isolated from CellSearch ® cartridges ( CTC s) and paired plasma‐ct DNA , in 56 cases of early and 27 cases of metastatic breast cancer, and 16 corresponding primary tumors. In plasma‐ct DNA , PIK 3 CA hotspot mutations were identified in 30/77(39.0%) early and 35/73(47.9%) metastatic BrCa cases; none (0/40, 0%) of the healthy donors’ plasma‐ct DNA samples were positive. Our direct comparison study in DNA s isolated from CellSearch ® cartridges ( CTC s) and paired plasma‐ct DNA from the same blood draws has shown a lack of concordance in early BrCa (27/56, 48.2%), while the concordance in the metastatic setting was higher (18/27, 66.6%). Our results were validated by dd PCR methodology, and the concordance between our assay and dd PCR for PIK 3 CA E545K hotspot mutation was 30/37 (81.1%). In many cases, PIK 3 CA hotspot mutations were detected in samples found to be negative for CTC s in CellSearch ® . Our data demonstrated for the first time that (a) PIK 3 CA hotspot mutations are present at high frequencies in CTC s isolated from CellSearch ® cartridges and paired plasma‐ct DNA both in early and metastatic BrCa, (b) the detection and concordance of PIK 3 CA hotspot mutations between plasma‐ct DNA and CTC s are higher in the metastatic setting, (c) PIK 3 CA mutational status significantly changes after therapeutic intervention, and (d) PIK 3 CA mutation detection in CTC s and plasma‐ct DNA provides complementary information.