circulating tumor cells

Malignant cells circulate in the bloodstream of patients with solid tumors.

Personalized cancer medicine requires the development of tumor-specific biomarkers to optimize selection of targeted therapies and to better assess response to therapy.

Current efforts in several tumor types have shown that patients in whom circulating tumor cells (CTCs) are detected have an inferior prognosis relative to those in whom CTCs are not detected and that the elimination or decrease of CTCs following treatment is associated with improved clinical outcomes.

Technological advances in the detection, isolation, capture, and characterization of CTCs from phlebotomy samples obtained in a routine clinical practice setting have enabled the evaluation of different CTC biomarkers.

Unmet needs in cancer diagnosis and treatment where CTC biomarkers have been studied include determining prognosis, assessing the effects of treatment, and as a source of tumor for the biologic identification and characterization of determinants to predict sensitivity to one form of treatment versus another and to understand mechanisms of treatment resistance.

At present, there is no single definition of a CTC and no single CTC "biomarker." Rather, multiple assays (tests) are in development for CTC biomarkers.

However, before the role of any biomarker in medical decision making can be determined, it is essential that the assays used to measure the biomarker are analytically validated in a sequence of trials to generate the evidence to support the biomarker’s use in the given context of use.

It is against this background that this review focuses on the process of developing CTC biomarker assays, with the objective of outlining the necessary steps to qualify specific CTC tests for medical decision making in clinical practice or drug development. The potential for point-of-care tests is clear.

Biomarkers in CTCSs

 biomarkers in circulating tumor cell

• DNA biomarkers in circulating tumor cells
• RNA biomarkers in circulating tumor cells
• miRNA biomarkers in circulating tumor cells
• protein biomarkers in circulating tumor cells

Reviews

 Punnoose EA, et al. Molecular biomarker analyses using circulating tumor cells. PLoS One. 2010;5(9):e12517. PMID: #20838621#

 Circulating tumor cells as emerging tumor biomarkers in breast cancer. Lianidou ES, Markou A. Clin Chem Lab Med. 2011 Oct;49(10):1579-90. PMID: #21801030# [Free]

 Mocellin S, Keilholz U, Rossi CR, Nitti D. Circulating tumor cells: the ’leukemic phase’ of solid cancers. Trends Mol Med. 2006 Mar;12(3):130-9. PMID: #16488189#

Open References

 Gene expression profile of circulating tumor cells in breast cancer by RT-qPCR. Strati A, Markou A, Parisi C, Politaki E, Mavroudis D, Georgoulias V, Lianidou E. BMC Cancer. 2011 Oct 4;11:422. PMID: #21967632# [Free]

 Assessment of a six gene panel for the molecular detection of circulating tumor cells in the blood of female cancer patients. Obermayr E, Sanchez-Cabo F, Tea MK, Singer CF, Krainer M, Fischer MB, Sehouli J, Reinthaller A, Horvat R, Heinze G, Tong D, Zeillinger R. BMC Cancer. 2010 Dec 3;10:666. PMID: #21129172# [Free]

References

 Circulating tumors cells as biomarkers: progress toward biomarker qualification. Danila DC, Pantel K, Fleisher M, Scher HI. Cancer J. 2011 Nov-Dec;17(6):438-50. PMID: #22157288#