liquid biopsy

Definition: Liquid biopsy is the analysis of therapeutic targets and drug resistance-conferring gene mutations on circulating tumor cells (CTC) and cell-free circulating tumor DNA (ctDNA) released into the peripheral blood from metastatic deposits.

Distant metastases harbor unique genomic characteristics not detectable in the corresponding primary tumor of the same patient and metastases located at different sites show a considerable intrapatient heterogeneity.

Thus, the mere analysis of the resected primary tumor alone (current standard practice in oncology) or, if possible, even reevaluation of tumor characteristics based on the biopsy of the most accessible metastasis may not reveal sufficient information for treatment decisions.

This dilemma can be solved by a new diagnostic concept: liquid biopsy, that is, analysis of therapeutic targets and drug resistance-conferring gene mutations on circulating tumor cells (CTC) and cell-free circulating tumor DNA (ctDNA) released into the peripheral blood from metastatic deposits.

CTCs and ctDNA are now biomarkers in clinical oncology.

Both CTCs and ctDNA are interesting complementary technologies that can be used in parallel in future trials assessing new drugs or drug combinations.

The liquid biopsy concept will contribute to a better understanding and clinical management of drug resistance in patients with cancer.

References

 Real-time liquid biopsy in cancer patients: fact or fiction? Pantel K, Alix-Panabières C. Cancer Res. 2013 Nov 1;73(21):6384-8. doi : 10.1158/0008-5472.CAN-13-2030 PMID: 24145355

 Circulating tumor cells and DNA as liquid biopsies. Heitzer E, Auer M, Ulz P, Geigl JB, Speicher MR. Genome Med. 2013 Aug 23;5(8):73. PMID: 23998943