Liquid biopsy for detection of actionable oncogenic mutations in human cancers and electric field induced release and measurement liquid biopsy (eLB)

Abstract

Oncogenic activations by mutations in key cancer genes such as EGFR and KRAS are frequently associated with human cancers. Molecular targeting of specific oncogenic mutations in human cancer is a major therapeutic inroad for anti-cancer drug therapy. In addition, progressive developments of oncogene mutations lead to drug resistance. Therefore, the ability to detect and continuously monitor key actionable oncogenic mutations is important to guide the use of targeted molecular therapies to improve long-term clinical outcomes in cancer patients. Current oncogenic mutation detection is based on direct sampling of cancer tissue by surgical resection or biopsy. Oncogenic mutations were recently shown to be detectable in circulating bodily fluids of cancer patients. This field of investigation, termed liquid biopsy, permits a less invasive means of assessing the oncogenic mutation profile of a patient. This paper will review the analytical strategies used to assess oncogenic mutations from biofluid samples. Clinical applications will also be discussed.

Figure 1

The homoduplex mechanism of detecting mutated signal using a fluorescence resonance energy transfer based strategy. (A) If the mutant signal is present in the DNA, during the PCR process the quencher unit will be gradually diluted out and a signal will be observed. (B) If the wildtype sequence is present in the DNA, there will be no dilution of the quencher unit during the PCR process and no significant amounts of fluorescing will occur. (Reprinted from Kitano et al, with permission from Elsevier 2015).

Figure 2

Example of integrated microfluidic mutation analysis in work. This work allowed the collection of whole blood samples, removal of red blood cells, DNA amplification, and fluorescent reporting that could be performed in one hour. (Reprinted from Wang et al, with permission from Elsevier 2015).

Figure 3

A schematic overview of the EFIRM technique. This method involves the novel application of electric potentials to facilitate hybridization of mutated sequences to a set of probes on the surface of an electrode and the usage of these probes to create readout of the signal. (Reprinted with permission of the American Thoracic Society Copyright © 2015 American Thoracic Society. From Wei et al. The American Journal of Respiratory and Critical Care Medicine is an official journal of the American Thoracic Society).