Circulating tumor cells (CTCs) present a viable alternative to access tumor materials other than primary biopsies in cancer. This disease is among the most widespread in the world and is difficult to target because of its complex nature, challenges in getting quality samples and dynamic temporal changes in response to treatment. Conventional methods of detection and monitoring the disease profile do not suffice to be able to target the heterogeneity that exists at the cellular level. CTCs have been identified as a possible substitute for tumor tissue samples, and can be used to complement current disease management. Challenges in CTCs molecular analysis lie in the purity of the sample, which is masked by the presence of large quantities of white blood cells (WBCs) . In this chapter, we present a microfluidic biochip platform that performs secondary purification to isolate single CTCs efficiently. Studying single CTCs will allow for sensitive detection of critical mutations and addressing intercellular variances that will be otherwise missed easily due to low mutation frequencies when evaluating bulk cell retrieval. Using the biochip, we isolated single CTCs, and conducted personalized integrated EGFR mutational analysis using conventional polymerase chain reaction (PCR) and Sanger sequencing. We also demonstrated that high quality next generation sequencing (NGS) libraries can be readily generated from these samples. In our initial study, we revealed that the dominant EGFR mutations such as L858R and T790M could be detected in Non Small Cell Lung Cancer (NSCLC) patients with low CTC counts. We envision the biochip will enable efficient isolation of rare single cells from samples. This technology coupled with downstream molecular characterization of CTCs will aid in realizing the personalized medicine for cancer patients.
Keywords: Cancer; Clonal heterogeneity; Drug resistance; Liquid biopsy; Single cell analysis.