Genotyping Assays

Xiaojun Chen, Daniel Lee, Yanbing Zu, Shujun Gao, Jerry Toh and Jackie Y. Ying

Recent advances in cancer diagnostics have led to the popularity of liquid biopsy for detecting the disease biomarkers in the body without invasive surgery. This method involves the extraction of a blood sample from the patient, which is then investigated for the presence of circulating tumor cells (CTCs). These are cells that detach from a primary tumor and travel in the bloodstream, leading to the spread of tumor in the body (metastasis). Capturing and analyzing CTCs can deepen our understanding of cancer metastasis and help to improve the treatment of cancer patients. The enumeration of CTCs has proven their prognostic value, and the molecular characterization of CTCs will pave the way toward the detection of genetic alterations in tumors, monitoring of tumor evolution and the assessment of treatment efficacy. However, CTCs are very rare compared to the large number of blood cells in the body, and there is a lack of universal cancer cell biomarkers to distinguish them from other circulating cells. Our lab has developed a microsieve that allows us to easily separate CTCs from a patient's blood sample in minutes based on their size and ability to deform to squeeze into tiny spaces. Our approach does not require complex instruments and has proven to be more effective in filtering CTCs from blood, as compared to current technologies. With our technology, intact and viable CTCs can be enriched easily, and then eluted for downstream molecular diagnosis, drug screening and other applications.

Yanbing Zu, Kian Ping Chan, Daniel Lee, Xiaojun Chen and Jackie Y. Ying

The genome is the database containing all cellular information in human cells, including when and how the cells will grow. Any genetic alteration can cause functional disruptions, resulting in diseases, such as cancer. These alterations may also cause people to become less sensitive or overly responsive to certain drugs, which in turn may lead to side effects and even death. Using gold-morpholino nanoprobes, we have developed a highly sensitive and specific method to detect the presence or alteration of certain genes by a simple color change. Our technology allows results to be interpreted easily and obtained inexpensively. Our method can also be applied to detect harmful bacteria and viruses, such as Human papillomavirus.

Currently, we are developing a number of clinically important assays or test kits incorporating our nanoprobes. Among them is an assay that aims to detect oncogenic (cancer gene) mutation via liquid biopsy. A liquid biopsy is anon-invasive alternative to surgical biopsy, which allows genetic analysis of a tumor via a simple blood draw. We have developed nanoprobe-based assays that have been preliminarily validated for the detection of EGFR, KRAS and BRAF cancer mutations with liquid biopsies. The insights from such tests will enable doctors to prescribe more effective treatment to the patient. The unique features of our nanoprobe lead to high analytical sensitivity (~0.01%, mutant in wildtype background) and 100% analytical specificity. Results obtained by our nanoprobes are superior to currently available methods. Our assays may help to provide actionable information for cancer diagnosis and targeted therapies in a fast and cost-effective manner. This would not only allow for earlier disease detection, but also help doctors to determine the appropriate treatment method for individual patients.