What is Liquid Biopsy

Exosomes as the new tool in the area of liquid biopsy.

Liquid biopsy was named as one 2015’s ten best breakthrough technologies according to the MIT Technology Review.  Although the practice has been around for some time, renewed pursuit of academic studies in the field of exosomes is pushing forward further scientific work looking at the benefits liquid biopsy. This renewed interest in exosomes partly explains the resurgence of interest in liquid biopsies as a way forward in cancer cell detection and treatment.

Scientists have been profiling for microRNAs from as far back as the early 2000s but now the thinking on exosomes is that micros RNAs could be better biomarkers for certain disease states. As microRNAs can be biomarkers for diseases such as breast cancer, the idea of exosome biology and exosome associated microRNAs as a better diagnostic tool for some kinds of cancer is being given further merit.  The worlds of medicine and academia are increasingly excited to look at exosomes in liquid biopsy and pursue further studies relating to the different potential biomarkers found in the exosomes.

Currently, indicators clinicians rely on such as a change in PSA levels in blood (in prostate cancer, for example) are not always the most reliable. Sometimes PSA levels do not change despite an advancement of the disease. Solid biopsies and tumour markers also have limitations in helping with cancer diagnosis.  Therefore, in between primary treatment and advanced stage treatment, it cannot always known for certain what is going on inside a patient’s body.

Tumours are not always accessible so tumour cells in the blood offer new opportunities to look at the genomic profiling. Aside from circulating tumour cells, tumour DNA can now be studied.  Both normal cells and cancer cells secrete packages with genetic information: exosomes. Additionally, modern tools such as more refined imaging can show us small amounts of cancer in the body where otherwise it might be assumed the patient is doing well.

Are liquid biopsies the answer?

In terms of the wider clinical world the innovative, non invasive and low cost technology of liquid biopsy field is becoming significant. Given that it is easy to take samples in high numbers this provides a renewable source from the wider patient population that could offer important information about how diseases work.  There is great potential of microRNAs from exosomes as microRNAs are linked with many other disease states besides cancer.

Capturing exosomes generally involves the gold standard approach of using ultracentrifuge, a method which is usually time-consuming.  The other option, immune purification, requires a priori knowledge of which exosome populations you are trying to extract. Isolation of genetic materials from bio liquids as an alternative is a new and minimally invasive method to diagnose different types of cancer seems to be an interesting alternative moving forward.