There have been lots of new developments in the world of the liquid biopsy and I have blogged about some of the most recent (see, for example: Grail Picks Specific Method for Liquid Biopsy Clinical Trials; Study Concludes That Liquid Biopsies Can Help Guide Cancer Treatment). However a recent article caught my attention because it involved urine as the required specimen rather than blood and also involved exosomes which are extracellular vesicles (EVs) produced in the endosomal compartment of most eukaryotic cells as well as cancer cells (see: Bio-Techne nets FDA breakthrough ticket in prostate cancer liquid biopsy). Exosomes contain various molecular constituents of their cell of origin including proteins and RNA. Below is an excerpt from the article:
Bio-Techne’s urine test, designed to track down the exosomes and genomic markers released from prostate cancer cells, has received a breakthrough device designation from the FDA for ruling out unnecessary tissue biopsies. The company describes its ExoDx Prostate IntelliScore test as the first liquid biopsy to receive breakthrough status for targeting exosomes, which are the small capsules released by cells carrying molecular cargo related to cell waste or communication and also bear RNA signatures of their home cell. The test aims to spare patients an unneeded tissue biopsy following the results of a prostate-specific antigen blood test, or PSA reading—which can give false positive results or mistake relatively small, benign tumors for something more, leading to overdiagnosis and overtreatment, according to the National Cancer Institute. And biopsies alone can have serious side effects, including infection risks, diminished sexual function, incontinence, pain and hospitalization.
Here is additional information about the ExoDx Prostate IntelliScore from the company web site:
How Does ExoDx Prostate(IntelliScore) Work? Patients submit a simple, non-digital rectal exam (DRE) urine sample. ExoDx Prostate (IntelliScore) analyzes the urine for three biomarkers on exosomal RNA that are expressed in men with high-grade prostate cancer. Using a proprietary algorithm that integrates the three-gene signature, the test assigns an individual risk score for patients that predicts the presence of high-grade (Gleason Score ≥ 7) prostate cancer. ExoDx Prostate (IntelliScore) is being designed to enable physicians, along with prostate-specific antigen (PSA) test and other standard of care factors (including age, race, and family history), to more accurately predict whether a patient presenting for an initial biopsy does not have high-grade prostate cancer and, thus, could potentially avoid an initial biopsy and, instead, continue to be monitored.
This is an interesting new chapter in the liquid biopsy story. Obviously, analysis of urine can be highly relevant for the diagnosis of malignant lesions of the prostate. One wonders whether the analysis of exosomes in serum from other cancerous lesion will have diagnostic relevance in the future.
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