If you ever had a bladder infection, that fact that you may feel like you’re peeing razor blades is a definitive diagnosis that you need an antibiotic. But no, your doctor will tell you to get to a lab for a urine test called a urinalysis. Once the results show bacteria present in your pee, your doc orders the miracle pills that will soon have you back to normal. What a relief!

What if a urine sample could tell if you have prostate cancer (PCa)? Not just that you have it, but how dangerous it is? Would it replace a needle biopsy? Now, that would REALLY be a relief for the one million American men who got through a conventional 12+ core needle biopsy each year.

The miR Sentinel Prostate Test

On Oct. 13, 2020, a company called miR Scientific, LLC, announced that it had received Breakthrough Device Designation by the U.S Food & Drug Administration for its miR Sentinel™ PCC4 Assay (miR Sentinel™ Prostate Test)^[ii]. The testing analyzes RNA molecules isolated from urinary exosomes.

Whoa! What the heck are exosomes? Actually, there is a tremendous surge of interest in and information about these tiny circulating particles that used to be viewed as cellular garbage bags. We now know that exosomes are a means by which cells communicate with each other throughout the body. Almost all types of cells, including cancer cells, produce them within the cell, then send them out into the body where they act like telegrams. Each exosome contains gene-directing information in the form of biochemical molecules, including RNA. When a receiving cell allows an exosome entry into itself, the information it receives can actually change the behavior of the receiving cell.

The exosomes have surface “ID tags” that identify what kind of parent cells produced them. Also, the genetic instructions encoded in the RNA molecules contained in the exosome can be “read” by today’s sophisticated devices, such as the one newly approved by the FDA for miR Scientific. Intercepting this information, if it’s from a PCa cell, would be like stopping a door-to-door salesman on the sidewalk and taking one of his flyers. Now you know what company he’s from, and what he’s selling.

Admittedly, this is a simplistic explanation of what the miR Sentinel Test does to determine if a man has PCa. The actual process of “reading” RNA extracted from exosomes is a molecular diagnostic testing technique called real-time polymerase chain reaction (PCR or real-time PCR) to determine if RNA of PCa is present. miR developed a proprietary algorithm to score samples, dividing them into four possible groups according to probability: no molecular evidence of PCa, low-risk PCa, intermediate-risk PCa, or high-risk PCa. How accurate is it?

Sentinel Test success data

In its September, 2020 issue, the Journal of Urology published a paper by Wang, et al. demonstrating greater than 90% overall accuracy (statistical sensitivity and specificity.) That’s WAY BETTER than standard TRUS biopsies!!

There are three Sentinel tests:

• The Sentinel PCa test (does a man have PCa or doesn’t he?) had 94% sensitivity/ 92% specificity
• The Sentinel CS test (predicting clinical significance or Grade Group ≥2 PCa) had 93% sensitivity/90% specificity
• The Sentinel HG test (predicting high grade or Grade Group ≥3 PCa) had 94% sensitivity/96% specificity^[iii]

Not widely available

In case you’re so impressed (as we are, at Sperling Prostate Center) don’t rush to get a paper cup and do a urine drop at your urologist’s office. These tests will be more expensive than a non-specific PSA blood test, and notice that they are separate analyses, not a 3-in-1 urine sample. However, the Sentinel prostate tests are a true breakthrough in urologic detection and diagnosis that stands to benefit millions of men around the world.

In fact, the technology is so noteworthy that during 2020’s National Prostate Cancer Month, miR Scientific was awarded the Fierce Innovation Award (Medical Device category) in recognition of its “industry leading medical device innovation.”^[iv] I anticipate that further clinical testing will confirm the apparent accuracy of the test, and that Artificial Intelligence (AI) will foster its precision and efficiency.

Meanwhile, until there is a proven 100% accurate urine or blood test for PCa biomarkers, in-bore mpMRI targeted biopsy will continue to play an unparalleled role in minimally invasive confirmatory biopsy, we can all look forward to a future in which needle biopsies of the prostate may become only a distant memory.

References

[i] Tosoian JJ, Zhang Y, Xiao L, et al. Development and Validation of an 18-Gene Urine Test for High-Grade Prostate Cancer. JAMA Oncol. 2024;10(6):726–736.
[ii] https://www.prnewswire.com/news-releases/mir-scientific-announces-fda-breakthrough-device-designation-for-its-prostate-cancer-liquid-biopsy-test-301151403.html?tc=eml_cleartime
[iii] Wang W-L, Sorokin I, Aleksic I, et al. Expression of small noncoding RNAs in urinary exosomes classifies prostate cancer into indolent and aggressive disease. J Urol. 2020 Sep;204(3):466-475.
[iv] https://www.prnewswire.com/news-releases/mir-scientifics-breakthrough-sentinel-disease-management-platform-receives-2020-innovation-award-301130117.html

About Dr. Dan Sperling

Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Prostate Center.