Researchers develop noninvasive biomarker for aggressive PCa

Researchers have identified a urine biomarker that noninvasively helps detect aggressive prostate cancer about as accurately as tissue-based prognostic markers, according to a recent study.

“For patients and clinicians, the decisions around entering and staying on active surveillance remain challenging. Urine biomarkers provide a noninvasive approach that can support those decisions by providing specific molecular evidence about tumor biology without the need for biopsies,” said senior author Paul Boutros, MD, of the David Geffen School of Medicine and director of cancer data science at UCLA. The findings were published in the Journal of the National Cancer Institute (June 4, 2019 [Epub ahead of print]).

Dr. Boutros and colleagues set out to develop a biomarker that would identify patients with clinically low-risk disease that might be stable for many years.

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“Ideally, that biomarker would be minimally invasive and would not change randomly over time based on patient behavior, such as diet and exercise,” he said. “And of course, that biomarker should faithfully represent the tumor itself.”

Those considerations led the authors to study small RNA molecules in the urine. They used a multi-stage approach, first studying longitudinal urine samples from patients on active surveillance for several years. They identified which molecules tended to change with diet and behavior and excluded those, then looked at the remaining molecules and compared them to the matched primary tumor biopsies to determine which ones best represented its biology.

“Finally, we created a biomarker from those molecules, and showed that it could distinguish low-risk from higher-risk disease with about 80% accuracy. This is about as accurate as invasive tissue-based tests, but of course is less invasive since it only uses a urine sample,” Dr. Boutros said.

Continue to the next page for more.The authors studied 149 prostate cancer patients to create and validate the biomarker. They followed the patients for at least 3 years. While each man has an individual urine miRNA fingerprint, the authors were able to create a novel biomarker for prostate cancer that overcomes that individual variability, according to the study.

The test will complement PSA and multi-parametric magnetic resonance imaging, according to Dr. Boutros. The noninvasive option would potentially provide a separate, cancer-specific test to complement PSA for patients who are uncertain about remaining on surveillance. It also could provide noninvasive data to trigger radiologic investigation. Dr. Boutros said he and his colleagues think that in the long run, this test will be used regularly to complement existing assays and give clinicians and patients more confidence in their treatment plans.

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While the test looks promising, the validation sample in this study alone isn’t enough to recommend it for widespread practice.

“We are now gearing up for a much larger study and working to reduce the volume of urine and cost of the test to make it as cheap as possible,” Dr. Boutros said.

Dr. Boutros holds a patent on the biomarker developed in this study.