A 64-Year-Old Man with Elevated PSA Levels - Episode 8

Real-World Use of an Exosome-Based Urine Biomarker Test

Judd W. Moul, MD, FACS, gives a real-world overview of how the exosome-based test is used in clinical practice.

Patient Case: A 64-Year-Old Man with Elevated PSA Levels

  • A 64-year-old-man underwent PSA testing during his annual physical with his primary care physician; PSA was 5.6 ng/mL and PSA density was 0.16.
  • He then saw a urologist, who ordered a multiparametric MRI; result was PI-RADS 4.
  • The patient was reluctant to undergo a prostate fusion biopsy, therefore the patient’s urologist recommended that he undergo exosome-based molecular testing to help determine risk of prostate cancer; his test score was 16.3.
  • The patient and urologist remained concerned about his PI-RADS 4 MRI score. The urologist also noted that the PSA density of 0.16 was slightly above the threshold of 0.1.
  • The patient elected to undergo TRUS-guided biopsy, which was negative for prostate cancer.

Judd W. Moul, MD, FACS: We are just coming out of a pandemic that lasted an excess of 2 years. COVID-19 has had a huge impact on all of us, including big changes in how we practice medicine. During the pandemic, patients were not able or not willing to necessarily come in for an in-person exam that would include a digital rectal exam. We did a lot of telehealth visits for patients who had an elevated PSA [prostate-specific antigen] and many times a borderline elevated PSA. Tests such as exosome [ExoDX] have really been helpful because No. 1, it could be done through mail order, and No. 2, it didn’t require a rectal exam. It was a secondary screening test or a biomarker test that I could employ for a patient who was having telehealth without having to have him come in for a rectal exam, and not even having to have him come in for a secondary blood test. What would happen is we would do the test. If the patient was fortunate to have a low value, then what I would typically do is reassure that patient and schedule him back for a follow-up in a year. Hopefully, now a year later, COVID-19 will be better, in-person visits will be safer and more doable. And that patient would be able to come in at that time and do his prostate exam, including a rectal exam.

The test is commercially marketed with an upper limit of normal of 15.6. I’m here to say that that is the gold standard, that’s what the validation studies used. However, in more simple practical terms, there are some clinicians who would keep it simpler and use a cut point of 20. That is, again, technically off-label because you’re changing the normal slightly. But if you increase it to 20, your negative predictive value is still about 90%. So you are sacrificing maybe a 1% or 2% risk of a Gleason 7 [score] if you increase the cut point to 20.

Transcript edited for clarity.