The IsoPSA test has been added to the National Comprehensive Cancer Network Prostate Cancer guidelines for early detection of the disease, according to Cleveland Diagnostics, the developer of the assay.1
The blood-based, non-invasive IsoPSA test is used prior to an initial biopsy to assess the likelihood that a patient has high-grade prostate cancer.
“IsoPSA is intended to be used in men over 50 who are being screened for prostate cancer as a way of helping to decide whether or not a biopsy should be done. So the standard paradigm is someone has a PSA test, and we know that PSA is only a little better than a coin flip in determining whether or not someone has prostate cancer. In our prior published studies, IsoPSA is far better than that. It has 80% accuracy or better in predicting for hi-grade cancer. And in fact, if it's used in conjunction with MRI, we found that it was close to 85% accurate. So it's far better than PSA in deciding whether or not someone might have a hi-grade cancer that deserves a biopsy,” Eric Klein, MD, fellow, Stanford University Distinguished Careers Institute and Emeritus Professor and Chair, Glickman Urological and Kidney Institute, Cleveland Clinic, said in an interview earlier this year with Urology Times.
Klein was the lead investigator on a real-world clinical validation study of IsoPSA that was published in the Journal of Urology Practice. The study included a diverse group of 38 community-based and academic sites withing the Cleveland Clinic health system. There were 900 patients under evaluation for prostate cancer who were enrolled at these locations. Of these, 734 met the study inclusion criteria, which comprised age ≥50 years, total serum PSA ≥4 ng/ml and <100 ng/ml, and no history of prostate cancer. The study investigators assessed biopsy recommendations of participating clinicians before and after receipt of IsoPSA results.
The results showed that in men with total PSA ≥4 ng/ml, IsoPSA led to a 55% (284 vs 638) net reduction in prostate biopsy recommendations. Further, there was also a 9% reduction in MRI imaging recommendations.
“What we found was really remarkable and it was what we had hoped for. The whole point of using IsoPSA is because it has improved sensitivity and specificity for finding higher grade cancers—grade seven or higher. The intended use of IsoPSA is to reduce the number of biopsies that show only benign tissue or show only low-grade cancer; those are things that we'd rather not find on labs,” said Klein.
“And what we found was that incorporating IsoPSA into practice for these 38 providers changed their recommendations about whether additional evaluation was necessary based on an initial total PSA; More than half—55%—of biopsies that otherwise would have been recommended, and probably would have happened, actually were recommended against. And so in this population of 900 patients, we saved a little more than half of them from the need for undergoing a biopsy with high confidence that we're not overlooking a hi-grade cancer,” Klein added.
Regarding the next steps with IsoPSA, Klein said, “Going forward we have a paper pending on a multinational, multicenter trial of little over 1000 men that confirmed the prior performance characteristics of IsoPSA in terms of sensitivity and specificity of positive and negative predictive value and that sort of thing; that's under review currently. And IsoPSA received FDA breakthrough technology designation about 2 years ago and so there is a pending FDA application for premarket approval.”
1. Scovell JM, Hettel D, Abouassaly R, et al. IsoPSA® Reduces Provider Recommendations for Biopsy and Magnetic Resonance Imaging in Men with Total Prostate Specific Antigen ≥4 ng/ml: A Real-World Observational Clinical Utility Study. Journal of Urology Practice. 2022;9(2):173-180. doi: 10.1097/UPJ.0000000000000291