The IsoPSA Test Is Available, and It Could Change the Diagnostic Paradigm for Prostate Cancer

Cleveland Clinic is now offering the IsoPSA™ test, a novel prostate-specific antigen assay, for patients with a PSA > 4ng/ml who are facing a decision on prostate biopsy.

This blood-based diagnostic test has demonstrated superiority over conventional tests in predicting the presence of high-grade prostate cancer, potentially resulting in a significant decrease in unnecessary prostate biopsies, according to Eric Klein, MD, urologic oncologist and Chairman Emeritus of the Glickman Urological & Kidney Institute.

“Our data show that the IsoPSA test reduces unnecessary prostate biopsies by about 45% by reliably differentiating between the risks of high-grade vs. low-grade cancer or benign biopsies,” says Dr. Klein.

Accelerated research to improve clinical care

This most recent development in the availability of the assay follows two multicenter, prospective clinical trials. These studies validate the superiority of this test compared to that of the prostate-specific antigen (PSA) assay, the gold standard for prostate cancer screening and staging.1, 2

Developed by the biotechnology company Cleveland Diagnostics, Inc.* in partnership with the Glickman Urological & Kidney Institute, the technology also received breakthrough device designation from the U.S. Food & Drug Administration in late 2019. This distinction recognizes the clinical significance of the biomarker and should help accelerate regulatory processes, getting tests into the hands of physicians quicker.

Filling an important need in diagnostic testing for prostate cancer

Conventional PSA testing, a decades-long standard-of-care strategy in prostate cancer screening and staging, has demonstrated value as a test for men with higher risk factors, such as age, race and family history.

“Large, randomized trials show that it’s a clinically valuable screening test, and it’s proven to reduce mortality rates and also reduce the need for treatment of metastatic disease,” remarks Dr. Klein. “But it does have limitations, most notably its imprecision when detecting the aggressiveness of the malignancy.”

IsoPSA is a reflex test, and it also takes a different biological approach. It interrogates broader, structural changes in a patient’s PSA levels as a result of disease pathogenesis, rather than assessing the concentration of the protein. Because the PSA biomarker protein is tissue-specific, and not cancer-specific, it commonly misrepresents protein levels associated non-cancerous conditions, such as benign prostatic hyperplasia or prostatitis. This, as a result, leads to an overdiagnosis of low-grade cancers and an overtreatment of low-mortality tumors. The IsoPSA test overcomes these shortcomings inherent to conventional PSA testing.

Integrating the test into clinical practice

Designed to stratify risk of biologically significant prostate cancer (Gleason grade > 7 prostate cancer), IsoPSA is intended to be used in men who are age 50 and older with a total PSA > 4 ng/ml with no previous prostate cancer diagnosis and not under active surveillance.

The test will be piloted within the Cleveland Clinic health system over the next several months. The team overseeing its implementation will be examining best practices and efficiencies in clinical application and specimen processing.

Dr. Klein notes that the team plans to scientifically assess how this test affects clinical practice. He stresses that if used as intended, the test will offer new clinical data points to guide the physician-patient conversation about prostate cancer biopsy.

“The physical, psychological and financial implications of unnecessary biopsy cannot be overlooked. Our goal with this test is to add an additional piece of evidence to the diagnostic toolkit to help providers and patients make what can be a difficult decision.”

Questions about the test can be directed to Dr. Klein (kleine@ccf.org) or Bob Rochelle, MBA, Chief Commercial Officer, Cleveland Diagnostics (Bob.Rochelle@ClevelandDx.com).

* Cleveland Clinic has an equity position in Cleveland Diagnostics. Dr. Klein has no direct or indirect personal financial interests in the company.

References

1. Klein EA, Chait A, Hafron JM, et al. Eur Urol. 2017:942-949
2. Stovsky M, Klein EA, Chait A, et al. Urol. 2019 (201): 1-5