SUO 2025 data confirm IsoPSA accuracy independent of mpMRI use

Newly presented data directly validate the blood-based IsoPSA test in patients for whom patients have not received multiparametric MRI (mpMRI) and those who mpMRI PI-RADS scores of 1 to 3.¹

The data, presented at the 2025 Society of Urologic Oncology Annual Meeting in Phoenix Arizona, come just days after the FDA approved IsoPSA to aid in the diagnosis of high-grade prostate cancer. The test works by analyzing “prostate cancer-specific structural variants of the prostate-specific antigen (PSA) protein” to aid in the decision for prostate biopsy in men who are 50 years of age or older with elevated PSA levels, according to developer Cleveland Diagnostics. The approval is supported by results from a large-scale, prospective study conducted across 14 clinical trial sites in the US, as well as from other supporting validation studies.²

For the SUO 2025 study, the investigators, led by Aaron Milbank, MD, of Minnesota Urology, sought to evaluate IsoPSA’s performance in patients who had not received pre-biopsy mpMRI as well as patients who had pre-biopsy mpMRI PI-RADS 1 to 3 scores. A total of 566 patients who were at least 50 years of age, with total prostate-specific antigen level of between 4 ng/mL and 10 ng/mL, were included the study. The entire cohort underwent prostate biopsy and received an IsoPSA test. Investigators as well as patients were blinded to the IsoPSA results. Patients were excluded if they had PI-RADS scores of 4-5 “due to high [prostate cancer] risk leading to a biopsy decision according to standard of care,” the investigators wrote in their poster. Patients were assessed in relation to a high-grade prostate cancer (defined as grade group 2 or higher) biopsy outcome “by likelihood ratio analysis of pre-test risk (prevalence) and post-test risk at an IsoPSA Index lower cut-off [of] 6.0 and an IsoPSA Index upper cut-off [of] 10.0,” according to the investigators.

Of the cohort, 362 (64%) patients had not undergone pre-biopsy mpMRI, and 204 (36%) had a pre-biopsy mpMRI PI-RADS score of 1 to 3. In patients who had no mpMRI, 84 had an IsoPSA Index of less than 6.0. Five of these patients had Gleason 7 or higher disease, and the probability estimate of Gleason 7 or higher in this group was 5.95% (95% CI, 1.96-13.35). In the 114 patients with an IsoPSA index of between 6.0 and 10.0, 29 had Gleason 7 or higher disease, with a 25.44% probability estimate of Gleason 7 or higher disease (95% CI, 17.75-34.34). For the 164 patients with an IsoPSA Index greater than 10.0, 80 had Gleason 7 or higher disease, with a 48.78% probability estimate of Gleason 7 or higher disease (95% CI, 40.91-56.70).

In the cohort with mpMRI PI-RADS score of 1 to 3, 39 patients had an IsoPSA index of 6.0 or lower. Two of these patients had Gleason 7 or higher disease, with a probability estimate of 5.13% (95% CI, 0.63%-17.32%). Seventy-eight patients had an IsoPSA index of between 6.0 and 10.0, of whom 10 were found to have Gleason 7 or higher disease. The probability estimate was 12.82% (95% CI, 6.32-22.32). Finally, in the 87 patients with an IsoPSA Index greater than 10, 27 had Gleason 7 or higher disease, with a probability estimate of 31.03% (95% CI, 25.55-41.86).

“IsoPSA is now directly validated both without and in combination with mpMRI PI- RADS 1-3 scores. Consequently, use of IsoPSA in clinical practice should produce demonstrable improvements in clinician-patient shared biopsy decision-making,” the authors wrote in their poster.

REFERENCES

1. Milbank A, Truesdale M, Belkoff L, et al. Clinical performance of IsoPSA® with and without multi-parametric MRI: a large-scale prospective study for high-grade prostate cancer detection. Presented at: Society of Urologic Oncology Annual Meeting; December 2-5, 2025; Phoenix, Arizona. Abstract 75. https://suo-abstracts.secure-platform.com/a/gallery/rounds/24/details/4460

2. FDA Approves IsoPSA® -- Cleveland Diagnostics’ Novel Blood-Based Prostate Cancer Test. News release. Cleveland Diagnostics, Inc. December 1, 2025. Accessed December 4, 2025. https://www.businesswire.com/news/home/20251201324198/en/FDA-Approves-IsoPSA----Cleveland-Diagnostics-Novel-Blood-Based-Prostate-Cancer-Test