NEW YORK (360Dx) – A team led by researchers from Cleveland Clinic and protein biomarker firm Cleveland Diagnostics has presented preliminary data from a study indicating that their IsoPSA prostate cancer test could offer more accurate diagnosis than standard prostate-specific antigen (PSA) testing.
The study, which was detailed in a paper published last month in European Urology, looked at 261 men scheduled for a prostate biopsy at five academic and community institutions across the US and found that the IsoPSA test was able to distinguish between patients with and without cancer with an area under the ROC curve of .79, compared to .61 for total PSA.
The test was able to distinguish between high-grade prostate cancer and low-grade cancer/benign histology with an AUC of .81, compared to .69 for total PSA.
The study also found that the IsoPSA test outperformed the modified Prostate Cancer Prevention Trial 2.0 Risk Calculator (PCPTRC), which looks at PSA along with clinical factors including digital rectal exam, age, race, and family and prior biopsy history to help diagnosis and assess prostate cancer. According to the study authors, their results found that use of IsoPSA would lead to a 48 percent reduction in unnecessary biopsies if the cutoff were set with the goal of identifying all patients with prostate cancer of any grade; and a 45 percent reduction in unnecessary biopsies in the case of a cutoff aimed at identifying only patients with high-grade prostate cancer.
The IsoPSA test employs Cleveland Diagnostics' Solvent Interaction Analysis (SIA) platform, a protein biomarker discovery and assay technology that uses different protein isoform populations to assess patient disease states. Rather than look at levels of individual proteins or isoforms, as is commonly done in biomarker research, the SIA platform measures bulk levels of protein isoforms associated with a given disease.
The platform consists of a two-phase aqueous solution containing various molecules like polymers and salts. Upon being added to this solution, patient samples will separate into the two phases, with different proteins moving to different phases according to their interactions with the various polymers and salts contained within. By testing different combinations of molecules, the researchers aim to develop two-phase solutions that separate patient proteins in a diagnostically useful way — the idea being that under the right conditions, a cancer-related protein isoform will move to the opposite phase from healthy protein isoforms, and that disease can be detected by analyzing the amount of proteins in each phase.
The European Urology study follows data published last year that similarly found that in a cohort of 132 patients undergoing prostate biopsy, the test outperformed PSA. In that study, the researchers found IsoPSA could distinguish between benign patients and those with prostate cancer with an AUC of .80, compared to .58 for standard PSA, and was able to distinguish between highly aggressive and less aggressive forms of the disease with an area under the curve of .85, compared to .61 for standard PSA testing.