Performance of the 4Kscore Test in Plasma and Serum and Stability of the Component Analytes in Clinical Samples.

Background: The 4Kscore Test determines a personalized risk score for aggressive prostate cancer by combining the blood sample measurements of total prostate-specific antigen (tPSA), free PSA (fPSA), intact PSA (iPSA), and human kallikrein-related peptidase 2 (hK2) with patient clinical information to generate the patient risk's score; thus, accuracy and precision of the 4Kscore depend on the reliability of these measurements. Although tPSA and fPSA are measured on a Food and Drug Administration (FDA)-approved platform, the performance of the iPSA and hK2 assays in the clinical setting has not previously been reported.

Methods: Analytical performance was determined for the iPSA and hK2 assays in both serum and EDTA plasma, according to Clinical and Laboratory Standards Institute guidelines.