The level of IgG proteolytic fragments as an additional prognostic biomarker of prostate cancer

Introduction. Prostate cancer (PC) leads the world structure of male cancer mortality. Understanding the prognosis for PC patients is vitally important and requires diagnostic enhancements such as developing biomarker panels. The studyaimed to estimate sensitivity, specificity, and prognostic significance of the level of immunoglobulin G (IgG) proteolysis products in the blood serum depending on PC Gleason score and detect how the levels of IgG proteolytic fragments were associated with the diagnostic marker expression. Materials and methods. The study included 90 PC patients. We used the Gleason score to evaluate tumor grade. The level of the IgG proteolysis products and total prostate-specific antigen (PSA) in the serum was detected with ELISA. We performed an immunohistochemical assay with Ki-67, plasminogen-binding protein enolase-1 (ENO-1), and prostate-specific membrane antigen (PSMA). Results. ROC analysis demonstrated 100% specificity of the IgG proteolysis products test regardless of Gleason score, while the sensitivity reached 72.2%, 57.5%, 52.6%, and 46.2% for ISUP stages 1, 2, 3, and 4, respectively. An intergroup comparison showed significant differences between patient groups according to Gleason score, preoperative PSA and IgG proteolysis product serum levels and Ki-67 index. We detected a positive correlation between the level of IgG proteolysis products in the PC patients’ serum and ENO-1 expression and a negative correlation with the Gleason score and PSMA expression. Conclusion. Preoperative detection of high levels of proteolytic IgG fragments in the serum of PC patients even with low Gleason score and PSMA expression may help predict a more aggressive disease course and choose the management strategy. Keywords: prostate cancer, plasminogen activation system, proteolytic fragments of immunoglobulin G, oncomarkers