Role of Ki-67, MRE11, and PD-L1 As Predictive Biomarkers for Recurrence Pattern in Muscle Invasive Bladder Cancer Following Radical Cystectomy
Abstract Background Muscle invasive bladder (MIBC) cancer is an aggressive disease with high rates of local recurrence following radical cystectomy (RC). Currently, there are no clinically validated biomarkers to predict local only recurrence (LOR) and guide adjuvant treatment decisions. This pilot study evaluated the role of Ki-67, MRE11 and PD-L1 as predictive biomarkers for recurrence patterns in patients undergoing RC for MIBC. Methods: Our institutional cystectomy database containing cases of urothelial MIBC from 1992–2014 was queried for patients with LOR and case-matched with patients who had distant recurrence (DR) and no recurrence (NR). Clinical and histopathological data were collected from selected patients and a tissue microarray was built and analyzed for presence of Ki-67, MRE11 and PD-L1 using immunofluorescence (IF) and immunohistochemistry (IHC). Univariate, multivariate, and principal component analyses (PCA) were performed to evaluate association of these biomarkers with recurrence pattern. Results: Pathologic specimens from 42 patients (18 NR, 16 LOR and 8 DR) were reviewed. Compared to adjacent normal bladder tissue, tumors had increased expression of PD-L1 on both IHC and IF (p < 0.05) and higher Ki-67 H-score on IHC (33 vs 0, p < 0.01). A high Ki-67 was associated with recurrence pattern (local vs distant) on univariate analysis (p < 0.05) and on multivariate regression, having positive surgical margins was associated with local recurrence (p = 0.04). Ki-67 cell density varied by recurrence type: LR (1354 cells/mm2), DR (557 cells/mm2) and NR (1111 cells/mm2) p = 0.034. Several PCAs were unable to identify a signature associated with recurrence pattern. Conclusion: The biomarkers used in this study were helpful in distinguishing tumor from normal tissue and high Ki-67 may be associated with LOR, however, a useful molecular signature for recurrence pattern could not be identified.