Role of Ki-67, MRE11, and PD-L1 as Predictive Biomarkers for Recurrence Pattern in Muscle-invasive Bladder Cancer

Muscle invasive bladder cancer (MIBC) 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.

Our institutional cystectomy database containing cases from 1992-2014 was queried for patients with local only recurrence (LOR), and case-matched to patients with distant recurrence (DR) and no recurrence (NR). Clinicopathological data were collected and a tissue microarray was analyzed for presence of Ki-67, MRE11, and PD-L1 using immunofluorescence and immunohistochemistry.

Pathologic specimens from 42 patients (18 NR, 16 LOR, and 8 DR) were reviewed. Compared to normal bladder tissue, tumors had increased expression of Ki-67 (p<0.01) and PD-L1 (p<0.05). High Ki-67 was associated with recurrence pattern (local vs. distant) on univariate analysis (p<0.05). Ki-67 cell density varied by recurrence type: LOR (1354 cells/mm²), DR (557 cells/mm²) and NR (1111 cells/mm²) (p=0.034).

Our selected biomarkers could distinguish MIBC from normal bladder tissue but could not classify samples by recurrence pattern.