152P - An epidemiologic study on PD-L1 expression with clinical observation of initial treatment pattern in the Chinese muscle invasive urothelial bladder carcinoma patients

Background

There is no relevant data of real-time programmed cell death-ligand 1 (PD-L1) expression and initial treatment pattern in Chinese muscle invasive urothelial bladder carcinoma patients (MIUBC). Thus, the aim of this multi-center, prospective, epidemiological study was to investigate the prevalence of high PD-L1 expression along with clinical observation of initial treatment pattern in the Chinese MIUBC patients (NCT03433924).

Methods

The study enrolled newly diagnosed patients with MIUBC and treatment naïve. The PD-L1 expression was tested by VENTANA PD-L1 (SP263) Assay. High PD-L1 expression is defined as ≥25% tumor cell (TC) + or 1) Tumor associated immune cell (IC) area >1%: ≥25% IC+; 2) IC area=1%: 100% IC+. The primary outcome was prevalence of high PD-L1 expression. The secondary outcomes included the PD-L1 expression profile in TC and IC, initial treatment pattern and concordance of PD-L1 testing between hospital and central laboratories. Further, an exploratory study was carried out to investigate correlation of PD-L1 and the infiltration of CD8+ T cells.

Results

Overall, 248 MIUBC patients were enrolled from 17 hospitals in China and 229 patients with PD-L1 data were included. High PD-L1 expression was observed in 52.4% of patients. The high PD-L1 expression was positive in 59 patients of TC and 82 patients of IC. The overall concordance rate between hospital and central labs for high PD-L1 expression was 80.4% (37/46, kappa=0.57). With respect to initial treatment pattern, 83.2% patients received radical cystectomy, and 2.2% received partial cystectomy, while 14.6% received transurethral bladder resection only. Only 7.3% patients received peri-operative treatment. Further, the Spearman’s rank correlation coefficient for percentage of TC with membrane PD-L1 positivity and CD8+ T cells, the percentage of IC with PD-L1 positivity and CD8+ T cells was determined as 0.27 and 0.34 respectively.

Conclusions

Our study reported high PD-L1 expression (52.4%) in MIUBC patients. Also, PD-L1 expression showed weak and positive association with infiltrated CD8+ T cells.

Clinical trial identification

NCT03433924.

Editorial acknowledgement

Legal entity responsible for the study

Liqun Zhou.

Funding

AstraZeneca.

Disclosure

All authors have declared no conflicts of interest.