8th Multidisciplinary Cancer Research Congress, 16 - 17 January 2021, pp.102
INTRODUCTION: Bladder cancer is among the ten most common cancers worldwide. It is the 6th most common
cancer and its incidence and mortality is approximately 4 times higher in men than in women in Turkey. The
median overall survival of patients with advanced or metastatic bladder cancer treated with standard therapy is
approximately 15 months from diagnosis. Immunotherapy has established an innovative approach to cancer
treatment with the approval of various checkpoint inhibitors. It has been reported that programmed death ligand-1
(PD-L1), play an important role in the immune-escape and immunosuppression mechanisms of tumors, is highly
expressed in various malignancies including bladder cancer. In this study, it was aimed to determine the
association of PD- L1 expression level with pathologic tumor grade and clinical stage in bladder cancer patients.
MATERIALS AND METHODS: RNA isolation was performed using monophasic phenol and guanidine
isothiocyanate method in FFPE tumor tissues of 49 patients diagnosed with bladder cancer. Total RNA was
converted to cDNA and gene expression levels were analyzed by qRT-PCR.
RESULTS: A statistically significant increase in PD-L1 expression was observed in the high-grade bladder tumor
group (n=28) compared to low-grade bladder tumor group (n=21) (p<0.05). However, no statistically significant
difference was found in PD-L1 expression levels between the pTa (n=33), pT1 (n=5) and pT2 (n=11) tumor stage
DISCUSSION AND CONCLUSION: Our results showed that, in line with the previous literature, high expression
of PD-L1 in bladder cancer may be a biomarker associated with tumor aggressiveness and tumor grade. The low
sample size in the pT1 group is thought to be the reason for non-significant difference in PD-L1 expression levels
between cancer stages. These results may provide a rational basis for further investigation of the treatment
option with anti-PD-L1 immunotherapy in bladder cancer patients with high PD-L1 expression in tumor tissues.