291P - PD-L1 over expression may predict disease aggressiveness in prostate cancer

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Prostate Cancer
Translational Research
Presenter Yasuhiro Hashimoto
Citation Annals of Oncology (2016) 27 (suppl_9): ix90-ix93. 10.1093/annonc/mdw584
Authors Y. Hashimoto, A. Imai, S. Hatakeyama, T. Yoneyama, T. Koie, C. Ohyama
  • Urology, Hirosaki University, 0368562 - Hirosaki/JP

Abstract

Background

Dramatic and long-lasting anti-tumor effects of immune checkpoint blockade has surprised the world. In the era of immunotherapy, it has been reported that tumor PD-L1 protein expression is associated with higher grade tumors and a lower survival rate for several neoplasms. It has been reported that programmed death-ligand 1 (PD-L1) expression is generally low in prostate cancer. However, no detailed investigation of this low expression has been conducted. A recent report has found that enzalutamide-resistant prostate cancer expressed high levels of PD-L1. In this study, we investigated PD-L1 expression in prostate cancer.

Methods

PD-L1 mRNA expression was compared across 492 prostate cancer cases, 404 bladder cancer cases and 534 renal cell carcinoma cases based on The Cancer Genome Atlas (TCGA). Furthermore, we conducted PD-L1 immunostaining of 110 clinical samples with the SP142 assay, of which 103 were from total prostatectomy and seven were from biopsies. One hundred and five cases were diagnosed as adenocarcinoma, four as ductal adenocarcinoma, and one as signet ring cell carcinoma.

Results

Comparison of PD-L1 mRNA expression based on the TCGA revealed that PD-L1 expression was significantly lower in prostate cancer than in bladder cancer and in renal cell carcinoma (p 

Conclusions

The present study showed that PD-L1 expression is very low in prostate cancer. The SP142 assay detected PD-L1 expression in only two cases and both had metastatic sites. These findings suggest that there may be an association between PD-L1 expression and prostate cancer metastasis.

Clinical trial indentification

Legal entity responsible for the study

N/A

Funding

Japanese Society for the Promotion of Science

Disclosure

All authors have declared no conflicts of interest.