Abstract 3186: Differential expression of PD-L1 between primary and metastatic Middle-Eastern epithelial ovarian carcinoma and its clinico-pathological correlation

Abstract

Abstract Ovarian cancer (OC) is one of the most common gynecologic cancer, which has the worst prognosis and highest mortality rate. The lack of curative treatment and the high relapse rate, especially in advanced OC, continues to present a clinical challenge, highlighting the need for new therapeutic strategies. This study was conducted to compare the expression of PD-L1 in Middle-Eastern primary epithelial ovarian carcinoma to that in peritoneal metastases and its correlation with clinico-pathological parameters. In total, 194 treatment naïve paired EOC and peritoneal metastases were analyzed by immunohistochemistry for PD-L1 expression. Clinico-pathological information was available for all patients. Significant differences in PD-L1 expression were found between primary EOC and peritoneal metastasis (p < 0.0001). We found discordant tumor cell PD-L1 expression between primary tumors and corresponding peritoneal metastasis in 34% (66/194) of cases. Furthermore, PD-L1 expression in peritoneal metastasis samples was significantly associated with adverse prognostic factors, such as high proliferative index (Ki67) (p = 0.0039) and high histologic grade (p = 0.0330). In conclusion, the heterogeneity of PD-L1 expression in EOC suggests its assessment as a potential biomarker for PD-L1 blockade may require analysis of metastatic lesions. Citation Format: Sandeep K. Parvathareddy, Abdul K. Siraj, Padmanaban Annaiyappanaidu, Felisa De Vera, Yan Kong, Zeeshan Qadri, Saeeda O. Ahmed, Hassan AlDossari, Khawla S. Al-Kuraya. Differential expression of PD-L1 between primary and metastatic Middle-Eastern epithelial ovarian carcinoma and its clinico-pathological correlation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3186.