PD-L1 immunohistochemical expression in ovarian serous carcinoma: Its relation to tumor grade, TILs, clinico-pathological prognostic parameters and patient?s survival

Abstract

Author(s): Mona Younis Youssef Abd Allah, Mostafa Abdel hakiem, Rania Mohamed Ali, and Maha Mazhar Mohamed Saif

Background: The most common reason for cancer-related mortality in women is ovarian cancer. Among all histological types, the serous carcinoma is the commonest. Immunotherapy has developed to be used in treating different cancers; among which Immune Checkpoint Inhibitors (ICIs) demonstrated great role in such cases. One of the significant challenges in cancer treatment is the selection of studied cases who will benefit from ICIs. It is established that ICI sensitivity in malignancies can be predicted using Programmed Cell Death Ligand 1 (PD-L1) expression. Prior research has confirmed a correlation among PD-L1 expression in ovarian tumours and Tumour Infiltrating Lymphocytes (TILs). However, regrettably, the Food and Drug Administration (FDA) has not yet approved use of anti-programmed cell death ligand 1 (antiPD-L1) in the treatment of ovarian cancer.

Aim and Scope: This study assesses an immunohistochemical expression of PD-L1 in ovarian serous carcinoma to testify its usage as a prognostic and predictive marker. We also investigate its association with tumor grade, TILs, clinico-pathological prognostic factors, and studied case’s survival.

Materials and Method: This work is retrospective research performed upon 100 cases of surgically resected ovarian serous carcinomas. Immunohistochemistry (IHC) for PD-L1 was applied to such biopsies then assessed and scored. TILs were also assessed using Haematoxylin and Eosin-stained slides. Finally, the outcomes were tabulated for statistical analysis.

Results: In this research, elevated PD-L1 expression had been significantly related to aggressive features of tumor including older age group, larger tumor size, higher tumor grade, advanced International Federation of Obstetrics and Gynecology (FIGO) stage and shorter patients’ mean survival time. On the other hand, tumors with positive TILs were significantly associated with younger age group, smaller tumor size, lower tumor grade, early FIGO stage and longer mean survival time. Consistently, PD-L1 overexpression show statistically significant association with tumors showing negative TILs (p ≤ 0.001).

Conclusion: We observed PD-L1 overexpression in aggressive features of ovarian serous carcinomas suggesting its poor prognostic and predictive role in such cases that require further studies.

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