Objectives Role of checkpoint inhibitors in ovarian cancer is still unknown and results from ongoing clinical trials are still awaited. We aim in this study to assess the expression of PD-L1 using the Combined Positive Score (CPS) and to evaluate its impact on the overall survival in a cohort of 49 patients diagnosed with high-grade serous ovarian cancer.

Methods Medical charts were reviewed of 49 patients with high-grade serous ovarian cancer operated on at the gynecologic oncology department in Hôtel-Dieu de France hospital, Lebanon, between 2015 and January 2020. Immunohistochemical staining was performed for PD-L1 (Agilent Dako, PDL-1 IHC 22C3) and for TP53 (Agilent Biogenex, clone D07, 1:100 dilution) on whole tissue sections from a representative block of formalin-fixed, paraffin-embedded tumor tissue.

Results 55% of patients presented a positive PD-L1 status. No correlation was found between the PD-L1 status and the stage of the disease. Lymph node status was similar between the two cohorts, positive vs. negative CPS score (p = 0.927). Median follow-up was 36 months (range, 12 – 72 months). Survival rate was similar between the two cohorts, positive vs. negative PD-L1 status (88.9% vs. 72.7% respectively, p = 0.14). No correlation was found between recurrence rate and PD-L1 status (p = 0.184). No correlation was found between PD-L1 status and TP-53 type (wild vs. mutated) (p = 0.154)

Conclusions PD-L1 status has no impact on the prognosis of patients with high-grade serous ovarian cancer. Also, patients with TP53-mutation do not present increased expression of PD-L1 in comparison to patients with TP53 wild-type.