66P PD-L1 expression following neoadjuvant chemotherapy is upregulated and serves as a prognostic factor in patients with advanced high-grade serous ovarian carcinoma

Patients with high-grade serous ovarian carcinoma (HGSOC) gradually acquire resistance to standard chemotherapy after recurrence. In our previous study of HGSOC, histone deacetylase (HDAC)6 upregulation led poor prognosis, and programmed cell death ligand-1(PD-L1) expressions positively correlated HDAC6 expression. We analyzed the expression PD-L1 pre- post-chemotherapy investigate their association resistance. were immunohistochemically using clinical samples obtained before (combination platinum taxane agents) from 54 patients HGSOC. The clinicopathological characteristics, including surgical status, RECIST response score, reviewed. High (≥ 5%) was detected in 5 8 cases post-chemotherapy, respectively. mean positive rate 3.88%, which significantly higher than 0.68% (p=0.045). high frequency increased 4 pre-chemotherapy 13 (p=0.019). score 3, signifying chemosensitivity. progression-free (p=0.037) overall survival (p=0.049), group complete resection. residual tumors had enhanced PD-L1, are associated tumor immunity, proliferation, hypoxic responses. also patient prognosis. These results suggest that may serve as therapeutic targets prognostic factors for