LAUSR

Background: Ovarian high-grade serous carcinoma (HGSC) gradually acquires chemoresistance after recurrence. Our previous study on ovarian clear-cell carcinoma found histone deacetylase 6 (HDAC6) overexpression led to chemoresistance. This study aimed to evaluate HDAC6 as a predictor of chemoresistance and a therapeutic target for ovarian HGSC. Patients and Methods: The clinical significance of HDAC6 as a predictor of prognosis and chemoresistance in HGSC was immunohistochemically evaluated. In addition, expression of programmed cell death ligand-1 (PD-L1), and hypoxia-inducible factor-1α (HIF1α) were analyzed using clinical samples from 88 patients with ovarian HGSC, and their clinicopathological characteristics were reviewed. Results: Twenty-three patients had high HDAC6 expression, 10 positive PD-L1 expression, and 33 high HIF-1α expression. HDAC6 up-regulation was correlated with not undergoing interval debulking surgery (p<0.001), incomplete surgical resection (p=0.002), and frequent occurrence of stable disease/progressive disease according to the Response Evaluation Criteria in Solid Tumors (p=0.005) criteria. On Kaplan-Meier analysis, high HDAC6 expression was significantly associated with reduced progression-free (p=0.001) and overall (p=0.008) survival. On multivariate analysis, high HDAC6 expression (hazard ratio=1.65, 95% confidence interval 1.03-2.66; p=0.039) and surgery status were independent prognostic factors of progression-free survival. PD-L1 and HIF1α expression positively correlated with that of HDAC6. Conclusion: HDAC6 may become a potential therapeutic target in patients with ovarian HGSC since its up-regulation is considered to be associated with a poor prognosis in patients with this cancer.