Epithelial ovarian cancer requires the development of treatments according to histology, and immune checkpoint inhibitors may be a new therapeutic strategy in ovarian clear cell carcinoma (OCCC). Lymphocyte activation gene 3 (LAG-3), an immune checkpoint, is a poor prognostic factor and a new therapeutic target for several malignancies.
In this study, we demonstrated a correlation between LAG-3 expression and the clinicopathological features of OCCC. We evaluated LAG-3 expression in tumor-infiltrating lymphocytes (TILs) by immunohistochemistry using tissue microarrays containing surgically resected specimens from 171 patients with OCCC.
The LAG-3-positive cases were 48 (28.1%); the LAG-3-negative cases were 123 (71.9%). The expression of LAG-3 significantly increased in patients with advanced stages (P = 0.036) and recurrence (P = 0.012). However, LAG-3 expression did not correlate with age (P = 0.613), residual tumor (P = 0.156), or death (P = 0.086). Using the Kaplan−Meier method, LAG-3 expression was observed to be correlated with poorer overall survival (P = 0.020) and progression-free survival (P = 0.019) than no expression. Multivariate analysis regarded LAG-3 expression (hazard ratio= 1.86; 95% confidence interval, 1.00−3.44, P = 0.049) and residual tumor (hazard ratio = 9.71; 95% confidence interval, 5.13−18.52, P < 0.001) as independent prognostic factors.
This study demonstrated that LAG-3 expression in patients with OCCC may be a useful biomarker for predicting prognosis and a new therapeutic target.