子宫内膜癌肉瘤中程序性死亡配体 1 与程序性死亡配体 2 的表达：与错配修复蛋白表达状态、TIL（肿瘤浸润淋巴细胞）浸润及临床结局的相关性

Endometrial carcinosarcomas have high malignant potential with a high recurrence rate and poor prognosis. Immunotherapy may be a promising treatment option. The aim of this study is to evaluate the expression of PD-L1/PD-L2 and its relationship to mismatch repair (MMR) protein status and tumor-infiltrating lymphocyte (TIL) density.

We performed immunohistochemical analyses of PD-L1 (clone 22C3), PD-L2 (clone TY25), MSH-2, MSH-6, PMS-2, and MLH-1 in 77 tumors. We count TILs using CD8 antibody. Clinicopathologic features were recorded and statistically correlated with immunohistochemical results. Kaplan-Meier analyses were used to analyze the prognosis.

While PD-L1 positivity was seen more commonly in MMR protein deficient tumors (p = 0.010), PD-L2 positivity was seen more commonly in MMR protein proficient tumors (p = 0.003). PD-L1 positivity was also found to be more common in carcinosarcoma with high TIL infiltration. PD-L2 positivity was associated with decreased overall survival (OS) rates (p = 0.043, p = 0.043, respectively), whereas the PD-L1 positivity and TIL density were not significantly associated with OS rate. The OS rate of patients with MMR protein proficient tumors was significantly lower compared with those with MMR protein deficient tumors (p = 0.042). The lower TILs infiltration was associated with a shorter disease-free survival (DFS) rate. PD-L1 and PD-L2 positivity did not affect the DFS rate.

PD-L1/PD-L2 might be a better target for immunotherapy in endometrial carcinosarcoma. PD-L2 positivity was also associated with a worse clinical outcome in patients with endometrial carcinosarcoma, suggesting that PD-L2 status can be used to predict clinical behavior. Further studies are needed to elucidate the relationship between PD-L1/PD-L2 expression and therapeutic response.