Abstract PS2-30: The expression of PD-L1 (Ventana SP142) in HER2-positive breast cancer and its relationship with clinicopathological characteristics
Authors: Zhang Ningning , Liu Yueping 
Published: February 2021

Abstract
Objective: This article aims to investigate the correlation between the expression of PD-L1 and tumor-infiltrating lymphocytes, clinicopathological features and prognosis in HER2-positive breast cancer.Methods: This study included 156 cases of HER2-positive breast cancer. Three 2mm tumor cores were selected for each case, and the expression of PD-L1 on ICs was detected by Immunohistochemistry. Statistical software SPSS 24.00 was used for analysis, χ2 test and Fisher exact test were used for correlation and consistency analysis; Logistic regression analysis was used for multivariate analysis; Kaplan-Meier analysis was used for univariate survival; Cox regression analysis was used for multivariate survival; TILs and PD-L1 correlation was analyzed by Spearman rank; P&lt;0.05 was considered statistically significant.Results: In HER2-positive breast cancer the expression rate of PD-L1 on ICs was 31.4%. In HER2-positive breast cancer the expression of PD-L1 on ICs was significantly correlated with the tumor size, the presence or absence of lymphovascular invasion, the expression of TILs, CD4 and CD8 (P&lt;0.05); obtained using Logistic multivariate regression analysis The tumor size, the presence or absence of vascular tumor plugs, the expression of TILs and CD8 were independent factors affecting PD-L1 expression (P &lt;0.05). Spearman rank correlation analysis showed that TILs infiltration level was positively correlated with interstitial immune cell PD-L1 expression in HER2-positive breast cancer patients (r = 0.486,P &lt;0.05). Univariate survival analysis of disease-free survival (DFS) for HER2-positive breast cancer the patient's tumor size, lymphovascular invasion, lymph node metastasis, TILs, tumor immune microenvironment classification-CD4 (TIME-CD4) and tumor immune microenvironment classification-CD8 (TIME-CD8) has a significant effect on patients' DFS (P&lt;0.05); multivariate survival analysis revealed that patients had lymphovascular invasion, TILs, TIME-CD4 and TIME-CD8 as HER2-positive breast cancer independent factors of DFS (P&lt;0.05).Conclusions: The expression of PD-L1 on ICs in HER2-positive breast cancer is related to tumor size, presence or absence of lymphovascular invasion, TILs,CD4 expression and CD8 expression.The independent influencing factors of disease-free survival in patients with HER2-positive breast cancer are the presence or absence of lymphovascular invasion, TILs, TIME-CD4 and TIME-CD8. Among them, patients with no lymphovascular invasion and higher levels of tumor infiltrating lymphocytes had better prognosis; CD4-/PD-L1- group had better prognosis in the TIME-CD4 and CD8+/PD-L1- group had better prognosis in the TIME-CD8. There is a positive correlation between TILs infiltration level and PD-L1 expression, suggesting that HER2-positive breast cancer patients can be accurately treated according to different TILs infiltration levels and PD-L1 expression.Key words: breast cancer; HER2-positive;PD-L1;TILs
Citation Format: Ningning Zhang, Yueping Liu. The expression of PD-L1 (Ventana SP142) in HER2-positive breast cancer and its relationship with clinicopathological characteristics [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-30.