Abstract P1-09-05: Overexpression of CD155 in breast cancer microenvironment, associated with higher counts of tumor-infiltrating lymphocytes and increased risk of relapse and death
Authors: Song Qingkun , Lv Shuzhen 
Published: March 2020

Abstract
Background: CD155 is poliovirus receptor and has an overexpression in malignant tissues. However the expression status and the association with prognosis and clinical characteristics were seldom reported in breast cancer patients. This study aimed to investigate the expression of CD155 and the association with prognosis and pathological features of breast cancer.
Methods: 126 patients were recruited this cohort study consecutively and CD155 expression on tumor cells were detected by immunohistochemistry. Kaplan-Meier survival curve and Cox Hazard Regression model were used to estimate the association.
Results: 38.1% patients had an overexpression of CD155 and the percentage of tumor cells overexpressing CD155 was 17%, 39%, 37% and 62% among Luminal A, Luminal B, HER2-positive and TNBC cases, respectively (p&lt;0.05). The percentage was higher in Luminal B and TNBC cases than that in Luminal A patients. Among patients with low expression of CD155, Ki-67 index was 26%, significantly lower than patients with CD155 overexpression (42%).Cell count of TILs was 144/HPF among patients with CD155 overexpression, in comparison of 95/HPF among patients with low expression of CD155 (p&lt;0.05). However, the percentage of PD-1+ TILs was significantly higher (17% vs. 13%) in patients with CD155 overexpression than that of patients with low expression of CD155 (p&lt;0.01) and the cell count of PD-1+ TILs was 52/HPF and 25/HPF among patients with overexpression and low expression of CD155, respectively (p&lt;0.01).
The median follow-up time was 75 months and the rate of loss of follow-up was 7.1% and 10.3% for relapse and overall survival respectively. The mean DFS length was 86 months among patients with low expression of CD155, significantly longer than patients (73 months) with CD155 overexpression. The mean OS length was 87 months among patients with low expression of CD155, significantly longer than patients (78 months) with CD155 overexpression.
The disease-free survival and overall survival rate was 88.5% and 87.2% among patients with low expression of CD155, however the survival rate reduced to 56.3% and 62.5% among patients with overexpression of CD155. The study power was 97.7% and 87.3% for disease-free and overall survival rate. In COX-Hazard regression analysis, the overexpression of CD155 was associated with a 5.41-fold high risk of relapse (95%CI 1.93, 15.20) and a 3.74-fold high risk of death (95%CI 1.25, 11.16); under further adjustment, the HR of relapse increased to 13.93 (2.82, 68.91) and the HR of death increased to 5.47 (95%CI 1.42, 20.99) (Table 1).
Conclusions: Overexpression of CD155 was correlated with more proliferative cancer cells and a dysfunctional immune microenvironment. CD155 overexpression introduced a worse relapse-free and overall survival and might be a potential immunotherapy target for breast cancer.
Table 1. Cox-Hazard regression on association between CD155 expression and prognosisCD155 expressionHRcrude95%CIHR*95%CIHR**95%CILow expression (n=78)Overexpression (n=48)Disease-free survival, n (%)Relapse6 (7.7)15 (31.3)5.411.93, 15.205.682.01, 16.0213.932.82, 68.91Survival69 (88.5)27 (56.3)Overall survival, n (%)Death6 (7.7)9 (18.8)3.741.25, 11.164.511.50, 13.635.471.42, 20.99Survival68 (87.2)30 (62.5)*further adjusting age, ** further adjusting age, histological grade and molecular subtype.
Citation Format: Qingkun Song, Shuzhen Lv. Overexpression of CD155 in breast cancer microenvironment, associated with higher counts of tumor-infiltrating lymphocytes and increased risk of relapse and death [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-09-05.