PD-L1 and TILS Expression among Triple Negative and HER2 Enriched Molecular Subtype of Breast Carcinoma

Abstract

Background
Triple negative and positive HER 2 subtype breast carcinoma are aggressive subtype that have worst prognosis among other
subtype. High level of tumor infiltrating lymphocytes (TILs) is associated with longer disease free survival and overall survival.
Breast cancer is also influenced by the presence of ligation between PD-1 and PD-L1, expressed by activated CD8+ T cells and
tumor cells, consecutively. To analysed the comparison of PD-L1 expression levels in triple negative breast cancer and HER2
enriched subtype.
Methods
A cross sectional study was conducted with 35 samples, which were immunostained with an anti-PD-L1 antibody. TILs were
measured on HE slides, and together with PD-L1 expression were calculated using image J. Clinicopathological data were obtained
from medical record. All data were analysed by SPSS V25.0
Results
A significant difference was observed between PD-L1 expression in HER2 enriched and triple negative samples, where the HER2
enriched subtype had a possibility to express PD-L1 3.3 times higher than those of triple negative (p = 0.021; OR = 3.3). There were
no significant differences in clinopathological characteristics or TILs density in both subtypes. Likewise, no significant differences
was found among PD-L1 expression, and intratumoral and stromal TILs expression.
Conclusion
Majority patient of both subtypes are mostly older than 40 years old, with positive LVI and higher histological grading. The HER2
expression showed a higher level of PD-L1 than triple negative. There was no significant difference of TILs expression between
these two subtypes of breast cancer.