Analysis of Immunoexpression of Programmed Death Ligand 1 (PD-L1) and Proliferation Index Ki-67 on Diffuse Astrocytic Tumours (DAT)

Abstract

Background
Diffuse astrocytic tumours (DAT) is a diffuse infiltrative astrocytoma tumor accompanied by molecular parameters in the form or absence of
Isocitrate Dehydrogenase (IDH) gene mutations. The DAT category without the examination of the IDH gene mutation is classified as Not
Otherwise Specified (NOS). Ki-67 is a marker for DAT proliferation so that it can assess the degree of DAT. Diffuse astrocytic tumours
behavior is influenced by proliferative ability and the presence of a tumor microenvironment. The tumor microenvironment PD-L1 factor
influences DAT behavior and allows the development of target therapy in DAT cases. This study aimed to analyze the relationship between
PD-L1 and Ki-67 imunoexpression in the histopathological degree of DAT.
Methods
Cross-sectional study of 30 paraffin blocks of DAT NOS cases from 2014-2018 in the Department of Anatomical Pathology RSUP dr. Hasan
Sadikin, Bandung. The sample consisted of 15 cases of grade II, 7 cases of grade III and 8 cases of grade IV, carried out
immunohistochemical staining with GFAP, PD-L1 and Ki-67. Assessment of PD-L1 immunoexpression was carried out by the histoscore
method. The Ki-67 assessment was assessed based on its distribution, which was <10% and ≥10%. PD-L1 and Ki-67 immunoexpression
with histopathological degrees in DAT were statistically analyzed by Kolmogorof Smirnov test, however association between
immunoexpression of PD-L1 and Ki-67 were analyzed by chi-square test.
Results
There was a significant relationship between PD-L1 immunoexpression and histopathological degree in DAT (p=0.005). There was a
significant relationship between Ki-67 immunoexpression and DAT histopathology degree and with PD-L1 (p=0.001 and p=0.010).
Conclusion
PD-L1 immunoexpression and proliferation rates affect the degree of DAT. Proliferation rate of DAT is influenced by PD-L1 so that in this
study, PD-L1 and Ki-67 can be used as a marker of prognosis predictors.