article = {COR-2020-1-106}
title = {Comparative Study of PD-L1 Status between Surgically Resected Specimens and Matched Biopsies of Gastric Cancer Reveal Major Discordances: A Potential Issue for Anti-PD-L1 Therapeutic Strategies}
journal = {Clinical Oncology and Research}
year = {2020}
issn = {2613-4942}
doi = {http://dx.doi.org/10.31487/j.COR.2020.01.06}
url = {https://www.sciencerepository.org/comparative-study-of-pd-l1-status-between-surgically_COR-2020-1-106 
author = {Hyae Min Jeon ,Hyo Song Kim,Kum Hee Yun,Min Ju Kim ,Min Kyung Jeon,Soo Hee Kim,Ye Young Rhee ,}
keywords = {	PD-L1, immunotherapy, immunohistochemistry, gastric cancer}
abstract ={Background: Inhibitors of programmed death-ligand 1 (PD-L1) have potential therapeutic value in gastric
cancer. We investigated PD-L1 expression patterns in paired biopsy and resection specimens.
Patients and Methods: Thirty-nine formalin-fixed, paraffin-embedded paired samples were assessed using
PD-L1 22C3 pharmDx immunohistochemistry technique. Combined positive score (CPS) was calculated as
the ratio of PD-L1 stained cells (tumor cells, lymphocytes, and macrophages) to the total number of viable
tumor cells, multiplied by 100. The CPS ≥1 indicated PD-L1 positivity.
Results: PD-L1 positivity was evident for 33 (84.6%) of 39 resection cases; all displayed low positivity
(1≤CPS<50). Only 10 (30.3%) of 33 positive cases in the resection specimens had simultaneous PD-L1
positivity in the paired biopsy specimens; two cases displayed high positivity (CPS 50 and 70) and eight
displayed low positivity (1≤CPS≤50). Among the 29 negative cases with biopsy specimens, 23 (79.3%)
displayed PD-L1 low positivity in the paired resection specimens and only six had concordant negativity in
both specimens with poor agreement (concordance rate 41.0%, k value = 0.118, correlation coefficient
0.234; p=0.152). All the high microsatellite instability cases had concordant PD-L1 positivity in resection
and biopsy specimens.
Conclusions: There was relatively poor agreement of PD-L1 expression between biopsy and resected tumor
specimens. The biopsy specimens underestimated the PD-L1 status observed for the total resected samples.
This indicates the necessity of obtaining multiple biopsies from different areas of the tumor to enhance the
validity and reliability of PD-L1 analysis.}