AUTHOR=KELANY MOHAMED , FE Barth Thomas , Salem Dina , Shakweer Marwa M.

TITLE=Prevalence and Prognostic Implications of PD-L1 Expression in Soft Tissue Sarcomas

JOURNAL=Pathology and Oncology Research

VOLUME=Volume 27 - 2021

YEAR=2021

URL=https://www.por-journal.com/journals/pathology-and-oncology-research/articles/10.3389/pore.2021.1609804

DOI=10.3389/pore.2021.1609804

ISSN=1532-2807

ABSTRACT=Background 
The expression rate of PD-L1 in malignant tumors has been reported to vary from 19% to 92%; the expression of PD-L1 is associated with poor prognosis in various neoplasias and may predict the response to immune checkpoint inhibitors. The purpose of this study was to investigate the expression of PD-L1 and its clinic-pathological feature in soft tissue sarcomas (STS).
Patients and Methods 
We collected paraffin embedded tissue of 50 patients with STS from the archives of from 2011-2017 and correlated the PD-L1 expression and the clinical features. For PD-L1 expression, we followed a 6-step proportional scoring system. The differences among variables were calculated by chi-square test. 
Results
PD-L1 expression was found in 12 (24%) of cases. Of all sarcoma subtypes, Rhabdomyosarcoma and desmoid tumors had the highest prevalence of PD-L1 expression in 2/2 and 2/3 respectively, followed by GIST in 2/4, and liposarcoma 3/11. We found that STS patients with PD-L1 expression have shorter survival with a median OS 11 vs. 19 months (p-value=0.1) as well as a mean PFS 6 vs. 11 months (p-value=0.1). 
Conclusion 
We report here that PD-L1 expression is as prognostic factor for poorer outcome. This finding points to a clinically relevant finding but does not reach the statistically significant levels due to small number of samples included. Its role beyond that of a prognostic biomarker remains to be established in the context of larger clinical trials.