PD-L1 expression in soft tissue sarcomas and its prognostic implication

Summary

The purpose of this study to investigate the expression of PD-L1 and its clinic-pathological feature in soft tissue sarcomas (STS). We collected Paraffin embedded tissue of 50 Patients with STS retrospectively from the archives of Pathology and Oncology Department, Ain Shams University Hospitals from 2011-2017, then we correlated between PD-L1 expression and the clinico-pathological features. PD-L1 expression was found in 12 (24%) of cases. Of all sarcoma subtypes, desmoid tumors had the highest prevalence of PD-L1 expression noted in 2/3 (66%) of samples followed by GIST 2/4(50%), then liposarcoma 3/11(27%). 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) in PD-L1 positive and negative respectively; this finding considered as clinically significant, but not reached to statistical significant. We report here that PD-L1 expression is as prognostic factor for poorer outcome. This finding may be clinically significant 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.