Prognostic Role of PD-L1 Expression in Oral Squamous Cell Carcinoma
Varies by Oral Compartments and Immunostaining Patterns: A Meta-analysis
Abstract
Blocking the PD-L1/PD-1 pathway efficiently enhanced antitumor immunity
that reduced tumour growth and improved survival, whereas the prognostic
roles of PD-L1 positivity in oral squamous cell carcinoma (OSCC) were
controversial. This study aimed to determine the clinicopathological and
prognostic significance of PD-L1 expression in tumor cells (TCs) or
tumor-infiltrating lymphocytes (TILs) of OSCC. The systematic retrieve
was performed for seeking suitable studies through PubMed, Web of
Science, the Cochrane Library and Scopus. 46 studies were ultimately
included in the meta-analysis. This study showed that the levels of
PD-L1 expression in TCs were relatively high in femal patients (P
<0.001), non-smoker (P <0.001), non-drinkers (P
=0.037), advanced stage (P =0.028), N+ status (P =0.027), and tumours
with high levels of PD-1 (P =0.024), and CD8+ (P =0.022). High PD-L1
expression in TCs had significant effect on worse LRFS (P=0.004), and
also was more likely to have worse OS in Asia (P =0.018). Both DSS (P
=0.035) and DFS (P =0.003), at a 5% cut-off of PPC, had positive
association with high PD-L1 expression. The results of OS showed that a
worse prognosis for 5H1 (P =0.032), and a favourable prognosis for
22C3(P =0.001). E1L3N was shown to be associated with an worse DSS (P
=0.014). High expressions of PD-L1 in TCs had a worse OS (P =0.023) and
DFS (P =0.003) in OSCC of the tongue. Consequently, future study should
especially consider oral compartments and methods for PD-L1
immunostaining as confounding factors when observing PD-L1 of response
to anti-PD1 therapy.