Overexpression of CD73 in pancreatic ductal adenocarcinoma is associated with immunosuppressive tumor microenvironment and poor survival.

Background: CD73, a newly recognized immune checkpoint mediator, is expressed in several types of malignancies. However, CD73 expression and its impact on tumor microenvironment and clinical outcomes in pancreatic ductal adenocarcinoma (PDAC) remain unclear.

Methods: This study included two cohorts: 138 patients from our institution (MDA) and 176 patients from TCGA dataset. CD73 expression, CD4, CD8, CD21 and CD45RO + tumor infiltrating lymphocytes (TILs) were evaluated by immunohistochemistry using tissue microarrays. The results of CD73 expression were correlated with clinicopathologic parameters, survival and TILs.

Results: CD73 overexpression correlated with poor differentiation (P = 0.002) and tumor size (P = 0.049). For CD73-low group, median overall survival (OS) and recurrence-free survival (RFS) were 26.9 ± 3.8 months and 12.6 ± 2.6 months, respectively, compared to 16.9 ± 4.4 months (P = 0.01) and 7.9 ± 1.2 months (P = 0.01), respectively, in CD73-high group. CD73 was an independent predictor for both RFS (P = 0.02) and OS (P = 0.01) by multivariate variate analysis. Similarly, CD73-high tumors had significantly shorter OS than CD73-low tumors in TCGA dataset (P < 0.0001). CD73-high correlated with decreased CD4 TILs in MDA cohort and decreased CD8A and CR2 (CD21) expression in TCGA cohort.

Conclusions: CD73 overexpression is associated with poor differentiation, tumor size, and shorter survival, and is an independent prognostic factor in PDAC patients. CD73 overexpression is associated with decreased CD4, CD8 and CD21 TILs. Our data support that CD73 plays an important role in immunosuppressive tumor microenvironment and promote tumor progression in PDAC.