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supplementary Table S1 to S3; Supplementary Figure S1 to S9

The ectonucleotidases CD39 and CD73 catalyze extracellular ATP to immunosuppressive adenosine, and as such, represent potential cancer targets. We investigated biological impacts of CD39 and CD73 in pancreatic ductal adenocarcinoma (PDAC) by studying clinical samples and experimental mouse tumors. Stromal CD39 and tumoral CD73 expression significantly associated with worse survival in human PDAC samples and abolished the favorable prognostic impact associated with the presence of tumor-infiltrating CD8+ T cells. In mouse transplanted KPC tumors, both CD39 and CD73 on myeloid cells, as well as CD73 on tumor cells, promoted polarization of infiltrating myeloid cells towards an M2-like phenotype, which enhanced tumor growth. CD39 on tumor-specific CD8+ T cells and pancreatic stellate cells also suppressed IFNγ production by T cells. Although therapeutic inhibition of CD39 or CD73 alone significantly delayed tumor growth in vivo, targeting of both ectonucleotidases exhibited markedly superior antitumor activity. CD73 expression on human and mouse PDAC tumor cells also protected against DNA damage induced by gemcitabine and irradiation. Accordingly, large-scale pharmacogenomic analyses of human PDAC cell lines revealed significant associations between CD73 expression and gemcitabine chemoresistance. Strikingly, increased DNA damage in CD73-deficient tumor cells associated with activation of the cGAS–STING pathway. Moreover, cGAS expression in mouse KPC tumor cells was required for antitumor activity of the CD73 inhibitor AB680 in vivo. Our study, thus, illuminates molecular mechanisms whereby CD73 and CD39 seemingly cooperate to promote PDAC progression.

The ectonucleotidases CD39 and CD73 catalyze extracellular ATP to immunosuppressive adenosine, and as such, represent potential cancer targets. We investigated biological impacts of CD39 and CD73 in pancreatic ductal adenocarcinoma (PDAC) by studying clinical samples and experimental mouse tumors. Stromal CD39 and tumoral CD73 expression significantly associated with worse survival in human PDAC samples and abolished the favorable prognostic impact associated with the presence of tumor-infiltrating CD8+ T cells. In mouse transplanted KPC tumors, both CD39 and CD73 on myeloid cells, as well as CD73 on tumor cells, promoted polarization of infiltrating myeloid cells towards an M2-like phenotype, which enhanced tumor growth. CD39 on tumor-specific CD8+ T cells and pancreatic stellate cells also suppressed IFNγ production by T cells. Although therapeutic inhibition of CD39 or CD73 alone significantly delayed tumor growth in vivo, targeting of both ectonucleotidases exhibited markedly superior antitumor activity. CD73 expression on human and mouse PDAC tumor cells also protected against DNA damage induced by gemcitabine and irradiation. Accordingly, large-scale pharmacogenomic analyses of human PDAC cell lines revealed significant associations between CD73 expression and gemcitabine chemoresistance. Strikingly, increased DNA damage in CD73-deficient tumor cells associated with activation of the cGAS–STING pathway. Moreover, cGAS expression in mouse KPC tumor cells was required for antitumor activity of the CD73 inhibitor AB680 in vivo. Our study, thus, illuminates molecular mechanisms whereby CD73 and CD39 seemingly cooperate to promote PDAC progression.

4060 Background: Immune scoring based on T-cell subsets and density can add prognostic value to conventional TNM staging for patients with solid tumors, but limited data are available for pancreatic adenocarcinoma. Methods: Using tissue microarrays, CD3, CD4, CD8, CD45RO, and FOXP3 T-cells were quantified by immunohistochemistry in the intratumoral (IT) compartment and peritumoral (PT) parenchyma of 111 consecutively resected specimens. T-cell counts were correlated with patient overall survival, disease-free survival, and time to recurrence (OS, DFS, TTR) by Cox regression, controlling for clinicopathological factors. An immune score (IS) based on IT CD4 T-cell count > median, PT CD8 T-cell count ≤ median, and IT/PT CD3 T-cell ratio >1, grouped patients into high, intermediate, or low categories if all 3, 1 to 2, or none of these immune features were present, respectively. Results: Median follow-up time was 20 months, and 85% of patients either died or recurred during the study period. By univariate analysis, PT CD8 T-cell count was associated with shorter OS (p=0.02), whereas both IT CD4 T-cell count and IT/PT CD3 T-cell ratio were associated with longer OS (p=0.01 and p=0.05, respectively). Alone, none of these immune features predicted TTR. Combined into an IS, patients in the high (n=23), intermediate (n=60), or low (n=23) categories had significantly different OS (respective medians 30, 17, and 13 months, log-rank p=0.01), DFS (28, 16, and 12 months, p=0.01), and TTR (21, 14, and 10 months, p=0.02). By multivariate analysis, the association between IS and clinical outcomes was independent of tumor size, extra-pancreatic invasion, and nodal metastases (TNM staging). The IS discriminated outcomes among patients with nodal metastases (n=80), such that node-positive patients with a high IS had a median survival similar to node-negative patients (30 and 33 months, p=0.7). FOXP3 and CD45RO T-cell counts did not appear to add prognostic value to the IS. Conclusions: An immune score that combines specific T-cell location and density may have prognostic value in patients with resected pancreatic adenocarcinoma, independently from pathologic features currently used for staging.