ENTPD1 and neoplasm: Co-expression of CD39 and CD103 has been proposed to identify tumor-reactive CD8+ T cells in different solid malignancies.32 33 Of the 11 patients studied here, we only found CD39+CD103+CD8+ T cells in one PDAC tissue (ISPIC20), constituting 35% of all CD45+ cells in this patient (figure 2B).