ENTPD1 and neoplasm: Studies have demonstrated the positive role of multiple biomarkers such as tumor mutation burden (TMB) (Goodman et al., 2017), the abundance of tumor-infiltrating immune cells (TICs) (Petitprez et al., 2020), and the expression level of PD-L1 (Jia et al., 2018) and CD39 (also known as ENTPD1) (Allard et al., 2017; Moesta et al., 2020) in predicting the response rate to immune checkpoint inhibitors (ICIs).