Neoantigen-specific TILs frequently exhibit stronger anti-tumor activity and tumor-specific expansion as compared to blood-emigrant bystander and regulatory TILs at various signatures and phenotypes.399–403 CD39, a marker of T cell reactivity to tumors and T cell exhaustion, can be used to identify the tumor-reactive T cells in a variety of malignancies. Here, ENTPD1 is linked to neoplasm.