ENTPD1 and neoplasm: In this study, PD-1 marker was used to enrich neoantigen-reactive T cells from tumor specimens.27–29 However, recent results suggested that PD-1 might not be the best marker for neoantigen-reactive T cells.43 Other markers, such as CD39 and CD103, have been proposed as more precise markers for neoantigen-reactive T cells.