They need additional steps of enzymatic processing as is the case of capecitabine, the prodrug of 5-FU, or have been reported as functional inhibitors of SAMHD1 as gemcitabine [55], indicating that predictive value of SAMHD1 is not limited to drugs that can be used as enzyme substrates but also goes far beyond its effects in hematological cancers. Here, SAMHD1 is linked to hematopoietic and lymphoid cell neoplasm.