OR21

OR21 is an **orally available, silylated deoxynucleotide analog** designed as a next-generation hypomethylating agent, developed to serve as an alternative to azacitidine or decitabine for the treatment of hematologic malignancies such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). It induces **global DNA hypomethylation by depleting DNA methyltransferase 1 (DNMT1)**, thereby promoting tumor suppressor gene expression, cell differentiation, and immune system activation in malignant cells. OR21 demonstrates antitumor activity through inhibition of cellular growth and induction of apoptosis in MDS and AML cells, both in vitro and in vivo. Its safety profile appears favorable compared to decitabine, with the added advantage of oral administration, attributed to its chemical modification (silylation) improving bioavailability[1].