(R) -OR-S1

(R) -OR-S1 is an isomer of OR-S1. The dual ZH1/2 inhibitors OR-S1 and OR-S2 exhibit strong inhibitory activity against both EZH1 and EZH2. OR-S1 and OR-S2 are highly selective methyltransferase inhibitors against EZH1 and EZH2, and they have very similar molecular features. Therefore, we investigated the effect of OR-S1 on acute myeloid leukemia (AML) . We found that OR-S1 was able to induce cell differentiation and apoptosis in AML cells. These findings encouraged us to investigate whether functional LT-HSCs could survive PRC2-targeted therapy with OR-S1 or OR-S1 combined with cytarabine. The results showed that OR-S1 did not cause significant myelosuppression, and BM cells treated with the combination therapy were able to undergo normal hematopoiesis even 4 months after treatment. Therefore, temporary inhibition of EZH1 and EZH2 is clinically tolerable, making this combination therapy suitable for AML patients. AML is generally believed to originate from myeloid progenitor cells that inherit a large number of biological properties.