OR-2100

Crizotinib and alectinib are first- and second-generation ALK TKIs, respectively, approved for the treatment of ALK-positive ALCL (ALK ALCL) and ALK NSCLC...Thus, to improve the clinical outcomes of ALK ALCL therapy, we investigated the synergistic efficacy of the combination of alectinib and the DNA-demethylating agent azacytidine, decitabine, or OR-2100 (an orally bioavailable decitabine derivative)...The combination of alectinib and OR-2100 markedly altered gene expression in ALCL cells, including that of genes implicated in apoptotic signaling, which possibly contributed to the synergistic anti-ALCL effects of this drug combination. Therefore, alectinib and OR-2100 combination therapy has the potential to improve the outcomes of patients with ALK ALCL.

The standard treatment for elderly patients with acute myeloid leukemia (AML) is venetoclax (Ven), a BCL-2-selective inhibitor, combined with hypomethylating agents (HMA) such as azacitidine or decitabine. The standard treatment for elderly patients with AML is Ven combined with HMAs. OR21, a new oral HMA plus Ven showed synergistic antileukemia effects in vitro and vivo, suggesting that the combination of OR2100 plus Ven is a promising candidate oral therapy for AML.

Here, we investigated the effect of combination treatment with DNA demethylating agents (azacytidine (AZA), decitabine (DAC), and OR-2100 (OR21), which is silylated derivative of decitabine) and inhibitors of enhancer of zeste homolog 2 (EZH2) (EPZ-6438 and DS-3201b) which catalyze trimethylation of H3K27, in ATL. DUSP5 was downregulated by DNA methylation and H3K27me3 accumulation in the promoter region in HTLV-1-infected cells from ATL patients during ATL leukemogenesis. The present results demonstrate that dual targeting of aberrant DNA and histone methylation synergistically suppresses tumor cell growth by restoring DUSP5, and the dual targeting of aberrant DNA and histone methylation is a feasible therapeutic approach for ATL.

Recently, we reported that regional DNA hypermethylation in HTLV-1-infected T-cells reflects the disease status of ATL and the anti-ATL effects of DNA demethylating agents, including azacitidine (AZA), decitabine (DAC) and a new DAC prodrug, OR-2100 (OR21), which we developed. Both genomic mutations might lead to loss of protein expression. Thus, inactivation of UCK2 and DCK might be a putative cause of phenotypes that are resistant to AZA and DAC/OR21, respectively.

We investigated the efficacy of OR-2100 (OR21), the first orally available single-compound prodrug of decitabine...OR21 in combination with imatinib significantly suppressed tumor growth in a xenotransplant model...These results demonstrate that targeting DNMT1 using OR21 exerts anti-tumor effects and impairs LSCs in CML. Therefore, combination treatment of TKIs and OR21 represents a promising treatment strategy in CML.