Targeting Acute Myelogenous Leukemia Using Potent Human Dihydroorotate Dehydrogenase Inhibitors Based on the 2-Hydroxypyrazolo[1,5-a]pyridine Scaffold: SAR of the Biphenyl Moiety

[Image: see text] The connection with acute myelogenous leukemia (AML) of dihydroorotate dehydrogenase (hDHODH), a key enzyme in pyrimidine biosynthesis, has attracted significant interest from pharma as a possible AML therapeutic target. We recently discovered compound 1, a potent hDHODH inhibitor (IC(50) = 1.2 nM), able to induce myeloid differentiation in AML cell lines (THP1) in the low nM range (EC(50) = 32.8 nM) superior to brequinar’s phase I/II clinical trial (EC(50) = 265 nM). Herein, we investigate the 1 drug-like properties observing good metabolic stability and no toxic profile when administered at doses of 10 and 25 mg/kg every 3 days for 5 weeks (Balb/c mice). Moreover, in order to identify a backup compound, we investigate the SAR of this class of compounds. Inside the series, 17 is characterized by higher potency in inducing myeloid differentiation (EC(50) = 17.3 nM), strong proapoptotic properties (EC(50) = 20.2 nM), and low cytotoxicity toward non-AML cells (EC(30)(Jurkat) > 100 μM).