ABSTRACT
High throughput screening and subsequent hit validation identified 4-isopropyl-3-(2-((1-phenylethyl)amino)pyrimidin-4-yl)oxazolidin-2-one as a potent inhibitor of IDH1R132H. Synthesis of the four separate stereoisomers identified the (S,S)-diastereomer (IDH125, 1f) as the most potent isomer. This also showed reasonable cellular activity and excellent selectivity vs IDH1wt. Initial structure-activity relationship exploration identified the key tolerances and potential for optimization. X-ray crystallography identified a functionally relevant allosteric binding site amenable to inhibitors, which can penetrate the blood-brain barrier, and aided rational optimization. Potency improvement and modulation of the physicochemical properties identified (S,S)-oxazolidinone IDH889 (5x) with good exposure and 2-HG inhibitory activity in a mutant IDH1 xenograft mouse model.
ABSTRACT
The Wnt signaling pathway is critical to the regulation of key cellular processes. When deregulated, it has been shown to play a crucial role in the growth and progression of multiple human cancers. The identification of small molecule modulators of Wnt signaling has proven challenging, largely due to the relative paucity of druggable nodes in this pathway. Several recent publications have identified small molecule inhibitors of the Wnt pathway, and tankyrase (TNKS) inhibition has been demonstrated to antagonize Wnt signaling via axin stabilization. Herein, we report the early hit assessment of a series of compounds previously reported to antagonize Wnt signaling. We report the biophysical, computational characterization, structure-activity relationship, and physicochemical properties of a novel series of [1,2,4]triazol-3-ylsulfanylmethyl)-3-phenyl-[1,2,4]oxadiazole inhibitors of TNKS1 and 2. Furthermore, a cocrystal structure of compound 24 complexed to TNKS1 demonstrates an alternate binding mode for PARP family member proteins that does not involve interactions with the nicotinamide binding pocket.