Discovery and structure-activity relationship study of novel hydantoin-based inhibitors targeting mutant isocitrate...

Mutations in isocitrate dehydrogenases (IDHs) are frequently observed in various malignancies. These mutations confer a neomorphic enzymatic activity, leading to the reduction of α-KG to the oncometabolite 2-HG. The aberrant accumulation of 2-HG inhibits α-KG-dependent histone and DNA demethylases, thus contributing to tumorigenesis. Consequently, considerable efforts have been directed toward the development of selective inhibitors targeting mutant IDHs. Herein, we report a high-throughput virtual screening campaign utilizing a chemical library of 1795658 compounds, which led to the identification of a promising IDH1 R132H inhibitor. Subsequent structure-based optimization yielded compounds 13e and 16a, which displayed potent inhibition of IDH1 R132H (IC₅₀ = 0.26 and 0.22 μM) and IDH1 R132C (IC₅₀ = 1.1 and 0.93 μM), while showing negligible activity against wt-IDH1 and wt-IDH2. Furthermore, both compounds effectively suppressed intracellular 2-HG production in U87-MG R132H cells (EC₅₀ = 0.55 and 1.45 μM). Additionally, 13e and 16a exhibited moderate antiproliferative effects against U87-MG R132H and HT-1080 cells, while exhibiting low cytotoxicity toward normal human cells even at concentrations up to 40 μM.