Inhibition of oncogenic transcriptional programs is a promising therapeutic strategy. A substituted tricyclic benzimidazole, SEL120-34A, is a novel inhibitor of Cyclin-dependent kinase 8 (CDK8), which regulates transcription by associating with the Mediator complex. X-ray crystallography has shown SEL120-34A to be a type I inhibitor forming halogen bonds with the protein's hinge region and hydrophobic complementarities within its front pocket. SEL120-34A inhibits phosphorylation of STAT1 S727 and STAT5 S726 in cancer cells in vitro. Consistently, regulation of STATs- and NUP98-HOXA9- dependent transcription has been observed as a dominant mechanism of action in vivo. Treatment with the compound resulted in a differential efficacy on AML cells with elevated STAT5 S726 levels and stem cell characteristics. In contrast, resistant cells were negative for activated STAT5 and revealed lineage commitment. In vivo efficacy in xenotransplanted AML models correlated with significant repression of STAT5 S726. Favorable pharmacokinetics, confirmed safety and in vivo efficacy provide a rationale for the further clinical development of SEL120-34A as a personalized therapeutic approach in AML.

Small unextended molecules based on the diamidophosphate structure with a covalent carbon-to-phosphorus bond to improve hydrolytic stability were developed as a novel group of inhibitors to control microbial urea decomposition. Applying a structure-based inhibitor design approach using available crystal structures of bacterial urease, N-substituted derivatives of aminomethylphosphonic and P-methyl-aminomethylphosphinic acids were designed and synthesized. In inhibition studies using urease from Bacillus pasteurii and Canavalia ensiformis, the N,N-dimethyl derivatives of both lead structures were most effective with dissociation constants in the low micromolar range (Ki = 13 ± 0.8 and 0.62 ± 0.09 μM, respectively). Whole-cell studies on a ureolytic strain of Proteus mirabilis showed the high efficiency of N,N-dimethyl and N-methyl derivatives of aminomethane-P-methylphosphinic acids for urease inhibition in pathogenic bacteria. The high hydrolytic stability of selected inhibitors was confirmed over a period of 30 days using NMR technique.

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Energy and biomass production in cancer cells are largely supported by aerobic glycolysis in what is called the Warburg effect. The process is regulated by key enzymes, among which phosphofructokinase PFK‐2 plays a significant role by producing fructose‐2,6‐biphosphate; the most potent activator of the glycolysis rate‐limiting step performed by phosphofructokinase PFK‐1. Herein, the synthesis, biological evaluation and structure–activity relationship of novel inhibitors of 6‐phosphofructo‐2‐kinase/fructose‐2,6‐biphosphatase 3 (PFKFB3), which is the ubiquitous and hypoxia‐induced isoform of PFK‐2, are reported. X‐ray crystallography and docking were instrumental in the design and optimisation of a series of N‐aryl 6‐aminoquinoxalines. The most potent representative, N‐(4‐methanesulfonylpyridin‐3‐yl)‐8‐(3‐methyl‐1‐benzothiophen‐5‐yl)quinoxalin‐6‐amine, displayed an IC50 of 14 nm for the target and an IC50 of 0.49 μm for fructose‐2,6‐biphosphate production in human colon carcinoma HCT116 cells. This work provides a new entry in the field of PFKFB3 inhibitors with potential for development in oncology.

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