Synthesis and biological evaluation of 4-(pyridine-4-oxy)-3-(tetrahydro-2H-pyran-4-yl)-pyrazole derivatives as novel, potent of ALK5 receptor inhibitors

The transforming growth factor type β receptor I (TGF-β R1, also known as activin-like kinase 5 or ALK5) plays a significant role in the pathogenesis of multiple diseases such as malignant tumors and tissue fibrosis. Specific inhibition of ALK5 provides a novel method for controlling the development of cancers and fibrotic diseases. Herein, a novel series of 4-(pyridine-4-oxy)-3-(tetrahydro-2H-pyran-4-yl)-pyrazole derivatives was synthesized and identified as ALK5 inhibitors. Among them, compound 8h inhibited ALK5 autophosphorylation and NIH3T3 cell activity with IC50 values of 25 nM and 74.6 nM, respectively. Compound 8h also showed favorable pharmacokinetic profile and ameliorated hERG inhibition. More importantly, 30 mg/kg oral administration of 8h could significantly induce tumour growth inhibition in CT26 xenograft model without obvious toxicity.