Discovery of pyrazole-based selective covalent ITK inhibitors with In vivo activity.

Interleukin-2 inducible T-cell kinase (ITK) plays a major role in T cell signaling downstream of the T cell receptor (TCR) and is a promising therapeutic target for inflammatory diseases and T cell-related blood cancers. Herein, a novel series of covalent ITK inhibitors was developed using a structure-based design. The optimized compound 19 demonstrated potent ITK inhibitory activity and effectively suppressed downstream protein phosphorylation as well as IL-2 secretion in Jurkat cells. It exhibits exceptional selectivity over BTK and other structurally related kinases. Moreover, compound 19 significantly inhibited IL-2 production in both a washout cellular assay and an anti-CD3 mAb-challenged mouse model, with sustained effects superior to its reversible counterpart. Thus, compound 19 represents a valuable tool for the further exploration of the potential benefits of ITK inhibition in basic and translational research.