ABSTRACT
Potent covalent inhibitors of Bruton's tyrosine kinase (BTK) based on an aminopyrazole carboxamide scaffold have been identified. Compared to acrylamide-based covalent reactive groups leading to irreversible protein adducts, cyanamide-based reversible-covalent inhibitors provided the highest combined BTK potency and EGFR selectivity. The cyanamide covalent mechanism with BTK was confirmed through enzyme kinetic, NMR, MS, and X-ray crystallographic studies. The lead cyanamide-based inhibitors demonstrated excellent kinome selectivity and rat pharmacokinetic properties.
ABSTRACT
Biochemical screening is a major source of lead generation for novel targets. However, during the process of small molecule lead optimization, compounds with excellent biochemical activity may show poor cellular potency, making structure-activity relationships difficult to decipher. This may be due to low membrane permeability of the molecule, resulting in insufficient intracellular drug concentration. The Cell Squeeze platform increases permeability regardless of compound structure by mechanically disrupting the membrane, which can overcome permeability limitations and bridge the gap between biochemical and cellular studies. In this study, we show that poorly permeable Janus kinase (JAK) inhibitors are delivered into primary cells using Cell Squeeze, inhibiting up to 90% of the JAK pathway, while incubation of JAK inhibitors with or without electroporation had no significant effect. We believe this robust intracellular delivery approach could enable more effective lead optimization and deepen our understanding of target engagement by small molecules and functional probes.
