Design, synthesis and biological evaluation of novel pyrazolo-pyrimidin-amines as potent and selective BTK inhibitors.

To discover the best-in-class Bruton's Tyrosine Kinase (BTK) inhibitors, for th treatment of autoimmune disorders like cancer (B-Cell Lymphoma (BCL)) and rheumatoid arthritis (RA), in the present investigation, novel structural optimizations were carried out. Introduction of novel bicyclic amine linkers and aromatic backbone led to series of compounds 9a-h and 14a-u. Compound 14b was found to be potent, orally bioavailable, selective and irreversible BTK inhibitor. In vitro, 14b showed IC50 of 1.0 nM and 0.8 nM, in BTK and TMD8 assays, respectively. In vivo,14b displayed robust efficacy in collagen-induced arthritis (CIA) and TMD8 xenograft models, which could be correlated with its improved oral bioavailability. In the repeated dose acute toxicity study, 14b showed no adverse changes, indicating that the BTK inhibitor 14b could be viable therapeutic option for the treatment of autoimmune disorders.