Identification of a Potent, Selective, and Efficacious Phosphatidylinositol 3‑Kinase δ (PI3Kδ) Inhibitor for the Treatment of Immunological Disorders

PI3Kδ plays an important role
controlling immune cell function and has therefore been identified
as a potential target for the treatment of immunological disorders.
This article highlights our work toward the identification of a potent,
selective, and efficacious PI3Kδ inhibitor. Through careful
SAR, the successful replacement of a polar pyrazole group by a simple
chloro or trifluoromethyl group led to improved Caco-2 permeability,
reduced Caco-2 efflux, reduced hERG PC activity, and increased selectivity
profile while maintaining potency in the CD69 hWB assay. The optimization
of the aryl substitution then identified a 4′-CN group that
improved the human/rodent correlation in microsomal metabolic stability.
Our lead molecule is very potent in PK/PD assays and highly efficacious
in a mouse collagen-induced arthritis model.