PI3Kδ-IN-21 (Compound 31) is a selective inhibitor of phosphoinositide 3-kinase δ (PI3Kδ), with an IC50 of 13.6 nM. It impedes the proliferation and differentiation of T cells through the PI3K/AKT/mTOR signaling pathway. In rat models, PI3Kδ-IN-21 exhibits favorable pharmacokinetic properties and demonstrates activity in improving experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein (MOG) in EAE models.

PI3Kδ:13.6 nM, PI3Kα:7034 nM, PI3Kβ:1660 nM