AM-9635 is a selective PI3Kδ inhibitor with oral bioavailability, good in vitro and in vivo activity and pharmacodynamic properties. AM-9635 inhibits PI3Kδ-dependent B cell receptor-mediated AKT phosphorylation and suppresses the production of specific IgG and IgM antibodies in rats immunized with Aplysia leocyanin (KLH).