KDU691 is an orally active imidazopyrazine class antiparasitic that inhibits Plasmodium & Cryptosporidium phosphatidylinositol-4-OH kinase, PI(4)K, in an ATP-competitive, highly potent and selective manner (IC50/[ATP] = 1.5 nM/10 µM/P. vivax & 17 nM/3 µM/C. parvum PI(4)K) with little or no activity against human PI3Kα/β/γ/δ, PI4KIIIβ, VPS34, and 36 human protein kinases. KDU691 is effective against human pathogens P. falciparum, P. vivax, C. parvum and C. hominis, as well as simian parasite P. cynomolgi. KDU691 blocks Plasmodium development in all life-cycle stages and displays in vivo efficacy in murine models of malaria and cryptosporidiosis.