KDU691 is an antimalarial compound. It inhibits recombinant P. vivax phosphatidylinositol 4-kinase (PI4K) with an IC50 value of 1.5 nM. KDU691 is selective for P. vivax PI4K over recombinant human PI4KβIII and PI3Kα, -β, -γ, and -δ (IC50s = 7.9, 8.8, 2.4, 8, and 3.4 μM, respectively), as well as VPS34 (IC50 = >9.7 μM) and 36 additional kinases in a panel of lipid and protein kinases (IC50s = >10 μM). It is active against P. falciparum and P. yoelii schizonts (IC50s = 0.06 and 0.04 μM, respectively), as well as P. cynomolgi schizonts and hypnozoites (IC50s = 0.11 and 0.2 μM, respectively). KDU691 completely prevents, but does not eradicate established, P. cynomolgi infection in rhesus monkeys when administered at a dose of 20 mg/kg.