PX-478 is HIF-1alpha inhibitor, is also an orally active small molecule with potential antineoplastic activity. PX-478 has excellent activity against established human tumor xenografts, providing tumor regressions with prolonged growth delays which correlate positively with HIF-1 levels. PX-478 is a highly water soluble molecule, with good i.v., i.p. and p.o. antitumor activity.