Hypoxia-inducible factor-$1{alpha}$ (HIF-$1{alpha}$) is a transcription factor produced by tumor cells under hypoxic conditions, and a key regulator of a number of genes important in cancer biology. Over-expression of HIF-$1{alpha}$ in human tumors is associated with poor prognosis and poor therapeutic outcomes and HIF-$1{alpha}$ has been suggested as a novel target for cancer therapy. This article provides a review of PX-478 as the first novel HIF-$1{alpha}$ inhibitor in clinical stage for the treatment of solid tumors.