BIRC5 and prostate cancer: Sepantronium bromide (YM155), which is four-ring aromatic heterocyclic cationic imidazolium (MW: 443.3 Da, molecular formula: [C20H19N4O3]+ Br−) was first described as a Survivin suppressant in a high throughput screen of a small chemical compound library reported to suppress the Survivin promoter in the PC-3 prostate cancer cell line7.