YM-155 hydrochloride is a novel small-molecule suppressant of surviving, the smallest member of inhibitor of apoptosis (IAP) gene family. It exhibits a potent suppressive activity against survivin but has little effect on expression levels of other IAP family members or B-cell lymphoma 2 (BCL-2) related proteins. YM155 also suppresses proliferation in a broad range of human cancer cell lines, induces tumor regression in non-small cell lung cancer (NSCLC), melanoma, bladder, aggressive non-Hodgkin lymphoma, and breast cancer xenograft models, reduces spontaneous metastases, and significantly prolongs the survival of animal harboring established metastatic tumors derived from a human triple-negative breast cancer (TNBC) cell lines.