OTS514 is a highly potent TOPK(T-LAK cell-originated protein kinase) inhibitor with an IC50 value of 2.6 nM. OTS514 induces cell cycle arrest and apoptosis.
OTS514 has growth inhibitory effect on five kidney cancer cell lines, VMRC-RCW, Caki-1, Caki-2, 769-P and 786-O, in which TOPK was highly expressed. The IC50 values range from 19.9 to 44.1 nM[1]. OTS514 strongly suppressed the growth of TOPK-positive cancer cells. It also shows significant growth-inhibitory effect on ovarian cancer cell lines with IC50 values of 3.0 to 46 nM[3].
Mouse xenograft studies with human lung cancer cells demonstrated the in vivo efficacy of OTS514 but found that the compound also caused severe hematopoietic toxicity [reduction of red blood cells (RBCs) and white blood cells (WBCs) associated with marked increase in platelets][2]. Oral administration of OTS514 significantly elongated overall survival in the ES-2 abdominal dissemination xenograft model, compared with vehicle control (P < 0.001)[3].
[1] Kato T, et al. Oncotarget. 2016, 7(14):17652-64. [2] Matsuo Y, et al. Sci Transl Med. 2014, 6(259):259ra145. [3] Ikeda Y, et al. Clin Cancer Res. 2016, 22(24):6110-6117.