The antiparasitic drug, potassium antimony tartrate, inhibits tumor angiogenesis and tumor growth in nonsmall-cell lung cancer.

Repurposing existing drugs not only accelerates drug discovery but rapidly advances clinical therapeutic strategies. In this article, we identified potassium antimonyl tartrate (PAT), an antiparasitic drug, as a novel agent to block angiogenesis by screening US Food and Drug Administration-approved chemical drugs. By comparing the cytotoxicity of PAT in various nonsmall-cell lung cancer (NSCLC) cells with that observed in primary cultured human umbilical vein endothelial cells (HUVECs), we found that HUVECs were much more sensitive to the PAT treatment. In in vivo tumor xenograft mouse models established either by PAT-resistant A549 cells or by patient primary tumors, PAT significantly decreased the tumor volume and tumor weight of NSCLC xenografts at dosage of 40 mg/kg (i.p., daily) and, more importantly, augmented the antitumor efficacy of cisplatin chemotherapy. Remarkable loss of vascularization in the treated xenografts indicated the in vivo antiangiogenesis property of PAT, which was well correlated with its tumor growth inhibition in NSCLC cells. Furthermore, in the in vitro angiogenic assays, PAT exhibited dose-dependent inhibition of HUVEC proliferation, migration, and tube formation in response to different stimuli. Consistently, PAT also abolished the vascular endothelial cell growth factor-induced angiogenesis in the Matrigel plugs assay. Mechanistically, we found that PAT inhibited the activities of several receptor tyrosine kinases and specifically blocked the activation of downstream Src and focal adhesion kinases in HUVECs. Taken together, our results characterized the novel antiangiogenic and antitumor function of PAT in NSCLC cells. Further study of PAT in anticancer clinical trials may be warranted.