The potent BCR-ABL1-targeting tyrosine kinase inhibitor (TKI) ponatinib is used for the treatment of patients with drug-resistant chronic myeloid leukemia (CML). However, an increased risk of development of cardiovascular events has been described in CML patients treated with ponatinib. The etiology of these adverse events is currently unknown. In an attempt to discover mechanisms underlying ponatinib-induced adverse vascular events, we have evaluated the effects of ponatinib in vitro on human vascular endothelial cells and on contraction of explanted mice aortic rings. In addition, we examined the effects of ponatinib on angiogenesis in vivo in a mouse model of hind limb ischemia. Ponatinib dose-dependently induced apoptosis in human coronary artery endothelial cells (HCAEC) in a caspase assay (relative apoptosis vs. 1% DMSO: ponatinib 50 nM: 1.79±0.38, p Disclosures Kirchmair:Ariad: Research Funding. Valent:Ariad: Honoraria, Research Funding; Amgen: Honoraria; Deciphera Pharmaceuticals: Research Funding; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.